Interaction of substrate particle size and other habitat variables, and their relation to the
microdistribution of benthos in a Montana spring-stream
by Richard Dale Lainhart
A thesis submitted to the Graduate Faculty in partial fulfillment of the requirements for the degree of
DOCTOR OF PHILOSOPHY in Zoology
Montana State University
© Copyright by Richard Dale Lainhart (1973)
Abstract:
A detailed analysis was made of the interaction of substrate particle size and other habitat variables and
their relation to the microdistribution of benthos in a Montana spring-stream. The 0.7 km headwater
section was chosen to minimize variation in some of the factors (temperature, discharge, water
chemistry, differential shading) which potential Iy may indirectly influence microdistribution. A
sampler was designed to collect both the benthos and the substrate within 0.049 m2.
A total of 143 samples were collected biweekly over nine months. Each sample was processed to
determine quantities of (1) each of the nine prominent insect genera in the stream, (2) each of the three
macrophytes, and (3) substrate in each of 14 designated size-classes.
Data were processed using a computer-programmed multiple regression analysis. Independent
variables included for each sample were the depth, microcurrent, specific location of the sample in the
study area, three factors of time to compensate for seasonal variations, and several measures of
substrate size distribution. The latter included percentiles, percentages in each size-class, shortness of
the outer and inner quar-tiles and outer deciles, mode and mean substrate size, and sample weight. t
statistics were used to determine the explanatory power of individual independent variables, while F
statistics and F tests were used to determine the explanatory power of groups of variables.
The mean substrate distribution by percent weight was a bimodal curve with the much smaller mode
corresponding to the smaller substrate sizes. The most significant substrate variables were those
corresponding to the smaller sizes: the I Oth and 25th percentiles (to 11 of the 13 insect taxa), the
lowest percentile group (0.25th, 1st, 5th, and 10th percentiles; 9 taxa), and the shortness of the lower
decile and lower quartile (6 taxa). Six insect taxa were significantly positively correlated to the moss
{Amblystegium noterophilum), but the few significant relations found to the watercress (Rorippa
nasiurtium-aquatioum) and the pondweed (ZannichelHa palustris) were negative.
It was deduced that the deposition with time of smaller substrate particles was a good indicator of a
corresponding deposition with time of detritus and other food material. Those microhabitats physically
most suitable to insects are those with at least some larger particles to provide stability and a greater
variety of habitat space. It was further deduced that areas which contain larger particles and were also
receptive to deposition of smaller particles promoted the development of a satisfactory food regime.
This resulted from not only the X deposition of food particles but also the availability of favorable
substrate for growth of algae and macrophytes, and the resultant congregation of prey species. It was
concluded that the precise distribution of food in microhabitats was both reflected by and affected by
substrate size composition, and food was thus the most critical factor influencing the microdistribution
of organisms in this stream.
' INTERACTION OF SUBSTRATE PARTICLE SIZE AND OTHER HABITAT VARIABLES,
AND THEIR RELATION TO THE MICRODISTRIBUTION OF BENTHOS
IN A MONTANA SPRING-STREAM
by
RICHARD DALE L A INHART
A th e s is su b m itte d to th e Graduate F a c u lty
in p a r t ia l f u l f i l l m e n t o f th e re q u ire m e n ts f o r th e degree
. of
DOCTOR OF PHILOSOPHY
“ in
Zoology
Chairm an, Exa^iTiYig Committee
G raduate Dean
MONTANA STATE UNIVERSITY
Bozeman, Montana
June, 1973
iii
ACKNOWLEDGMENT
I w ish to th a n k D r. C. J . D. BROWN who d ir e c te d th e f i e l d
and
la b o r a to r y p o r tio n s o f th e s tu d y and D r. CALVIN M. KAYA f o r h is a s s is t ­
ance in p re p a rin g th e m a n u s c rip t.
Thanks a ls o to th e o th e r members
on my g ra d u a te com m ittee - - D rs . JOHN C. WRIGHT, WILLIAM R. GOULD,
HAROLD D. PI CTON, ROBERT E. MOORE, AND JOHN MONTAGNE — f o r re a d in g th e
m a n u s c rip t and o f f e r in g s u g g e s tio n s .
A s p e c ia l thanks to Dr. RICHARD E. LUND o f th e Departm ent o f Mathe­
m a tic s f o r h is a d v ic e and a s s is ta n c e in p re p a rin g th e d ata a n a ly s is and
in t e r p r e t in g th e r e s u lt s .
The Ennis N a tio n a l F ish H a tc h e ry cooperated
in a llo w in g access to th e stu d y a re a .
A s p e c ia l thanks to my w ife D ix ie f o r her a s s is ta n c e in th e c a lc u ­
la t io n s and th e p re p a ra tio n and ty p in g o f th e m a n u s c rip t.
T h is s tu d y was su pp orted in p a r t by a N a tio n a l S cience Foundation
tr a in e e s h ip and th e A g r ic u lt u r a l E xperim ent S ta tio n o f Montana S ta te
U n iv e r s ity .
CONTENTS
Page
V I T A ........................................................................................................................................ i i
ACKNOWLEDGMENT..........................
iii
TABLES ........................................................................................
FIGURES................................... ' .........................................................................................v i i i
ABSTRACT............................................................................................................................... ix
INTRODUCTION....................................... ................................................................. ....
.
DESCRIPTION OF STUDY AREA................................................................................... .
I
6
METHODS AND MATERIALS. . . . . ................................... ...................................... IO
F-teld...............................................................................................................................................
Ldbovabovij................................................................................................................................
Data analysis..........................................................................................................................
10
13
20
RESULTS.............................................................................................................................. 23
Covvelation coefficient matvix .............................................................................
Multiple vegvession m o d e l s .............................................. '.......................................
23
25
Substvate...................................................................■ .................................................... 48
Plants as independent variables..................................................................
50
Othev variables...........................................................................................................
54
Plants as dependent variables.............................................. .....
55
Pvediction of change in the quantity of ovganisms with
changes in magnitude of the independent vaviables............................... 56
Substvate ............................................................................................................
Plants as independent vaviables........................................................ •.
.
56
60
DISCUSSION................................................................................... .................................. 65
Evaluation of the vesults............................................................................................ 65
'
Substvate. . .......................................................................................................■ . .
65
Plants as independent variables...................................................................68
Othev independent variables. . . ...............................................................68
Plants as dependent variables........................................................................71
V
CONTENTS (c o n tin u e d )
Page
Interrelationships of substrate, insect, and
plant quantities........................................................................................................ 72
Autecological considerations ........................................................................
82
Interaction of factors influencing microdistribution .....................
APPENDIX . . . . .
.............................................................
85
. . . . . . . . .
95
The sampler used in this s t u d y ...............................
Multiple regression analyses ,in stream benthos studies . . . .
96
98
LITERATURE CITED . ........................................................................................................ 120
vi
.TABLES
T ab le
1.
Page
F a c to rs in flu e n c in g m ic r o d is t r ib u t io n , re s e a rc h e rs
making s ig n if ic a n t c o n t r ib u t io n s , and ta xa con­
s id e re d . .................................................................................................... ....
3
.
2.
Taxa from B la in e S p rin g Creek analyzed in t h i s s tu d y . . . .
17
3.
S u b s tra te s iz e c l a s s i f i c a t i o n and s ie v e s u se d ...................... . . .
19
4.
C o r r e la tio n c o e f f ic ie n t s between a l l v a r ia b le s in th e
study which were s ig n ific a n t a t the 5% l e v e l ............................
24
5.
Independent v a r ia b le s in c lu d e d in re g re s s io n s A -U ......................
26
6.
F s t a t is t ic s , the le v e ls a t which the n u ll hypotheses are -
re je c te d , and the J?2 v a lu e s .fo r the dependent v a ria b le s in
each o f th e re g re s s io n s .
7.
. . ..................................................... ....
27
Independent v a r ia b le s w hich were s ig n if ic a n t t o each p la n t
ta xo n a t th e P = 0.0 5 l e v e l ......................................................................
34
Independent v a r ia b le s w hich were s ig n if ic a n t to each in s e c t
ta xo n a t th e P = 0.05 l e v e l ............................................................. .... .
35
Means o f th e dependent and independent v a r ia b le s computed
from th e mean va lu e s from each o f th e 143 sam ples......................
46
10.
T e s ts o f F between re g re s s io n s .............................................
51
11.
The e s tim a te d w e ig h t o f each p a r t i c l e and numbers o f
p a r t ic le s in each phi c la s s f o r th e mean s u b s tra te
d is tr ib u tio n
.............................................................................................
74
8.
9.
12.
13.
The p a r t it io n in g ’o f th e w e ig h ts o f th e s u b s tra te on those
s ie v e s w hich were used to b ra c k e t th o s e s iz e ranges ( 0 [ - 2]
to 0 [ - 5 ] ) where th e s p e c if ic s ie v e s needed were n o t a v a i l ­
a b le ................................................
101
Percentages o f s u b s tra te in each phi c la s s f o r each o f th e
e ig h t stream s e c tio n s .................................................................................... 102
vii
TABLES (c o n tin u e d )
T a b le
Page
14.
The t o t a l d ry w e ig h t in grams o f th e in d iv id u a l p la n t
genera and t h e i r combined w e ig h t c o lle c te d fro m each
o f th e e ig h t stream s e c tio n s d u rin g t h is . s t u d y , th e d ry
w e ig h t per s q u a re -m e te r, th e percen tag e d i s t r i b u t i o n o f
each ta xo n r e l a t i v e to th e o th e r ta x a w it h in each sec­
t i o n , and th e percen tag e d i s t r i b u t i o n w it h in each taxon
r e l a t i v e to th e o th e r stream s e c tio n s ................................................ 103
15.
The t o t a l number o f in s e c t ta xa c o lle c te d f o r each o f
th e e ig h t stream s e c tio n s d u rin g t h is s tu d y , th e num­
bers per s q u a re -m e te r, th e perce n ta g e d i s t r ib u t i o n o f
each taxon r e la t iv e to th e o th e r ta x a w it h in each sec­
t i o n , and th e percentage d i s t r i b u t i o n w it h in each ta xo n
r e l a t i v e to th e o th e r stream s e c tio n s ......................
16.
104
Computer da ta o f th e f i n a l m u lt ip le re g re s s io n m o d e lre g re s s io n S .................................................................................................... 107
v iii
FIGURES
F ig u re
Rage
1.
The headwater s e c tio n o f B la in e S p rin g C re e k...............................
2.
The sam pler designed f o r t h is s t u d y ................................................ 11
3.
Lab procedures used in p ro c e s s in g preserved samples to
o b ta in th e d ry w e ig h t o f each p la n t s p e c ie s , th e num­
ber o f each in s e c t ta x o n , and th e w e ig h t o f each sub­
s t r a t e s i z e - c l a s s ..................................................................
14
D e v ia tio n o f th e fo u r lo w e s t p e r c e n tile s (0 .2 5 , I , 5,
10 ) from t h e i r means and th e p re d ic te d changes in
number o f each in s e c t taxon w hich was s ig n if ic a n t to
th e s e p e r c e n tile s a t th e 5 p e rc e n t l e v e l ........................................
57
P re d ic te d changes in th e number o f each in s e c t taxon
w hich was s i g n i f i c a n t l y r e la te d (5 p e rc e n t le v e l) to
th e q u a n tity o f each p la n t sp e cie s in re g re s s io n S
(th e f i n a l m odel) and re g re s s io n T ...............................................
61
4.
5. •
6.
7
I n t e r r e la t io n s h ip s o f h a b ita t v a r ia b le s in flu e n c in g
th e m ic r o d is t r ib u t io n o f organism s............................................................87
IX
ABSTRACT
A d e ta ile d a n a ly s is was made o f th e in t e r a c t io n o f s u b s tra te p a r­
t i c l e s iz e and o th e r h a b it a t v a r ia b le s and t h e i r r e la t io n to th e m ic ro ­
d i s t r ib u t i o n o f benthos in a Montana s p rin g -s tre a m . The 0 .7 km head­
w a te r s e c tio n was chosen to m in im iz e v a r ia t io n in some o f th e fa c to r s
(te m p e ra tu re , d is c h a rg e ,, w a te r c h e m is try , d i f f e r e n t i a l s h a d in g ) w hich
p o te n tia l I y may i n d i r e c t l y in flu e n c e m ic r o d is t r ib u t io n .
A sam pler was
designed to c o l le c t both th e benthos and th e s u b s tra te w it h in 0.049 m^.
A t o t a l o f 143 samples were c o lle c te d b iw e e k ly over n in e m onths. Each
sample was processed to d e te rm in e q u a n titie s o f ( I ) each o f th e nine
p rom ine nt in s e c t genera in th e stre a m , ( 2 ) each o f th e th re e m acrophytes,
and (3 ) s u b s tra te in each o f 14 d e s ig n a te d s iz e -c la s s e s .
Data were processed u s in g a computer-programmed m u lt ip le re g re s s io n
a n a ly s is .
Independent v a r ia b le s in c lu d e d f o r each sample were th e d e p th ,
m ic r o c u r re n t, s p e c if ic lo c a tio n o f th e sample in th e s tu d y a re a , th re e
f a c to r s o f tim e to compensate f o r seasonal v a r ia t io n s , and se ve ra l
measures o f s u b s tra te s iz e d i s t r i b u t i o n .
The l a t t e r in c lu d e d p e r c e n tile s ,
percentages in each s iz e - c la s s , s h o rtn e s s o f th e o u te r and in n e r q u a rt i l e s and o u te r d e c ile s , mode and mean s u b s tra te s iz e , and sample w e ig h t.
t s t a t i s t i c s were used to d e te rm in e th e e x p la n a to ry power o f in d iv id u a l
independent v a r ia b le s , w h ile F s t a t i s t i c s and F te s ts were used to d e t e r ­
mine th e e x p la n a to ry power o f groups o f v a r ia b le s .
The mean s u b s tra te d i s t r i b u t i o n by p e rc e n t w e ig h t was a bimodal
curve w ith th e much s m a lle r mode c o rre s p o n d in g to th e s m a lle r s u b s tra te
s iz e s . The most s ig n if ic a n t s u b s tra te v a r ia b le s were th o s e co rre sp o n d ­
in g to th e s m a lle r s iz e s :
th e I Oth and 25th p e r c e n tile s ( to 11 o f th e
13 in s e c t t a x a ) , th e lo w e s t p e r c e n tile group (0 .2 5 th , 1 s t , 5 th , and 10th
p e r c e n tile s ; 9 t a x a ) , and th e sh o rtn e ss o f th e lo w er d e c ile and lo w er
q u a r t ile (6 ta x a ) .
S ix in s e c t ta xa were s i g n i f i c a n t l y p o s i t i v e l y c o r r e ­
la te d to th e moss {Amblystegium noteroph.ilum), b u t th e few s ig n if ic a n t
r e la t io n s found to th e w a te rc re s s {Rcrippa nasiurtium-aquatioum) and
th e pondweed {Zanniehellia palustris) were n e g a tiv e .
I t was deduced t h a t th e d e p o s itio n w ith tim e o f s m a lle r s u b s tra te
p a r t ic le s was a good in d ic a t o r o f a co rre s p o n d in g d e p o s itio n w ith tim e
o f d e t r it u s and o th e r food m a te r ia l. Those m ic r o h a b ita ts p h y s ic a lly
most s u ita b le to in s e c ts a re th o se w ith a t le a s t some la r g e r p a r t ic le s
to p ro v id e s t a b i l i t y and a g re a te r v a r ie t y o f h a b ita t space.
I t was
f u r t h e r deduced t h a t areas which c o n ta in la r g e r p a r t ic le s and were a ls o
re c e p tiv e to d e p o s itio n o f s m a lle r p a r t ic le s promoted th e developm ent
o f a s a t is f a c t o r y food regim e. T h is r e s u lte d from n o t o n ly th e
X
d e p o s itio n o f fo o d p a r t ic le s b u t a ls o th e a v a i l a b i l i t y o f fa v o ra b le sub­
s t r a t e f o r grow th o f a lg a e and m acro phytes, and th e r e s u lt a n t congrega­
t io n o f p re y s p e c ie s .
I t was concluded t h a t th e p re c is e d i s t r ib u t i o n
o f food in m ic r o h a b ita ts was bo th r e fle c t e d by and a ffe c te d by s u b s tra te
s iz e c o m p o s itio n , and food was thus th e most c r i t i c a l f a c t o r in flu e n c in g
th e m ic r o d is t r ib u t io n o f organism s in t h i s stream .
INTRODUCTION
P re vio u s s tu d ie s on d i s t r ib u t i o n s o f stream organism s can be
grouped, in g e n e ra l, in t o th o se concerned w ith lo n g it u d in a l d i s t r i b u t i o n
a lo n g a s tre a m 's course o r between a d ja c e n t stream s ( " m a c r o d is t r ib u t io n " ) ,
and d i s t r i b u t i o n w it h in li m i t e d , g e n e r a lly s u p e r f i c i a l l y homogeneous,
p o r tio n s o f a stream ( " m i c r o d is t r i b u t io n " ) .
M ic r o d is t r ib u t io n a l
s tu d ie s are o f in t e r e s t because organism s tend to be non-random ly d i s ­
t r ib u t e d even w it h in sm all areas o f a s in g le r i f f l e
U sin g e r 1956).
(Needham and
Such non-random d i s t r i b u t i o n can be a t t r ib u t e d to v a r i ­
a tio n o f e n viro n m e n ta l f a c to r s among m ic r o h a b ita ts o r to th e b e h a v io r
o f th e a n im a ls them selves ( A lle n 1959).
E n vironm ental f a c to r s a t t r ib u t e d t o in flu e n c in g m a c r o d is tr ib u tio n
o f v a rio u s organism s in c lu d e e ro s io n - - d e p o s itio n
(Moon 1 9 3 9 ), w a te r
te m p e ra tu re (Id e 1935, S p ru le s 1947, A rm ita g e 1961, Kamler 1965),
chem ical c o m p o s itio n o f th e w a te r (R ic k e r 1934, A rm itage 1 95 8), and
aufwuchs c o n c e n tra tio n a lo n g a s tre a m 's course (S tadnyk 1 97 1).
W hile
extrem es o f th e se f a c to r s beyond th e l i m i t s o f to le ra n c e by organism s
may l i m i t d i s t r i b u t i o n alo n g a s tre a m 's course (Jaag and Ambtihl 1964),
th e f a c to r s g e n e r a lly become m in im a lly s i g n i f i c a n t , and can be con­
s id e re d to e x e r t u n ifo rm e f f e c t , w it h in g iv e n sm all s e c tio n s o f a
stream (Cummins 1964, Cummins and L a u ff 1969).
E n vironm ental fa c to r s
a t t r ib u t e d to in flu e n c in g m ic r o d is t r ib u t io n , re s e a rc h e rs making s ig n i­
f ic a n t c o n t r ib u t io n s , and th e organism s c o n s id e re d , a re summarized in
- 2"
T a b le I .
S u b s tra te s iz e is f r e q u e n t ly c o n s id e re d to be th e most s ig n if ic a n t
f a c t o r in flu e n c in g m ic r o d is t r ib u t io n o f stream benthos (T a b le I )
because i t
in t e r a c t s w ith c u r r e n t v e l o c it y , p la n t g ro w th , and food
d e p o s itio n , as w e ll as p ro v id e s s u ita b le h a b ita t space f o r fo ra g in g and
p r o t e c tio n .
Cummins (1962, 1964, 19 6 6 ), Cummins and L a u ff (1 9 6 9 ), and
Thorup (1 966) a ls o s ta te t h a t th e s u b s tra te s iz e d i s t r i b u t i o n a t each
sam pling s i t e can and sh o u ld serve as th e common den om inator in e c o lo g i­
ca l s tu d ie s o f stream benthos because i t
can r e a d ily and p r e c is e ly be
measured, as opposed t o th e c o n tin u o u s v a r ie t y o f m ic ro c u rre n ts and
p re c is e lo c a tio n o f fo o d .
In c h a r a c te r iz in g s u b s tra te s iz e however,
v i r t u a l l y a l l re s e a rc h e rs (Cummins e xce p te d ) have used some form o f
p h e n o ty p ic ( s u p e r f ic ia l appearance) d e s c r ip tio n o f s u b s tr a te as i t
v a r ie s fro m p la c e t o p la c e , o r a t m ost, have measured o n ly th e la r g e s t
p a r t ic le s .
S ince t h i s ty p e o f a n a ly s is n e c e s s a r ily r e q u ire s c o n s id e ra ­
t io n o f la r g e r s e c tio n s o f a stream and th u s says l i t t l e
about th e p re ­
c is e s u b s tra te s iz e c o m p o s itio n where th e organism s a re c o lle c t e d ,
Cummins f e e ls i t
is necessary to c o l le c t th e s u b s tra te a lo n g w ith each
in d iv id u a l sample to p r e c is e ly assess i t s
in flu e n c e on m ic r o d is t r ib u t io n .
In a d d it io n , th e s p e c if ic f a c t o r o r f a c to r s chosen f o r c o n s id e ra ­
t io n in many stream b e n th ic m ic r o d is t r ib u t io n a l s tu d ie s have been con­
s id e re d in areas where v a r ia t io n s in o th e r f a c to r s p o t e n t ia ll y i n t e r ­
a c tin g and in flu e n c in g m ic r o d is t r ib u t io n have been ig n o re d .
A lle n
(1 959)
T ab le I .
F a c to rs in flu e n c in g m ic r o d is t r ib u t io n , re s e a rc h e rs making s ig n if ic a n t c o n t r ib u tio n s ,
and ta x a c o n s id e re d .
S u -- s u b s tra te , [ - - c u r r e n t , F - -fo o d , D --d e p th , B --b e h a v io r,
0 --o x y g e n , S h --S h a d tn g , d i r e c t illu m in a t io n .
Researchers
F a c t o r s __________________________Taxa
P e rc iv a l and W hitehead (1929)
Su
In v e r te b ra ta
Hunt (1930)
Su
s e le c te d In v e r te b ra ta
Moon (1 939)
Su
In s e c ta
Wene and W i c k l i f f (1940)
Su
In s e c ta
Linduska (1942)
Su
Ephemeroptera
Pennak and Van Gerpen (1947)
Su
In s e c ta , H y d ra c a rina, N a ididae (O lig o c h a e ta )
E rik s e n (1963, 1964)
Su
Ephemera Sinutansi Eexagenia limbata
(Ephem eroptera)
^
B e ll (1969)
Su
In s e c ta
1
Cummins and L a u ff (1969)
Su
s e le c te d In S e c ta , Helisoma aneeps (G astropoda)
H e n d ric k s , e t a l . (1969)
Su
In v e r te b ra ta
Kamler and R iedel
Su1C
Ephem eroptera, P le c o p te ra , T ric h o p te ra
L a va n d ie r and Dumas (1971)
Su1C
s e le c te d In v e r te b ra te
S c o tt (1958)
Su 1C1F
T ric h o p te ra
U lfs tr a n d
Su 1C1F1D
Ephem eroptera, P le c o p te ra , T r ic h o p te r a ,
S im u liid a e (D ip te ra )
A lle n (1959)
Su 1C1B
Pyenooenivodes (T ric h o p te ra ), P arnidae (C o le o p te ra ),
Chironom idae ( D ip te r a ), Potamopyvgus (G astropoda)
E gglishaw (1969)
Su 1F1 1D
In v e r te b ra te
Cummins (1964)
Su 1F1B
Pyenopsyehe Iepidai P. guttifev (T ric h o p te r a )
(1967)
(1960)
T a b le I
(c o n tin u e d )
Researchers
Taxa
F a cto rs
S p ru le s (1947)
Su,B
In s e c ta
E rik s e n (1968)
Su,0
EiphemeTa Simulans3 Eexagenia limbata
(Ephem eroptera)
Jaag and Ambtihl (1964)
C,0
s e le c te d Ephemeroptera and T ric h o p te ra
E g g lishaw (1 964)
FZ
In s e c ta and o th e r In v e r te b ra te
Buscemi (1966)
F3
In s e c ta , O lig o c h a e ta , S p h a e riid a e (Pelecypoda)
Cushing (1963)
F4
Ephem eroptera, P le c o p te ra , T ric h o p te ra
Hughes (1966a)
Sh
In v e rte b ra te
Sh
Baetis havrisoni3 Trioorythus disoolor
(Ephem eroptera)
Hughes (1966&)
^ p la n t d e t r it u s , moss. alg a e
Z p la n t d e t r it u s
^ o rg a n ic seston and sedim ents
^ p la n k to n , suspended o rg a n ic m a tte r
■
f"
-5 suggests t h a t a more p ro m is in g approach is to s tu d y th e s e fa c to r s o ve r
s u p e r f i c i a l l y more homogeneous a re a s , a lth o u g h i t
p re s e n ts g re a te r
te c h n ic a l problem s in making p re c is e measurements and in t e r p r e t in g th e
r e s u lt s .
U lfs tr a n d
(T968) suggests t h a t new e x p e rim e n ta l approaches
a re needed.
C onsequently th e purpose o f my s tu d y was, f i r s t , t o c o n s id e r p re ­
c is e ly th e r e la t io n s h ip o f s u b s tra te p a r t i c l e s iz e to benthos d i s t r i b u ­
t io n w it h in a s u p e r f i c i a l l y homogeneous s e c tio n o f a stream where th e
v a r i a b i l i t y in many o f th e o th e r f a c t o r s , e s p e c ia lly th o s e w hich may
p o t e n t ia ll y in flu e n c e m ic r o d is t r ib u t io n i n d i r e c t l y , were m in im iz e d .
S e condly, th e purpose was to a n a lyze in d e t a il th e in t e r r e la t io n s h ip s
between a l l f a c to r s w hich appeared to v a ry s i g n i f i c a n t l y w it h in th e
s tu d y area and t h e i r r e la t io n s h ip to benthos d i s t r i b u t i o n .
DESCRIPTION OF STUDY AREA
The headwaters o f B la in e S p rin g Creek (45° 13' N9 111° 4 7 - 1 /2 ' W)
was s e le c te d f o r t h i s s tu d y .
I t is a t r i b u t a r y o f th e Madison R iv e r
(M is s o u ri R iv e r d r a in a g e ) , 16.1 km s o u th -s o u th w e s t o f E n n is 9 in Madison
C ounty 9 Montana.
The stream is form ed by th e d is c h a rg e from two a d ja ­
c e n t s p rin g s (F ig u re I ) .
The w a te r from both s p rin g s converges a s h o r t
d is ta n c e downstream and from here th e stream flo w s southw ard to a p o in t
j u s t n o rth o f th e Ennis N a tio n a l F is h H a tche ry where i t
underground.
is d iv e rte d
The s tu d y area s e le c te d was th e 0 .7 km s e c tio n from below
th e s p rin g s (above th e convergence) to j u s t above th e underground d iv e r ­
s io n .
E le v a tio n o f th e s p rin g s is 1701 m and th e average g ra d ie n t o f
th e s tu d y area is 26 m/km.
Average w id th and dep th o f th e s tu d y area
below th e convergence a re 5 .4 m (ra n g e : 3 .0 - 6 ;4 m) and 0 .26 m (maximum:
0.51 m) r e s p e c t iv e ly .
0.83 m /sec.
C u rre n t v e lo c it y below th e convergence averages
3
D ischarge from th e s p rin g s is c o n s ta n t a t 0 .9 4 m /s e c
(u n p u b lis h e d re c o rd s , Ennis N a tio n a l F is h H a tc h e ry ).
However 9 sm all
q u a n t it ie s o f w a te r a re removed below th e so u th s p rin g above s e c tio n 3
(F ig u re I ) f o r h a tc h e ry use, and from th e r e s e r v o ir near th e m id d le o f
th e s tu d y area (above s e c tio n 6 ) f o r i r r i g a t i o n d u rin g th e summer
m onths.
S u b s tra te p a r t i c l e s iz e s are w e l l - d i v e r s if ie d th ro u g h o u t th e s tu d y
area e x c e p t a t s e c tio n I .
Except f o r o c c a s io n a l la rg e co b b le (128-
256 mm), th e la r g e s t p a r t ic le s c o n s is te n tly encountered a re sm all
-7-
MONTANA
Missouri R.
J e ffe rs o r/R.^//.,Gal la tin R.
Madison R.
irrig a tio n
■canal
Bl a i n e Spr ing Creek
elevation of springs - - 1701 m
kilometers
Figure I .
vegetation
screen 1
The headwater section of Blaine Spring Creek, Montana.
The brackets indicate- the eight sampling sections.
“8 co b b le ( 6 4 - T28 mm).
Most o f th e s u b s tra te below th e n o rth s p rin g (s e c ­
t io n I ) c o n s is ts o f la y e re d m arl and r u b b le , w ith p r o g r e s s iv e ly much
le s s q u a n t it ie s downstream th ro u g h s e c tio n 2.
No m arl o ccu rre d w ith in
the rem a ind er o f th e s tu d y are a .
A p r e lim in a r y su rve y o f w a te r c h e m is try u s in g sta n d a rd methods
d e s c rib e d by th e Am erican P u b lic H e a lth A s s o c ia tio n (1965) showed no
d iffe r e n c e s in th e q u a li t y o f th e w a te r d isch a rg e d from th e two s p rin g s
o r lo n g it u d in a lly a lo n g th e s tu d y a re a .
C o n d u c tiv ity was 440 ymhos.
The p rin c ip a l catio ns were calcium (2 .7 me/£) and magnesium (1 .5 me/5,),
w ith minor amounts o f sodium (0 .1 3 me/5,) and potassium (0 .0 4 me/5;).
The
p rin c ip a l anions were bicarbonate (3 .0 me/5,) and s u lfa te (1 .3 me/5,),
w ith a tra ce amount o f c h lo rid e (0 .0 5 me/5,).
V a ria tio n o f temperature
both seasonally and downstream through the study area is m inim al; the
extremes measured during the sampling period (J u ly 1969 - A p ril 1970)
were 1 3 .0 ° (August 9, 1969) and 11. 9°C (January 10, 19 7 0 ).
The o n ly deciduous v e g e ta tio n alo n g th e stream w it h in th e study
area was a few w illo w s near th e lo w e r end.
These d id n o t a p p re c ia b ly
shade th e stre a m , and v i r t u a l l y no a llo c h th o n o u s d e t r it u s appeared in ;
th e sam ples.
V e g e ta tio n w it h in th e stream i t s e l f was p r in c i p a l ly moss
(Amblystegivm noterophilum) and w a te rc re s s
(Rorippa nasturtium-
aquatieum), th e l a t t e r being c o n fin e d m a in ly near th e s h o r e lin e s .
Small
q u a n t it ie s o f a horned-pondweed (Zannichellia palustris) and fila m e n to u s
a lg a e were a ls o o c c a s io n a lly fo u n d .
Most o f th e v e g e ta tio n in th e
-9 s p rin g s above th e s tu d y area was removed by a h a tc h e ry crew on 15 Sep­
tem ber 1969, some o f w hich p ro b a b ly d r i f t e d th ro u g h th e s tu d y a re a .
L ik e w is e , some o f th e v e g e ta tio n from th e s tu d y area i t s e l f was removed
between 29 O ctober and 11 November 1969.
The headwaters o f B la in e S p rin g Creek were e s p e c ia lly s u ita b le f o r
t h i s s tu d y because, though th e re was c o n s id e ra b le d i v e r s i t y o f s u b s tra te
p a r t ic le s iz e s , th e r e was m inim al v a r ia t io n in some o f th e o th e r f a c to r s
(te m p e ra tu re , d is c h a rg e , w a te r c h e m is try , s h a d in g ) w h ich may a t le a s t
i n d i r e c t l y in flu e n c e m ic r o d is t r ib u t io n o f b en tho s..
In a d d it io n , th e
stages o f developm ent o f th e in s e c ts in t h i s area had l i t t l e
v a r ia t io n
w it h in s p e c ie s , th u s m in im iz in g e f f e c t s o f d i f f e r e n t i a l b e h a v io r.
Because th e s tu d y area was a headwater s e c tio n , no d r i f t o f organism s
was p o s s ib le from above, and i t was s p e c u la te d t h a t more m ature form s
o f many in s e c ts tended t o d r i f t o u t o f th e a re a .
METHODS AND MATERIALS
A sam pler designed by m y s e lf f o r t h i s s tu d y (F ig u re 2) was used to
s im u lta n e o u s ly c o l le c t bo th th e organism s and th e s u b s tra te a t each
sam pling s i t e .
I t c o n s is te d o f a m etal c y lin d e r mounted a t one end
th ro u g h a c i r c u l a r plywood p la tfo r m .
A s e c tio n o f foam ru b b e r w ith th e
same dim ensions as th e p la tfo r m was g lu e d t o i t s
bottom .
A h o le th e
same d ia m e te r as th e c y lin d e r was c u t in t o th e c e n te r o f th e foam.
Two
s m a lle r c y lin d e r s were g lu e d w ith epoxy in t o th e la r g e r c y lin d e r
o p p o s ite each o th e r and s l i g h t l y above th e p la tfo r m .
A fla n g e was
a tta c h e d w ith epoxy around one o f th e s m a lle r c y lin d e r s to h old a n e t
t ie d to i t .
The n e t used in t h i s s tu d y had 36 th re a d s/cm (<0 .25 mm
o p e n in g s ).
The p r in c ip le o f th e sam pler was to seal o f f a sa m pling s it e from
th e s u rro u n d in g s u b s tra te and in flu e n c e o f th e c u r r e n t.
However, c u r ­
r e n t was a llo w e d to flo w th ro u g h th e sam pler th ro u g h th e two s m a lle r
c y lin d e r s t o sweep d is lo d g e d suspended m a te ria l in t o a n e t.
A bucket
w ith a t r ip o d stand (F ig u re 2) was used t o h o ld m a te ria l scooped from
w it h in th e sam ple r.
The s tu d y area was d iv id e d in t o 8 s e c tio n s
s y s te m a tic s a m p lin g .
(F ig u re I ) to f a c i l i t a t e
One sample was c o lle c te d from each s e c tio n b i ­
w eekly between m id - J u ly 1969 and m id - A p r il 1970.
S p e c ific sam pling
SAMPLER
BUCKET
and
STAND
^bucket (10 & c a p a c ity )
m etal c y lin d e r
(25 cm d ia m ., 42 cm lo n g )
b u c k e t-s ta n d
(24 cm i . d . )
w a te r le v e l
in ta k e c y lin d e r
(1 2 .5 cm d ia m .,
edge is 3 cm above p la tf o r m ’
plywood p la tfo r m
(65 cm d ia m ., 4 cm t h ic k )
F ig u re 2.
Sampler designed f o r t h is s tu d y .
-7 2 -
s it e s w it h in each s e c tio n were s e le c te d u s in g a biased-random procedure
(Cummins•1962) to assure w ide v a r ia t io n in both s u b s tra te s iz e com posi­
t io n and amounts and sp e cie s o f v e g e ta tio n .
Once s e le c te d , a s it e was
marked by p la c in g th e b u c k e t-s ta n d im m e d ia te ly downstream from i t .
Water te m p e ra tu re was measured a t th e s i t e to th e n e a re s t 0 .1 °C w ith a
la b o r a to r y therm om eter.
C u rre n t v e lo c it y was measured w ith a L e u pold-
Stevens m id g e t c u r r e n t m e te r.
Readings in number o f r e v o lu tio n s f o r
one m in u te Were made 2 cm above th e s u b s tra te by p la c in g th e end o f th e
m eter o n to th e stones o r as c lo s e to th e v e g e ta tio n as p o s s ib le a t th e
c e n te r o f th e s i t e .
m eter ro d .
Depth was recorded from th e s c a le on th e c u r re n t
A ll p re sa m p lin g o p e ra tio n s were made by app ro a ch in g th e
s i t e from downstream.
The sam pler was pressed in t o th e w a te r im m e d ia te ly upstream from
th e sam pling s i t e to compensate f o r i t s
downstream d r i f t .
I t was
im m e d ia te ly seated on th e sam pling s i t e by k n e e lin g on th e p la tfo rm
w ith one knee on e it h e r s id e o f th e main c y lin d e r .
Thus p o s itio n e d ,
th e p la tfo r m a b u tte d two le g s o f th e bucket stand w hich prevented
s h i f t in g o f th e sa m ple r.
The enclosed s u b s tra te was i n i t i a l l y
a g ita te d
and rubbed to d is lo d g e th e la r g e r masses o f v e g e ta tio n and most o f th e
in v e r te b r a te s .
These org a n ism s, a lo n g w ith most o f th e f i n e r sus­
pended s u b s tra te m a t e r ia l, were c a r r ie d in t o th e n e t.
No a tte m p t was
made to d is lo d g e a l l organism s a t t h is tim e because i t was d e s ira b le
to com plete th e c o lle c t io n w it h in a few m in u te s to a void e xce ssive
-13e ro s io n o f th e s u b s tra te from beneath th e foam ru b b e r.
S u b s tra te
p a r t ic le s a lo n g w ith th e re m a in in g organism s were then scooped by hand
from th e sam pler in t o th e b u c k e t.
a depth o f about 15 cm was removed.
A ll lo o s e s u b s tra te n o t exceeding
Firm ness o f th e s u b s tra te preven ted
removal to t h is depth in most cases however, and i t was th u s assumed
t h a t most organism s c o u ld n o t have p e n e tra te d beyond t h i s p o in t .
A fte r
w a te r in th e sam pler had c le a re d , th e n e t was removed and placed in th e
b u c k e t.
The sam pler was then taken from th e stream fo llo w e d by th e
sample.
C onte nts o f th e n e t and bucke t f o r each sample were immersed in
5 p e rc e n t fo rm a lin and s to re d s e p a ra te ly to e v a lu a te th e e f f ic ie n c y o f
th e a g it a t io n proced ure in sweeping organism s in to th e n e t.
Cobble to o
la rg e f o r s to ra g e c o n ta in e rs were scraped o f org a n ism s, p laced in paper
sacks and la b e le d .
Laboratory
The o b je c tiv e s o f th e la b o r a to r y procedures (F ig u re 3 ) were to
d e te rm in e th e number o f in s e c ts in each genus, th e d r y w e ig h ts o f each
species o f p la n t , and th e w e ig h t o f each s iz e - c la s s o f s u b s tra te in
each sam ple.
s e p a ra te ly .
Net and bucket p o r tio n s o f a sample
were q u a n tifie d
S ince th e n e t p o r tio n s c o n ta in e d o n ly f in e s u b s tr a te , i t
was p o s s ib le to e lim in a te some o f th e in te rm e d ia te ste p s shown in
F ig u re 3.
I t was nece ssary to d iv id e th e bucket sam ple, w hich g e n e r a lly
PRESERVED SAMPLE (organisms and substrate)
—P re -e lu tria tio n Preparation
• removed from sample:
< — -------- preservative solution
0
S
I
D
----->
vegetation masses — removed and washed
vegetation *
sand
< — -----wash water
E
S
G
cobble - scraped and washed
< -----
----->
• remainder of sample washed
< — ----- wash water
set of miscellaneoussized soil screens
used to rough-grade
plant fragments, in sects and smaller subs trate to f a c ilit a t e
sorting
—E lu tria tio n
• sample partitioned into manageable lo ts ;
each lo t poured in d ivid u alIy into e lu tria to r
through 13 and 9 mm sieves
sieves washed of organisms
leaving larger substrate
<
• each lo t elu tria te d (minimum of 4 washings)
— wash water
substrate
----- >
----->
vegetation *
- > sieve contents sorted
vegetation insects substrate
vegetation with
clinging insects
y
drying table
cobble removed
in d ivid u ally
I
I
_______rewashed________
vegetation
wash water
hand-operated
sieve shaker,
8-64 mm sieves
bottom pan
sieves
I
examined over lig h t table
vegetation sorted
insects
to species
removed
4
dried (drying ta b le ,
then oven)
I
'I'
motor-driven shaker
<0.0625-4 mm sieves
id e n tified and counted
under magnification in
gridded enamel pan
- > weighed
'I'
L
A
B
D
A
T
A
dry weight of each
plant species/sample
Figure 3.
number of each insect
taxon/sample
weight of each substrate
size-class/sample
Lab procedures used in processing preserved samples to obtain the dry
weight of each plant species, the number of insects in each taxon, and
the weight of each substrate size-class.
-15c o n ta in e d 4 to 8 £ o f s u b s tra te in t o s m a lle r p o r tio n s and process each
s e p a ra te ly .
An e l u t r i a t o r was c o n s tru c te d f o r s e p a ra tin g le s s dense m a te ria l
( in v e r t e b r a t e s , p la n t fra g m e n ts , and th e o c c a s io n a l d e t r it u s ) from th e
denser s u b s tr a te .
I t s d e sig n was s im ila r to t h a t d e s c rib e d by L a u ff
e t a l . (1 9 6 1 ), exce p t t h a t a 64 mm r a th e r than a 51 mm d ia m e te r d r a in
spou t was used, and th e main column was extended an a d d itio n a l 15 cm
above t h e i r s p e c ifie d 60 cm h e ig h t.
The la r g e s t s u b s tra te p a r t ic le s
from th e sample were f i r s t removed in d iv i d u a l ly and scraped o f v e g e ta ­
t io n and in s e c ts .
P o rtio n s o f a sample were then washed in d iv i d u a l ly
in t o th e e l u t r i a t o r th ro u g h 13 and 9 mm s ie v e s to f u r t h e r c u l l o u t
la r g e r p a r t ic le s .
The e l u t r i a t i o n proced ure used was s im il a r to t h a t
d e s c rib e d by L a u ff e t a l . , though a f t e r a few t r i a l s
i t was found more
e f f i c i e n t to a g it a t e th e m a te ria l a t th e bottom o f th e column n o t o n ly
w ith a i r in je c te d th ro u g h th e bottom b u t a ls o w ith a j e t o f w a te r from
th e to p w hich s im u lta n e o u s ly f i l l e d , th e colum n.
The sample p o r tio n
was a g ita te d , d ra in e d o f th e suspended m a te ria l and r e a g ita te d a m in i­
mum o f f o u r tim e s .
F iv e s o il s ie v e s were used to c o l le c t th e suspended m a te ria l from
th e e l u t r i a t o r and t o ro u g h ly grade p la n t frag m en ts and in v e rte b ra te s
f o r e a s ie r r e c o g n itio n and s e p a ra tio n .
M a te ria l on th e la r g e r sie ve s
was washed in t o a g rid d e d enamel pan, w h ile t h a t on th e s m a lle r s ie v e s
-1 6was washed in t o a fla t- b o tto m e d g la s s d is h .
M a te ria l in th e d is h was
examined o v e r a l i g h t ta b le w hich c o n s is te d o f an illu m in a t e d g la ss
p la te on w hich was drawn a 5 cm g r id .
The g r id s a llo w e d th e e n t ir e
sample to be s y s te m a tic a lly examined a sm a ll p o r tio n a t a tim e .
Because o f t h e i r sm all s iz e , n e a r ly a l l o f th e in v e r te b r a te s in both
th e pan and th e d is h were removed w ith an a s p ir a t o r .
The a s p ir a to r
was used w ith p ip e tte s w ith t i p s o f v a rio u s c o n s t r ic t io n s , depending
upon th e s iz e o f in v e r te b r a te s being removed.
P la n t fra g m e n ts were
se pa ra ted fro m th e f in e s u b s tra te p a r t ic le s u n a v o id a b ly e lu t r ia t e d by
c a r e f u lly d e c a n tin g th e w a te r and p la n ts from both th e pan and d is h
in t o a fin e -m e s h n e t.
The la rg e masses o f v e g e ta tio n removed in th e p r e - e lu t r i a tio n
proced ure s (F ig u re 3 ) p lu s fra g m e n ts ga th e re d in l a t e r s o r tin g p ro ­
cesses were teased a p a rt o v e r th e l i g h t t a b le to remove th e re m a in in g
in v e r te b r a te s and s e p a ra te th e p la n ts in t o sp e cie s (T a b le 2 ) .
were p laced on f i l t e r p a p e r, d r ie d i n i t i a l l y
P la n ts
o ve r a d r y in g ta b le
(m etal t r a y s placed o v e r s e v e ra l l i g h t b u lb s ) and th e n in a d ry in g oven
a t IOO0C f o r 6 h o u rs , and w eighed.
The in v e r te b r a te s
were
p la c e d ,
g r i tided enamel pan p a r t i a l l y f i l l e d
a p o r tio n a t a tim e ,
w ith w a te r.
in to
a
The n in e most numer­
ous in v e r te b r a te ta x a (T a b le 2) s e le c te d f o r c o u n tin g were in s e c ts ; a l l
o f th e o th e r in s e c ts and in v e r te b r a te s combined numbered le s s than any
o f th e genera c o u n te d .
Because v i r t u a l l y a l l o f th e in s e c ts were sm all
-17-
T a b le 2.
Taxa from B la in e S p rin g Creek analyzed in t h i s s tu d y .
PLANTS
B ryophyta (M usci)
-AmblysHegium noteropkilum
(a q u a tic moss)
Tracheophyta (Angiosperm ae)
-Rovippa nastuvtium-aquaticum
(w a te rc re s s )
-Zanniohellia palustvis
(horned-pondweed)
INSECTS
P le c o p te ra ( s t o n e f lie s )
P e r lid a e 5 A cro n e u rin a e
-Aovoneuria paoifioa
P e rlo d id a e and Nemouridae
- " o t h e r s t o n e f lie s "
T ric h o p te ra ( c a d d is f lie s )
H y d ro p tilid a e
-Ochvotviohia sp.
R h y a c o p h ilid a e
-Rhyaoophila sp.
-Glossosoma sp.
Ephemeroptera ( m a y flie s )
B a etidae
Ephemerellin a e ■
-Ephemevella infvequens
B a etinae
-Baetis sp.
L e p to p h le b iin a e
-Pavaleptophlebia sp.
C o le o p te ra ( b e e tle s )
Elmidae
-Optiosewus sp.
-18“
and r e l a t i v e l y im m ature, i t was necessary to examine th e sample under
2X m a g n ific a tio n w h ile c o u n tin g f o r p o s it iv e r e c o g n itio n o f genera.
A ls o , because o f th e d i f f i c u l t y
in re c o g n iz in g and c o u n tin g th e
im m ature s t o n e f ly nymphs in la rg e q u a n t it ie s , a l l s t o n e f lie s o th e r
th a n Aeroneuvia paeifica were ta b u la te d to g e th e r .
Most o f th e se in
th e " o th e r s t o n e f lie s " group (T a b le 2) were lscperla sp. though
Nemoura sp. o ccu rre d o c c a s io n a lly .
The s u b s tra te s iz e c la s s i f i c a t i o n used in t h i s s tu d y (T a b le 3) was
m o d ifie d s l i g h t l y a f t e r Cummins (1 962, 19 6 4 ), who in tu r n b ro a d ly m odi­
f ie d th e sta n d a rd W entworth c l a s s if ic a t io n o f p a r t ic le s iz e s .
W ith
th e 2 mm c la s s as th e base, th e minimum s iz e s o f s u c c e e d in g ly la r g e r
and s m a lle r c la s s e s a re th e f u n c tio n o f th e exponents 2 and 1/2 re s p e c t­
iv e ly .
The p h i (0 ) s c a le used to d e s ig n a te each c la s s is th e n e g a tiv e
lo g t o th e base 2 o f th e minimum s iz e o f each c la s s .
Because s ie v e
s iz e s 8 , 16, and 32 mm were n o t l o c a l l y a v a ila b le f o r t h i s s tu d y , each
o f th e se c o rre s p o n d in g minimum s iz e s f o r t h e i r r e s p e c tiv e c la s s e s was
b ra cke te d by s ie v e s o f a d ja c e n t s iz e s
(T a b le 3 ) .
The e n t ir e s u b s tra te sample was c o m p le te ly d r ie d o v e r th e d ry in g
t a b le .
A 128 mm w ire fram e was used to s o r t o u t th e la r g e r from th e
s m a lle r c o b b le .
The re m a in in g s u b s tra te sample was p a r t it io n e d and
shaken a sm all p o r tio n a t a tim e in o rd e r n o t to o v e rlo a d th e s ie v e s .
Each p o r t io n was f i r s t shaken th ro u g h th e fo u r la r g e s t s ie v e s (641 8 .9 mm. T a b le 3 ) w ith a hand-operated p o r ta b le s ie v e -s h a k e r f o r 0 .5
T a b le 3.
S u b s tra te s iz e c l a s s if ic a t io n and s ie v e s used.
f ie d a f t e r Cummins (1 962, 196 4).
S u b s tra te c la s s te rm in o lo g y m odi­
P a r t ic le s iz e range (mm)
Phi s c a le
la rg e co b b le
128-256
-7
sm all cobb le
64-128
-6
64
la rg e pebble
32-64
-5
38.1
26.7
sm all pebble
16-32
-4
S u b s tra te c la s s
8-16
-3
Sieves used
U.S. Sieve S e rie s no.
in d iv id u a l 128 mm w ire square
I
coarse g ra v e l
S ize (mm)
—
—
—
18.9
13,3
■ ■ ■
9.42
I
6.68 ■
to
medium g ra v e l
4-8
-2
4 .0 0
5
f in e g ra v e l
2-4
-I
2.00
10
v e ry coarse sand
1-2
0
1.00
18
I
0.50
35
2
0.25
60
3
0.125
120
0.062
230
co arse sand
medium sand
f in e sand
0.5-1
0 .2 5 -0 .5
0 .1 2 5 -0 .2 5
'
v e ry f in e sand
0 .0 6 2 5 -0 .1 2 5
4
s i l t and c la y
<0.0625
5-9
bottom pan
-20m in u te s .
T h is p e rio d o f sh a king was adequate f o r s o r tin g s u b s tra te
th ro u g h th e s ie v e s la r g e r than 2 mm.
The s u b s tra te c o lle c t e d in th e
bottom pan was th e n shaken th ro u g h th e n e x t f o u r s ie v e s (1 3 .3 -4 mm)
u s in g th e same p ro ce d u re .
The s u b s tra te th e n c o lle c te d in th e bottom
pan (<4 mm) was shaken f o r 15 m inutes th ro u g h th e re m a in in g s ix s ie v e s
(2 -0 .0 6 2 mm) u s in g a m o to r-d riv e n s ie v e -s h a k e r.
The c o n te n ts on each
o f th e 14 s ie v e s p lu s t h a t in th e f i n a l bottom pan (<0.062 mm) was
weighed t o th re e s i g n i f i c a n t f ig u r e s .
The w e ig h ts from th e in d iv id u a l
p o r tio n s o f th e sample were summed t o g iv e th e t o t a l w e ig h t p e r s ie v e
f o r each sam ple.
For
th o se s iz e c a te g o rie s where th e s ie v e s needed
were n o t a v a ila b le ( 8 , 16, and 32 mm), th e t o t a l w e ig h ts o f th e sub­
s t r a t e on each p a ir o f s ie v e s used to b ra c k e t th e minimum c la s s s iz e
were p a r t it io n e d
(T a b le 12) a c c o rd in g t o th e lin e a r d is ta n c e between
th e s iz e o f each s ie v e and th e minimum c la s s s iz e .
Data analysis
A m u lt ip le re g re s s io n a n a ly s is computer-programmed by D r. R ichard
E. Lund o f th e D epartm ent o f M a th em a tics, Montana S ta te U n iv e r s it y ,
was used to e v a lu a te th e r e la t io n s h ip between both m acrophyte q u a n tity
(w e ig h t o f each sp e cie s and t o t a l w e ig h t) and in s e c t numbers (ta b u ­
la te d a c c o rd in g t o c la s s , o rd e rs , and g e n e ra ), and th e h a b it a t para­
m eters measured
144 c o lle c te d
fo r
each o f
was d is c a rd e d ).
th e
143
samples (one sample
In a d d it io n ,
th e
of
th e
q u a n tity o f each o f
-21 th e th re e m acrophytes was co n sid e re d an independent v a r ia b le in r e la ­
t io n to th e in s e c t numbers, b u t as a dependent v a r ia b le in r e la t io n to
a l l o f th e o th e r indepe nden t v a r ia b le s .
in c lu d e d f o r each sample w ere:
The o th e r indepe nden t v a r ia b le s
c u r r e n t v e l o c it y ; d e p th ; a dummy v a r i ­
a b le in d ic a t in g w hether o f n o t fila m e n to u s a lg a e was mixed w ith th e
m acrophytes ( in 15 o f th e 143 sa m p le s); li n e a r , q u a d ra tic and c u b ic
f a c to r s o f tim e to accou nt f o r seasonal v a r ia t io n s ; dummy v a r ia b le s
re p re s e n tin g each stream s e c tio n to accou nt f o r u n reco gnize d v a r i a b i l i t y
lo n g i t u d in a l ly a lo n g th e s tu d y s e c tio n n o t accounted f o r by measured
v a r ia b le s ; and s e v e ra l measures o f s u b s tr a te s iz e c o m p o s itio n .
la tt e r
The
(tho ugh n o t a l l used in one re g re s s io n m odel) were th e p e rc e n t­
age q u a n tity in each s iz e - c la s s , p e r c e n tile s
(0 .2 5 , I ,
5, 10, 25, 50,
75, 9 0 ), th e sh o rtn e s s o f th e in n e r q u a r t il e and th e upper and low er
q u a r t ile s and d e c ile s in phi u n it s , mean, mode s iz e - c la s s , and t o t a l
s u b s tra te sample w e ig h t as a rough in d e x t o a v a ila b le h a b it a t space.
S t a t i s t i c s produced (see T ab le 16 f o r exam ples) were th e v a r ia b le
means, sim p le and p a r t ia l c o r r e la t io n s , re g re s s io n c o e f f ic ie n t s ,
sta n d a rd e r r o r s , t and F v a lu e s , in t e r c e p t , ^ -s q u a re d , and ANOVA
(a n a ly s is o f v a r ia n c e ) .
The i n i t i a l re g re s s io n models programmed were used in c o n ju n c tio n
w ith th e c o r r e la t io n m a tr ix o f a l l v a r ia b le s to d e te rm in e , f i r s t ,
th e group o f independent v a r ia b le s used i n i t i a l l y
if
were s i g n i f i c a n t , and
second, to e lu c id a te w hich o f th e v a r ia b le s were most s ig n if ic a n t
-22S uccessive models were developed e lim in a tin g th o s e independent v a r i ­
a b le s w h ich were n o t s ig n if ic a n t t o th e m a jo r it y o f in s e c t ta x a .
In
some c a se s, v a r ia b le s were s i g n i f i c a n t l y c o r r e la te d t o v a rio u s ta xa
when c o n s id e re d in d e p e n d e n tly (s im p le c o r r e la t io n c o e f f ic ie n t s ) , b u t
in s i g n i f i c a n t when c o n s id e re d w ith o th e r indepe nden t v a r ia b le s in th e
m u lt ip le re g re s s io n a n a ly s is .
C o r r e la tio n between th e independent
v a r ia b le s them selves i s th u s in d ic a te d .
I t would have been p o s s ib le
to d e ve lo p r e fin e d models f o r each in d iv id u a l ta xo n had tim e and
fin a n c e s p e r m itte d .
However, th e
t v a lu e s a r e , in most ca se s, ade­
quate in d ic a to r s o f s ig n if ic a n c e f o r th o s e v a r ia b le s in c lu d e d o n ly in
th e i n i t i a l m odels.
In a few ca se s, * va lu e s f o r th e same independent
and dependent v a r ia b le c o m b in a tio n v a rie d c o n s id e ra b ly between re g re s ­
s io n s , depending on th e m u l t i - c o l i n e a r i t y o f th e indepe nden t v a r ia b le s
in c lu d e d in th e p a r t ic u l a r m u lt ip le re g re s s io n m odels.
T w e n ty -th re e
d i f f e r e n t models were programmed b e fo re a f i n a l re g re s s io n model was
chosen as r e p r e s e n ta tiv e f o r th e m a jo r it y o f in s e c ts .
Most o f these
models were nece ssary t o deve lo p and r e f in e param eters d e s c r ib in g seg­
ments o f th e s u b s tr a te - s iz e d i s t r i b u t i o n .
RESULTS
Correlati-On coefficient matrix
The c o r r e la t io n m a tr ix (T a b le 4) l i s t s
th e c o e f f ic ie n t s among a l l
independent and dependent v a r ia b le s w hich were s ig n if ic a n t a t th e 5 p e r­
ce n t le v e l.
Some o f th e s ig n if ic a n t c o r r e la t io n s l i s t e d
p r a c t ic a l s ig n if ic a n c e however.
have l i t t l e
An example is th e s ig n if ic a n t c o r r e la ­
t io n s o f lo w e r ta x a to t h e i r co rre s p o n d in g h ig h e r ta x a , o f w h ich ,
n u m e r ic a lly , th e y may c o n tr ib u te a c o n s id e ra b le p o r t io n .
S everal taxa
were c o r r e la te d to depth (T able 4 ) , b u t o n ly one to th e c u r re n t measure­
m ents.
C o r r e la tio n between depth and th e c u r r e n t measurements near th e
le v e l o f th e s u b s tra te was s ig n if ic a n t and n e g a tiv e .
T h is is expected
because th e maximum c u r r e n t o f deeper w a te r g e n e r a lly te n d s to be p ro ­
p o r t io n a lly f u r t h e r from th e bottom .
Many ta x a were s i g n i f i c a n t l y c o r r e la te d to th e percen tag e w e ig h ts
in th e s u b s tra te s iz e -c la s s e s and to th e p e r c e n tile s .
The tre n d o f th e
c o r r e la t io n s w it h in many o f th e ta xa t o th e percentages was f o r s ig ­
n ific a n c e in s e v e ra l a d ja c e n t s iz e - c la s s e s , fo llo w e d by one o r two
c la s s e s w ith o u t s ig n if ic a n c e , and f i n a l l y fo llo w e d aga in by cla sse s
w ith s ig n if ic a n c e b u t c o e f f ic ie n t s w ith th e o p p o s ite s ig n .
The f a c t
th a t s e v e ra l a d ja c e n t c la s s e s tend to be s i g n i f i c a n t l y c o r r e la te d to
ta x a in d ic a te s t h a t th e degree to w hich th e s u b s tra te was graded in to
c la s s e s was more than adequate.
Many ta x a were a ls o s i g n i f i c a n t l y
-24-
A. noterophilum
R. nasturtiurr-aquat.
IN SEC TS
P le c o p te ra
Table 4.
3735
2450
2504
o th e r stone flie s
E p h e m e ro p te ra
E. tn&qgugxs
7380
Baetis sp.
Paraleptophlebia sp
2513
3689 3390
2612
T rie h o p te ra
Ochrotriohia sp
Glossosoma sp.
0349
6363
o.c.
(d.f. = 143)
4756
0.0Z5
0.010
0.005" Q.OOT
0.1871
0.2140
0.2326
0.2707
-2273
Optioservus sp.
-1844
4021
2836
2892
depth
c u r r e n t v e lo c ity
-1755
n.a.
-1 97 9
3438
2014
2096
-2 14 9
1722
-2325
-2 72 9
-2664
2789 -1 89 0
n.a.
n.a.
6059
4701
7427
5397
2406
n.a.
-2127
-2046
-2267
-2 26 6
-2 87 4
-4615
-3542
-2 95 6
-2 72 5
-2782
-2003
-1887
-1721
-1772
-1 78 2
-2 56 0
-1657
3217
3872
0 .2 5 th
3723
3747
2679
4986
3702
to ta l w e ig h t
mode s iz e - c la s s
0.050
0.1634
2149
-2 91 5
3749
0(-3)
Correlation coefficients between all measured variables in the study
which were significant at the 5 percent level. The values in the
table are {a.a.) x (104). A blank space indicates that the correla­
tion coefficient was not significant at the 5 percent level; "n.a."
(not available) indicates that the value for that relationship was
-3 76 5
3416
3372
3025
2192
2126
-2 59 9
-2 77 9
-2 90 8
-3 05 8
2480
2971
-2 82 9
-2492
-2 17 5
-1661
-1 91 9
3316
2455
n.a.
n.a.
n.a.
n.a.
n.a.
3529
-2 25 3
-3 29 6 -3274
-6187 -5 68 9 -3762
-5237 -5582 -5991 -5 15 0 -2 63 0
-3598 -4377 -4 69 9 -5 12 9 -3997 -3124 -1 92 0
n.a.
5488
n.a.
5826
n.a.
n.a.
n.a.
n.a.
n.a.
-3 78 0
-4889
-4933
-3976
-5305 -6099
-6019 -5768
-6183 -5417
-5541 1-5328
-5 50 0
7008
6585
5576
5393
-1 76 9
-1803
4468
2146
-1912
2290 -2543
1865
-2218 -3 37 5
-1681
6843
4934
-5 67 3 -5469 -4877 -3247
n.a.
-4 32 9 -5596 -4428
p e rc e n t w e ig h ts
7479
6713
-5789 -5811 -6047 -6005 -5763
9066
p e rc e n tile s
S u b s t r a t e
-5475
-25c o r r e la t e d t o s e v e ra l a d ja c e n t p e r c e n t i l e s , though t h e r e were no changes
o f s ig n here w i t h i n ta x a .
Several ta xa were s i g n i f i c a n t l y c o r r e l a t e d ,
e i t h e r p o s i t i v e l y o r n e g a t i v e l y , t o th e t o t a l sample w e ig h t, b u t t h e r e
were few c o r r e l a t i o n s to th e mode s iz e - c l a s s .
The many s i g n i f i c a n t
c o r r e l a t i o n s o f b oth a d ja c e n t percentages and a d ja c e n t p e r c e n t i l e s
r e p r e s e n tin g s u b s t r a te d i s t r i b u t i o n a re expe cted ; i f
it
i s accepted
t h a t c u r r e n t r o u g h ly grades s u b s t r a t e p a r t i c l e s by d i s t r i b u t i n g and
r e d e p o s it in g them a c c o rd in g t o th e i n t e r a c t i o n o f eddy c u r r e n t s , t u r ­
bulence and o t h e r f a c t o r s , i t would be h i g h l y u n l i k e l y t o f i n d th e
d i s t r i b u t i o n o f p a r t i c l e s between a d ja c e n t s iz e - c la s s e s t o be random.
Multiple regression models
The F s t a t i s t i c s o f th e i n i t i a l
r e g r e s s io n models ( re g r e s s io n s A
and B, Tables 5 and 6) in d ic a te d t h a t high s i g n i f i c a n t r e l a t i o n s h i p s
e x is te d between th e i n i t i a l
a l l o f th e t a x a .
s e t o f independent v a r ia b le s and n e a r ly
In most cases, t h i s r e l a t i o n s h i p was s i g n i f i c a n t a t
' le s s than th e 0.1 p e rce n t l e v e l .
The o n ly ta xa n o t s i g n i f i c a n t a t th e
5 p e rce n t le v e l were 2 o f th e 3 species o f m acrophytes, Rorippa
nasturtium^aquatiaum ( w a te rc re s s ) and Zanniohellia palustris (pondweed), which t o g e t h e r comprised o n ly 3 p e rc e n t o f th e t o t a l p l a n t
biomass (Table 1 4 ).
Because these F s t a t i s t i c s
in d ic a t e d h ig h s i g n i ­
f ic a n c e in th e independent v a r ia b le s as a group , subsequent models
were developed (Tables 5 and 6) t o i s o l a t e and remove v a r ia b le s
A lT T T T
Table 5. Independent variables included in regressions A-U.
D e p e n d e n t v a r ia b le n o t a tio n :
4 - e a c h in s e c t ta x o n :
1 - e a c h p la n t g e n u s
c la s s , o r d e r ,
6 - b o th n o . I a n d n o . 2
and genus
2 - p la n t g e n u s d a ta c o m b in e d
7 - b o th n o . 3 a nd n o . 4
5 - in s e c t c la s s d a ta o n ly
3 - b o th n o . I and n o . 2
IN D E P E N D E N T V A R IA B L E S
4 Hx X X X X X X X
X X X X X X
XX
XXX
R E G R E S S IO N
9 0 th
s t r e a m s e c tio n
tim e (3)
7 5 th
5
[2 5 1 5
[5 0 th
J
X X X X X X X
S
I lo th
X
p e r c e n tile s
I u p p e r d e c ile
I 0 .2 5 th
I
I u p p e r q u a r t ile j
S
O E
TS TS ©
I
TS
I
I in n e r q u a r t il e j
I
-L I I f
TS TS "3 -S
I0)
L S
TS +
+ +
I lo w e r q u a r t ile j
XX
XX
X X X X X
s h o r tn e s s o£
I
H
I es<-5)
c la s s
0
|m o d e
I s a m p le w e ig h t
I d e p th
I c u r r e n t v e lo c it y
I a lg a e
I pondw eed
I w a te rc re s s
3 I
B
is
J
A
S S
£ c3
3 TS 3
W
I m oss
.
DEPENDENT
V A R IA B L E S
I_____
R E G R E S S IO N
S u b s t r a t e
p e r c e n t w e ig h ts
X X
X X X
A
X
X X X
B
(Ti
I
C
2
X X X
X
X
X
C
D
5
X X X X X X
X
X
X
D
E
6
F 2
5
G
H 7
5
I
J 5
K 4
XX
X X X X X
X X X X X X X X
X X
X
X
X X X
X X X
4
X X X
M
4
X X X
X X X
N
4
4
X X X
X X X
X X X
O
P
4
X X X
X X X
Q
R
4
X X X
X X X
4
4
X X X
X X X
X
X
X X X
S
T
U
3 I
X
X X
X
X X
XX
X X
X
X X
X
X
XX
E
X X X X X X X
XX
L
4
XX
X
X X X X X
XX X X
XX XX
XX XX
X X
X X
X X
F
G
H
I
,1
K
X X
L
X X
M
X
N
X
O
X
X X
X X
P
9
R
X X
S
X X
X X
T
U
I
PO
-27-
F s t a t i s t i c s , th e l e v e l s a t which th e n u l l hypotheses are r e ­
j e c t e d , and th e EZ values f o r th e dependent v a r ia b le s in each
Table 6.
o f th e r e g r e s s io n s .
Independent v a r ia b le s f o r each r e g r e s ­
s io n are g iv e n in Table 5. f l i s th e degrees o f freedom due
t o r e g r e s s io n ; /2 th e t o t a l degrees o f freedom , i s 142 f o r a l l
re g r e s s io n s (N = 143).
Dependent v a r i a b l e
Regression
A
B
'
.6738
8.0558
<0.001
.6740
I .8390
<0.100
.3206
1.0594
>0.250
.2138
6.5992
<0.001 •
.6575
P le c o p te ra
Aoroneuria pacifica
o th e r s to n e flie s
4.3382
2.3046
4.3338
<0.001
<0.001
<0.001
' .5579
.4013
.5577
Ephemeroptera
Ephemereila infrequens
Baetis sp.
Paraleptophlebia sp.
5.2945
5.3844
1.6737
4.1929
<0.001
<0.001
<1.050
<0.001
.6063
.6103
.3275
,5495
T r ic h o p te r a
Oohrotrichia sp.
Glossosoma sp.
Rhyaeophila sp.
2.7830
3.2563
3.3096
3.4783
<0.001
<0.001
<0.001
<0.001
.4474
.4865
.4905
.5029
C o le o p te ra :
Optioservus
5.6545
<0.001
.6219
12.2716
<0.001
.5311
INSECTS
5.8632
<0.001
.4092
PLANTS
4.5807
<0.001
.1919
INSECTS
9.7220
<0.001
.3352
Amblystegiwm
rx>tevophil-um
PiOrippa nasturtiwnaquatiaum
Zannichellia palustvis
•;
PLANTS
C
Sp.
12
/l
D
15
fl
E
/I
i?2
<0.001
INSECTS
32
/I
P
le v e l
8.0478
PLANTS
29
fl
F-.
s ta tis tic
7
-28“
T ab le 6 ( c o n tin u e d )
Regression
F
Dependent v a r i a b l e
F
s ta tis tic
P
le v e l
P2
PLANTS
9.7352
<0.001
.6148
INSECTS
7.2488
<0.001
.5706
13.7147
<0.001
.5802
12.5575
<0.001
.5787
0.9581
>0.250
.0949
1.4447
<0.250
■.1365
13.1523
<0.001
.5895
8.1855
2.4310
8.2109
<0.001
<0.005
<0.001
.4724
.2100
.4731
11.4411
11.9873
3.1277
3.8970
<0.001
<0.001
<0.001
<0.001
.5558
.5673
.2549
.2989
3.9236
4.4663
4.0886
7.2051
<0.001
<0.001
<0.001
<0.001
.3003 •
.3282
.3090
.4407
11.2995
<0.001
.5527
INSECTS
11.0738
<0.001
.5055
INSECTS
13.8597
<0.001
. 5613
INSECTS
10.7927
<0.001
.6104
6.6755
2.7009
<0.001
<0.001
.4921
.4949
20
G
fl = 23
PLANTS
H
■Fn
IIA4
Tl
A. notevo-philian
R. -nasturtiumaquaticum
Z. palustris
INSECTS
P le c o p te ra
A. pacifica
o th e r s to n e flie s
Ephemeroptera
E. infrequens
Baetis sp.
Paraleptophlebia sp.
T r ic h o p te r a
Ochrotriohia sp.
Glossosoma sp.
Rhyacophila sp.
Optioservus sp.
I
fl = 12
0
12
fl
K
fl
18
P le c o p te ra
A. paeifiaa
-2 9 T a b le 6 ( c o n tin u e d )
Regression
P
le v e l
E2
6.7495
<0.001
.4949
8.5805
8.6570
2.2198
6.3396
<0.001
<0.001
<0.005.
<0.001
.5547
.5569
.2437
.4792
4.3801
4.0265
. 3.9195
5.4023
<0.001
<0.001
<0.001
<0.001
.3887
.3689
.3626
.4395
9.2851
<0.001
.5741
12.7986
<0.001
.6019
P le c o p te ra
A . paoifica
o t h e r s t o n e f l ie s
7.2232
2.2775
7.3026
<0.001
<0.010
<0.001
.4604
.2120
.4631
Ephemeroptera
E. infvequens
Baetis sp.
Favaleptophlebia sp. .
9.5773
9.9936
2.4908
6.1607
<0.001
<0.001
<0.005
<0.001
.5308
.5414
.2273
.4212
T r ic h o p te r a
Ochvotviohia sp.
Glossosoma sp.
Rhyacophila sp.
4.8806
4.2584
4.4366
6.5361
<0.001
<0.001
<0.001
<0.001
13657
.3346
.3438
.4357
11.2401
<0.001
.5704
9.0101
<0.001
.5336
P le c o p te ra
A. pacifioa
o t h e r s t o n e f l ie s
7.3418
2.9412
7.4288
<0.001
<0.001
<0.001
.4825
.2719
.4854
Ephemeroptera
E. infvequens
Baetis sp.
Pavaleptophlebia sp.
8.8505
8.5225
2.1615
6.8525
<0.001
<0.001
<0,010
<0.001
.5292
.5197
.21 54
.4653
T r ic h o p t e r a
Oehvotviohia sp.
2.2744
2.3614
<0.010
<0.005
.2241
.2307
Dependent v a r i a b l e
o th e r s to n e flie s
Ephemeroptera
S. i-nfrequens
Baetis sp.
Bavale-Ptoyhlebia sp.
T r ic h o p t e r a
Oohvotvichia sp.
Glossosomq sp.
Rhyaoophila sp.
Optiosevvus sp.
L
fl
-~ II D
C
INSECTS
Optiosevvus sp.
M
—IC
fl - I D
INSECTS
F
s ta tis tic
-3 0 T a b le 6 ( c o n tin u e d )
Dependent v a r i a b l e
B
s ta tis tic
P
le v e l
S2
Glossosoma sp.
Khyacophila sp.
4.2445
6.0375
<0.001
<0.001
.3502
.4340
Optioservus. sp.
8.7234
<0.001
.5256
9.2802
<0.001
.4380
P le c o p te ra
A. paeifiea
o th e r s to h e flie s
5.9989
2.5176
6.0442
<0.001
<0.001
<0.001
.3350
.1745
.3367 ,
Ephemeroptera
K. infvequens
Baetis sp.
PavaleptopKlebia sp.
9.0555
9.6172
1.8531
9.1846
<0.001
<0.001
<0.050
<0.001
.4319
.4468
.1347
.4354
T r ic h o p te r a
Oehvotvichia sp.
Glossosoma sp.
Rhyaeophila sp.
4.9797
4.1909
3.5960
3.7791
<0.001
<0.001
<0.001
<0.001
.2949
.2603
.2319
.2409
10.7008
<0.001
.4733
11.1781
<0.001
.4002
8.2906
2.6008
8.3417
<0.001
<0.001
<0.001
.3311
.1344
.3324
11.4151
12.3151
2.1027
9.7213
<0.001
<0.001
<0.050
<0.001
.4053
.4237
.1115
.3672
5.4607
3.9468
3.9866
5.1944
<0.001
<0.001
<0.001
<0.001
.2459
.1907
.1922
.2367
13.0011
<0.001
.4370'
5.4765
<0.001
.2704
6.0237
2.9543
6.0850
<0.001
<0.001
<0.001
.2896
.1666
.2917
Regression
INSECTS
N
fl
- nI I
Optiosevvus sp.
INSECTS
0
/I
= 8
•
P le c o p te ra
A . paeifica
o th e r s to n e flie s
Ephemeroptera
. TH. infvequens
Baetis s p .
Paxaleptophlebia sp.
T r ic h o p te r a
Oehvotviehia sp.
Glossosoma sp.
Rhyacophila sp.
Optiosevvus sp.
INSECTS
P
/I
-
y
P le c o p te ra
A. po.cifieoo t h e r s t o n e f l ie s
T a b le 6 ( c o n tin u e d )
Regression
Dependent v a r ia b le
Ephemeroptera
E. infvequens
Baetis sp.
ParaleptoTphlebia sp.
T r ic h o p te r a
Octirotrichia sp.
Glossosoma s p .
Rhyaeophila sp.
Optioservus sp.
Il
PO
Q
INSECTS
Il
>
P
le v e l
R2
9.2134
8,8341
1.7834
11.0006
<0.001
<0.001
<0.100
<0.001
.3840
.3741
.1077
.4267
1.5109
1.9223
3.9713
4.4909
<0.100
<0.100
<0.001
<0.001
.1145
.1151
.2118
.2331
8.0382
’ <0.001
.3523
10.2887
<0.001
.6410
..5 4 0 0
P le c o p te ra
A . paeifiea
o th e r s to n e flie s
6.7650
3.6552
6.7768.
<0.001
<0.001
<0.001
1 .5405
Ephemeroptera
E. infrequens
Baetis sp.
Pccraleptophlebia sp.
7.9896
8.5292
2.4604
4.9704
<0.001
<0.001
<0.005
<0.001
.5810
.5968
.2992
.4631
T r ic h o p te r a
Oelrrotrichia Sp.
Glossosoma sp.
Rhyaeophila sp.
3.9764
4.5150
4.1377
5.1926
<0.001
<0.001
<0.001
<0.001
.4083
.4393
.4180
.4740
8 .2 7 2 8
<0.001
.5895
9.3471 ,
<0.001
.5597
P le c o p te ra
A. . paeifiea
o th e r s to n e flie s
7.1774
3.5669
7.2483
<0.001 '
<0.001
<0.001
.4940
.3266
.4964
Ephemeroptera
E. infrequens
Baetis sp.
Paraleptophlebia sp.
8 .9 3 9 3
9 .3 6 6 2
<0.001
<0.001
<0.001
<0.001
.5 4 8 7
.5 6 0 2
T r ic h o p te r a
Oehrotriehia S p .
Glossosoma sp.
2.9005
<0.001
<0.001
<0.001
.2829
.3400
Optioservus sp.
R
F
s ta tis tic
INSECTS
2.5991
5.5921
3 .7 8 7 7
3 .9 3 8 8
.3 8 8 1
.2612
.4320
.3 4 8 8
-3 2 T a b le 6 (c o n c lu d e d )
Regression
S
/I
= 17
Dependent v a r i a b l e
/I
- no
IO
,4507
Optioservus sp.
8.2998
<0.001
.5302
12.1375
<0.001
.6227
8.2085
3.1393
8.1802
<0.001
<0.001
<0.001
.5275
.2992
.5266
9.7712
10.3502
2.8685
6.0072
<0,001
<0.001
<0.001
<0.001
.5706
.5847
.2806
.4496
T r ic h o p te r a
Ochrotriohia S p .
Glossosoma sp.
Rhyaoophila sp.
3.7011
4.1036
4.9216
6.1458
<0.001
<0.001
<0.001
<0.001
.3348
..3 5 8 2
.4010
.4553
Optioservus sp.
10.3592
<0.001
.5849
11.7654
<0.001
.5425
9.5792
2.3522
9.6271
<0.001
<0.001
<0.001
.4912
.1916
.4924
<0.001
<0.001
<0.001
<0.001 ■
.5329
.5448
.2365
.3970
1.8195
2.1572
4.8246
7.8333
<0.050
<0.025
<0.001
<0.001
.1549
.1786
.3271
.4412
10.2772 .
<0.001
.5088
11,5782
<0.001
.6270
11.3335
<0.001
.6220
1.4197
<0.250
.1709
1.2621
<0.250
.1548 .
INSECTS
P le c o p te ra
A. paoifica
o th e r s to n e flie s
INSECTS
P le c o p te ra
A. paoifica
o t h e r s t o n e f l ie s
Op'tioservus sp.
- II O
O
.
<0.001
T r ic h o p te r a
Ochrotrichia sp.
Glossosoma sp.
Rhyaoophila sp.
fl
/
6.0338
Ephemeroptera
Z?. infrequens
Baetis sp.
Paraleptophlebia sp.
U
P
I eve!
Rhyaooph-Cla sp.
Ephemeroptera
E. infrequens
Baetis sp.
Paraleptophlebia sp.
T
F
s ta tis tic
PLANTS
A. noterophilum
R. nasturtiumaquatioum
Z. palustris
11.3202
11.8770
3.0737
6.5330
.
-3 3 -
i n s i g n i f i c a n t t o th e m a j o r i t y o f t a x a .
F t e s t s between re g re s s io n s
(T able 10) were used t o determ ine th e s i g n i f i c a n c e o f i n d i v i d u a l v a r i ­
a b le s d e s c rib e d by more than one param eter ( s u b s t r a t e and stream sec­
t i o n ) , and
t s t a t i s t i c s were used both t o e l im in a t e th o s e independent
v a r ia b le s d e s c rib e d by o n ly one param eter and to d e te rm in e which o f
th e se v e ra l i n d i v i d u a l parameters used t o d e s c r ib e th e s u b s t r a te d i s ­
trib u tio n
had th e g r e a t e s t s i g n i f i c a n c e .
C o m p ila tio n o f th e s i g n i f i c a n t
t s t a t i s t i c s (Tables 7 and 8) f o r
v a r ia b le s which were s i g n i f i c a n t in a l l
o f th e r e g r e s s io n s g iv e s i n s i g h t
i n t o which v a r ia b le s are s i g n i f i c a n t t o each ta x o n .
But some c a u tio n
should be e x e rc is e d t o a vo id u sin g th e a b s o lu te fre q u e n c y t h a t s p e c i f i c
t s t a t i s t i c s should
v a r ia b le s appear as th e s o le b a s is o f s i g n i f i c a n c e ,
be e v a lu a te d in c o n t e x t w i t h what o t h e r v a r ia b le s are in c lu d e d in s p e c i­
fic
r e g r e s s io n s (Table 5 ) .
As mentioned e a r l i e r , th e
t va lu e s o f p a ra ­
m eters may v a ry c o n s id e r a b ly between re g r e s s io n s depending on whether
c o r r e l a t e d v a r ia b le s are used.
For example, th e use o f one parameter t o
d e s c r ib e t h e r e l a t i o n o f a v a r i a b l e w i t h known s i g n i f i c a n c e t o th e de­
pendent v a r i a b l e w i l l
l i k e l y produce a s i g n i f i c a n t
t v a lu e .
However, i f
a d d i t i o n a l parameters are in s e r t e d which a l s o s i g n i f i c a n t l y d e s c r ib e th e
r e l a t i o n by means o f a s i m i l a r v a r i a b l e
( o r v a r i a b l e s ) , and th e v a r i ­
a b le s them selves a re s i g n i f i c a n t l y c o r r e la t e d among each
o t h e r , then
th e v a lu e o f t s t a t i s t i c s produced f o r any one param eter w i l l g e n e r a lly
be reduced, and some o r a l l
o f the se param eters may i n d i v i d u a l l y no
T ab le 7.
Independent v a r ia b le s which were s i g n i f i c a n t t o each p l a n t taxon a t th e P = 0.05
le v e l ( * > [ 1 . 9 7 7 ] ) .
P l a n t taxa
Amblystegium noterophilum
(moss)
O ^ d r y w t . ” 429 ,2 9
Rorippa nastnrtium-aquaticum
( w a te rc re s s )
-W
w t. = 9 - 018 a/m2
Zanniahellia palustris
(pondweed) ■
O
Independent
v a ria b le
t va lu e
depth
p e rc e n t w t . , 0 [ - 4 ]
lo w e r q u a r t i l e
upper q u a r t i l e
- 90th p e r c e n t i l e
1 .977
-2.4 14
2.427
-2 .3 4 4
-2.551
c u rre n t v e lo c ity
mode phi c la s s
p e rc e n t w t . , 0 [ - 7 ]
1st p e rc e n tile
5 th p e r c e n t i l e
50th p e r c e n t i l e
-2 .1 2 8
1.977
2.962
2.876
-2.4 68
-2.1 52
Regression
c o e ffic ie n t
Regression
342.6
-2 0 .6 1
115.8
-1 8 8 .0
-2 0 2 .4
•
A
A
H
H
A
-3 5 .8 5
7.030
2.518
40.05
-3 5 .0 4
-1 9 .1 5
A
A
A
U
U
A
2.025
379.3
2 .5 9 5
4 5 7 .3
-2 .2 8 9
6.504
-2 .3 4 0
-4.687
2.551
5.321
-2.4 9 2
-2 1 .1 4
156.8
C
F
A
H
H
C
F
C
A
F
none
x d r v w t . = 3 - 603 3/™
c u rre n t v e lo c ity
Combined w e ig h t o f a l l
t h r e e p l a n t genera
W
w t . = 4 41-8 3/m2
p e rc e n t w t . , 0 [ - 4 ]
lo w e r q u a r t i l e
upper d e c i l e
in n e r q u a r t i l e s
25th p e r c e n t i l e
50th p e r c e n t i l e
90th p e r c e n t i l e
-2 .8 9 3
-1 8 7 .4
-128.3
171.8
110.2
-1 9 9 .9
-235.1
-3 5 -
Table 8.
Independent v a r ia b le s which were s i g n i f i c a n t t o each in s e c t
taxon a t th e P = 0.05 le v e l ( £ > [ 1 . 9 7 7 ] ) .
a)
INSECTS
(Xn o . = 8454/m2 )
t v a lu e
r e g r e s s io n
c o e ffic ie n t
r e g r e s s io n
2.258
3.082
2.485
2.669
4.020
2.642
3.430
3.275
3.170
3.793
N
0
P
R
T
-2 .1 9 4
- 2 .4 7 0
-2 .0 7 2
-2 .2 4 0
-2 .2 7 6
-2 .1 0 3
- 2 .1 0 0
-2 5 .2 2
-2 7 .2 5
-25.01
-2 9 .3 3
-2 9 .4 0
-2 4 .0 9
-24 .0 3
K
L
M
N
0
Q
S
-2 .2 1 2
-2 .6 9 2
-2.7 42
-3 2 .7 5
-3 8 .8 4
-3 9 .6 4
L
Q
S
depth
1.979
13,424
' D
p e rc e n t w t: 0 ( 0 ) + 0 ( - l )
2.472
198.0
M
- 2 .4 5 9
-2 .0 3 2
-154.3
-140.1
N
P
2946
1520
H
J
-2 .8 9 2
2.542
-1750
841.7
H
I
0 .2 5 th p e r c e n tile
2.165
2569
S
I Oth p e r c e n t i l e
4.041
4.363
4.805
5.011
5.658
2823
3043
2941
2919
3777
B
G
K
L
0
25th p e r c e n t i l e
-2 .5 9 4
. -3 .2 7 2
-3 .9 6 8
-2072
-1766
-2446
K
L
0
independent v a r i a b l e
Amblystegi-Iim
noteroTphilum
Rorippa nasturtiumaquaticum
Zanniohellia palustris
p e rc e n t w t: 0 ( - 2 ) + 0 ( - 3 )
lo w e r d e c i l e
lo w e r q u a r t i l e
4.976
5.123
:
-3 6 -
T ab le 8 ( c o n tin u e d )
b)
P le c o p te ra
(Xn 0 . = 1626/iti2)
r e g r e s s io n
c o e ffic ie n t
re g re s s io n
.7166
.8078
8082
.7859
.7584
N
0
P
R
T
-2 .1 5 4
-2 .3 7 5
-2 .2 1 9
-2 .1 6 2
-2 .4 1 5
-2 .2 6 4
- 2 .7 6 0
-2 .8 2 2
-2 .7 0 3
- 2 .9 3 6
-9 .1 9 6
-8 .4 7 4
-7.841
-8 .5 5 8
-9 .1 5 5
-8.847
-10.31
-1 0 .3 5
-9.9 7 3
-1 0 .5 5 .
B
L
M
N
0
P
R
S
T
2.142
2.304
59.70
54.02
K
M
lo w er d e c i l e
2.587
500.3
H
IO th p e r c e n t i l e
2.031
3.086
383.0
604.6
L
0
25th p e r c e n t i l e
-2.311
-4 1 8 .0
0
independent v a r i a b l e
Amblystegium
notevophilum
Rorippa nasturtiumaquaticum
p e rc e n t w t:
0(0) + 0 ( - l )
t v a lu e
2.027
2.473
2 237
2.142 .
2.645
Q
-3 7 T a b le 8 ( c o n t in u e d )
c)
Aoroneuria pacifioa
(Xn0i = 43.45/m 2 )
t v a lu e
r e g r e s s io n
c o e ffic ie n t
r e g r e s s io n
2.189
2.028
2 044
2.138
3.380
.03134
.02459
02274
.02363
.03596
B
L
N
P
T
sample w e ig h t
-2 .0 5 6
-.005166
B
mode 0 c la s s
-2.461
-13.77
B
1.996
16.47
R
p e rc e n t w t: 0 ( - 4 )
- 2 .6 2 9
-3 .7 5 4
B
p e rc e n t w t: 0 ( - 7 )
-2 .2 1 2
-3 .0 1 5
B
p e rc e n t w t: 0(2.) + 0 ( 1 )
2.663
2.719
2.392
1.562
.9535
.7946
K
M
P
p e rc e n t w t: 0 ( - 2 ) + 0 ( - 3 )
3.210
3.004
2.327
2.259
2.008
1 .813
1 .389
1.306
K
M
N
P
lo w er d e c i l e
2.036
14.18
H
upper q u a r t i l e
2.233
20.90
H
IO th p e r c e n t i l e
-2.341
-31.31
S
25th p e r c e n t i l e
-2 .5 1 2
-2 7 .9 9
B
50th p e r c e n t i l e
2.128
29.74
B
independent v a r i a b l e
Ambtystegium
noterophilvm
p e rc e n t w t: 0 ( 4 )
-3 8 -
T a b le 8 ( c o n t in u e d )
d)
O ther s t o n e f l i e s
(Xno
= 1583/m2 )
t v a lu e
r e g r e s s io n
c o e ffic ie n t
r e g r e s s io n
1.976
2.427
2.187
2.104
2.543
.6939
.7873
.7846
.7639
.7225
N
0
P
r
R
T
-2 .1 7 4 .
-1 .9 8 5
-2 .4 0 6
-2 .2 5 6
-2 .2 0 8
-2 .4 5 5
-2 .3 0 6
-2 .7 5 7
-2.8 23
-2 .7 0 6
-2 .9 4 5
-9.2 13
-7 .1 7 9
-8 .5 1 5
-7 .9 0 4
-8 .6 8 0
-9.241
-8.947
-10.21
-1 0 .2 5
-9 .9 1 4
-1 0 .4 8
B
K
. L
M
N
0
. P
Q
R
S
T
p e rc e n t w t: 0 ( 0 ) + 0 ( - l )
2.181
2.375
60.27
55.22
K
M
lo w e r d e c i l e
2.535
486.0
H
IO th p e r c e n t i l e
2.047
3.084
382.5
600.1
L
0
25th p e r c e n t i l e
-2 .3 3 2
-4 1 9 .0
0
independent v a r i a b l e
Amblystegivm
noteroiphilum
Rorippa nasturtiumaquaticum
-3 9 -
Table 8 ( c o n tin u e d )
e)
Ephemeroptera
(Xn0i = 2108/m^)
r e g r e s s io n
c o e ffic ie n t
re g r e s s io n
■ - 2 .4 2 9
-38 .1 7
M
1.975
2.425
81.15
85.35
K
M
- 2 .0 4 6
- 2 .0 0 9
- 2 .4 1 0
- 2 .4 3 9
-5 6 .1 4
-54.33
-6 6 .4 9
-6 7 .5 5
K
M
N
2.514
650.8
H
-2 .2 9 7
- 6 0 8 .0
H
0 .2 5 th p e r c e n t i l e
2.298
1227
S
IO th p e r c e n t i l e
2.664
2.922
3.335
762.4
808.3
969.2
K
L
0
-2 .8 2 3
-3 .1 3 8
-72 3 .3
-842.3
0
t v a lu e
independent v a r i a b l e
p e rc e n t w t: 0 ( 2 ) + 0 ( 1 )
p e r c e n t w t: 0 ( 0 ) + 0 ( - D
p e rc e n t w t : 0 ( - 2 ) nH 0 ( - 3 )
lo w e r d e c i l e
- lo w e r q u a r t i l e
25th p e r c e n t i l e
:
P
L
-4 0 Tab] e 8 ( c o n tin u e d )
f )
independent v a r i a b l e
t va lu e
= 1463/m^)
r e g re s s io n .
c o e ffic ie n t
re g r e s s io n
- 2 .0 9 0
-2 .1 4 2
-2.1 03
-2 .1 9 8
-2 .1 9 4
-2 .0 9 5
-9 .8 0 0
-9 .6 9 4
-9 .8 5 0
-1 0 .9 2
-1 0 .6 2
-10.57
K
L
M
N
0
P
2.217
68.91
M
-2 .2 4 8
-2 .0 9 5
-5 3 .4 9
-51 .1 3
N
P
2.877
630.7
H
- 2 .5 6 0
-5 7 3 .4
H
2.286
1021
S
I Oth p e r c e n t i l e
2.293
3.154
' 3.479
4.032
615.6
787.1
831.7
1008
B
K
L
0
25th p e r c e n t i l e
-2 .9 4 8
-3.4 33
-6 5 2 .9
-7 9 3 .0
L
0
Rorippa nasturtiumaquaticum
p e rc e n t w t: 0 ( 0 ) + 0 ( - l )
p e rc e n t w t: 0 ( - 2 ) + 0 ( - 3 )
lo w er d e c i l e
lo w e r q u a r t ! Ie
0 .2 5 th p e r c e n t i l e
g)
(X
EphemerelZa iZnfrequens
Baetis s p .
independent v a r i a b l e
none s i g n i f i c a n t
<*no.
t va lu e
= 414.1/m 2 )
re g r e s s io n
c o e ffic ie n t
r e g r e s s io n
” 41 -
Table 8 (c o n tin u e d )
h)
Pavale-pto-pKlebia sp.
(X
= 2 3 0 .0/m^)
t va lu e
re g r e s s io n
c o e ffic ie n t
3.223
4.145
4.828
4.121
3.251
3.820
3.349
4.702
5.290
4.654
5.435
.2564
.2949
.3413
.2944
. 2035
.2332
.2089
.3610
.3879
.3475
.3201
B
. K
L
• M
N
0
P
2.328
2.002
2.068
2.922
2.482
2.750
2.056 .
1.653
1.421
1.427
2.047
1.758
1.855
1.507
K
L
M
N
0
P
R
depth
2.048
824.4
B
p e rc e n t w t: 0 ( 0 )
2.432
30.56
B
p e rc e n t w t: 0 ( - 5 )
2.027
14.44
B
p e rc e n t w t: 0 ( - 7 )
3.284
24.89
B
p e rc e n t w t: 0 ( 2 ) + 0 ( 1 )
-3 .1 6 8
-2.4 2 7
-6 ,4 7 8
-4.551
M
P
p e rc e n t w t: 0 ( 0 ) + 0 ( - l )
3.404
. 3.537
3.551
3.799
18.46
16.20
18.67
16.59
K
M
N
P
lo w e r d e c i l e
2.068
86.92
H
0 .2 5 th p e r c e n t i l e
2.514
195.9
S
IO th p e r c e n t i l e
2.109
79.10
L
25th p e r c e n t i l e
-2 .2 3 0
-77.47
L
75th p e r c e n t i l e
2.051
137.5
B
independent v a r i a b l e
Amblystegium
notevopkilum
Rorippa nasturtiumaquatieum
r e g re s s io n
Q
R
S
T
-4 2 -
T a b le 8 ( c o n tin u e d )
D
T r ic h o p t e r a
(Xpo
= 915.4/m2 )
t va lu e
r e g r e s s io n
c o e ffic ie n t
-2 .9 1 3
-3 .5 9 5
-3 .5 0 7
-3 .0 8 6
-2 .6 8 2
-2.1 87
-2 .7 9 8
-3.1 77
-.6541
-.9 2 7 6
-.8 6 9 0
-.88 94
-.62 82
-.4 8 7 9
-.5757
-.6 6 5 6
B
K
L
M
N
0
Rovippa nasturtiumaquaticum
-2 .1 2 2 .
-5 .4 9 5
0
-7 .6 3 6
-6 .9 0 2
-7.3 37
-6.241
-6.901
B
L
Zanniehella palustvis
-2 .8 4 8
-2 .0 6 6
-2 .8 5 5
-2 .2 8 3
-2.591
Q
p e rc e n t w t: 0 ( 2 )
2.051
2.486
52.66
68.42
Q
p e rc e n t w t: 0 ( 2 ) + 0 (1 )
2.235
2.303
18.43
17.97
M
P
lo w e r d e c i l e
4.574
489.5
H
-3.2 67
-357.3
H
IO th p e r c e n t i l e
3.608
5.530
5.086
4.979
443.0
758.0
668.5
666.1
B
K
L
0
25th p e r c e n t i l e
-2 .7 4 6
-2 .5 6 9
-2 .9 8 2
-4 9 0 .9
-3 1 2 .9
-36 8 .5
K
L
0
independent v a r i a b l e
Amblystegium
noterophilum
lo w er q u a r t i l e
re g re s s io n
Q
S
R
S
R
-4 3 -
T a b le 8 ( c o n t in u e d )
Ochvotriohia s p .
j )
independent v a r i a b l e
Amblystegium
notevophilum
Zannichellia palustvis
( X fi0
= 5 2 8 . 0 /m ^ )
t v a lu e
re g re s s io n
c o e ffic ie n t
-2 .6 9 2
-3 .1 9 7
-3 054
-2 .7 9 6
-2 .1 5 4
-2.2 0 7
-2 .5 1 0
- .5 7 0 0
-.8 4 1 3
- 7781
-.8 0 5 2
-.5 1 8 6
-.43 17
-.5 0 4 5
-2 .2 2 2
- 5 .6 2 0 '
-5.1 27
-2 .0 9 8
r e g r e s s io n
B
K
I
M
N
•
Q
S
B
q
sample w e ig h t
- 2 .2 3 0
-.0 8 2 8 7
B
p e rc e n t w t: 0 ( 3 )
-2.0 87
-2 .2 0 5
-1 1 9 .0
-126.7
Q
p e rc e n t w t: .0(2)
2.670
3.016
65.18
77.75 .
Q
2.642
1.980
2.899
21.78
25.08
M
p e rc e n t w t: 0 ( 2 ) + 0 ( 1 )
2 2 .7 1
N
P
3.773
387.0
H
-2 .1 4 3
-224.7
H
3 2 6 .5
IO th p e r c e n t i l e
2.820
4.941
4.306
4.102
B
K
L
0
25th p e r c e n t i l e
- 2 .3 4 0
-2 .1 6 9
-2 7 8 .7
K
0
50th p e r c e n t i l e
-2 .4 6 4
-5 0 9 .6
B
lo w e r d e c i l e
lo w er q u a r t i l e
690.7
582.0
570.6
-4 2 6 .8
.
R
R
•
-4 4 T a b le 8 ( c o n tin u e d )
k)
Glossosoma sp
■
t v a lu e
independent v a r i a b l e
= 228.6/m2 )
r e g r e s s io n
c o e ffic ie n t
r e g r e s s io n
-2 .1 8 5
-2 .9 9 7
-3 551
-2 .8 3 6
-2 .4 4 4
-2 .6 7 3
-3 .5 2 0
-.1 3 3 6
-.1 7 7 7
- 1989
-.1 6 8 5
-.1 5 8 8
-.16 93
-.1 7 8 0
S
T
-2 .0 5 8
-1.651
T
algae
2.331
201.0
B
lo w er d e c i l e
2.264
76.65
H
- 2 .9 9 0
-1 0 3 .5
H
3.169
3.739
237.1
246.9
S
-2.181
-2 .7 2 5
-2 2 6 .7
-2 6 2 .4
Q
IO th p e r c e n t i l e
2.333
2.060
2.248
87.55
66.81
75.51
B
L
0
25th p e r c e n t i l e
-2 .2 1 9
-66.67
L
90th p e r c e n t i l e
-2 .1 9 7
,1 2 9 .2
B
Amblystegium
noteroiphilim
Zannichellia palustris
lo w e r q u a r t i l e
0 .2 5 th p e r c e n t i l e
1st p e rc e n tile
I)
<Xno
Rhyaeophila sp,
independent v a r i a b l e
Amblystegium
notevophilum
•
<Xno.
t v a lu e
2.279
L
M
o
P
Q
Q
S
= 158.8/m2 )
r e g r e s s io n
c o e ffic ie n t
■ .07802
r e g r e s s io n
0
-4 5 -
Table 8 (conclu ded)
m)
C o le o p te ra :
Optioservus sp.
independent v a r i a b l e
t va lu e
(%no. = 3805/m2)
re g r e s s io n
co e ffic ie n t
r e g r e s s io n
2.251
2.669
2.822
2.660
3.894
4.480
3.966
2.813
5.034
1.661
1.725
35.18
1.799
2.365
2.592
2.641
1 .899
2.708
B
K
L
M
N
0
P
R
T
Zanniahella palustris
-2 .1 9 5
-2.251
-1 8 .6 3
-1 8 .7 8
Q
p e rc e n t w t: 0 ( - 2 ) + 0 ( - 3 )
-2.1 57
-7 0 .2 8
M
lo w e r d e c i l e
3.841
1306
H
upper d e c i l e
-2 .4 5 5
-1433
H
3.697
3.322
3.264
4.429
14.92
1141
1060
1536
B
K
L
0
-2.551
-8 1 7 .2
0
Amblystegium
noterophilum
IO th p e r c e n t i l e
2 5th p e r c e n t i l e
S
-46-
Table 9.
Means o f th e dependent and independent v a r ia b le s computed from
th e mean values from each o f th e 143 samples.
These means may
be used i n c o n ju n c t io n w i t h th e r e g r e s s io n c o e f f i c i e n t s l i s t e d
in Table 8.
V a r ia b le
8454/m2
INSECTS
P l ecop tera
Aovoneuvia paoifica
o th e r s to n e flie s
Ephemeroptera
EphemeveZla infvequens
Baetis sp.
Pavaleptophlehia sp.
T r ic h o p te r a
Ochvotvichia sp.
Glossosoma sp.
Rhyaeophila sp.
C o le o p te ra :
PLANTS
Optiosewus sp.
,
Amhlystegium notevophilum
Rovippa nastuvtiujn-aquaticum
Zanniehellia palustvis
algae
sample depth
c u rre n t v e lo c ity
sample w e ig h t
mode phi c la s s
lo w e r
lo w e r
in n e r
upper
upper
Mean
d e c i l e s h o rtn e ss
q u a r t ! I e shortness
q u a r t i l e shortness
q u a r t i l e shortness
d e c i l e s h o rtn e ss
1626/m2
43.45/m 2
1583/m2
2108/m2
1463/m2
414.1/m2
2 3 0 .0/m2
915.4/m2
528.0/m 2
228.6/m2
158.8/mZ
3805/m2
441.8 g/m2
429.2 g/m2
9.018 g/m2
3.603 g/m2
p re s e n t i n 10.49%
(15) o f th e samples
0.2347 m
0.4101 m/sec
5936 g
0 ( - 4 . 042)
2.858
4.422
2.776
1.801
1.101
0'
0
0
0
0
-4 7 T a b le ' 9 (c o n tin u e d )
V a r ia b le
Mean
re g r e s s io n s
A-P
p e rc e n t
w e ig h t
in
phi c la s s e s
p e r c e n t i le s
4
3
2
I
O
-I
-2
-3
-4
-5
-6
-7
[2 ] +
[0 ] +
>2] +
0.25 '
I
5
10
25
50
75
90
•
7.329%
6.451%
6.676%
4.840%
6.199%
10.01%
18.94%
25.45%
13.30%
.8196%
13.78%
11.46%
16.12%
.4246
-2.2 17
-4 .5 1 9
-5.611
-6 .3 5 6
0
0
0
0
0
4.153
2.995
1.799
I .003
-1.6 65
-4.4 15
-5 .5 6 9
-6.3 1 9
0
0
0
0
0
0
0
0
dummy v a r ia b le s (7) t o
account f o r th e l o n g i t u ­
d in a l v a r i a b i l i t y i n th e
stream s e c tio n s (8)
stream s e c tio n s
tim e
.6904%
2.751%
6.282%
5.775%
.
[1 ]
[-1 ]
[-3 ]
re g r e s s io n s
Q-U
I i near
cu b ic
q u a d r a tic
9 538 ( b iw e e k ly sampling
•jjy g date s numbered conTpoc s e c u t i v e l y from I
th ro u g h 18)
-4 8 -
lo n g e r be s i g n i f i c a n t .
w ill
s till
An
F t e s t (as d e s c rib e d in Table 10) however,
show s i g n i f i c a n c e o f th e group o f param eters, j u s t as th e
s ta tis tic w ill
t
i n d i c a t e s i g n i f i c a n c e i f o n ly one param eter i s used.
Substrate.
Parameters used t o re p r e s e n t s u b s t r a t e - s i z e d i s t r i b u ­
t i o n in th e i n i t i a l
r e g r e s s io n models (re g re s s io n s A and B, Tables 5
and 6) were th e percentage w e igh t, in each o f th e s iz e - c la s s e s 0 [ - 7 ]
th ro u g h 0 [ 1 ]
( 0 [ 2 ] was o m itte d
here due t o th e s t a t i s t i c a l
t h a t th e percentages do n o t t o t a l
n e c e s s ity
1 0 0 ), th e 1 0 th , 2 5 th , 50th (m e d ia n ),
75th and 90th p e r c e n t i l e s , th e mode s i z e - c l a s s , and. th e t o t a l sample
w e ig h t.
In subsequent models (re g re s s io n s C thro ugh P, Tables 5 and 6 ) ,
v a r io u s c o m b in a tio n s o f the se p lu s a d d i t i o n a l parameters were used.
These in c lu d e d th e 50th ( re g re s s io n s C and D ) , and th e 10 th and 25th
p e rc e n tile s
( re g re s s io n s K, L, N, 0) as th e o n ly p e r c e n t i l e s in c lu d e d ,
th e s h o rtn e ss o f th e in n e r q u a r t i l e in phi u n i t s
( re g re s s io n s C and D ),
th e s h o rtn e ss o f th e lo w e r and upper q u a r t i l e s and d e c i le s both
s e p a r a te ly and t o g e t h e r (re g re s s io n s H - J ) , and th e combined lower
s iz e - c la s s e s — 0 [ 2 ] + 0 [ 1 ] , 0[O ] + 0 [ - l ] , 0 [ - 2 ] + 0 [ - 3 ]
K, M, N, P).
From th e s e analyses i t
(re g re s s io n s
became e v id e n t t h a t , w h ile e x p la ­
n a t o r y power o ver dependent v a r ia b le s was i n independent v a r ia b le s
d e s c r ib in g th e m id d le s u b s t r a t e s iz e range and le s s e r power in the
upper range (Tables 7 and 8 ) , th e s t r o n g e r e x p la n a to r y power was in
th o s e v a r ia b le s d e s c r ib in g th e s m a lle r s u b s t r a te s iz e s .
The I Oth and
25th p e r c e n t i l e s and th e sho rtn e ss o f th e lo w er d e c i l e were s i g n i f i c a n t
-4 9 -
t o Tl o f th e 13 i n s e c t t a x a ; th e lo w e r q u a r t i l e was s i g n i f i c a n t t o 6
ta xa .
O ther s u b s t r a te parameters were s i g n i f i c a n t o n ly o c c a s i o n a lly .
The i n i t i a l
c a l c u l a t i o n s o f s u b s t r a t e parameters were based on
data f o r th e d i s t r i b u t i o n i n s iz e - c la s s e s 0 [ - 7 ] th ro u g h 0 [ 2 ] o n ly .
Though data were a v a i l a b l e f o r phi c la s s e s [ 3 ] th ro u g h [ 5 + ] , th e y were
ig n o re d because the.mesh s iz e o f th e sampler n e t (36 th re a d s/cm ) a llo w e d
some p a r t i c l e s le s s than 0.25 mm ( 0 [ 2 + ] ) t o pass th ro u g h .
However,
c o n s id e r a b le q u a n t i t i e s le s s than t h i s s iz e were r e ta in e d by th e n e t
and scooped o u t o f th e sampler by hand.
Because th e re g r e s s io n s models
showed s i g n i f i c a n c e down t o th e s m a lle s t s iz e - c l a s s ( 0 [ 2 ] ) in c lu d e d t o
t h i s p o i n t , th e s iz e - c l a s s percentages were r e c a lc u la t e d t o in c lu d e
s u b s t r a t e in c la s s e s 0 [ 3 ] th ro u g h 0 [ 5 + ] ; th e p e r c e n t i le s were r e c a lc u ­
la t e d and th e 0 . 2 5 t h , 1 s t , and 5 th p e r c e n t i l e s were a ls o d eterm ined .
These r e v is e d data were used i n subsequent re g r e s s io n s (re g re s s io n s Q
th ro u g h U).
I t had t o be assumed t h a t t h i s bias o f th e lo s s o f some
p a r t i c l e s le s s than 0.25 mm was r e l a t i v e l y p r o p o r t io n a l i n a l l
in d iv i­
dual samples.
The subsequent models developed ( re g re s s io n s Q th ro u g h U, Tables
5 and 6) showed t h a t th e 0 .2 5 th th ro u g h I Oth p e r c e n t i l e s as r e p r e s e n ta ­
tiv e s o f s u b s tra te d i s t r i b u t i o n
th e m a j o r i t y o f t a x a .
(Tables 7 and 8) were s i g n i f i c a n t t o
To dete rm in e w hether th e p e r c e n t i l e s o r th e
s iz e - c l a s s percentages had g r e a t e r s i g n i f i c a n c e in r e l a t i o n t o th e
o t h e r , both groups were excluded i n d i v i d u a l l y and s im u lta n e o u s ly from .
-5 0 what o th e rw is e was th e f i n a l r e g r e s s io n model - - r e g r e s s io n S (Tables
5, 6, 1 6 ).
I,
F t e s t s (Table 10) in d ic a t e d t h a t th e p e r c e n t i l e s ( 0 .2 5 ,
5, 10) had f a r g r e a t e r s i g n i f i c a n c e t o v i r t u a l l y a l l
o f th e in s e c t
ta xa than d id th e s iz e - c la s s e s r e g a r d le s s o f whether o r not th e l a t t e r
were in c lu d e d in th e r e g r e s s io n .
Thus th e IO th and 25th p e r c e n t i le s
and th e lo w e r d e c i l e and q u a r t i l e s were co n sid e re d th e best r e p r e s e n ta ­
t i v e s o f s u b s t r a te d i s t r i b u t i o n u s in g th e data e x c lu d in g s iz e - c la s s e s
0 [ 3 ] t o 0 [ 5 + ] , w h ile th e 0 .2 5 , 1 s t , 5th and 10th p e r c e n t i l e s were th e
most s i g n i f i c a n t r e p r e s e n t a t iv e s u s in g data f o r a l l o f th e s iz e c la sse s measured ( 0 [ - 7 ] th ro u g h 0 [ 5 + ] ) .
No new re g r e s s io n s were com­
puted w i t h th e a d d i t i o n a l data u s in g th e 10th and 25th p e r c e n t i le s o r
th e lo w e r d e c i l e and q u a r t i l e s as th e o n ly s u b s t r a te param eters, but
i t can re a s o n a b ly be assumed t h a t t h e i r s i g n i f i c a n c e would have changed
little .
The a c tu a l c o n t r i b u t i o n by w e ig h t o f s iz e - c la s s e s 0 [ 3 ] to
0 [5 + ] compared t o t o t a l
sample w e ig h t was s l i g h t (2.75%) and thus
a l t e r e d th e va lu e s o f th e o r i g i n a l parameters o n ly s l i g h t l y .
Plants as inde-pendent variables.
Regressions in which each o f th e
p la n t species was considered an independent v a r ia b le
(Tables 5 and 6)
in d ic a t e d t h a t each species was s i g n i f i c a n t l y c o r r e la t e d t o several
in s e c t ta x a (T able 8 ) .
Because the s ig n o f th e
t v a lu e s tended to be
c o n s is t e n t w i t h i n species but to v a ry among them, i t was deemed un­
d e s i r a b le t o c o n s id e r th e t o t a l q u a n t i t y o f a l l th r e e sp e cie s combined
as a s in g l e independent v a r i a b l e beyond th e i n i t i a l
r e g r e s s io n s .
-51 T ests o f F between r e g r e s s io n s .
R efer t o T ab le 5 f o r th e
com plete s e t o f independent v a r ia b le s in c lu d e d in each
r e g r e s s io n .
Table 10.
jp
—
(«?«£>. a - s. 5« h ) / (.fl • a ~ f I " b )
r e s id u a l m.s.
( re g . a - re g . b)
sum o f squares
due t o r e g r e s s io n
f _ degrees o f
^' "
freedom
*
m* s * "
mean square
e rro r
An a l t e r n a t e method f o r c a l c u l a t i n g F between any o f th e re g re s s io n s i n
t h i s s tu d y (Table 5) i s t o use th e f o l l o w i n g fo rm u la w i t h th e i f 2 , n ,
and f va lu e s from T ab le 6.
F
(if2a - i?2h ) / ( . f l . a
Tl - if^s
f]
( re g . a - re g . b)
DISTRIBUTION
POINTS
OF
(.fI • a - f I • h )
4
7
r
2
3
0.250
0.100
0.050
0.025
0,010
0.005
0.001
1.40
2.34
3 .05
3.77
4.75
5.46
7.22
1 .39
2.12
2.66
3.20
3.91
4.44
5.69
1.37
1.98
2.43
2.86
3.44
3.86
4 .85
1.31
1.76
2.07
2.36
2.75
3.01
3.67
)
F
9
10
1.29
1.67
1.94
2.19
2.52
2.73
3 .28
1.28
1.64
1 .89
2.13
2.43
2.63
3 .14
S i g n i f i c a n c e o f th e sho rtn e ss o f lo w e r and upper q u a r t ! Ie s and
d e c ile s .
Regression P a ir
Independent
V a r ia b le s Tested
(f-|.a - f i- h )
INSECTS
H —
I
H ----
J
low er and upper
d e c i le s
low er and upper
q u a r t ! Ie s
2
2
13.17
4 .46
-5 2 -
T ab le 10 ( c o n tin u e d )
b)
S i g n i f i c a n c e o f th e p e rc e n t w e ig h ts i n th e s iz e - c l a s s com bin a tio n s o f
0 [ 2 ] + 0 [ 1 ] , 0[O ] + 0 [ - l ] , 0 [ - 2 ] + 0 [ - 3 ] , th e I Oth and 25th percen­
t i l e s , stream s e c t io n s , and c o m b in a tio n o f th e stream s e c tio n s w i t h
th e s u b s t r a te param eters.
Independent
V a r ia b le s Tested
( A •a ”
•b^
INSECTS
K -M
K - N
O
I
v:
Regression p a i r
K -P
phi
groups
p e r c e n t i le s
s e c tio n s
s e c t io n s ,
phi groups
s e c t io n s ,
p e rc e n tile s
3
2
7
10
9
0.91
12.22
7.84
6.69
12.02
5.49
K -L
2.58
1.18
5.48
3.93
Acroneuvia
yacijisca
4.01
0.84
2.64
2.54
o th e r s to n e flie s
2.60
1.16
5.55
3.99
5.54
2 .2 2
3.56
4 .88
4 .1 6
5,28
1.45
5.19
4.40
3.73
5.68
0.90
2.33
2.56
2.17
2.48
4.61
I .66
1 .49
2.67
1.39
1.55
2.24
1.13
0.29
16.69
13.58
1.07
0.62
2.72
3.05
3.61
6.27
2 .9 0
3 .5 0
3 .3 0
4 .4 9
6.18
5.55
3.24
5.08
0.37
7.07
. 4.19
3.99
7.18
P l ecop tera
Ephemeroptera
Ephemevella
infvequens
Baetis S p .
Pazaleptoiphlebia
sp.
T r ic h o p te r a
Oohvotvichia sp.
Glossosomo, sp.
Rhyacophila sp.
C o !e o p te ra : '
Opttosevvus sp.
.
2.21
-5 3 -
Table 10 (co n clu d e d )
c)
S i g n i f i c a n c e o f p e rc e n t w e ig h ts i n s iz e - c la s s e s 0 [ 4 ] , 0 [ 3 ] , 0 [ 2 ] ,
and 0 [ 1 ] , and th e 0 . 2 5 t h , 1 s t , 5 t h , and I Oth p e r c e n t i l e s .
Regression P a ir
Q - R
Q - S
R - T
S - T
Independent
V a ria b le s Tested
p e rc e n tile s
phi
c la s s e s
phi
c la s s e s
p e r c e n t i le s
4
4
4
4
6.85
1.54
1.22
6.65
3.03
3.04
2.90
0.83
4 .4 0
0.91
0.17
6.27
0.25
2.40
4 .80
2.26
2.33
2.75
1.64
1 .75
0.75
0.91 '
0.80
0.76
1.09
1 .09
1 .04
1.92
2.75
3.40
1.92
2.99
6.41
5.36
3.59
1.34
3.76
4.38
0.88
1.08
5.58
7.64
1 .04
0.55
8.45
8.75
3.85
0.81
4 .3 6
0.34
1.43
5.73
Vl'.a - A-b'
INSECTS
P le c o p te ra
Acroneuria paeifica
o th e r s to n e flie s
Ephemeroptera
Ephemerella infrequens
Baetis sp.
EaFdleptophlebia sp.
T r ic h o p te r a
Oehrotrichia sp.
Glossosoma sp.
Rhyaeophila sp.
C o le o p te r a :
Optioservus sp.
-5 4 -
Because each o f th e p l a n t species tended t o be s i g n i f i c a n t t o seve ra l
i n s e c t ta x a i n th e i n i t i a l
r e g r e s s io n s , th e y were in c lu d e d i n subse­
quent models as w e ll as th e f i n a l model chosen — r e g r e s s io n S (Table
1 6 ).
The dummy v a r i a b l e in s e r t e d t o note th e occu rre n ce o f s i g n i f i c a n t
q u a n t i t i e s o f f ila m e n to u s alg a e mixed w i t h th e h ig h e r a q u a tic p la n ts
(15 o f th e 143 samples) proved i n s i g n i f i c a n t i n i n i t i a l models and was
n o t in c lu d e d in subsequent r e g r e s s io n s .
Othev variables.
The l i n e a r , q u a d r a tic and c u b ic f a c t o r s o f tim e
in s e r t e d t o a d j u s t th e re g r e s s io n s f o r seasonal v a r i a t i o n s were s i g n i f i ­
c a n t as determ ined from th e i n d i v i d u a l
t values (see T ab le 1 6 ).
The
dummy v a r ia b le s in s e r t e d t o account f o r p o s s ib le l o n g i t u d i n a l v a r i a t i o n s
along th e s tu d y area
not
accounted f o r by measured v a r ia b le s were a ls o
s i g n i f i c a n t as a group as determ ined from th e d i f f e r e n c e i n th e
between re g r e s s io n s K and N (Table 10b ).
F te s t
Both th e f a c t o r s f o r tim e and
stream s e c t io n were thus in c lu d e d i n most subsequent r e g r e s s io n s ,
i n c lu d in g th e f i n a l model.
d is trib u tio n fo r a ll
(The s e c t io n a l d if f e r e n c e s in s u b s tr a te
samples are summarized in Table 13 and th e sec­
t i o n a l d i f f e r e n c e s i n p l a n t biomass and in s e c t numbers a re summarized
i n Tables 14 and 15 r e s p e c t i v e l y . )
C u rre n t v e l o c i t y measurements in c lu d e d in r e g r e s s io n s A through
D, F and G, were s i g n i f i c a n t l y c o r r e la t e d o n ly to th e w a te rc re s s and
th e t o t a l w e ig h t o f a l l
t h r e e p l a n t species (Table 7 ) .
Depth was a ls o
s i g n i f i c a n t l y c o r r e la t e d t o th e w a te r c r e s s , but u n l i k e c u r r e n t v e l o c i t y ,
-55th e c o r r e l a t i o n m a t r ix a ls o in d ic a t e d s e v e ra l s im p le c o r r e l a t i o n s o f
depth t o o t h e r t a x a .
Because both v a r ia b le s were i n s i g n i f i c a n t l y c o r r e ­
la t e d t o o t h e r ta xa in th e r e g r e s s io n analyses i t s e l f however, th e y
were n o t co n sidered beyond th e i n i t i a l
Plants as dependent variables.
r e g r e s s io n models.
The independent v a r ia b le s which
were s i g n i f i c a n t t o each p l a n t ta xa in tho se re g r e s s io n s
(A, C, E, F5
H, U, Table 5) in which th e p la n t s were considered as dependent v a r i ­
a b le s are in c lu d e d in Table 7.
th e i n i t i a l
Because th e re g r e s s io n s subsequent t o
ones were r e f i n e d p r i m a r i l y f o r th e in s e c t t a x a , no f i n a l
model was developed e x c l u s i v e l y f o r th e p l a n t ta x a .
However, th e
independent v a r ia b le s which were s i g n i f i c a n t i n d i c a t e t h a t th e tre n d
w i t h r e s p e c t t o s u b s t r a te s iz e was s i m i l a r t o t h a t f o r most in s e c t
ta x a .
In g e n e r a l, s i g n i f i c a n t n e g a tiv e r e l a t i o n s h i p s r e s u lt e d f o r
param eters r e p r e s e n t in g l a r g e r s u b s t r a t e and s i g n i f i c a n t p o s i t i v e
r e l a t i o n s h i p s f o r parameters r e p r e s e n t in g s m a lle r s u b s t r a t e .
This
tr e n d i s g e n e r a ll y t y p i c a l f o r both th e moss and th e w a te r c r e s s , as
w e ll as f o r th e combined p l a n t biomass.
No s i g n i f i c a n t c o r r e l a t i o n s
t o th e pondweed, which c o n t r ib u t e d le s s than one p e rc e n t o f th e t o t a l
p l a n t biomass (Table 1 4 ) , r e s u lt e d between any o f th e s u b s t r a t e o r
o t h e r parameters in any o f th e r e g r e s s io n models.
-56-
'Prediction of change in the quantity of organisms
with changes in magnitude of the inde-pendent variables
Substrate.
The mean s u b s t r a te d i s t r i b u t i o n curve ( F ig u re 4a)
determ ined by summing th e i n d i v i d u a l sample percentages i n each s iz e c la s s
(T able 13) i s e s s e n t i a l l y bim od al.
i s a t a p p ro x im a te ly 0 [ - l ]
The low p o i n t between modes
(2 mm) and th e mode r e p r e s e n t in g th e l a r g e r
s u b s t r a te s iz e s peaks a t n e a r ly 0 [ - 5 ]
(64 mm).
The l a t t e r i s about
f o u r tim es th e magnitude o f th e broad mode a t 0.[2] t o 0 [O ] (0 .1 2 5 1 .0 mm) r e p r e s e n t in g th e s m a lle r s iz e s .
To g r a p h i c a l l y r e p re s e n t th e
changes in ta xa numbers as th e f o u r lo w e s t p e r c e n t i le s
and 10 ) v a r y from th e mean d i s t r i b u t i o n , a l l
( 0 .2 5 , I , 5,
f o u r p e r c e n t i l e s have
been a r b i t r a r i l y s h i f t e d by th e same degree ( F ig u re 4 a ) .
The c o r r e s ­
ponding q u a n t i t a t i v e changes p r e d ic te d i n th e n in e i n s e c t ta x a which •
were s i g n i f i c a n t l y r e la t e d t o th e p e r c e n t i l e s in r e g r e s s io n S (Table
10c) are re p re s e n te d i n F ig u re 4b.
A l l n in e o f these ta x a show t h a t as
th e s u b s t r a te co m p o s itio n i s p r o p o r t i o n a l l y d i s t r i b u t e d toward the
s m a lle s t s u b s t r a te s iz e s , p r e d ic te d numbers in c re a s e .
I t would a ls o
be p o s s ib le t o dem onstrate changes i n ta x a numbers w i t h s h i f t s o f th e
p e r c e n t i l e s t o any o t h e r degree o r even i f
changed i n d i v i d u a l I y by
u sin g th e c o rre s p o n d in g r e g r e s s io n c o e f f i c i e n t s and mean va lu e s (Tables
8 , 9, and 1 6 ).
A s i m i l a r tr e n d toward g r e a t e r numbers o f in s e c t ta x a w i t h
Figure 4. Deviation of the four low est percentiles (0.25, I, 5, 10) from their means and the predicted
change in number of each insect taxon which was significant to these percentiles at the 5 percent level.
a) The mean substrate distribution ("0") determined by averaging the percent weights in each phi
c la ss from each of the 143 sam ples (Table 13). The curves of the hypothetical substrate d is­
tributions (I 5 , I, - I , -2 , -3) were calculated after shifting all four percentiles as a group by
the amount in phi units indicated. All hypothetical distributions are well within ranges found
in individual sam ples.
b) The predicted change in number of each insect taxon (9 of the 13 taxa) which were significant
in the final model to changes in the four low est percentiles. The F statistics are from Table
Percentile location (phi units)
percentile
0.025
>
- I
Q
-2
(5.563)
(5.153)
4.153
3.153
2.153
1.153
4.495 3.299 2.503
3.995 2.799 2.003
2.995 1.799 1.003
1.995 0.799 0.003
0.995 -0.221 -0.997
-0.005 -1.221 -1.997
50th percentile
(-4.415) —
75th percentile
" (-5.569)
90th percentile _J
(-6.319)
^"25th percentile
(-1.665)
0 CLASS
.0625 .125
0.625 .125 .250
b)
Y " Y + b0.25(P) + bI(Q ) + b5 (r) + b i 0 (s)
qraph lin e
p , q, r , s = X p e rc en tiIe - X p e rc en tiie
—
14000- 3500-
x 0.25 = 4 .1 5 3
Xi
= 2.995
350-
X 5 = 1.799
X io = 1.003
F a -b
12000- 3000-
300- 1=1
XEP
Y IN
YEp
10000- 2500-
Xop
250- XTR
YAc
= 230.0
= 228.6
= 2108
= 8454
= 1463
= 3805
: 915.4
= 528.0
= 43.45
+
+
+
+
-
89.38(p)
107.5(p)
2 9 3 . 5(p)
12 3.0(p)
3 9 8 .2 (p)
9 5 8 .0(p)
5 4 .3 3 (p)
1 7 2 .2 (p)
31.31(p)
+ 3 1 .9 8 (q)+ 1 7 8 .2 (q)- 21 5.3(q) - 91.89(q) + 1 2 5 .4 (q)- 10 76(q)+
+ 3 0 1 .7 (q)+ 14 7.6(q)+
+ 3 9 .8 2 (q)+
71.93(F) +
262.4(F) +
160.9(F) +
2 7 1 .1 ( f ) +
184.2(F) +
380.1(F) +
12 7 .4 ( f ) +
49.60(F) 20.63(F) -
195.9(s)
246.9(5)
1228(5)
2569(s)
1021 (s)
864.7(5)
62.15(s)
146.8(5)
20.80(5)
CXJ
E
8000- 2000 -
200-
k■
Od
=C
S
3 6000- 1500H 150Z
4000- 1000-
2000■
100-
500-
50-
-
I
-3
I
I
-2
I
I
I
"I
-I
0
DEVIATION OF PERCENTILES (0 units)
I
T
I
T
p r o p o r t i o n a l l y s m a lle r s u b s t r a t e p a r t i c l e s i s noted i n t h e o t h e r sub­
s t r a t e param eters n o t in c lu d e d in th e f i n a l r e g r e s s io n model (Table 8 ) .
The most s i g n i f i c a n t o f these t o th e m a j o r i t y o f ta xa were th e IO th and
25th p e r c e n t i le s and th e lo w e r d e c i le s and q u a r t i l e s , a lth o u g h o th e r
s u b s t r a te parameters were o c c a s i o n a lly s i g n i f i c a n t .
S im ila r p re d ic ­
t i o n s o f numbers as g ive n in F ig u re 4b can be made u s in g th e r e g r e s ­
s io n c o e f f i c i e n t s l i s t e d , in Table 8 w i t h th e means l i s t e d
i n Table 9 .
Examination o f th e parameters r e p r e s e n t in g th e s m a lle s t s u b s tr a te
s iz e s ( th e 0 .2 5 th th ro u g h I Oth p e r c e n t i l e s , th e s m a lle s t s u b s t r a te
c la s s e s , th e lo w er d e c i l e - - Table 8 ) show t h a t th e s ig n s o f th e
r e g r e s s io n c o e f f i c i e n t s o f ta xa s i g n i f i c a n t to these v a r ia b le s are
p re d o m in a n tly p o s i t i v e .
Thus, g r e a t e r numbers o f in s e c t s are g e n e r a ll y
p r e d ic te d when t h e r e i s a r e l a t i v e l y g r e a t e r p r o p o r t io n o f s u b s tr a te
i n th e s iz e - c la s s e s from a p p ro x im a te ly 0 [ 2 ] t o 0 [ O ] .
However, exam­
i n a t i o n o f parameters r e p r e s e n tin g th e lo w e r-m id d le s u b s t r a t e d i s t r i ­
b u tio n (2 5 th and 50th p e r c e n t i l e s , sh o rtn e s s o f th e lo w e r and in n e r
q u a r t i l e , percentages in th e s iz e - c la s s e s 0 [ - l ] th ro u g h about 0 [ 4 ] ) ,
show t h a t g r e a t e r numbers o f taxa a re c o n c u r r e n t ly p r e d ic te d when th e
d i s t r i b u t i o n o f s u b s t r a te in t h i s s iz e range (about 2-16 mm) i s p ro ­
p o r t i o n a l l y toward th e l a r g e r p a r t i c l e s .
p a i r s o f th e I Oth and 25th p e r c e n t i le s
The Tl r e g r e s s io n c o e f f i c i e n t
(Table 8 ) c o rre s p o n d in g t o th e
s i g n i f i c a n t taxa show t h a t th e c o e f f i c i e n t s f o r th e 10t h p e r c e n t i l e
are a l l
p o s i t i v e w h ile tho se f o r th e 25th p e r c e n t i l e are a l l
n e g a tiv e .
-6 0 -
These p e r c e n t i l e s l i e on e i t h e r s id e o f th e low p o i n t a t about 0 [ 1 ]
( F ig u re 4a) in th e mean s u b s t r a te d i s t r i b u t i o n .
L ik e w is e , th e same
t r e n d o f o p p o s ite s ig n s occurs f o r th e s i x c o e f f i c i e n t p a i r s o f th e
lo w e r d e c i l e and q u a r t i l e .
In summary, th e g r e a t e s t numbers in th e
in s e c t taxa are p r e d ic te d t o be p re s e n t when th e s u b s t r a te d i s t r i b u t i o n
by w e ig h t i s d i s t i n c t l y low a t about th e 0 [ - l ]
s i z e - c l a s s , p r o p o r t io n ­
a l l y h ig h between th e s iz e - c la s s e s from about 0 [ 2 ] t o 0 [ O ] , and p ro ­
p o r t i o n a l l y high from beyond s iz e - c l a s s 0 [ 1 ] t o about 0 [ 4 ] .
The s i g n i ­
f ic a n c e o f t h i s a spe ct o f th e s u b s t r a t e d i s t r i b u t i o n a long w i t h i t s
r e l a t i o n s h i p t o o t h e r v a ria b le s , w i l l
be discussed l a t e r .
Plants as indeipendent variables.
Taxa which were s i g n i f i c a n t l y
c o r r e la t e d t o each o f th e th r e e p la n t species (Table 8 ) i n th e f i n a l
r e g r e s s io n model, r e g r e s s io n S (Table 1 6 ) , and th e p r e d ic te d changes in
numbers w i t h changes i n each p l a n t ' s biomass are shown i n F ig u re 5.
t s t a t i s t i c s from t h i s model i n d i c a t e t h a t t h r e e in s e c t ta x a ( T r ic h o p t e r a ,
Ockrotvichia sp. and Glossosoma s p . ) are n e g a t i v e l y c o r r e la t e d to th e
moss
{Amblystegium notevo-philum), b u t one taxon [Paraleyto-Phlebia s p . )
is p o s it iv e ly c o rre la te d .
The model a ls o in d ic a te d t h a t t h r e e taxa
( I n s e c t s , P le c o p te r a , and " o t h e r s t o n e f l i e s " ) are n e g a t i v e l y c o r r e la t e d
t o th e w a te rc re s s
[Rorippa nasturtium-aquatieum) and t h r e e taxa
( I n s e c t s , T r ic h o p t e r a and
th e pondweed
Optioservus sp.) are n e g a t i v e l y c o r r e la t e d t o
{Zanniehellia palustris).
t s t a t i s t i c s from re g r e s s io n T
(Table 8 ) however, show a c o n s id e r a b le d i f f e r e n c e ( F ig u re 5) in the
-61 F ig u re 5.
P r e d ic te d changes i n th e number o f each in s e c t taxon which
was s i g n i f i c a n t l y r e la t e d (5 p e rc e n t l e v e l ) t o th e q u a n t i t y o f each p l a n t
species i n r e g r e s s io n S ( th e f i n a l model) and r e g r e s s io n T. The general
r e g r e s s io n fo rm u la i s J 1- = Yj + Zj1- ( j p - X p), where i r e f e r s t o in s e c t
taxa and p t o p l a n t t a x a . The r e g r e s s io n c o e f f i c i e n t s and t s t a t i s t i c s
are from T a b le 8 , and th e p l a n t and i n s e c t means from T a b le 9.
r e g r e s s io n S — s o l i d l i n e
r e g r e s s io n T — broken l i n e
a) Amblysteqium noterophilum (moss)
_________R eg ressio n S (solid lin e )_________
Yt R
Y Pa
YQc
Yg i
= 9 1 5 .4 - 0 .6 6 5 6
= 2 3 0 .0 + 0.3475
= 5 2 8 .0 - 0.5045
= 228.6 - 0.1693
13,00011,000
-
( X - 4 2 9 .2 ) ,
( X - 4 2 9 .2 ) ,
( X - 4 2 9 .2 ) ,
( X - 4 2 9 .2 ) ,
t = -3 .1 7 7
I = +4.654
t
-2 .5 1 0
t = -2 .6 7 3
R egression T (broken lin e )_______
Yin
Xop
XMXOS
XPa
Z
8454 + 3.793 (X - 4 2 9 .2 ) ,
= 3 8 05+ 2.708 ( X - 4 2 9 .2 ) ,
1626 + 0.7584 (X - 4 2 9 .2 ) ,
= 1583 + 0.7225 (X - 4 2 9 .2 ) ,
= 23 0.0 + 0.3201 (X - 4 2 9 .2 ) ,
= 2 2 8 .6 -0 .1 7 8 0 ( X - 4 2 9 .2 ) ,
= 43.45 + 0.03596 (X - 4 2 9 .2 ) ,
UiStcJJ1----
9000C
X
J
E
7000
5000
---------
O 3000LO
Z
LU
26002200
on
LU
QD
18001400-
O
O
O
1200'
1000-
LU
on
Cl.
800
600400200-
0
PERCENT OF MEAN DRY WEIGHT (XI OF MOSS
t = + 4 .0 2 0
t = + 5 .0 3 4
t = +2.645
t = + 2 .5 4 3
t = + 5 .4 3 5
t = -3 .5 2 0
t = +3.380
-62-
b) Rorippa nasturtium-aquaticum (watercress)
8600 H
X 82004
8000 H
78004
z 17004
% 15004
13004
PERCENT OF MEAN DRY WEIGHT (X) OF WATERCRESS
-63-
PREDICTED NUMBER OF INSECTS I m
c) Zannichellia palustris (pondweed)
PERCENT OF MEAN DRY WEIGHT (X) OF PONDWEED
-64s i g n i f i c a n t in s e c t ta x a and t h e i r p r e d ic te d numbers t o th e p l a n t s .
ta xa ( I n s e c t s , P le c o p te r a ,
S ix
Aaroneur-Lapacif-Ioa3 " o t h e r s t o n e f l i e s " ,
Pcfraleptophlebia sp. and Optioservus s p . ) are now s i g n i f i c a n t l y c o r r e ­
la te d p o s i t i v e l y t o th e moss, w h ile
c o r r e la t e d t o i t .
Glossosoma sp. i s s t i l l n e g a t iv e ly
The o n ly change in th e c o r r e l a t i o n s t o th e w a te r­
c re s s i s t h a t th e in s e c t taxon i s no lo n g e r s i g n i f i c a n t t o i t .
The
t h r e e ta xa s i g n i f i c a n t l y c o r r e la t e d n e g a t i v e l y t o th e pondweed in
r e g r e s s io n S are no lo n g e r s i g n i f i c a n t in r e g r e s s io n T, but
Glossosoma
sp. i s now s i g n i f i c a n t l y c o r r e la t e d n e g a t i v e l y t o pondweed i n th e
l a t t e r r e g r e s s io n .
The c o n s id e r a b le v a r i a t i o n in th e s i g n i f i c a n c e o f
th e in s e c ts t o th e p la n t s between the se two r e g r e s s io n s , and a
r a t i o n a l e o f which r e g r e s s io n appears t o be more a p p r o p r i a t e , w i l l
discussed l a t e r .
be
DISCUSSION
Evaluation of the results
The v a r ia b le s in c lu d e d in th e m u l t i p l e r e g r e s s io n (Table 5) chosen
as th e f i n a l m odel, r e g r e s s io n S (T able 1 6 ) , accounted f o r over 62 p e r ­
cent
= 0.6227, Table 16a) o f th e v a r i a t i o n i n th e i n s e c t taxon ( th e
sum o f a l l in s e c t num bers).
The
R
s t a t i s t i c s p lu s th e
F s ta tis tic s
( v i r t u a l l y a l l o f w hich were s i g n i f i c a n t a t le s s than th e 0.1 p e rce n t
l e v e l ) from a l l
re g r e s s io n s (Table 6 ) i n d ic a t e s t h a t a v e r y s u b s t a n t ia l
p o r t io n o f th e v a r i a t i o n r e l a t i n g t o th e m i c r o d i s t r i b u t i o n o f th e
in s e c ts was accounted f o r .
Snedecor and Cochran (1967) s t a t e t h a t , ,
even when th e v a r ia b le s in c lu d e d in a r e g r e s s io n are s t a t i s t i c a l l y
s ig n ific a n t, i t
i s n o t uncommon t o f i n d t h a t th e percentage o f th e
v a r ia n c e o f th e dependent v a r i a b l e a t t r i b u t e d to th e r e g r e s s io n i s
much le s s than 50 p e rc e n t.
V a r i a t i o n n o t accounted f o r in m u l t i p l e
r e g r e s s io n a n a ly s e s , a cc o rd in g t o Snedecor and Cochran, are due to
v a r ia b le s not co n sid e re d im p o r t a n t , v a r ia b le s n o t f e a s i b l e t o measure,
and unknown v a r i a b l e s .
stu d y w i l l
Some o f the se p o s s i b i l i t i e s as a p p lie d t o t h i s
be mentioned l a t e r .
Substrate.
The parameters r e p r e s e n t in g the s u b s t r a te s iz e d i s t r i ­
b u tio n (Tables 7 and 8 ) show t h a t th e g r e a t e s t q u a n t i t y o f both in s e c t
and p l a n t ta x a are r e la t e d t o a bimodal s u b s t r a te d i s t r i b u t i o n by
w e ig h t, s i m i l a r t o t h a t re p re s e n te d by th e mean d i s t r i b u t i o n summed
-66“
from th e i n d i v i d u a l samples ( F ig u re 4 a ) .
The IO th and 2 5 th percen­
t i l e s , th e sh o rtn e s s o f th e lo w er d e c i l e and th e lo w e r q u a r t i l e , and
t o a le s s e r e x t e n t th e percentage w e ig h ts i n th e a p p r o p r ia t e s iz e c la s s e s (T able 8 ) show t h a t 11 o f th e 13 in s e c t ta x a a re s i g n i f i c a n t l y
r e la t e d t o a d i s t i n c t low p o i n t i n th e s u b s t r a t e d i s t r i b u t i o n between
th e two modes.
F u r t h e r , g r e a t e r numbers are r e la t e d t o an in c re a s e in
th e mode r e p r e s e n t in g th e s m a lle s t s u b s t r a t e p a r t i c l e s
(determ ined
p r i n c i p a l l y by th e 0 . 2 5 t h , 1 s t , 5 t h , and IO th p e r c e n t i l e s and th e
lo w e r d e c i l e s h o r tn e s s , b u t a ls o by th e percentages i n t h e co rre s p o n d in g
s iz e -c la s s e s ).
But c o n c u r r e n t l y , g r e a t e r numbers are s i g n i f i c a n t l y
r e l a t e d , though le s s s t r o n g l y , t o a r i s e toward th e mode r e p r e s e n tin g
th e l a r g e r s u b s t r a te p a r t i c l e s
(determ in ed p r i n c i p a l l y by th e 25th p e r ­
c e n t i l e and lo w e r q u a r t i l e , and t o a much le s s e r e x t e n t by th e h ig h e r
p e r c e n t i l e s and c o rre s p o n d in g s i z e - c l a s s e s ) .
L i t t l e s i g n i f i c a n c e was
a t t r i b u t e d t o t h i s mode, however, from near i t s
toward th e l a r g e s t s u b s t r a t e p a r t i c l e s .
peak ( a t about 0 [ - 5 ]
The f a c t t h a t th e se two modes
a re s im u lta n e o u s ly r e l a t e d t o g r e a t e r numbers in th e i n s e c t taxa
i n d ic a t e s t h a t few er numbers are p r e d ic te d i f th e s u b s t r a t e i s com­
posed o f p a r t i c l e s by w e ig h t p r e d o m in a n tly in th e s iz e ranges w i t h i n
e i t h e r one o r th e o t h e r modes.
The r e l a t i o n s h i p t h a t e x i s t s here, th e n ,
i s one where th e g r e a t e s t numbers i n most ta xa are r e l a t e d t o a bimodal
d i s t r i b u t i o n which c o n s is t s o f p a r t i c l e s g r o s s ly grouped i n t o both a
l a r g e r ( r o u g h ly 0 [ - 2 ] t o 0 [ - 6 ] , F ig u re 4a) and a s m a lle r s iz e group
-67“
( 0 [ 4 ] t o 0 [ O ] ).
In th e p u b lis h e d re se a rch r e l a t i n g t o a s s o c ia t io n s between b e n th ic
fauna and s u b s t r a te (Table I ) ,
th e general c o n c lu s io n drawn i s t h a t
g r e a t e r numbers and d i v e r s i t y o f organisms are a s s o c ia te d w i t h e i t h e r
l a r g e r s u b s t r a t e s iz e s o r s u b s t r a te co m p o s itio n s t h a t a re w e l l re p re se n te d by a l l
p a r t i c l e s iz e s .
Hynes (1 970) p o in t s o u t t h a t areas
w i t h l a r g e r stones are g e n e r a ll y more complex and are a s s o c ia te d w it h
g r e a t e r d i v e r s i t y o f fa u n a .
In v i r t u a l l y a l l
o f th e s t u d ie s on sub­
s t r a t e , o n ly p h e n o ty p ic d e s c r i p t i o n s o f areas have been used, neces­
s i t a t i n g th e c o n s id e r a t io n o f s e c tio n s o f streams w i t h g r o s s , r e a d i l y
d is c e rn ib le d iffe re n c e s .
In g e n e r a l, s m a lle r s u b s t r a te s iz e s have been
s tu d ie d o n ly in areas where th e y e x i s t i n a r e l a t i v e l y homogeneous
s t a t e , r a t h e r than in t h e i r p r o p o r t io n and r e l a t i o n t o l a r g e r p a r t i c l e s ,
The q u e s tio n which a r is e s here th e n , i s whether th e r e s u l t s o f t h i s
s tu d y conform t o any o f th e above o b s e rv a tio n s i n p re v io u s s t u d ie s , and
what th e s i g n i f i c a n c e i s o f th e s m a lle r p a r t i c l e s .
I t is r e la t iv e ly
easy t o deduce why l a r g e r s u b s t r a te p a r t i c l e s are f a v o r a b le f o r in s e c t
h a b ita ts .
In clu d e d are a v a i l a b l e space f o r p r o t e c t i o n and f o r a g in g ,
s ta b ility ,
places f o r d e p o s it io n o f f o o d , and g r e a t e r v a r i a b i l i t y o f
m ic r o c u r r e n t s .
L a rg e r p a r t i c l e s were found t o be s i g n i f i c a n t t o some
e x t e n t in t h i s s tu d y .
The reasons why th e s m a lle r s u b s t r a te p a r t i c l e s
were so much more s i g n i f i c a n t w i l l
be co n sid e re d w i t h a d is c u s s io n o f
th e o t h e r v a r ia b le s a f t e r th e l a t t e r have been co n sid e re d i n d i v i d u a l l y .
-68-
Plants as independent variables.
The r e s u l t s from th e f i n a l
r e g r e s s io n model f o r p la n t s as independent v a r ia b le s t o th e in s e c t
ta xa showed t h a t , w i t h one e x c e p tio n
{Pavaleptophlebia sp. t o Ambly-
steginm noterophilum, F ig u re 5 a ), th e few c o r r e l a t i o n s t h a t were s i g ­
n i f i c a n t between in s e c t taxa and th e p l a n t species were n e g a tiv e .
p la n t s them selves a c t as a h a b i t a t f o r many i n s e c t s .
The
They a ls o p r o v id e
them w i t h food e i t h e r d i r e c t l y , o r i n d i r e c t l y by s e r v in g as a s u b s t r a te
f o r p e r ip h y t o n .
In s o r t i n g th e preserved samples in th e la b o r a t o r y , a
s tro n g r e l a t i o n s h i p seemed t o e x i s t between in s e c t numbers and the
q u a n t i t y o f p l a n t s , e s p e c i a l l y th e moss.
T h is o b s e r v a tio n i s s u b s t a n t i ­
ated by th e v e r y s i g n i f i c a n t sim p le c o r r e l a t i o n
( c . c . = 0.5533 , Table
4 ) between th e moss and th e r i f f l e
{Optioservus s p . ) , and
b e e tle la r v a
between th e moss and th e in s e c t taxon as w e ll
it
in itia lly
(c.o. = 0 .3 7 3 5 ).
Thus,
seems s u r p r i s i n g t h a t t h e r e were v i r t u a l l y no s i g n i f i c a n t .
p o s i t i v e c o r r e l a t i o n s i n th e r e g r e s s io n analyses between th e in s e c t
taxa and th e p l a n t s .
T h is m a tte r w i l l
l i k e w is e be discu sse d i n c o n te x t
w i t h th e o t h e r v a r ia b le s a f t e r c o n s id e r in g th e o t h e r v a r i a b l e s i n d i v i ­
d u a lly .
Other independent variables-
The l i n e a r , q u a d r a t i c , and cubic
f a c t o r s o f t im e , in c lu d e d in most r e g r e s s io n s i n c lu d in g th e f i n a l m odel,
compensated f o r u n a vo id a b le seasonal v a r i a t i o n s i n q u a n t i t i e s o f org a n ­
isms d u r in g th e 9-month sampling p e r io d .
Some l i k e l y reasons f o r th e
s i g n i f i c a n c e o f these f a c t o r s in c lu d e changes in h a b i t a t w i t h m a t u r i t y .
-6 9 -
emergence, and seasonal v a r i a t i o n i n th e d r i f t r a t e .
have been m inim ized had i t
a s h o r t p e r io d o f tim e .
These f a c t o r s may
been p r a c t i c a l t o sample i n t e n s i v e l y over
Cummins (1 9 6 2 ), however, d isco u ra g e s a g a in s t
t h i s , e s p e c i a l l y i f a u t e c o lo g ic a l c o n s id e r a t io n s are t o be made.
The dummy v a r ia b le s in s e r t e d to account f o r p o t e n t i a l v a r i a t i o n
between th e e i g h t stream s e c tio n s from which one sample was taken
b iw e e k ly proved s i g n i f i c a n t .
Consequently, th e y were used in most
re g re s s io n s i n c lu d in g th e f i n a l model t o a d j u s t f o r t h i s b ia s .
The
f a c t t h a t these v a r ia b le s proved s i g n i f i c a n t in d ic a t e s t h a t th e re i s
p ro b a b ly some f a c t o r o r f a c t o r s n o t accounted f o r by th e measured v a r i ­
a b le s .
One f a c t o r l i k e l y in v o lv e d i s th e in s e c t d r i f t r a t e from sec­
t i o n t o s e c t io n .
Because th e stu d y area was a headwater s e c t io n , no
d r i f t co u ld e n te r th e area from above.
But i t would be expected t h a t
p r o g r e s s i v e ly g r e a t e r amounts o f d r i f t o ccu rre d downstream thro ugh th e
s e c tio n s u n t i l
e n t e r in g i t .
th e q u a n t i t y le a v in g an area was equaled by th e q u a n t i t y
C o nsequently, because o f t h i s f a c t o r a lo n e , i t would be
expected t h a t g r e a t e r q u a n t i t i e s o f in s e c ts should occu r a t th e low er
s t a t i o n s than th e u pp er, a l l o t h e r f a c t o r s being e q u a l.
The t o t a l
number o f in s e c t s c o l l e c t e d from each s e c t io n w i t h equal sampling
e f f o r t (Table 14) show a wide v a r i a t i o n in numbers among s e c t io n s , w i t h
a d e f i n i t e b ia s toward g r e a t e r d e n s it y a t th e lo w er s e c t io n s .
v a ria tio n ,
This
however, must a ls o be co n s id e re d in c o n te x t w i t h th e measured
v a r ia b le s f o r each'sam ple from each o f th e s e c t io n s , as was done i n th e
-70m u l t i p l e r e g r e s s io n a n a ly s e s .
The c u r r e n t measurements made a t each sampling s i t e were i n s i g n i ­
f i c a n t t o v i r t u a l l y a l l ta x a .
The o n ly s i g n i f i c a n t r e l a t i o n s h i p s o f
c u r r e n t in th e m u l t i p l e r e g r e s s io n ana lyses were a p o s i t i v e c o r r e l a t i o n
to
Amblystegium noterophilum (moss) and a n e g a tiv e r e l a t i o n c o r r e l a t i o n
to
Rorippa nasturtium-aquatioum ( w a t e r c r e s s ) .
The s i g n i f i c a n t c o r r e ­
l a t i o n s above are l o g i c a l s in c e th e moss was d i s t r i b u t e d on rocks in
th e main channel exposed t o th e f a s t e r c u r r e n t s , w h ile th e w a te rcre ss
o ccu rre d along th e s id e s o f th e channel and thus in s lo w e r c u r r e n t .
The la c k o f s i g n i f i c a n c e o f th e c u r r e n t measurements t o most ta xa
does n o t n e c e s s a r ily r e f l e c t th e la c k o f im portance o f c u r r e n t , but
p ro b a b ly t o th e method used.
Though Cummins (1962) f e e l s t h a t a
Leupold-S tevens c u r r e n t meter (used in t h i s s tu d y ) i s s u i t a b l e f o r
m i c r o d i s t r i b u t i o n a l s t u d ie s (re a d in g s can be taken 2 cm from th e b o tto m ) ,
E rik s e n (1966) c o n s id e rs t h a t t h i s and o t h e r d e v ic e s , though b e t t e r
than those which measure average c u r r e n t , are o f d o u b tf u l use because
th e y cannot measure c u r r e n t among v e g e t a t io n , under r o c k s , in c r e v ic e s ,
in i n t e r s t i t i a l
spaces o r even a t th e boundary la y e r s o f s u rfa c e s
where th e organisms are found.
C o nsequently, w h ile no p r a c t i c a l method
y e t e x i s t s t o o b ta in an a c c u ra te index o f c u r r e n t w i t h i n th e s p e c i f i c
h a b i t a t o f organism s, such data i f a v a i l a b l e m ig h t have accounted f o r
some o f th e unaccounted v a r i a t i o n
found
in th e r e g r e s s io n s .
Though t h e r e were se v e ra l p o s i t i v e sim ple c o r r e l a t i o n s which were
-7 1 -
s i g n i f i c a n t between depth and in s e c t ta xa (Table 4 ) , t h e r e were v i r t u ­
a l l y no s i g n i f i c a n t r e l a t i o n s found in th e m u l t i p l e re g r e s s io n a n a ly ­
ses.
The f a c t t h a t th e r e a ls o was a s i g n i f i c a n t sim ple n e g a tiv e
c o r r e l a t i o n between depth and c u r r e n t measurements in d i c a t e s t h a t th e
a c c u ra te depth measurements p ro b a b ly served as an i n d i c a t o r f o r c u r r e n t
measurement about as w e ll as th e c u r r e n t measurements themselves taken
2 cm above th e s u b s t r a t e .
The n e g a tiv e r e l a t i o n s h i p i s l o g i c a l as th e
c u r r e n t a t th e bottom o f streams tends t o be p r o p o r t i o n a l l y slow er as
depth in c re a s e s .
tio n s
between
W hile t h e r e were s e v e ra l s i g n i f i c a n t s im p le c o r r e l a ­
ta xa
and
depth
c u r r e n t , o n ly one s i g n i f i c a n t
but
o n ly one
between
taxa
and
t r e l a t i o n s h i p o ccurred f o r d e p th , but
two o cc u rre d f o r c u r r e n t (Table 8 ) .
T h is i n d ic a t e s t h a t th e depth
measurements were l i k e l y c o r r e la t e d t o one o r more o f th e o t h e r v a r i ­
ables used in th e re g r e s s io n s which had g r e a t e r s i g n i f i c a n c e t o organ­
ism q u a n t i t i e s .
Depth i s p ro b a b ly n o t a f a c t o r in l i m i t i n g photosyn­
t h e s is i n t h i s stream s in c e most sam pling depths were much le s s than
0.51 m ( th e maximum depth sampled) and t u r b i d i t y a t a l l
tim e s was
e x tre m e ly low.
Plants as dependent variables.
As in d ic a te d e a r l i e r ,
some o f th e
same s i g n i f i c a n t r e l a t i o n s h i p s between th e in s e c t ta xa and s u b s tr a te
parameters corresponded t o those parameters s i g n i f i c a n t t o th e p la n t
taxa (Table 7 ) .
S i g n i f i c a n t parameters were m a in ly those r e p r e s e n tin g
th e s m a lle s t p a r t i c l e s .
In p ro c e s s in g th e samples, an app arent
-7 2 -
r e l a t i o n s h i p was noted between th e q u a n t i t y o f th e moss and th e q u a n t i t y
o f s m a lle r s u b s t r a te m a t e r ia l
sim ple c o r r e l a t i o n s
( " s a n d " ) p re s e n t in th e samples.
The
(Table 4) s u b s t a n t ia t e t h i s o b s e r v a t io n ; th e r e are
v e ry s i g n i f i c a n t p o s i t i v e c o r r e l a t i o n s between th e moss and th e s m a lle r
s u b s t r a te s iz e - c la s s e s and a ls o v e ry s i g n i f i c a n t n e g a tiv e c o r r e l a t i o n s
between th e m ost'and th e l a r g e r c la s s e s .
Hence, sin c e th e s m a lle r
p a r t i c l e s were a ls o s i g n i f i c a n t l y c o r r e la t e d t o a l l
but one o f th e
in s e c t t a x a , i t can be concluded t h a t th e q u a n t i t y o f s m a lle r s u b s tr a te
m a te r ia l was in some way r e la t e d t o th e q u a n t i t y o f in s e c t s over and
above t h a t c o n t r ib u t e d by th e moss i t s e l f .
T h is i n t e r r e l a t i o n s h i p
between th e s u b s t r a t e , p l a n t and i n s e c t q u a n t i t i e s w i l l
be considered
n e x t.
Intervelationships of
S u b s tr a te 3
insect3 and plant quantities.
In
th e p reced ing d i s c u s s io n s , th e r e l a t i o n s h i p s o f both p l a n t and in s e c t
ta x a t o a s u b s t r a te d i s t r i b u t i o n s i m i l a r t o th e mean d i s t r i b u t i o n by
w e ig h t ( F ig u re 4a) were d e s c rib e d .
In a d d i t i o n , i t was p o in te d o u t t h a t
th e p l a n t s , n o t a b ly th e moss, were s t r o n g l y c o r r e la t e d t o th e s m a lle r
s u b s t r a te p a r t i c l e s .
But when th e r e l a t i v e s i g n i f i c a n c e o f both p la n t s
and s m a lle r s u b s t r a te p a r t i c l e s was compared as they r e l a t e t o the
i n s e c t t a x a , th e c h a r a c t e r i s t i c s o f th e s u b s t r a te d i s t r i b u t i o n were
more im p o r t a n t .
F i n a l l y , i t was q u e stio n e d how these r e s u l t s r e l a t e
t o th e o b s e rv a tio n s o f p re v io u s i n v e s t i g a t o r s , in which organisms have
been a s s o c ia te d , a t l e a s t p h e n o t y p ic a lI y , w it h th e l a r g e r s u b s t r a te
■' o
-7 3 -
p a rtic le s .
U n lik e th e more obvious b e n e f i t s o f l a r g e r p a r t i c l e s iz e s
(such as s t a b i l i t y , space f o r p r o t e c t i o n and f o r a g in g , p la ce s f o r food
d e p o s it io n , v a r i e t y o f m ic r o c u r r e n t s , and h a b i t a t o f p rey s p e c ie s ) , i t
i s d i f f i c u l t t o v i s u a l i z e a l o g i c a l d i r e c t r e l a t i o n s h i p o f in s e c ts t o
S m a lle r p a r t i c l e s .
The mean d i s t r i b u t i o n presented in F ig u re 4a i s based on th e p e r ­
c e n t w e ig h t i n each s i z e - c l a s s combined from th e data o f each i n d i v i ­
dual sample.
T h is d i s t r i b u t i o n , however, can a ls o be e va lu a te d ih
terms o f th e e s tim a te d number o f p a r t i c l e s i n each s iz e - c l a s s
1 1 ).
(Table
The volume, and hence w e ig h t o f p a r t i c l e s o f equal d e n s it y ,
changes by a f a c t o r o f e i g h t when s iz e i s reduced o r in c re a s e d by a
f a c t o r o f two i n th e c r i t i c a l
dimension ( r a d iu s in t h i s case s in c e th e
p a r t i c l e s were co n sidered t o be spheres f o r s i m p l i c i t y ) .
Thus, w h ile th e
a c tu a l w e ig h t o f a l l p a r t i c l e s in th e s iz e - c la s s e s decreases s h a r p ly
a t two p la ce s along th e mean curve ( F ig u r e 4a) - - from about s iz e c la s s
0 [ - 5 ] t o about 0 [ - l ] and a ga in beyond c la s s 0 [ 2 ] - - th e a c tu a l number
o f p a r t i c l e s in c re a s e s h e re , though a t a d e c e le ra te d r a t e , w i t h each
s u c c e s s iv e ly s m a lle r s i z e - c l a s s .
A t p o i n t s where th e s lo p e o f the
curve i s n e g a tiv e , th e r a t e o f in c re a s e i s a c c e l e r a t in g
(T able 11).
The h i g h l y n e g a tiv e s lo p e o f th e d i s t r i b u t i o n between 0 [ - 8 ] and
a p p ro x im a te ly 0 [ - 5 ] and hence th e r a p id r i s e in p a r t i c l e numbers i s
a t t r i b u t e d t o th e s iz e l i m i t o f p a r t i c l e s in th e stream .
(T h is area
o f th e c u rv e i s somewhat s i m i l a r t o t h a t o f a standard normal
T ab le 11.
The e stim a te d w e ig h t o f each p a r t i c l e and numbers o f p a r t i c l e s in each phi c la s s
f o r th e mean s u b s t r a te d i s t r i b u t i o n ( F ig u re 4a and Table 1 3 ).
C a lc u la t io n s were
based on th e f a c t t h a t median volumes o f p a r t i c l e s o f any u n ifo rm shape in a phi
c la s s w i l l change by a f a c t o r o f 8 i n any a d ja c e n t phi c la s s .
For s i m p l i c i t y ,
a l l p a r t i c l e s were co n sid e re d t o be s p h e r ic a l and t o have a s p e c i f i c g r a v i t y o f
3. The median r a d i i o f th e p h i - c l a s s s iz e range s, r a t h e r than th e r a d i i o f the
median volumes, were used in th e c a l c u l a t i o n s in o rd e r t o p a r t i a l I y m in im ize the
b ia s , e s p e c i a l l y in th e l a r g e r s iz e c la s s e s , o f th e non-random d i s t r i b u t i o n o f
p a r t i c l e s toward th e minimum s iz e in each c la s s .
Median
Magnitude o f change
Phi
Size range
Number o f
in p a r t i c l e numbers
c la s s
(mm)
^
fa I
9
p a rtic le s
between a d ja c e n t phi cla sse s
_________________________________ ______________________________ la r g e
small
small -> la rg e
5
4
3
2
I
0
-I
-2
-3
-4
-5
-6
-7
<0.0625
0.0625 -0 .12 5
0 .1 2 5 -0 .2 5
0 .2 5 -0 .5
0.5-1
1-2
2-4
4-8
8-16
16-32
32-64
64-128
128-256
1.618
1.294
1 .035
8.283
6.626
5.301
4.241
3.393
2.714
2.171
1.737
1 .390
X
X
X
1.112
X
X
10-7
IO i
!C r3
10-5
ICT 4
X
X 10-3
X 10-2
X lo - i
X 10°
X I Ql
X 102
X IO 3
IO4
1 .082
3.167
1.578
4.502
5.174
6.906
6.395
1.048
2.134
5.076
8.474
5.785
4.329
X
X
X
X
X
X
X
X
X
X
X
X
X
10®
-IO 6
IO 5
IO4
IO 3
IO 3
S
IO 01
IO-T
ICT 3
3.416
2.0073.505
8 .7 Ol
7.492
10.70
6 . 1 02
4 .9 ll
4.204
5.990
14.65
1 3 3 .6
2.927
4.983
2.853
1 .149
1.335
9.260
1.639
2.036
2.379
1.669
6.827
7.483
x
x
x
x
x
x
x
x
x
x
x
x
ICr
!C r]
!C r ]
10-1
10-1
10-2
1010-1
10-1
10-1
!Cr?
ICT 3
-fZ -
. , . , - L f
-75d is trib u tio n . )
The s lo p e o f th e c u rve from a p p ro x im a te ly 0 [ - 5 ] to
0 [ - l ] i s q u i t e h i g h l y p o s i t i v e and re p re s e n ts a r e l a t i v e l y slow but
u n ifo rm r i s e in p a r t i c l e numbers w i t h s u c c e s s iv e ly s m a lle r c la s s e s .
The change o f th e s lo p e back t o n e g a tiv e and hence an a c c e l e r a t io n in
th e in c re a s e in numbers o f p a r t i c l e s from c la s s e s 0 [ - l ]
t o 0 [ 2] r e p r e ­
sents th e areas where th e r e g r e s s io n models in d ic a t e d th e g r e a t e s t
s e n s i t i v i t y i n p r e d i c t i n g taxa q u a n t i t i e s .
A t th e lo w e r end o f the
d i s t r i b u t i o n beyond about 0 [ 2] , th e slo p e o f th e d i s t r i b u t i o n again
becomes p o s i t i v e , though e s tim a te d numbers o f p a r t i c l e s s t i l l
in c re a s e
but a t a d e c e le ra te d r a t e .
In th e s iz e range o f p a r t i c l e s having th e g r e a t e s t s e n s i t i v i t y f o r
p r e d i c t i o n o f ta xa numbers ( 0 [ - l ] t o about 0 [ 3 ] ) , th e number o f p a r t i c l e s
necessary t o make a s i g n i f i c a n t change i n th e p e rc e n t w e ig h t d i s t r i b u t i o n
becomes i n c r e a s i n g l y la r g e (Table I T ) .
Thus th e s i g n i f i c a n c e a tta ch e d t o
these s iz e - c la s s e s by th e re g r e s s io n s re p re s e n ts g r e a t s e n s i t i v i t y in
m inute changes in q u a n t i t y .
A t th e o t h e r extrem e, one l a r g e p a r t i c l e
added t o a sample would change th e percentage d i s t r i b u t i o n c o n s id e r a b ly ,
y e t c o u ld have l i t t l e
Thus i t
p r a c t i c a l e f f e c t on m i c r o d i s t r i b u t i o n o f ta x a .
i s easy t o see why th e l a r g e s t p a r t i c l e s were f a r more e r r a t i c
v a r ia b le s w i t h regard t o t h e i r a c tu a l s i g n i f i c a n c e and le s s r e l i a b l e
i n d i c a t o r s o f organism q u a n t i t i e s .
I f an a c t i v e process i s a t work i n
d i s t r i b u t i n g th e s m a lle r p a r t i c l e s i n d i v i d u a l l y (as w i l l
s h o r tly ) ,
it
be discussed
i s easy t o see why th e s m a lle r p a r t i c l e s have such
-76s i g n i f i c a n c e when c o n s id e r in g th e magnitude o f change in numbers o f
p a r t i c l e s necessary t o measurably a l t e r th e parameters (percentage by
w e ig h t) used in t h i s s tu d y .
In an area w i t h u n ifo rm c u r r e n t v e l o c i t y , both th e s iz e o f th e p a r t i ­
c l e th e c u r r e n t i s capable o f e n t r a i n i n g
( liftin g
and t r a n s p o r t i n g ) and
th e d is ta n c e th e p a r t i c l e can be c a r r i e d i s i n v e r s e l y p r o p o r t io n a l t o th e
p a r t i c l e ' s s iz e and w e ig h t.
I f a curve i s p l o t t e d w i t h th e s iz e , w e ig h t,
o r d is ta n c e c a r r i e d as th e a b scissa and th e fre q u e n c y as th e o r d in a t e ,
th e curve w i l l
be concave and n e g a tiv e .
In B la in e S p rin g Creek, where
th e d is c h a rg e i s s t a b le th e y e a r around and p e r io d ic s c o u r in g thus does
n o t o c c u r , stream bottom d is tu r b a n c e s which do o c cu r r e s u l t from the
e n t r a i n i n g o f s m a lle r p a r t i c l e s and th e s h i f t i n g o f l a r g e r p a r t i c l e s as
th e l a t t e r lo s e s u p p o rt from around them.
As th e l a r g e r p a r t i c l e s do
s h i f t , th e s m a lle r p a r t i c l e s i n th e immediate area once s h e lte r e d by
th e l a r g e r p a r t i c l e s
(Hynes 1970) w i l l
now be s u b je c te d t o g r e a t e r
in f l u e n c e o f th e c u r r e n t and p o s s i b l y w i l l
become e n t r a in e d .
I f th e
d is t u r b e d area has a good r e p r e s e n t a t io n o f a l l p a r t i c l e s iz e s (such as
th e mean d i s t r i b u t i o n . F ig u re 4 a ) , th e s m a lle r p a r t i c l e s w i l l
be swept
away i n p r o p o r t io n t o t h e i r s i z e , th e i n t e n s i t y o f th e c u r r e n t and th e
degree o f t u r b u le n c e .
The r e s u l t i n g s u b s t r a t e d i s t r i b u t i o n
by w e ig h t
w i l l tend toward a unimodal curve skewed toward th e l a r g e r p a r t i c l e
s iz e s
( l i k e t h a t d e p ic te d f o r th e " - 3 " phi d e v i a t io n o f th e f o u r lo w e st
p e rc e n tile s
i n F ig u re 4 a ).
-7 7 -
R e d e p o s itio n o f p a r t i c l e s once e n tr a in e d by th e c u r r e n t i s a ls o
i n v e r s e l y p r o p o r t io n a l t o p a r t i c l e s iz e and w e ig h t and p r o p o r t io n a l t o
c u r r e n t v e l o c i t y under u n ifo rm c o n d it io n s .
La rg e r p a r t i c l e s tend t o
break up u n ifo rm c u r r e n t f l o w , causing g r a d ie n t s from tu rb u le n c e to
q u ie sce n ce , such as th e dead-w ater areas t y p i c a l l y found on th e down­
stream s id e s o f la r g e stones (Jaag and AmbOhl 1964).
Areas o f q u ie s ­
cence tend to be r e c e p t iv e t o d e p o s it io n o f p a r t i c l e s , though th e p a r ­
t i c u l a r mechanisms in v o lv e d are n o t f u l l y understood .(Hynes. 1970).
If
th e areas which are r e c e p t iv e t o d e p o s it io n remain s t a b i l i z e d over a
p e rio d o f t im e , th e y w i l l
p r o p o r t i o n a l l y c o l l e c t g r e a t e r numbers o f
re d e p o s ite d p a r t i c l e s ; i f
such areas c o n t a in a high p r o p o r t io n o f
la rg e r p a r t ic le s ,
m ic r o h a b it a t s w i l l
th e r e d i s t r i b u t i o n o f s m a lle r p a r t i c l e s in these
s h i f t th e o r i g i n a l d i s t r i b u t i o n
by w e ig h t from a
skewed unimodal d i s t r i b u t i o n t o one which p r o g r e s s i v e ly becomes b i modal
( s i m i l a r t o th e mean d i s t r i b u t i o n d e p ic te d in F ig u re 4 a ) .
th e curve o f th e mean d i s t r i b u t i o n
beyond s iz e - c l a s s 0 [ 3 ] toward th e
s m a lle s t p a r t i c l e s i s l i k e l y due t o two f a c t o r s .
F i r s t , th e m a j o r i t y
o f s m a lle s t p a r t i c l e s picked up by th e c u r r e n t w i l l
out u n til
The drop in
l i k e l y not s e t t l e
th e average c u r r e n t i s reduced a p p r e c ia b ly .
n o t o c cu r in th e stream s e c tio n s sampled.
Such areas d id
Second, th e mesh s iz e o f
th e sampler n e t a llo w e d some p a r t i c l e s in th e s iz e - c la s s e s beyond 0' [ 2 ]
t o pass th ro u g h .
T h is corresponds t o th e p o i n t in th e mean d i s t r i b u ­
t i o n where th e cu rv e d ro p s.
The r e a l d i s t r i b u t i o n i n t h i s s iz e range .
-7 8 -
I f n o t c o n t in u in g a p p ro x im a te ly le v e l o r upward, would a t le a s t not
drop q u i t e so r a p i d l y .
The presence o f s m a lle r p a r t i c l e s in areas w it h l a r g e r s u b s t r a t e ,
t h e r e f o r e , do n o t i n any way appear t o in f l u e n c e th e benthos d i s t r i b u ­
tio n d ir e c tly .
Rather i t
i s an i n d i c a t i o n o f both how lo n g a m ic ro ­
h a b i t a t has remained s t a b le and i t s
c le s .
r e c e p t i v i t y t o d e p o s it io n o f p a r t i ­
Areas w i t h o u t la r g e s u b s t r a te p a r t i c l e s w i l l ,
s m a lle r
p a r tic le s
to o ,
sometimes
in
la r g e
o f co u rs e , r e c e iv e
q u a n titie s .
But the
r e g r e s s io n models in d ic a t e d t h a t th e s m a lle r p a r t i c l e s and t o a le s s e r
e x t e n t th e l a r g e r p a r t i c l e s were both r e la t e d to benthos d e n s it y .
F u r t h e r , th e models showed t h a t a dominance o f s m a lle r p a r t i c l e s w it h
few l a r g e r p a r t i c l e s was le s s f a v o r a b le f o r in s e c t d e n s it y .
These
m ic r o h a b it a t s are tho se areas which a re le s s complex (Hynes 1970),
where l i t t l e
space and v a r i e t y o f h a b i t a t e x i s t s f o r organism s.
On
th e o t h e r hand, areas w i t h a dominance o f l a r g e r p a r t i c l e s are f a v o r a b le
f o r h a b i t a t i o n , but th e la c k o f s m a lle r p a r t i c l e s l i k e l y in d ic a t e s t h a t
th e area i s e i t h e r n o t r e c e p t iv e t o d e p o s it io n , o r was r e c e n t l y d i s ­
tu rb e d and has n o t y e t become f u l l y c o lo n iz e d .
Areas r e c e p t iv e t o d e p o s it io n o f s u b s t r a te p a r t i c l e s ' w i l l a ls o
l i k e l y r e c e iv e d e t r i t u s and food organism s.
S ta b le groups o f stones
w i l l a llo w p e r ip h y to n t o develop on th e upper s u r fa c e s .
p la n t s are
a llo w e d
t o anchor and d e v e lo p .
H ighe r a q u a tic
I t appears t h a t once an
area develops a s a t i s f a c t o r y food regim e, in s e c ts are a t t r a c t e d to i t
-7 9 -
i f o t h e r f a c t o r s are n o t l i m i t i n g .
I f l a r g e r s u b s t r a te p a r t i c l e s
themselves were th e p r i n c i p l e f a c t o r t o success i n c o l o n i z a t i o n , in s e c t s
would im m e d ia te ly c o lo n iz e these p a r t i c l e s .
L ik e w is e , i f c u r r e n t was
th e p r i n c i p l e f a c t o r , in s e c ts should im m e d ia te ly c o lo n iz e th e l a r g e r
stones which p r o v id e an i n f i n i t e v a r i e t y o f m ic r o c u r r e n t s .
But organ­
isms tend t o be found i n areas where th e y are o u t o f a t l e a s t th e d i r e c t
in f l u e n c e o f c u r r e n t , and in a l l
but p o o r ly oxygenated strea m s, th e
renewing o f w a te r around organisms does n o t appear t o be c r i t i c a l
( U l f s tra n d 1967).
Because th e in s e c ts are s t r o n g l y c o r r e la t e d t o th e
s m a lle r s u b s t r a te p a r t i c l e s which are d e p o s ite d w i t h t im e , th e l a r g e r
s u b s t r a te and c u r r e n t f a c t o r s do n o t appear t o be o f immediate im por­
tance here.
The d e p o s it io n o f s m a lle r p a r t i c l e s r e f l e c t s s t r o n g ly on
th e development o f a s a t i s f a c t o r y food regim e, which appears t o be th e
p r i n c i p l e f a c t o r i n th e development o f f a v o r a b le m ic r o h a b it a t s f o r
in s e c t s .
The m ic r o h a b it a t s were e s p e c i a l l y s e n s i t i v e t o changes in q u a n t i t i e s
o f s m a lle r p a r t i c l e s because i t can be expected t h a t th e o n ly p a r t i c l e s
c a r r i e d by th e c u r r e n t were those from e r o s io n w i t h i n th e stream i t s e l f .
The p r e d i c t i v e v a lu e o f t h i s f a c t o r was enhanced by th e f a c t t h a t no
m a t e r i a ls were c a r r i e d i n t o th e area from above, no f e e d e r streams
e n te re d th e area s t u d ie d , and th e d is c h a rg e and thus v e l o c i t y remained
c o n s ta n t y e a r around.
A ls o , gross s u b s t r a te v a r i a b i l i t y in th e stream
areas was m in im a l, and p h e n o t y p ic a lI y would have been co n sidered
-8 0 -
u n ifo rm th ro u g h o u t as based on th e d e s c r ip t i o n s o f s u b s t r a t e c o n ta in e d
in v i r t u a l l y a l l o t h e r s t u d ie s o f s u b s tr a te -o r g a n is m r e l a t i o n s h i p s .
The r e l a t i o n s h i p o f p l a n t s , e s p e c i a l l y th e moss, which were a ls o
found c o r r e l a t e d to s m a lle r s u b s t r a te p a r t i c l e s have been ig n o re d t o
t h is p o in t.
In tho se re g r e s s io n s where both th e moss and th e f i n e r
s u b s t r a t e p a r t i c l e s were co n s id e re d independent v a r ia b le s t o th e in s e c t
t a x a , i t was th e s u b s t r a te which was f a r more s i g n i f i c a n t .
Because
s tro n g s im p le c o r r e l a t i o n s e x i s t between moss and th e s m a lle r p a r t i c l e s ,
i t becomes e v id e n t t h a t th e moss i t s e l f a c ts s i m i l a r l y t o th e l a r g e r
s u b s t r a te by causing p a r t i c l e s t o s e t t l e from th e c u r r e n t .
Thus these
p a r t i c l e s a re a dependent v a r i a b l e t o th e moss which i t s e l f becomes
independent in t h i s case.
The i n i t i a l
presence o f moss i t s e l f und o u b te d ly
adds t o th e s t a b i l i t y o f th e s u b s t r a te underneath i t .
In a d d i t i o n , .
o b s e rv a tio n s re v e a le d t h a t th e moss i t s e l f anchors onto r e l a t i v e l y
la r g e stones which in them selves tend t o be more s t a b le .
I t i s now e v id e n t t h a t th e s m a lle r s u b s t r a te p a r t i c l e s contained
in th e samples were from th e streambed i t s e l f w i t h i n th e complex o f
l a r g e r p a r t i c l e s and from t h a t c o l l e c t e d by th e moss.
W hile i t s p re s ­
ence from both sources i n d i r e c t l y and u l t i m a t e l y r e f l e c t s on a f a v o r ­
a b le food regime and th u s does n o t a l t e r th e c o n c lu s io n s drawn p re ­
v i o u s l y about i t s
s i g n i f i c a n c e , i t does c a l l f o r a d i f f e r e n t o u tlo o k
on th e r e l a t i o n s h i p o f moss as an independent v a r ia b le t o in s e c t s .
T h is i s e s p e c i a l l y t r u e f o r th e f i n a l m odel, re g r e s s io n S, where th e
-81 s t r o n g e s t i n d i c a t o r s o f s u b s t r a t e ( th e lo w er p e r c e n t i l e group which
r e f l e c t s on th e s iz e range o f p a r t i c l e s trap ped by moss) were d e l i b e r ­
a t e l y chosen, i n a d v e r t e n t l y f u r t h e r m in im iz in g th e s i g n i f i c a n c e o f
th e moss.
The o n ly r e g r e s s io n a v a i l a b l e where p la n t s were considered
independent v a r ia b le s t o th e i n s e c t . t a x a , but no s u b s t r a te parameters
were in c lu d e d , i s r e g r e s s io n I .
A comparison o f th e
t va lu e s o f taxa
s i g n i f i c a n t t o th e p la n t s i n both r e g r e s s io n T and r e g r e s s io n S (th e
l a t t e r i s th e same as r e g r e s s io n R w i t h th e lo w e s t p e r c e n t i l e group
added) shows th e f o l l o w i n g r e l a t i o n s h i p s
CO
<D
Mrd
S<D
CL
O
O
Ul
CU
LU
U
CL
CO
CO
SZ
8
•
Q CL
SL co
-P
2 :6 4 5 . 3.380
2.543
§
O
-P
I
U
I—■
4.654
4 .0 2 0
SOZ
S-
O
reg S
E
CL
*
-3.1 77
CL
CO
CO
SCU
P
-P
SCU
CL
CO
fO
O
4)
reg T
■s
rQ
0)
CU
CZ
iR sO
(data from T ab le 8 ):
S
- 2 .5 1 0
5.435
CO
CO
O
r-i
3
CD
CO
•s
-P
Oj
-2 .6 7 5
-3 .5 2 0
5.034
T h is phenomenon o c c u rs , as mentioned e a r l i e r , because both th e moss and
th e s m a lle r s u b s t r a te p a r t i c l e s are i n d i v i d u a l l y s i g n i f i c a n t t o in s e c ts
and both are a ls o s t r o n g l y c o r r e la t e d to each o t h e r .
Note t h a t , in s te a d
o f th e f o u r taxa n e g a t i v e l y c o r r e la t e d and one ta xa p o s i t i v e l y c o r r e ­
la t e d t o th e moss in r e g r e s s io n S ( F ig u re 5 a ), f i v e ta x a are p o s i t i v e l y
I
-8 2 -
c o r r e la t e d and one taxa n e g a t i v e l y c o r r e la t e d i n r e g r e s s io n I .
T h is
now c l o s e l y corresponds w i t h th e o b s e rv a tio n s made w h ile s o r t i n g th e
organism s.
Consequently, s in c e th e s m a lle r s u b s t r a te p a r t i c l e s c o l l e c t e d
by th e moss and dependent on i t
co u ld n o t have been analyzed s e p a r a te ly
from a l l o t h e r small p a r t i c l e s , th e s i g n i f i c a n c e o f th e moss t o the
in s e c ts was m inim ized i n th e a n a ly s is because th e s m a lle r s u b s tr a te
independent from th e moss- i t s e l f was so s t r o n g l y r e la t e d t o in s e c t
d e n s it y .
Auteootogioat considerations.
Though th e approach o f t h i s study
was s y n e c o lo g ic a l, some aspects o f th e a u t e c o lo g ic a l r e l a t i o n s h i p s should
be noted here.
From general o b s e rv a tio n i t was noted t h a t th e moss
(AmbtyStegium noterophilum) p r i m a r i l y in h a b ite d areas o f f a s t c u r r e n t
whereas th e w a te rc re s s
{Rorippa nasturtiuni-aquaticwn) in h a b ite d shore­
l i n e s where th e c u r r e n t was reduced, o r o t h e r slo w er w a te r areas not
sampled.
The c u r r e n t measurements i n f a c t were s i g n i f i c a n t l y nega­
t i v e l y c o r r e la t e d t o th e w a te r c r e s s , b u t n o t c o r r e la t e d t o any o th e r
ta x a .
M ic r o c u r r e n ts measured w i t h i n sampled areas a t th e s u b s tr a te
le v e l tended t o v a ry c o n s id e r a b ly depending on p r e c i s e l y where the
m eter was placed and th u s were inadeq uate measurements w i t h re s p e c t t o
p r e c is e l o c a t i o n o f most ta x a .
However, gross c u r r e n ts i n areas occu­
pied by moss and areas occupied by w a te rc re s s d i f f e r e d enough t h a t th e y
r e f l e c t e d on th e o v e r a l l range o f th e m ic r o c u r r e n ts measured.
pondweed
{Zanniohettia patustris) was n o t p re se n t in s u f f i c i e n t
The
-8 3 -
q u a n t i t i e s in any o f th e sampled areas t o make general o b s e rv a tio n s on
its
re la tio n s h ip to c u rre n t.
The elm id b e e tle l a r v a ,
Optioservus s p . , was th e most s t r o n g ly
c o r re la te d , t o th e moss o f a l l
in s e c t t a x a .
Both th e f a c t t h a t i t
is
a h e r b iv o r e and i s a c l i n g i n g , non-swimming la r v a l i k e l y c o n t r ib u t e
to t h is
h a b i t a t p re fe re n c e .
from th e stream was
Most
numerous
o f th e s t o n e f l i e s c o l le c t e d
Isoperla s p . , a c a r n iv o r e .
Acroneuria paoifioa,
a n o th e r c a r n iv o r e , was a ls o c o l l e c t e d though in small numbers compared
to
Isoperla sp. (T able 1 5 ).
sm all numbers compared t o
c a lly .
Because both
Nemoura s p . , a h e r b iv o r e , was p re se n t i n
Isoperla sp. i n tho se samples examined c r i t i ­
Isoperla sp. and Nemoura sp. were to o small t o
se pa ra te f e a d i l y in q u a n t i t i e s even under m a g n i f i c a t i o n , i t was neces­
s a ry t o t a b u l a t e them to g e t h e r as th e " o t h e r s t o n e f l y " group .
s t o n e f l ie s were s t r o n g l y c o r r e la t e d
th e e x c e p tio n o f
Glossosoma sp.
The
(T able 4) t o o t h e r i n s e c t taxa w i t h
Though no a n a ly s is was made in t h i s
s tu d y o f s p e c i f i c food h a b it a t s o f th e
taxa
from t h i s stre a m , i t
is
p l a u s i b l e t h a t th e c a r n iv o ro u s s t o n e f l ie s were d i s t r i b u t e d w i t h i n th e
m ic r o h a b it a t s p r i m a r i l y in r e l a t i o n t o l o c a t i o n o f s u i t a b l e prey as
lo ng as o t h e r h a b i t a t requ ire m e n ts were not l i m i t i n g .
Baetis sp. and Paraleptophlebia sp. are f r e e - r a n g in g m a y fly genera
which can c l i n g t o s u b s t r a t e i n f a s t c u r r e n t s
( Pennak 195 3).
Bphemerella
infrequens, however, i s more t y p i c a l l y found c l i n g i n g i n c r e v ic e s .and
u n d ersides o f s to n e s.
A l l th r e e genera are h e r b iv o r o u s , fe e d in g on a lgae
and t is s u e s o f h ig h e r a q u a tic p l a n t s .
c a n t l y c o r r e la t e d t o
Though no v a r ia b le s were s i g n i f i ­
Baetis sp. in any o f th e r e g r e s s io n a n a ly s e s , t h i s
genus showed sim p le n e g a tiv e c o r r e l a t i o n s t o each o f th e p e r c e n t i l e s .
a d d itio n , i t s
r e l a t i v e num erical p r o p o r t io n a t s t a t i o n 3 (T able 1 5 ) , w h ich
c o n ta in e d th e g r e a t e s t p r o p o r t io n o f la r g e s u b s t r a te p a r t i c l e s
was h ig h .
In
And, except f o r
(Table 1 3 ) ,
Glossosoma s p . , i t s o ccurrence on those ro cks
scooped from th e sampler was p r o p o r t i o n a l l y g r e a t e r than any o th e r i n s e c t
taxon (see
The sampler used in this study in th e A p p e n d ix ) . . T h is evidence
p lu s th e f a c t t h a t n o th in g was c o r r e la t e d t o i t
r e f l e c t s on i t s
i n th e r e g r e s s io n a n a ly s i s
f r e e - r a n g in g b e h a v io r and a b i l i t y t o move q u i c k l y from
p la c e t o p la c e , thus a l lo w in g i t t o randomly d is p e r s e i t s e l f and i n h a b i t
Paraleptophlehia s p . , on th e o t h e r
more areas than any o f th e o t h e r ta x a .
hand, showed s i g n i f i c a n t c o r r e l a t i o n t o th e moss.
Ephemerella infrequens
showed s i g n i f i c a n t n e g a tiv e c o r r e l a t i o n t o th e w a te r c r e s s , l i k e l y r e f l e c t ­
in g on i t s c r a w lin g b e h a v io r among s to n e s .
D i s t i n c t d i f f e r e n c e s were noted between
two caddi f l y
Glossosoma sp. and th e o t h e r ,
genera,Rhyacophila sp. and Oahrotrichia sp. Glossosoma s p . ,
a stone c a s e - b u ild e r which a tta c h e s i t s cases to u n d e rs id e s o f l a r g e r
s to n e s , was n e g a t i v e l y c o r r e la t e d in numbers to th e o t h e r two genera.
C o n s is te n t w i t h i t s
observed h a b i t a t ,
it
showed th e most d i s t i n c t tr e n d
toward n e g a tiv e c o r r e l a t i o n s t o s m a lle r s u b s t r a te p a r t i c l e s , and p o s i t i v e
c o r r e l a t i o n ,to th e l a r g e r p a r t i c l e s .
The o t h e r c a d d i s f l i e s showed a y *
" -v
general though le s s d i s t i n c t tre n d in th e o p p o s ite d i r e c t i o n .
Al so ^ ,
-8 5 -
Glossosoma sp. showed s tro n g n e g a tiv e c o r r e l a t i o n t o th e moss in th e
sim p le c o r r e l a t i o n m a t r ix (th e o n ly in s e c t taxa t o do so) and in th e
m u l t i p l e r e g r e s s io n a n a ly s e s .
Ochrotrichia sp. which uses sand p a r t i ­
c le s f o r i t s
purse-shaped case, tended to be n e g a t i v e l y c o r r e la t e d t o
th e p l a n t s .
Rhyacophila s p . , an e n t i r e l y f r e e - l i v i n g and t y p i c a l l y
c a r n iv o ro u s c a d d i s f l y , was m o d e ra te ly c o r r e la t e d to th e o t h e r in s e c t
ta x a .
As w i t h th e c a r n iv o ro u s s t o n e f l i e s , t h i s p ro b a b ly r e f l e c t s on
th e s i g n i f i c a n c e o f th e food f a c t o r in t h e i r d i s t r i b u t i o n .
Interaction of factors influencing microdistribution
From p u b lis h e d re s e a rc h d a t in g back t o about th e y e a r 1930, and
e s p e c i a l l y w i t h i n th e p a st decade, s e v e ra l f a c t o r s have been a t t r i b u t e d ,
o r a t l e a s t shown t o be c o r r e l a t e d , t o m i c r o d i s t r i b u t i o n o f organism s.
The degree o f s i g n i f i c a n c e a tta ch e d t o each f a c t o r i s v a r i e d , due in
p a r t t o th e p a r t i c u l a r stream s t u d ie d . Al s o , f a i l u r e to re c o g n iz e t h a t
f a c t o r s tend t o v a ry in p a r a l l e l fa s h io n because th e y are i n t e r r e l a t e d
(U1 f s tra n d 1968) has a ls o le d to some o f th e d is c re p a n c y .
Most
re s e a rc h e rs th ro u g h o u t th e p e r io d , however, would be i n agreement w i t h
th e p r o p o s it io n s ta te d by Cummins (1 964) t h a t , w i t h i n th e framework o f
c e r t a i n f a c t o r s which in f lu e n c e m a c r o d is t r i b u t io n
( d is trib u tio n of
organisms o ver g r o s s ly d i f f e r e n t s e c tio n s o f streams o r even a d ja c e n t
s tre a m s ), o t h e r f a c t o r s o p e ra te under th e c o n d it io n s imposed by those
i n f l u e n c i n g m a c r o d is t r i b u t io n t o r e g u la t e l o c a li z e d d i s t r i b u t i o n o f
-8 6 -
organism s.
As in d ic a t e d in th e i n t r o d u c t i o n , those f a c t o r s g e n e r a lly
considered to e x e r t a more u n ifo rm e f f e c t over gross s e c t io n s o f a
stream in c lu d e th e d i r e c t o r i n d i r e c t e f f e c t s o f te m p e ra tu re , chemical
p r o p e r t ie s o f th e strea m , oxygen c o n t e n t , and a l t i t u d e .
Under t h i s
fram ework, f a c t o r s a t t r i b u t e d to p ro d u cin g th e non-random d i s t r i b u t i o n
o f benthos i n lo c a l i z e d areas (T able I ) are s u b s t r a te c h a r a c t e r i s t i c s ,
c u r r e n t v e l o c i t y , food d i s t r i b u t i o n , shading versus d i r e c t i l l u m i n a t i o n ,
oxygen c o n c e n tr a t io n when near minimal t o le r a n c e t o organism s, and
d ep th.
The i n t e r a c t i o n o f h a b i t a t v a r ia b le s a t t r i b u t e d t o i n f l u e n c i n g
m i c r o d i s t r i b u t i o n are complex, and th e i n v e s t i g a t o r s l i s t e d
i n Table I
and o th e r s have proposed v a r io u s i n t e r a c t i o n s o f th e p a r t i c u l a r f a c t o r s
th e y in v e s t i g a t e d w i t h th e benthos.
I n t e r a c t i o n s o f the se f a c t o r s p lu s
those e lu c id a te d in t h i s s tu d y are presented s c h e m a t ic a lly in F ig u re 6.
Because o f th e v a r i a b i l i t y o f d i f f e r e n t stream s, not a l l o f these may
be s i g n i f i c a n t o r o p e ra b le in each stream.
I n t e r r e l a t i o n s h i p s w i t h s u b s t r a te are perhaps th e most v a rie d
( F ig u re 6 ) .
S u b s tra te p ro v id e s h a b i t a t space f o r f o r a g in g and p r o t e c t i o n
a g a in s t p r e d a to r s , a p la c e f o r d e p o s it io n o f food substa n ce s, a place f o r
p e r ip h y to n growth and atta chm e nt o f h ig h e r a q u a tic p l a n t s , and a p la ce
where th e c u r r e n t i s broken up i n t o a v a r i e t y o f m ic r o c u r r e n ts and t u r ­
bulence.
Under s p e c ia l c o n d i t i o n s , i t s
c h a r a c t e r determ ines th e success
w i t h which c e r t a i n organisms can burrow i n t o i t and th e c o rre s p o n d in g
87
gross- and microd is trib u tio n
SHADING — DIRECT
ILLUMINATION
DEPTH
s ta b ilit y
respiration
photosynthesis
ALGAE <■
substrate
MACROPHYTES I -
biT fz e"s’ 'partTcTels '
base for
attachment
mechanical influence
respiration
INSECTS
support
d is trib u tio n of
DETRITUS and
FOOD ORGANISMS
microcurrents
Figure 6.
Interrelationships of habitat variables influencing the m icrodistribution
of organisms.
-88q u a n t i t y o f oxygen t h a t must be consumed ( e .g . b u rro w in g m a y f l ie s ,
E rik s e n 1963, 1964 ).
A ls o , th e s u b s t r a t e i s a p la c e onto which c a d d is -
f l i e s anchor cases o r c o n s t r u c t n e t s , and p ro v id e s m a t e r ia l from which
t o c o n s t r u c t cases.
H ighe r a q u a tic p la n t s and d e t r i t u s must be consid e re d
s u b s tr a te s i n themselves as w e ll as food sources f o r a p p r o p r ia t e i n v e r t e ­
b r a te s .
Cummins (1962, 1964, 1966) and Cummins and L a u f f (1969) have suggested
th a t, o f a ll
th e f a c t o r s g e n e r a ll y a t t r i b u t e d t o i n f l u e n c i n g m i c r o d i s t r i ­
b u tio n i n streams ( e s p e c i a l l y th e t h r e e predominant ones - - s u b s t r a t e ,
c u r r e n t and f o o d ) , s u b s t r a t e should be th e basic denom inator in stream
b e n th ic e c o lo g y .
They, along w it h Moon (1 939) and Thoroup (1966 ), p o i n t
o u t t h a t s u b s t r a te n o t o n ly i n t e r a c t s w i t h most o t h e r f a c t o r s
but i t
o th e rs .
( F ig u re 6 ) .
a ls o i s r e l a t i v e l y easy to p h y s i c a l l y analyze compared to the
The problem w i t h p re v io u s s t u d ie s on s u b s t r a te i s t h a t , except
f o r Cummins'
(1964) work w i t h two sp e cie s o f c a d d i s f l i e s , no re s e a rc h e rs
have made d e t a i le d ana lyses o f th e s u b s t r a te p r e c i s e l y from where the
organisms were c o l l e c t e d .
In most e a r l i e r s t u d ie s , th e phenotype
( s u p e r f i c i a l appearance) o f areas have been used t o e v a lu a te the e f f e c t
o f s u b s t r a te on m i c r o d i s t r i b u t i o n .
T h is ty p e o f approach n e c e s s ita te s
th e c o n s id e r a t io n o f l a r g e r s e c tio n s o f streams than d e s i r a b le to f i n d
h a b it a t s which are s u p e r f i c i a l l y d i f f e r e n t .
perhaps unknown o r un re co g n ize d , f a c t o r s w i l l
in c re a s e d .
The p o t e n t i a l t h a t o t h e r ,
e n te r in i s thus g r e a t l y
Most o f th e m o re .re c e n t s t u d ie s have used more r e fin e d
-89methods, g e n e r a ll y e i t h e r measuring th e dimensions o f th e l a r g e s t stone
i n th e a re a , o r one dim ension o f a l l th e l a r g e r stones above a given
s iz e .
The problem here i s t h a t much o f th e r e l a t i v e l y l a r g e r m a te r ia l
and a l l o f th e s m a lle r p a r t i c l e s are s t i l l
c r itic a l
ig n o re d .
In t h i s s tu d y ,
g ra d in g o f th e s u b s t r a te p o r t i o n o f th e samples and d e t a i le d
a n a ly s is o f th e data showed t h a t
s u p e rfic ia lly
i d e n t i c a l areas o f sub­
s t r a t e can d i f f e r c o n s id e r a b ly , and such d i f f e r e n c e s can be r e la t e d t o
v a r i a t i o n s in benthos d e n s it y .
The macro- and m ic r o - c u r r e n t s o f a stream d e te rm in e th e s iz e and
d i s t r i b u t i o n o f p a r t i c l e s , th e d i s t r i b u t i o n o f d e t r i t u s and o th e r
o r g a n ic m a t t e r , and th e renewing o f w a te r around organisms lo c a te d in
boundary la y e r s o r deadwater areas ( F ig u re 6 ).
C o n sid e ra b le a t t e n t i o n
was paid by re s e a r c h e r s , e s p e c i a l l y in e a r l i e r p u b l i c a t i o n s , t o th e
p o te n tia l
in f l u e n c e o f th e c u r r e n t in m e c h a n ic a lly d i s lo d g in g organ­
isms from s u b s tr a te s where th e f u l l
co n ta c t.
A cco rding t o these s t u d ie s , t h i s
b a s is of. i t s
6.
f o r c e o f th e c u r r e n t came i n t o d i r e c t
a lle g e d
in f l u e n c e was th e
s i g n i f i c a n c e o ver o t h e r e f f e c t s o f c u r r e n t shown in F ig u re
More re c e n t concepts o f boundary la y e r s and tu r b u le n c e (Jaag and
AmbUhl 1964, E rikse n 1966, U lf s t r a n d 1967) g e n e r a lly d is m is s th e o l d e r
concept o f th e c u r r e n t ' s mechanical
except under extreme c o n d it io n s .
in f l u e n c e as a s i g n i f i c a n t f a c t o r
I t i s now suggested t h a t th e boundary
la y e r o f r e l a t i v e l y q u i e t w a ter which extends above s u b s t r a t e p a r t i c l e s
i s g e n e r a ll y a t l e a s t as high as th e organism i t s e l f , and has l i t t l e
“ 90-
c o r r e l a t i o n t o th e c u r r e n t d i r e c t l y above i t .
The s i g n i f i c a n c e o f
r e a e r a t io n by c u r r e n ts a ls o may be over-em phasized.
U l f s t r a n d (1967)
p o in t s o u t t h a t , unless a s tre a m 's oxygen c o n c e n tr a t io n i s near minimal
t o le r a n c e s ,
th e
c o n c e n tr a t io n o f oxygen anywhere w i t h i n th e h a b it a t
space o f th e organisms i s w e ll w i t h i n l i m i t s and i s n o t a c r i t i c a l
f a c t o r i n most stream s.
Thus th e assessment from th e most re c e n t
s t u d ie s i s t h a t m ic r o c u r r e n ts them selves are o f le s s s i g n i f i c a n c e than
f o r m e r ly a t t r i b u t e d w i t h regard t o i t s mechanical in f l u e n c e and a e r a t io n .
They s t i l l
r e t a i n t h e i r s i g n i f i c a n c e in d e p o s it io n o f food and o th e r
p a r t i c l e s t o s p e c i f i c l o c a t i o n s , and on a l a r g e r s c a le in d e te rm in in g
th e make-up o f th e s u b s t r a t e c o m p o s itio n (Macan 1961).
The food f a c t o r i s one t h a t i s o f t e n ig n o r e d , and in a l l
but th e
most r e c e n t s t u d ie s , has been n e g le cte d w i t h regard t o s p e c i f i c d i s t r i ­
b u tio n o f benthos.
U lfs tra n d
(1967) p o in t s o u t t h a t , o f th e th re e f a c ­
t o r s - - s u b s t r a t e , c u r r e n t , and food - - a t t r i b u t e d t o be most s i g n i f i c a n t
in a l l
b u t s p e c ia l s i t u a t i o n s , s u b s t r a te and c u r r e n t can p ro b a b ly be t o l ­
e ra te d under s u b -o p tim a l c o n d it io n s more r e a d i l y than can fo o d .
Y e t, th e
food f a c t o r i s perhaps th e most d i f f i c u l t t o assess w i t h regard to m ic r o ­
d i s t r i b u t i o n s in c e i t would r e q u i r e d e te r m in in g s p e c i f i c a l l y what o rgan­
isms are fe e d in g on and in which s p e c i f i c h a b i t a t s .
streams in c o n ju n c t io n w i t h f i e l d
p ro m isin g
Use o f la b o r a t o r y
s t u d ie s c e r t a i n l y appears t o be a
s o l u t i o n here.
O ther f a c t o r s o c c a s i o n a lly are a t t r i b u t e d t o i n f l u e n c i n g
m ic ro d is trib u tio n .
Depth has o c c a s i o n a lly been shown t o be c o r r e l a t e d ,
b u t s t a t i c p re ssu re i s n o t a f a c t o r a t s h a llo w depths ( U lf s t r a n d 1967).
C o r r e l a t i o n o f depth t o m i c r o d i s t r i b u t i o n i s l i k e l y due t o i t s own
c o r r e l a t i o n to some o t h e r f a c t o r s more d i r e c t l y r e la t e d t o th e organism s,
such as i t s e f f e c t on l i m i t i n g
l i g h t f o r a lg a l growth o r b e h a v io ra l
aspects such as emergence near s h o r e l in e s .
Hughes (1966&) found t h a t
f o r two species o f m a y fly nymphs, th e e f f e c t s o f v e g e t a t iv e shading on
m i c r o d i s t r i b u t i o n were due p r i m a r i l y t o responses t o l i g h t s t i m u l i ,
r a t h e r than i n d i r e c t l y th ro u g h in f l u e n c e on a lg a l grow th o r te m p e ra tu re ,
o r by d e p o s it io n o f a llo c th o n o u s l e a f d e t r i t u s .
From t h e i r e v a lu a t io n o f th e use o f l a b o r a t o r y streams in th e s tu d y
o f m i c r o d i s t r i b u t i o n , Cummins and L a u f f (1 969) suggested th e concept o f a
h ie r a r c h y o f f a c t o r s which a f f e c t m i c r o d i s t r i b u t i o n .
U lfs tra n d
(1967,
1968) s i m i l a r l y suggested t h a t f a c t o r c o m b in a tio n s , r a t h e r than s in g le ,
f a c t o r s a lo n e , must be c o n s id e re d , and urged t h a t methods f o r a n a ly z in g
the se f a c t o r s as a group be found.
I t i s q u i t e p l a u s i b l e , and demon­
s t r a t e d t o some e x t e n t from th e most re c e n t p u b lish e d re s e a rc h and in
t h i s s tu d y , t h a t th e p a r t i c u l a r h ie r a r c h y i s v a r i a b l e n o t o n ly in d i f f e r ­
e n t streams b u t w i t h i n c o m p a r a tiv e ly l o c a l i z e d s e c tio n s o f th e same
stream .
Anyone o f th e t h r e e p r i n c i p a l f a c t o r s - - s u b s t r a t e , food o r
c u r r e n t — can be l i m i t i n g no m a tte r how f a v o r a b le th e c o n d it io n s o f th e
o t h e r two m ig h t be.
I f none are c r i t i c a l l y
l i m i t i n g , as would be
expected i n most s i t u a t i o n s , then th e i n t e r a c t i o n o f a t l e a s t th r e e
f a c t o r s should be co n sid e re d t o d e te rm in e which i s dom inant.
-92O pin io n v a r ie s as t o which f a c t o r dominates o v e r a l l w i t h i n th e i n t e r ­
a c t io n s o f f a c t o r s .
Each f a c t o r has i t s
pro p o n e n ts, which r e f l e c t s con­
s i d e r a b ly on th e s p e c i f i c stream systems w i t h which th e re s e a rc h e rs are
fa m ilia r.
Among th e more re c e n t s t u d i e s , Cummins (1962, 1966) f a v o r s th e
s u b s t r a te f a c t o r , though he does n o t m in im iz e th e s i g n i f i c a n c e o f fo o d .
Though t h i s p re fe re n c e f o r s u b s t r a te i s r e la t e d t o th e p r a c t i c a l aspect
th a t i t
i s th e o n ly p r i n c i p l e f a c t o r which can r e a d i l y be measured in
n a tu r a l h a b i t a t s , he as w e ll as
Thorup
(1966) a ls o note t h a t s u b s tr a te
has many i n t e r r e l a t i o n s h i p s w i t h o t h e r f a c t o r s o f th e enviro nm ent.
S c o tt (1 9 5 8 ), Jaag and Ambtlhl
re s e a rc h e rs ( Kamler and Riedal
(1964 ), and a m a j o r i t y o f European
1960) f e e l t h a t th e c u r r e n t i s the most
im p o r ta n t f a c t o r , though t h i s i s based on th e p rim a ry i n t e r a c t i o n s o f
c u r r e n t w i t h more d i r e c t f a c t o r s
( F ig u re 6 ).
Jaag and Ambtlhl a d m it,
however, t h a t c u r r e n t i s i n s i g n i f i c a n t in th e boundary la y e r s which th e
organisms i n h a b i t .
U l f s t r a n d (1967) fa v o r s th e food f a c t o r because, as
mentioned above, i t
can be t o l e r a t e d under s u b -o p tim a l c o n d it io n s t o a
le s s e r degree than can c u r r e n t o r s u b s t r a t e ty p e .
In my s tu d y , c u r r e n t
appears t o be th e l e a s t s i g n i f i c a n t o f th e th r e e main f a c t o r s a t th e
immediate le v e l o f th e organism s.
In B la in e S pring Creek, th e general
c u r r e n t does not v a r y s e a s o n a lly l i k e most stream s, and co n se q u e n tly does
n o t have p e rio d s o f g r e a t l y in c re a se d f l o w which can scour e s ta b lis h e d
h a b ita ts .
Because t h i s
was a h e a d w a t e r
w it h o u t v e g e t a t iv e sh a d in g , v e ry l i t t l e
s e c tio n
of
th e
s tre a m
a llo c th o n o u s d e t r i t u s entered o r
-9 3 -
was c o n t r ib u t e d here.
Thus, c u r r e n t does n o t f u n c t io n t o d i s t r i b u t e
o r g a n ic m a tte r o t h e r than r e l a t i v e l y m inor amounts re le a s e d by th e
stream i t s e l f .
Creek, i t
T h e r e f o r e , i n th e headwater s e c t io n o f B la in e Spring
i s th e i n t e r a c t i o n o f th e e s ta b lis h m e n t o f s t a b le s u b s tr a te
w i t h th e development o f a s u i t a b l e food regime which appears to dom inate.
I f these areas o f s t a b le s u b s t r a te p r o v id e th e minimal requ ire m e n ts f o r
space and p r o t e c t i o n , i t
i s th e a v a i l a b i l i t y o f s u i t a b l e food sources
which u l t i m a t e l y r e g u la t e s m i c r o d i s t r i b u t i o n in t h i s stream .
The s tu d y showed t h a t a d e t a i l e d a n a ly s is o f s u b s t r a t e s iz e com­
p o s it io n
as suggested by Cummins (1962, 1964, 1966 ), Cummins and L a u f f
(1969) and Thorup (1966) can be used t o e lu c id a t e i t s
d is trib u tio n .
Secondly, t h i s s tu d y in t e g r a t e d a l l
e f f e c t s on m ic r o ­
re cogn ized and
measured v a r ia b le s w i t h each o t h e r and r e la t e d t h e i r in f l u e n c e to
m ic ro d is trib u tio n .
E rikse n (1966) makes th e plea t h a t , because gross
measurements o f th e environm ent are o f l i t t l e
va lu e t o th e und e rsta n d in g
o f th e m ic ro e n v iro n m e n t, th e parameters w i t h i n th e m ic r o h a b it a t s o f th e
g ive n organisms must be de te rm in e d .
A d m it t e d ly , th e stream in t h i s
stu d y was chosen t o m in im iz e v a r i a b i l i t y o f f a c t o r s t y p i c a l l y more
v a r i a b l e in most o t h e r streams to reduce th e c o m p le x ity o f a n a ly s is .
However, A lle n
(1959) suggests t h a t th e pro p e r approach t o such s tu d ie s
i s t o choose a stream w i t h minimal v a r i a t i o n i n a l l
f a c t o r to be c o n s id e re d .
,
b u t th e prime
-94A l o g i c a l f o l l o w - u p t o t h i s stu d y c o u ld in v o lv e s e v e ra l aspe cts.
F i r s t , i t would be i n t e r e s t i n g t o a n a lyze th e r e s u l t s from c a r e f u l l y
placed t r a y s o f v a r i o u s l y graded s u b s t r a t e w i t h i n th e stream s tu d ie d
t o d e te rm in e i f th e o r i g i n a l d i s t r i b u t i o n o f s u b s t r a te p a r t i c l e s does
e vo lve w i t h tim e i n th e manner h y p o th e s iz e d .
Second, i t would be i n t e r ­
e s t in g t o a p p ly th e methods o f ana lyses used in t h i s s t u d y , namely th e
i n t e g r a t i o n o f a l l p o t e n t i a l v a r ia b le s w i t h a m u l t i p l e r e g r e s s io n
a n a l y s i s , t o a stream which has more v a r i a t i o n i n o t h e r f a c t o r s than
found here.
And t h i r d ,
i t would be i n t e r e s t i n g t o ana lyze th e d i s t r i ­
b u tio n o f organisms in l a b o r a t o r y streams where th e m agnitude o f th e
v a r io u s f a c t o r s c o u ld be c a r e f u l l y c o n t r o l l e d , and th e movements o f
organisms d i r e c t l y observed.
APPENDIX
APPENDIX
The sampler used in this study
Data com piled s e p a r a te ly from th e net and bucket p o r t io n s o f th e
sampler (see Methods- and M a t e r i a ls ) show t h a t the f o l l o w i n g percentages
o f each taxon were o b ta in e d from each p o r t i o n :
PLANTS
net
bucket
72.85
27.15
72.57
A. noterOTpliilvm
R. nasturtium-aquat. 82.08
Z. palustris
80.14
27.43
17.92
1 9 .8 6 .
Ephemeroptera
E. infrequens
Eaetis sp.
Paraleptophlebia sp.
T r ic h o p te r a
INSECTS
P le cop tera
.
A . pacifioa
o t h e r s to n e - flie s
71.12
28.88
75.28
71.31
75.39
24.72
28.69
24.61
net
bucket
70,77
72.92
59.48
29.23
27.08
40.52
84.29
15.71
57.59
42.41
27.46
79.08
47.77
Oahrotriekia sp. 72.54
20.92
Glossosoma sp.
Rhyaoophila sp. 52.23
C o le o p te ra :
Optioservus sp.
No d e l i b e r a t e a tte m p t was made t o d is lo d g e a l l
72.90
27.10
o f th e organisms i n t o
th e n e t , as i t was d e s i r a b le t o com plete th e sampling process w i t h i n th e
s h o r t e s t p o s s ib le p e rio d o f tim e .
Even so, over 70 p e rc e n t o f both p l a n t
and in s e c t q u a n t i t i e s were c o l le c t e d in th e n e t.
e ffo rt,
With a l i t t l e
more
however, i t should be p o s s ib le t o d is lo d g e v i r t u a l l y a l l o f th e
organisms by t h o r o u g h ly s c ra p in g and ru b b in g a l l ro cks b e fo r e p la c in g
them in th e b u cke t.
A ls o , some v e g e ta t io n was d e l i b e r a t e l y placed i n t o
th e bucket r a t h e r than being a llo w e d t o f l o w i n t o th e n e t i f
would have tended t o c lo g th e n e t.
i t s presence
T h is sampler ( F ig u re 2) has th e advan­
tage over a S u rb e r- ty p e in t h a t no backwash due t o th e r e s is t a n c e t o f l o w
-97can o c cu r around th e s id e s , th u s p r e v e n tin g th e escape o f organism s.
Though w e ig h ts on th e p la t f o r m were n o t used w h ile sam pling in th e s tu d y
a re a , th e sampler was m o d ifie d so t h a t b r ic k s co u ld e a s i l y be added as
needed t o both sid e s o f th e p la t f o r m t o g iv e i t g r e a t e r d e n s it y and s t a ­
b ility
in s w i f t e r o r deeper w a te r.
A re c e n t p u b l i c a t i o n by Mundie (1971) d e s c rib e s a sam pler designed
f o r use by a q u a tic b i o l o g i s t s
( e s p e c i a l l y those in t e r e s t e d i n s u b s tr a te
s iz e d i s t r i b u t i o n s ) , as w e ll as by f i s h b i o l o g i s t s and g e o m o rp h o lo g is ts .
The frame i s r e c t a n g u la r w i t h a tapered p o r t io n e x te n d in g from one s id e
t o be p o in te d i n t o th e c u r r e n t t o m in im iz e r e s is t a n c e .
C u rre n t can be
r e g u la te d t o reduce backwash w i t h a s l i d i n g gate a t th e end o f th e
tapered s e c t io n .
A coarse net i s in s e r t e d in s id e a f i n e r n e t on th e
downstream s id e o f th e sample.
T h is system ro u g h ly grades th e c o n te n ts
and a llo w s r e t e n t i o n o f f i n e r p a r t i c l e s than o th e rw is e would be pos­
s i b l e w it h o u t causing backwash.
In use, th e sampler i s placed on th e
s u b s t r a te and g ra v e l i s p i l e d around i t t o p re v e n t m a t e r i a ls o r c u r r e n t
from escaping underneath.
An o p t io n a l frame w i t h th e same shape as th e
sampler bottom can be im p la n te d i n t o th e streambed and th e s u b s tr a te
in s id e a llo w e d t o r e c o lo n iz e b e fo re p la c in g th e sampler on i t .
The advantages o f M undie1s sampler i s th e s tre a m lin e d design and use
o f th e double n e t.
The method o f s e a lin g th e sampler a t th e bottom, how­
e v e r , seems q u e s tio n a b le , e s p e c i a l l y f o r use in a stream such as th e one
I sampled.
Though M undie1s method o f p i l i n g
s u b s tr a te around th e edges
-9 8 -
may work w e ll w i t h f i n e r s u b s t r a t e m a t e r i a l , more d i f f i c u l t y would o c c u r
in t r y i n g t o seal i t
adequate where i t
in coarse s u b s t r a t e .
i s d e s ire d t o r e t a i n a l l
I t would n o t appear t o be
s u b s t r a te p a r t i c l e s .
Mundie
s t a t e s t h a t t h i s method i s s u p e r io r t o th o se types o f samplers using a
s t r i p o f foam r u b b e r, a p p a r e n t ly meaning a narrow s t r i p around th e p e r i ­
m ete r.
My sampler ( F ig u re 2) uses a s e c t io n o f foam ru b b e r which i s
20 cm wide from th e edge o f th e opening i n th e m id d le t o th e edge o f
th e p l a t f o r m .
I t p resen ted no problem whatever d u r in g th e s tu d y in
p r e v e n tin g th e c u r r e n t from f lo w in g underneath th e foam ru b b e r i t s e l f .
In e v a lu a t in g th e two sam ple rs, i t would appear t h a t th e basic
desig n o f M undie's sam ple r, which does o f f e r some advantages (though
mine was t h o r o u g h ly adequate f o r purpose i t was designe d) co u ld be
adapted t o a p l a t f o r m such as on my sam pler.
p o s s ib le t o adapt i t
In f a c t , i t would seem
so t h a t a p la t f o r m w i t h th e a tta c h e d foam rubber
co u ld be added o r removed as d e s ir e d , th u s r e t a i n i n g th e advantages o f
both d e s ig n s .
Multi-pie regression analyses in stream benthos studies
In v i r t u a l l y a l l
s tu d ie s which have been conducted on th e m ic r o d is ­
t r i b u t i o n o f stream organism s, a c e r t a i n v a r ia b le o r v a r ia b le s were
chosen f o r s tu d y and o t h e r s were g e n e r a ll y ig n o re d .
Graphs o r sim ple
c o r r e l a t i o n s were chosen in most cases t o dem onstrate th e r e l a t i o n s h i p
which e x is te d between an independent v a r i a b l e and th e dependent v a r i a b l e .
-99The most thorough a n a ly s is o f f a c t o r s found in a l l th e s t u d ie s on m ic r o ­
d i s t r i b u t i o n was t h a t made by Egglishaw (1969) who d e r iv e d p a r t i a l d e v i ­
a t io n s from th e r e l a t i o n s h i p s o f th e i n s e c t numbers t o th e amount o f
d e t r i t u s , th e sample depth and th e le n g t h o f th e l a r g e s t stone in th e
sam pling a re a .
The f a l l a c y w i t h s im p le r analyses i s t h a t v a r ia b le s
o p e r a tin g w i t h i n th e h a b i t a t are n o t co n s id e re d t o be r e la t e d t o each
o th e r o r i f
t h e ' r e l a t i o n s h i p s are re c o g n iz e d , th e y are ig n o re d .
R e la t io n ­
sh ip s c e r t a i n l y do e x i s t ( F ig u re 6 ) and c e r t a i n v a r ia b le s may p a r a l l e l
o t h e r v a r ia b le s which have a more d i r e c t r e l a t i o n s h i p t o th e actual
organisms co n sid e re d ( U lf s t r a n d 1967).
A m u l t i p l e r e g r e s s io n a n a ly s i s ,
however, compensates f o r r e l a t i o n s h i p s between r e la t e d v a r ia b le s by
h o ld in g each o f th e independent v a r ia b le s a t i t s mean w h il e o th e r v a r i ­
a b le s are a na lyzed .
Several examples e x i s t in th e s tu d y t o dem onstrate
t h i s where th e r e s u l t s from th e s im p le c o r r e l a t i o n m a t r ix d i f f e r con­
s id e r a b l y from r e s u l t s o b ta in e d in th e m u l t i p l e r e g r e s s io n ana lyses.
T h is approach a ls o a llo w s f o r compensation o f u n a vo id a b le v a r i a t i o n s
which a re n o t o f d i r e c t concern i n a s tu d y .
In t h i s s t u d y , tim e and sec­
t i o n v a r ia b le s were in c lu d e d r e s p e c t i v e l y t o compensate f o r seasonal
v a r i a t i o n and unmeasured v a r i a t i o n between th e s e c tio n s sampled.
A n oth er
use o f m u l t i p l e r e g r e s s io n analyses i s t h e d e te r m in a tio n o f which o f
se ve ra l v a r ia b le s o r groups o f v a r ia b le s d e s c r ib in g th e b a s ic source o f
v a r i a t i o n have th e g r e a t e s t r e l a t i o n t o independent v a r i a b l e s .
In t h i s
s tu d y , s u b s t r a t e was d e s c rib e d by s e v e ra l v a r ia b le s t o dete rm in e which
-100-
most a d e q u a te ly d e s c rib e d th e in f l u e n c e o f th e d i s t r i b u t i o n .
Since a l l
o f these v a r ia b le s were c o r r e la t e d as expected t o each o t h e r , th e s i g ­
n i f i c a n c e o f any one param eter was d i f f u s e d over a l l
such a c irc u m s ta n c e , i t
w ill
param eters.
In
i s p o s s ib le t h a t few o r none o f th e parameters
i n d i v i d u a l l y show s i g n i f i c a n t
t s ta tis tic s .
However, an
(Table 10) on th e group o f parameters i n q u e s tio n w i l l
th e group as a whole has s i g n i f i c a n c e , j u s t as th e
F te s t
determ ine whether
t s ta tis tic s w ill
i n d i c a t e s i g n i f i c a n c e i f o n ly one param eter i s used.
The m u l t i p l e r e g r e s s io n analyses in d ic a t e d why organisms should be
d iv id e d i n t o th e lo w e s t ta xa p o s s ib le f o r a n a ly s i s .
For example, r e s u l t s
f o r th e p l a n t species and th e c a d d i s f l y genera were o f t e n o p p o s ite be­
tween th e lo w e s t t a x a .
A n a ly s is o f th e h ig h e r ta x a in both cases f r e ­
q u e n tly showed t h a t th e o p p o s ite e f f e c t s o f lo w e r ta x a tended t o cancel
each o t h e r o u t , r e s u l t i n g in app arent i n s i g n i f i c a n c e o f c e r t a i n v a r i ­
a b le s .
- I Ol -
Table 12.
The partitioning of the weights of the substrate on those sieves
which w ere used to bracket those size ranges [0 (-2 ) to 0 (-5 )]
where the specific siev es needed were not available.
Phi class
Size range
(mm)
-I
2-4
-2
-3
4-8
Percent assigned to
each phi cla ss by the
siev e s used
-------- -
2.00
I----------
100
------------
4.00
"---------------
48.2 ---------51.8 ---------100 ---------48.2 ---------51.8 ---------100 ---------46.5 ---------53.5 —:------100 ---------100 -----------
8-16
16-32
-5
32-64
-6
64-128
(mm)
--------- 100
---------------4
Sieve used
--------------'-----------------
6.68
9.42
13.3
18.9
26.7
38.1
64.0
-102-
Table 13.
Percentages of substrate in each phi cla ss for each of the 8 stream
section s. Data is based on the percentages of substrate contained
in each individual sample. Size ranges of phi c la sse s are listed in
Table 3,
Section_______________________
7
6
8
5 .
All sam ples
combined
I
2
3
4
5
.2 3 2 8
.3 3 2 2
.1578
.2 6 8 2
.3733
.5117
.2150
.2 6 6 7
.2949
4
.8250
.5867
.1311
.3124
.7878
1.435
.4 6 2 8
.9617
.6904
3
3.810
2.819
.3211
1.220
2.531
6 .5 0 8
1.499
3.212
2.751
2
7.454
7 .8 6 8
1.027
4.730
5.985
15.08
3.390
4.634 ■
6 .2 8 2
I
4.267
9.102
2.416
6 .8 2 3
6.337
8.777
4.100
4.439
5.775
0
6 .2 2 6
8 .3 7 5
4 .6 2 2
8.221
5.572
6 .2 3 6
5.521
4 .6 8 8
6.168
-I
5.999
5.046
4.312
5 .6 4 1
4 .8 2 2
3.295
3 .9 0 2
3 .5 9 2
4 .5 6 9
-2
7.685
5.742
6.274
7.211
7.464
3 .6 3 8
4.732
5.262
5.993
-3
15.38
7.696
10.41
9.764
11.98
6.432
7.643
8.734
9 .7 5 5
-4
19.96
1 8 .3 3
19.64
2 0 .0 8
21.72
14.13 ' 17.78
17.05
18.58
-5'
2 0 .3 3
2 6 .8 8
25.90
2 6 .6 6
21.80
2 0 .8 2
31.11
25.00
24.80
-6
7.833
7.226
24.78
9.072
9 .8 0 3
10.47
19.65
19.29
13.55
-7
0 .0 0 0
0 .0 0 0
0 .0 0 0
0 .0 0 0
.9078
2.672
0 .0 0 0
2 .8 6 7
.8115
The t o t a l d r y w e ig h t in grams o f th e i n d i v i d u a l p l a n t genera and t h e i r combined
w e ig h t c o l l e c t e d from each o f th e e i g h t stream s e c tio n s d u r in g t h i s study (re g u ­
l a r t y p e ) , th e d r y w e ig h t per squa re -m eter ( p a re n th e s e s ), th e percentage d i s t r i ­
b u t io n o f each taxon r e l a t i v e t o th e o t h e r ta xa w i t h i n each s e c t io n ( i t a l i c s ) ,
and th e percentage d i s t r i b u t i o n w i t h i n each taxon r e l a t i v e t o th e other, stream
s e c tio n s ( b r a c k e t s ) . A t o t a l o f 18 - - 0.049 m2 samples were processed f o r stream
s e c tio n s 1-3 and 5-8 d u r in g th e s tu d y p e r io d .
For s e c t io n 4, where, o n ly 17 sam­
p le s were used, th e t o t a l w e ig h t in d ic a t e d f o r each group i s a d ju s te d upward by
18/17 t o make comparisons between s e c t io n s .
P la n t taxon
I
.
2
3
Stream s e c t io n
5
4
6
7
8
Mean per
s e c tio n
T o ta l
PLANTS
305.5
115.2
284.2
713.3
611.4
162.8
471.2
459.4
390.4
3123
(1 8 4 .6 ) (5 3 4 .3 ) (1 3 0 .6 ) (3 4 6 .4 ) (322.2) (808.7) (6 9 3 .2 ) (520.9) (442.6) (4 4 2 .6 )
100.0
100.0
100.0
100.0
100.0
200.0
299.9
100.0
100.0
100. 0
[5 .2 1 3 ] [1 5 . 0 9 ] [3 .6 8 9 ] [9 .7 8 2 ] [9 .1 0 0 ] [ 2 2 .8 4 ] [1 9 .5 8 ] [1 4 . 7 1 ] [1 2 .5 0 ] [ 100. 0]
Amblystegiim
noteroghilum
113.2
283.6
274.2
699.6
148.0
452.7
610.2
445.9
378.4
3027
(1 6 7 .8 ) (5 1 3 .3 ) (1 2 8 .3 ) (3 2 1 .5 ) (310.9) (7 9 3 .2 ) (6 9 1 .8 ) (505.6) (429.0) (429.0)
90.91
92.93
99.49
9g. Of
99.20
99.99
99.99
97.99
99.93
99.93
[4 .8 8 9 ] [1 4 .9 6 ] [ 3 .7 4 0 ] [9 .3 6 9 ] [9 .0 5 8 ] [ 2 3 .1 1 ] [2 0 . 1 6 ] [ 1 4 .7 3 ] [1 2 .5 0 ] [ 100. 0]
Rorippa
nasturtiumaquatioum
1.990
1.670
4.460 .
18.53
( 21 . 01 ) (2 .2 5 6 ) (1 .8 9 3 ) (5 .0 5 7 )
2.727
1.569
.5499
[2 1 . 3 4 ] [2 6 . 7 9 ] [2 .8 7 7 ] [ 2 .4 1 4 ] [6 .4 4 8 ]
Zanniohetlia
patustris
14.76
(1 6 .7 3 )
13.17
1.270
13.32
8.650
69.17
(14.93) (1 .4 4 0 ) (15.10) (9.807) (9 .8 07)
7.949
.2977
2.999
2.225
2.225
[ 1 9 .0 4 ] [ 1 .8 3 6 ] [1 9 .2 6 ] [1 2 .5 0 ] [ 100. 0]
0.000
20.22
5.480
.5400
.04000
0.000
0.000
.2000
3.310
26.48
(.04 535) ( 0 . 000) ( 0 . 000) (2 2 .9 3 ) (6 .2 1 3 ) (.61 22) ( 0 . 000) (.2 2 6 8 ) (3 .7 5 3 ) (3 .7 53)
6.619
0. 000
.02457
I. 929 .97579
9. 999 .94354
0.000
.9479
.9479
[ .1 5 1 1 ] [ 0 . 000] [ 0 . 000] [7 6 . 3 6 ] [2 0 .6 9 ] [2 .0 3 9 ] [ 0 , 000] [.7 5 5 3 ] [1 2 .5 0 ] [ 100. 0]
-E O l-
Table 14.
T ab le 15.
The t o t a l number o f i n s e c t ta xa c o l l e c t e d f o r each o f th e e i g h t stream s e c tio n s
d u r in g t h i s s tu d y ( r e g u l a r t y p e ) , th e numbers per square-m eter (p a re n th e s e s ), the
percentage d i s t r i b u t i o n o f each taxon r e l a t i v e t o th e o t h e r taxa w i t h i n each sec­
t i o n ( i t a l i c s ) , and th e percentage d i s t r i b u t i o n w i t h i n each taxon r e l a t i v e to th e
o t h e r stream s e c tio n s ( b r a c k e t s ) .
A t o t a l o f 18 - - 0.049 m2 samples were processed
f o r stream s e c tio n s 1-3 and 5-8 d u r in g th e stu d y p e r io d .
For s e c t io n 4, where o n ly
17 samples were used, th e t o t a l number in d ic a te d i s a d ju s te d upward by 18/17 to
make comparisons between s e c t io n s .
I n s e c t taxon
INSECTS
2
3
Stream s e c t io n
5
4
Mean per
6
7
8
T o ta l
section
5995 12,156
2983
7466
7906 10,133
2290 10,846
7472 59,775
(8465)
(2596) 0 2 ,2 9 7 )
(3382)
(6796) (13,782)
(8964) (11,489)
(8472)
(8472)
200.8
200.0
100. 0
200.0
200.0
200.0
200.0
200.0
200.0
100. O
[3 .8 3 1 ] [ 1 8 . 1 4 ] [ 4 .9 9 0 ] [1 2 . 4 9 ] [ 1 0 . 0 3 ] [ 2 0 .3 4 ] [ 1 3 . 2 3 ] [1 6 . 9 5 ] [ 1 2 .5 0 ] [ 100. 0]
224.0
(2 5 4 .0 )
9.782
1983
700.0
(2248) (7 9 3 .7 )
1593
(1806)
1210
2441
(1372)
(2768)
1563
(1772)
1802
(2043)
28.28
22.34
1440 11,516
(1632)
(1632)
20.28
20.08
29.77
27.78
29.27
23.47
[1 .9 4 5 ] [ 1 7 . 2 2 ] [ 6 .0 7 8 ] [ 1 3 .8 3 ] [1 0 . 5 1 ] [21.20] [1 3 . 5 7 ] [1 5 . 6 5 ] [ 1 2 .5 0 ]
[ 100. 0]
Acvoneuvia
paeifiaa
34.00
76.00
27.00
25.00
38.00
33.00
45.00
38.38
307.0
(8 6 .1 7 ) (3 0 .6 1 ) (38.55) (2 8 .3 4 ) (43.08) (37.41) (5 1 .0 2 ) (43.51) ( 4 3 . 5 1 )
. 9051
2.208
.4170
.7007
.4554
.3228
.4274
. 5137
.4442
. 5137
[9 .4 4 6 ] [2 4 . 7 6 ] [ 8 .7 9 5 ] [1 1 . 0 7 ] [8 .1 4 3 ] [ 1 2 .3 8 ] [ 1 0 .7 5 ] [1 4 . 6 6 ] [ 1 2 .5 0 ] [ 100 . 0]
o th e r
s to n e flie s
2403 . 1530
1757
1401 11,209
(2724)
(1735)
(1992)
(1589)
(1589)
8. 515
27.58
22.58
20.88
29.77
19.35
17.34
29.77
18. 75
28.75
[1 .7 4 0 ] [1 7 . 0 1 ] [6 .0 0 4 ] [ 1 3 .9 1 ] [1 0 . 5 7 ] [ 2 1 .4 4 ] [1 3 . 6 5 ] [1 5 . 6 7 ] [ 1 2 .5 0 ] [ 100. 0]
Ephemeroptera
2159
2709
753.0
1850
1977
26 8 3
2908
1864 14,910
(2448)
(2098)
(2357) ( 8 5 3 . 7 )
(3042)
(2241)
(3297)
(2113)
(2113)
22.88
19.17
25.24
28.92
30.88
22.07
25. 01
28.70
24.94
24.94
[3 .3 6 0 ] [1 3 . 9 4 ] . [5 .0 5 0 ] [ 1 4 .4 8 ] [1 2 . 4 1 ] [1 7 .9 9 ] [ 1 3 .2 6 ] [1 9 . 5 0 ] [ 1 2 .5 0 ] 100 0
29.00
(3 2 .8 8 )
195.0
(221.1)
1907
673.0
(2162) (7 6 3 .0 )
1559
(1768)
-104-
P le c o p te ra
I
1185
(1344)
501.0
(5 6 8 .0 )
[
,]
Table 15 ( c o n tin u e d )
ETphemevella
rLnfvequens
I
176.0
(1 9 9 .5 )
[ 1 .6 9 9 ]
Baetis sp.
2
3
Stream s e c t io n
4
5
6
7
8
Mean per
s e c tio n
T o ta l
320.0
1561
1381
1649
1250
2189
1832
1295 10,358
(1770)
(2482)
(1870) (3 6 2 .8 )
(1417)
(1566)
(2077)
(1468)
(1468)
25. 2 0
20.73
20. 91
20.95
29.02
27.47
29.09
27.33
27.33
[ 1 5 .9 2 ] [3 .0 8 9 ] [1 5 . 0 7 ] [12.07]. [ 2 1 .1 3 ] [1 3 . 3 3 ] [1 7 . 6 9 ] [ 1 2 .5 0 ] [1 0 0 .0 ]
333.0
400.0
402.0
430.0
326.0
827.0
366.0
2928
(3 6 9 .6 ) (4 5 3 .5 ) (4 5 5 .8 ) (377.6) (4 8 7 .5 ) (9 3 7 .6 ) ( 4 1 5 . 0 ) .( 4 1 5 .0 )
1.21 7
20.93
5.359
2.739
5.439
9.709
9.292
4.999
4.999
[2 .6 6 4 ] [4 ,5 0 8 ] [1 1 . 1 3 ] [1 3 . 6 6 ] [1 3 . 7 3 ] [1 1 . 3 7 ] [1 4 .6 9 ] [2 8 . 2 4 ] [ 1 2 .5 0 ] [1 0 0 .0 ]
. 78.00
(8 8 .4 4 )
132.0
(1 4 9 .7 )
Pavaleptophlebia sp.
197.0
161.0
107.0
198.0
166.0
298.0
249.0
202.9
1623
(3 3 7 .9 ) (121.3) (2 2 3 .4 ) (224.5). (182.5) (1 8 8 .2 ) (2 8 2 .3 ) (230.0) (230.0)
2.324
2.457
3.597
2.939
3.303
2.200
2.749
2.725
2.725
[1 5 . 2 2 ] [ 1 8 .3 6 ] [6 .5 9 3 ] [1 2 . 1 4 ] [ 12 . 20] [ 9 .9 2 0 ] [1 0 .2 3 ] [1 5 . 3 4 ] [1 2 .5 0 ] [1 0 0 .0 ]
T r ic h o p te r a
548.0
866.0
1159
532.0
946.0
955.0
673.0
795.0
809.3
6474
(9
8
1
.9
)
(6
0
3
.2
)
(1314)
(1073)
(1083) (917.5) (917.5)
(7 6 3 .0 ) (9 0 1 .4 ) (6 2 1 .3 )
29.37
22.90
9.974
9.534
22.97
29.39
9.425
7.330
20.93
20.93
[1 0 . 4 0 ] [1 2 . 2 8 ] [ 8 .4 6 5 ] [ 1 3 .3 8 ] [8 .2 1 7 ] [1 7 .9 0 ] [1 4 .6 1 ] [1 4 . 7 5 ] [ 1 2 .5 0 ] [1 0 0 .0 ]
Ochvotviehia
sp.
Glossosoma
sp.
247.0
(2 8 0 .0 )
156.0
217.0
874.0
197.0
677.0
672.0
486.0
463.9
3711
(5 5 1 .0 ) (1 7 6 .9 ) (2 4 6 .0 ) (2 2 3 .4 ) (9 9 0 .9 ) (767.6) (7 6 1 .9 ) (525.9) (525.9)
2.907
5.230
3.299
7.290
9.593
9.932
4.492
9.209
9.209
[1 1 . 6 4 ] [1 3 . 1 0 ] [ 4 .2 0 4 ] [ 5 .8 4 7 ] [5 .3 0 9 ] [2 3 .5 5 ] [ 1 8 .2 4 ] [1 8 . 1 1 ] [1 2 .5 0 ] [1 0 0 .0 ]
432.0
(4 8 9 .8 )
79.00
239.0
283.0
216.0
426.0
183.0
95.00
115.0
204.5
1636
(2 7 1 .0 ) (3 2 0 .9 ) (2 4 4 .9 ) (4 8 3 .0 ) (2 0 7 .5 ) (89.57). (1 0 7 .7 ) (1 3 0 .4 ) (231.9) (231.9)
20.-44
7.242
3. 053
.9499
2.202
5.709
2.235
2.909
2.737
2.737
[ 1 4 . 6 1 ] [1 7 . 3 0 ] [1 3 . 2 0 ] [2 6 . 0 4 ] [1 1 . 1 9 ] [4 .8 2 9 ] [ 5 .8 0 7 ] [7 .0 2 9 ] [1 2 .5 0 ] [1 0 0 .0 ]
-SO L-
I n s e c t taxon
Table 15 (conclu ded)
Rhyaaophila
sp.
C o le o p te ra :
Optioservus
sp.
I
2
3
2.000
26.00
(2 .2 6 8 )
(29.48)
.2 3 9 7
892.0
( 1011)
5989
(6790)
982.0
3 8 .9 5
5 5 .2 2
3 2 .9 2
Stream :s e c tio n
4
5
(1113)
(252.8)
2 .9 8 7
2849
(3230)
3 8 .7 8
152.0
(1 7 2 .3 )
(233.6)
2403
(2724)
5873
(6659)
4 0 .0 8
4 8 .3 7
7
8
Mean per
s e c t io n
T o ta l
174.0
168.0
140.9
1127
(197.3) (190.5) ( 1 5 9 . 7 ) (159.7)
2 .5 3 5
1.695 2 . 2 0 7
7. 858
.0 8 7 3 4
5 .9 0 0
7 .8 8 8
7 .8 8 8
[ .1 7 7 5 ] [2 .3 0 7 ] [1 5 . 6 2 ] [1 9 . 7 9 ] [1 3 . 4 9 ] [1 8 . 2 8 ] [1 5 . 4 4 ] [1 4 . 9 1 ] [1 2 . 5 0 ] [1 0 0 .0 ]
176.0
(1 9 9 .5 )
223.0
6
206.0
3420
(3878)
4 3 .2 8
4468
(5066)
4 4 .0 9
3360
(3809)
4 4 .9 7
26,876
(3809)
4 4 .9 7
[3 .3 1 9 ] [ 2 2 . 2 8 ] [3 .6 5 4 ] [ 1 0 . 6 0 ] [8 .9 4 1 ] [2 1 . 8 5 ] [1 2 .7 3 ] [1 6 . 6 2 ] [1 2 . 5 0 ] [ 1 0 0 .0 ]
-90 L-
I n s e c t taxon
-107-
Table 16.
a)
Computer data o f th e f i n a l m u l t i p l e r e g r e s s io n model — r e g r e s ­
s io n S. A l l means are raw data based on th e i n d i v i d u a l l y sam­
p le d a r e a — 0.049 m2. Regression c o e f f i c i e n t s f£;_used i n th e
g e n e r a liz e d r e g r e s s io n form ula_(% c = y . f -b1(x1 - X1) +
^2(X£ - Xg) + ■ • • + bn(Xn - xn) should be m u l t i p l i e d by 20.37
(0.0 49 m2 x 20.37 = I m2) i f in s e c t o r p l a n t q u a n t i t y i s l i k e ­
w ise co n ve rte d t o q u a n t i t y per square m ete r.
One e x c e p tio n i s
when th e p l a n t and in s e c t q u a n t i t i e s a re both conve rted and th e
p la n t s are in depe nden t; in , t h i s case, th e r e g r e s s io n c o e f f i c i ­
e n t t o be used i s as g iv e n ,
t = 1.977 when p = 0.05 w it h 142
degrees o f freedom.
INSECTS
= 4 1 5 .0 )
Independent
v a ria b le
Mean
P a rtia l
c o rre la tio n
Regr.
c o e f.
S td .e rro r
re g r.c o e f.
Computed
t v a lu e
A. noterophilum
R. nasturt-ium-aquat.
Z. palustr-is
21.07
.4427
.1769
. 5799E-01
-.1 8 4 6
- .2 3 8 2
.7385
-24.03
-3 9 .6 4
1.137
11.44
14.46
.6494
- 2 . TOO
- 2 .7 4 2
0 .2 5 th
4.153
2.995
1.799
1.003
.1901
-.1402E-01
-.46 62E -02
.9512E-02
126.1
-13.31
-4.511
6.040
58.24
84.86
86.53
56.79
2.165
-.1 5 6 8
-.0 5 2 1 2
.1064
- 2 7 9 .0
114.4
-178.1
21.34
.-8 5 .1 8
193.9
26.71
49.04
49.03
50.93
49.88
47.63
49.76
51.04
- 5 .6 9 0
2.332
-3 .4 9 8
..4279
-1 .7 8 8
3.897
.5233
-2 6 8 .2
29.56
-.9 0 3 0
39.92
4.842
.1675
- 6 .7 1 9
6.105
- 5 .3 9 0
s td . e rro r
(sy3x)
pfcilf U G M u
I iGS
S'fcil
10t h
dummy v a r ia b le s f o r
stream s e c t io n
v a r ia b ility
tim e
.0000
.0000
.0000
-.4 5 3 6
.2042
-.2 9 8 6
-.69 93E -02 .3824E-01
- .1 5 7 9
.0000
.3292
.0000
.4676E-01
.0000
i n t e r c e p t = 579.9
-.5151
.4793
-.4 3 4 2
9.538
117.9
1635
I in e a r
q u a d r a tic
c u b ic
R squared = 0.6227
=
210.1
ANALYSIS OF VARIANCE FOR THIS REGRESSION
Source
d.f.
S.S.
M.S.
F Value
12.1375
17
.910560E+07
535623
Residual
125
.551622E+07
44129.7
T o ta l
142
■ .146218E+08
Due t o Regression
(n = 143)
- 1 08-
T a b l e 16 ( c o n t i n u e d )
b)
(^no^ = 79.8 4 )
P le c o p te ra
Independent
v a ria b le
■Mean
P a rtia l
c o r re la tio n
Regr.
c o e f.
S td .e rro r
re g r.c o e f.
Computed
t v a lu e
21.07
.4427
.1769
.8790E-01
-.2 3 5 0
-.1 3 3 2
.3618
-9.9 73
-7.0 07
.3667
3.690
4.662
.9866
-2 .7 0 3
-1.5 0 3
4.153
2.995
1.799
1 .003
. 9646E-01
- . 5 8 1 1 E-Ol
.1399
-.1 4 1 4
20.35
-17.81
44.07
-2 9 .2 4
18.78
27.37
27.90
18.31
1.083
-.6 5 0 8
1.579
-1 .5 9 7
-.3 3 1 4
.1215
-.1 5 4 7
-.6993E-02
.3826E-01
-.7856E-01
.0000
.2284
.0000
.0000
.2945E-01
-6 2 .1 0
21.63
-2 8 .7 5
-13.53
42.08
5.422
15.81
15.81
16.42
16.09
15.36
16.05
16.46
-3 .9 2 7
1 .368
- 1 .7 5 0
.4281
-.8811
2.623
.3294
-8 1 .1 9
9.973
-.3 1 5 0
12.87
1.561
.5403E-01
-6 .3 0 8
6.387
-5.831
st d . e r r o r
(sy3x)
A. noteroph-ilum
R. nastuvtium-aquat.
Z. palustris
p e rc e n tile s
0 .2 5 th
I st
5th
10t h
dummy v a r ia b le s f o r
stream s e c t io n
v a r ia b ility
tim e
.0000
.0000
.0000
9.538
117.9
1635
I in e a r
q u a d r a tic
c u b ic
i n t e r c e p t = 127.8
-.4 9 1 4
.4961
-.4 6 2 4
R squared = .5275
6.886
= 67.74
ANALYSIS OF VARIANCE FOR THIS REGRESSION
Source
d.f.
2 .3 .-
M.S.
Due t o Regression
17
640351.
37667.7
Residual
125
573610.
4588.88
T o ta l
142
(n = 143)
. I 21396E+07
.
F Value
8.20848
-109-
Table 16 (c o n tin u e d )
Acvoneuvia pacifica (X
c)
Independent
v a ria b le
-.1 3 4 4
.9 1 96E-01
.1721
-.2 0 4 9
- 1.021
1.013
1.955
-1.5 37
-.6089E-01
.2596
.6700E-01
-.69 93E -02 - .2 5 4 1 E-Ol
-.1 4 1 4
.0000
-.1 3 5 2
.0000
-.4946E-01
.0000
-.38 63
1.703
.4421
-.1 6 3 9
-.8 7 9 4
-.8781
-.3 2 6 8
4.153
2.995
1.799
1.003
^
IO th
dummy v a r ia b le s f o r
stream s e c t io n
v a r ia b ility
.0000
.0000
.0000
S td .e rro r
re q r.c o e f.
R squared = .2992
s td . e rro r
Computed
t v a lu e
1.425
-.44 83
-.6 6 3 6
.6567
-1 .5 1 6
1 .033
1.953
- 2 .3 4 0
.5670
.5669
.5889
.5768
.5508
.5754
.5902
-.6821
3.005
.7508
-.2 8 4 2
-1 .5 9 6
-1 .5 2 6
-.5 5 3 6
.6734
.9813
1.001
-.15 37
.4616
-.2976E-01
.4911E-Ol 6599E-01
.7822E-01
-.9480E-01 -.2063E-02 .1937E -02
9.538
117.9
1635
lin e a r
q u a d r a tic
c u b ic
i n t e r c e p t = .6648
Regr.
c o e f.
.1264
. 1874E-01 .1315E-01
-.4007E-01 - . 5932E-01
.1323
-.1 1 0 9
.1672
-.5925E-01
21.07
.4427
.1769
0 .2 5 th
tim e
P a rtia l
c o rre la tio n
Mean
A. notevophilum
R. nastuvtiwn-aquat.
Z. patustvis
p e r c e n t i le s
2.133)
(sy3x)
=
-.3 3 2 9
.8772
-1 .0 6 5
2 .429
ANALYSIS OF VARIANCE FOR THIS REGRESSION
2. 2.
M.S.
F Value
17
314.902
18.5236
3.13928
Residual
125
737.574
5.90059
T o ta l
142
1052.48
Source
Due t o Regression
(n = 143)
d.f.
-1 1 0 -
Table 16 ( c o n tin u e d )
d)
o th e r s to n e flie s
{X
= 77.71)
no.
Independent
v a ria b le
Mean
P a rtia l
c o r re la tio n
Regr.
c o e f.
S td .e rro r
re g r.c o e f.
Computed
t v a lu e
A. noterophilim
R. nasturt-Lum-aquat.
Z . palustris
21.07
.4427
.1769
.8396E-01
-.2 3 5 2
- .1 3 2 0
.3430
-9 .9 1 4
-6 .8 9 6
.3642
3.664
4.630
.9420
-2 .7 0 6
- 1 .4 8 9
0 .2 5 th
I c"h
5th
4.153
2.995
1.799
1 .003
.1019
-.6183E-01
.1347
- .1 3 5 0
21.37
-1 8 .8 2
42.12
-27.71
18.65
27.18
27.71
18.19
1.146
-.6 9 2 6
1.520
-1 .5 2 3
-.3 3 1 6
.1128
-.1581
.3944E-01
-.6993E -02
-.7399E-01
.0000
.0000
.2344
.3144E-01
.0000
-61.71
19.93
-2 9 .1 9
7.050
-1 2 .6 5
42.96
5.749
15.70
15.70
16.31
15.97
15.25
15.94
16.35
- 3 .9 3 0
1.269
- 1 .7 9 0
.4413
-.8 2 9 6
2.696
.3517
-81 .0 4
9.924
-.3 1 3 0
12.78
1.551
. 5366E-01
s td . e rro r
(sy3x)
p e rc e n tile s
10t h
dummy v a r ia b le s f o r
stream s e c t io n
v a r ia b ility
tim e
.0000
.0000
.0000
i n t e r c e p t = 127.1
-.4 9 3 2
.4968
-.4 6 2 6
9.538
117.9
1635
I in e a r
q u a d r a tic
c u b ic
n
R squared = .5266
'
,
= 67.28
ANALYSIS OF VARIANCE FOR THIS REGRESSION
M.S.
F Value
628398
37023.4
8.18017
125
565750
4526.00
142
. 11951E+07
Source
d.f.
Due t o Regression
17
Residual
T o ta l
(n = 143)
2. 2.
- 6 .3 3 9
6.400
-5.8 3 3
-Til­
la b le
e)
16 ( c o n t i n u e d )
Ephemeroptera (%
= 103.5)
Independent
v a ria b le
Mean
P a rtia l
c o r re la tio n
Regr.
c o e f.
S td .e rro r
re g r.c o e f.
Computed
t v a lu e
A. notevophiZvm
R. nasturti-um-aquat.
Z. palustris
21.07
.4427
.1769
.3722E-01
-.12 77
-.9507E-01
.2132
-7 .4 1 9
-6.951
.5120
5.152
6.510
.4164
- I .440
-1 .0 6 8
0 .2 5 th
I st
5th
4.153
2.995
1.799
1.003
.2013
-.1849E-01
-.2425E-01
- . 5034E-01
60.26
-7 .9 0 0
-10.57
-14.41
26.22
38.21
38.96
25.57
2.298
-.20 67
-.2 7 1 2
-.5 6 3 5
-.2 8 8 2
.0000
. 2684E-01
.0000
-.21 87
.0000
.7398E-01
- . 6993E-02
-.7804E -02
.0000
.1922
.0000
-.9576E -02
.0000
-7 4 .2 9
6.626
-57.47
18.63
-1.8 72
49.07
-2.461
22.08
22.07
22.93
22.46
21.45
22.40
22.98
-3 .3 6 5
.3002
-2 .5 0 6
.8294
-.08 726
2.190
-.1071
-1 5 7 .2
15.44
-.4301
17.97
2.180
.7544E-01
-8 .7 4 6
7.082
-5.701
p e r c e n t i le s
IO th
dummy v a r ia b le s f o r
stream s e c t io n
v a r ia b ility
tim e
s td . e rro r
U
R squared = .5706
I
i n t e r c e p t = 297.1
-.6161
.5351
-.4 5 4 3
9.538
117.9
1635
lin e a r
q u a d r a tic
c u b ic
94.59
ANALYSIS OF VARIANCE FOR THIS REGRESSION
Source
d.f.
S.S.
M.S.
F Value
Due t o Regression
17
.1486205+07
87423.6
9.77119
Residual
125
.1118385+07
8947.07
T o ta l
142
• .2604585+07
(n = 143)
/
-112-
Table 16 ( c o n tin u e d )
f )
EgkemeveVla 'Infvequens
P a rtia l
c o rre la tio n
Regr.
c o e f.
S td .e rro r
re g r.c o e f.
Computed
„ c v a lu e
21.07
.4427
.1769
-.4309E-01
-.1 3 9 7
-.8916E-01
-.2 0 6 4
-6 .7 9 5
-5 .4 4 6
.4280
4.307
5.442
-.4 8 2 2
-1 .5 7 8
-1.001
4.153
2.995
1.799
1 .003
.2003
- .2 5 3 1 E-Ol
.1691 E-Ol
-.8T53E-01
50.12
-9 .0 4 4
6.157
-19 .5 5
21.92
31.94
32.57
21.38
2.286
-.2831
.1890
-.9 1 4 5
- .3 0 4 9
.0000
.0000 .
.5975E-01
.0000
-.2321
-.6993E -02
.6550E-01
.0000
-.3401E-01
.2537
.0000
.0000
•2590E-01
-66.07
12.35
-5 1 .1 3
13.78
-6.8 23
54.91
5.565
18.46
18.45
19.17
18.78
17.93
18.73
19.21
- 3 .5 7 9
.6692
-2 .6 6 7
.7339
- .3 8 0 5
2.932
.2896
-1 3 3 .6
12.85
-.3 5 4 5
15.02
1.823
.6306E-01
- 8 .8 9 2
7.049
-5.621
A. notevoghtlwi
R. ndstuvtium-aquat.
Z,. galustvis
0 .2 5 th
*|Cf
5"th
„ 10th
dummy v a r ia b le s f o r
stream s e c t io n
v a r ia b ility '
tim e
-.6 2 2 5
.5333
-.4 4 9 2
9.538
117.9
1635
I in e a r
q u a d r a tic
c u b ic
i n t e r c e p t = 257.9
= 71.8 3 )
Mean
Independent
v a ria b le
ptiiutiMLi Ig S
(JT
R squared = .5847
s td . e rro r
(sy3x) = 79 .07
ANALYSIS OF VARIANCE FOR THIS REGRESSION
d.f..
S',s.
Due t o Regression
17
.110015E+07
64714.9 . 10.3502
6252.51
Residual
125
781564
T o ta l
142
. 188172E+07
(n = 143)
M.S.
F Value
Source
-U S -
T a b l e 16 ( c o n t i n u e d )
Baetis sp. (Z
= 20.33)
■
no.
g)
37
Mean.
P a rtia l
c o r re la tio n
Regr.
c o e f.
S td . e rro r
re g r.c o e f.
Computed
t v a lu e
21.07
.4427
.1769
.4215E-01
-.1 0 2 0
- . 6003E-01
.7210E-01
-1 .7 6 4
-1.3 07
.1529
1.538
1.943
.4716
-1.1 4 7
-.6 7 2 3
4.153
2.995
1.799
1.003
.5992E-02
.3663E-01
-.1 3 9 3
.1109
.5245
4.675
-1 8 .3 0
9.528
7.829
11.41
11.63
7.635
.06699
.4098
-1 .5 7 3
1.248
-.1 8 7 6
.0000
- .1 1 3 6
.0000
-.8137E-01
.0000
.4656E-01
-.6993E-02
.4365E-01
. .0000
.6099E-02
.0000
- . 2004E-01
. 0000
-14.08
-8 .4 2 6
-6 .2 4 9
3.495
3.128
.4562
-1 .5 3 8
6.592
6.591
6.846
6.706
6.404
6.689
6.862
-2 .1 3 5
-1 .2 7 8
-.9 1 2 8
.5212
.4885
.06819
-.2241
Independent
v a ria b le
A. notevopkilion
R. nastuvtivm-ac[uat.
Z. palustris
0 .2 5 th
ptirc&n u i I 6S
5 th
IO th
dummy v a r ia b le s f o r
stream s e c t io n
v a r ia b ility
tim e
i n t e r c e p t = 44.45
-.2241
.2208
-.2 0 5 6
9.538
117.9
1635
lin e a r
q u a d r a tic
c u b ic
R squared = .2806
-1 3 .7 9
5.366
1.648
.6509
-.5292E-01 2252E-01
s td . e rro r
(sy3x)
= 28.24
ANALYSIS OF VARIANCE FOR THIS REGRESSION
. M.S.
F Value
38891.2
2287.72
2.86853
125
99690.3
797.522
142
138582
Source
d.f.
s.s.
Due t o Regression
17
Residual
T o ta l
(n = 143)
- 2 .5 7 0
2.531
-2 .3 4 9
-1 1 4 -
Table 16 (c o n tin u e d )
PardleTptophlebia sp. (^no = 11 .2 9 )
h)
Independent
v a ria b le
Mean
P a rtia l
c o rre la tio n I
A. noterophilum
R. nasturtium-aquat.
Z. palustris
21.07
.4427
.1769
.3843
.1344
-.1868E-01
.3475
1.139
-.1 9 8 3
.7467E-01
.7513
.. .9493
4.654
1.517
- .2 0 8 9
0 .2 5 th
1s t
5th
4.153
2.995
1.799
1 .003
.2194
-.5659E-01
.2471E-01
-.1 0 4 7
9.615
-3.531
1.570
-4.3 88
3.824
5.572
5.682
3.729
2.514
-.6 3 3 7
.2763
-1 .1 7 7
3.220
3.219
3.344
3.275
3.128
3.267
3.352
1.818
.8397
-.02 664
.4128
.5828
-1 .9 2 8
-1 .9 3 6
pet cen n i e s
IO th
dummy v a r ia b le s f o r
stream s e c t io n
v a r ia b ility
tim e
Regr.
c o e f.
S td .e rro r
re g r.c o e f.
.1605
5.855
.0000
2,703
.7489E-01
.0000
-.2382E -02 -.8907E-01
.0000
1.352
-.6993E -02
.3690E-01
1.823
.0000
. 5205E-01
-6 .2 9 9
.0000
-.1 6 9 9
-6.4 8 8
-.1 7 0 6
.0000
I in e a r
q u a d r a tic
c u b ic
i n t e r c e p t = - 5 .2 7 9
-.3171
.2570
-.1 8 1 7
9.538
117.9
1635
R squared = .4496
Computed
t v a lu e
2.621
-9 .7 9 9
.9453
.3180
-.2272E-01 .1100E-01
s td . e rro r
(sy3x)
= 13.79
ANALYSIS OF VARIANCE FOR THIS REGRESSION
d.f.
s.s.
M.S.
F Value
17
19431.3
1143.02
6.00717
Residual
125
23784.4
, 190.275
T o ta l
142
43215.7
■ S o u rc e s ,
Due t o Regression
(n = 143)
-3 .7 3 9
2.973
-2 .0 6 5
-1 15-
T a b l e 16 ( c o n t i n u e d )
I)
T n c h o p te ra
= 4 4 .9 4 )
Mean
P a rtia l
c o r re la tio n
Regr.
c o e f.
S td .e rro r
re g r.c o e f.
Computed
t v a lu e
21.07
.4427
.1769
-.2 7 3 3
.2131E-Ol
-.2 2 5 8
- . 6656
.5023
-6.901
.2095
2.108
2.664 .
-3 .1 7 7
.2383
-2.591
4.153
2.995
1.799
. 1.003
.2543E-01
-.3576E-01
.8282E-01
.2279E-01
3.051
-6 .2 5 5
14.81
2.667
10.73
15.64
15.94
10.46
.2844
- .4 0 0 0
.9292
.2549
- .1 6 6 0
.0000
-.1471
.0000
- . 9 5 1 0E-01
.0000
.3884E-01
-.6993E-02
-.1 9 2 2
.0000 .
.1467
.0000
.2238
.0000
-17.01
-1 5 .0 2
-1 0 .0 2
3.994
-19.21
15.20
24.14
9.035
9.033
9.383
9.191
8.777
9.168
9.404
-1 .8 8 2
-1 .6 6 3
-1 .0 6 8
.4346
- 2 .1 8 9
1.658
2.567
-2 0 .8 9
2.960
-.1057
7.354
.8921
.3087E-01
- 2 .8 4 0
3.317
-3 .4 2 3
Independent
v a r ia b le
A. rwterophilum
R. nasturtium-aquat.
Z. pdlustris
0 .2 5 th
per Ufciti Li IeS
I
Q "h
5th
10t h
dummy v a r ia b le s f o r
stream s e c t io n
v a r ia b ility
tim e
i n t e r c e p t = 81.82
-.2 4 6 2
.2845
-.2 9 2 8
9.538
117.9
1635
I in e a r
q u a d r a tic
c u b ic
R squared = 0.3348
s td .e rro r
(sy3x) = 38,.71
ANALYSIS OF VARIANCE FOR THIS REGRESSION
Source
d.f.
2 .2 .
M.S.
F Value
Due t o Regression
17
94257.0
5544.53
3.70106
Residual
125
187261.
1498.09
T o ta l
142
' 281518.
(n = 143)
-1 1 6 -
T a b l e 16 ( c o n t i n u e d )
Oohrotviohia sp.
r (Zno. = 25.92)
j)
Independent
v a ria b le
A. notevophihan
R. nastuvtium-aquat.•
Z. palustris
0 .2 5 th
p e rc e n tile s
IO th
dummy v a r ia b le s f o r
stream s e c tio n
v a r ia b ility
tim e
P a rtia l
c o rre la tio n
21.07
.4427
.1769
-.2191
.8205E-01
-.15 52
-.5 0 4 5
1.861
-4.4 87
.2010
2.022
2.555
- 2 .5 1 0
.9205
-1 .7 5 6
4.153
2.995
1.799
1.003
- .6 2 5 1 E-Ol
.1452E-01
•4234E-01
.7511 E-Ol
-7.2 08
2.435
7.246
8.453
10.29
15.00
15.29
10.04
-.7 0 0 2
.1623
.4738
.8421
-8 .7 7 5
-1 2 .5 2
-8 .5 9 9
-1 3 .0 4
-1 7 .8 4
14.74
26.30
8.667
8.665
9.001
8.817
8.419
8.795
9.021
-1 .0 1 2
-1 .4 4 4
-.9 5 5 3
-1 .4 7 9
-2 .1 1 9
1.676
2.915
Regr.
c o e f.
- . 9 0 1 9E-01
.0000
-.1281
.0000
-.8513E-01
.0000
-.1311
-.6993E -02
- .1 8 6 2
.
.0000
.1483
.0000
.2523
.0000
S td .e rro r
re g r.c o e f.
Computed
t' v a lu e
-2 .6 8 6
3.211
-3 .3 6 2
-.2 3 3 6
.2761
- .2 8 8 0
. -1 8 .9 5
2.748
-.9955E-01
7.055
.8558
.2961E-Ol
R squared = 0.3582
s td . e rro r
(sy3x) - 37 .13
9.538
117.9
1635
lin e a r
q u a d r a tic
c u b ic
i n t e r c e p t = 77.44
Mean
ANALYSIS OF VARIANCE FOR THIS REGRESSION
Source
d.f.
S.S,
Due t o Regression
17
96171.1
5657.12
Residual
125
172324.
1378.59
T o ta l
142
268495.
(n = 143)
F Value
4.10356
T a b l e 16 ( c o n t i n u e d )
Glossosoma sp. (Z
k)
= 11.22)
Mean
P a rtia l
c o r re la tio n
21.07
.4427
.1769
-.2 3 2 6
-.1 0 1 4
-.1 6 1 8
-.1 6 9 3
-.7 2 5 9
-1 .4 7 6
.6332E-01
.6371
.8050
-2 .6 7 3
- 1 .1 3 9
-1 .8 3 4
4.153
2.995
1.799
1.003
.3171
-.2 3 6 8
.1602
-.1 4 7 6
12.12
-12.88
8.746
-5 .2 7 8
3.243
4.726
4.819
3.162
3.739
-2 .7 2 5
1.815
- 1 .6 6 9
-.6 0 0 9
3.802
-4.4 6 7
11.85
-1.6 3 2
-2.343
-3 .2 9 9
2.731
2.730
2.836
2.778
2.652
2.771
2.842
-.2 2 0 0
1.393
-1 .5 7 5
4.265
-.6151
-.8 4 5 5
-1.161 .
independent
v a ria b le
A. notevoiphilum
R. nasturti-wn-aquat.
Z. palustris
p e rc e n tile s
0 .2 5 th
1s t
5th
10t h
dummy v a r ia b le s f o r
stream s e c t io n
v a r ia b ility
tim e
-.1968E-01
.0000
.1236
.0000
-.1 3 9 5
.0000
,3564
-.69 93E -02
- . 5494E-01
.0000
- .7 5 4 1 E-Ol
.0000
-.1 0 3 3
.0000
S td .e rro r
re q r.c o e f.
2.223
-.5654E-01
-1 .4 0 7
.2696
-.1794E -02 -.5409E-02
.2626E-01
.2740E-02 S329E-02
9.538
117.9
1635
I in e a r
q u a d r a tic
c u b ic
i n t e r c e p t = 4.273
Regr.
c o e f.
R squared = 0.4010
s td . e rro r
Computed
t v a lu e
-.6331
-.02 006
.2937
(sy3«J = 11.70
ANALYSIS OF VARIANCE FOR THIS REGRESSION
M.S.
E Value
■ 11448.5
673.443
4.92159
. 125
17104.3
136.834
142
28552.8
Source
d.f.
Due t o Regression
17
Residual
T o ta l
(n = 143)
S.S.
-1 1 8 -
Table 16 ( c o n tin u e d )
Rhyaoophila sp.
I)
= 7 .7 9 7 )
Independent
v a ria b le
A . noterophiIvm
R. nasturtiwn-aquat.
Z. palustris
ptii C6H uI I GS
0 .2 5 th
I C+
5*tli
IO th
dummy v a r ia b le s f o r
stream s e c t io n
v a r ia b ility
tim e
P a rtia l
c o rre la tio n
21.07
.4427
.1769
.1931 E-Ol
-.1471
-.1 7 1 8
4.153
2.995
1.799
1.003
- .8 5 7 1 E-Ol
.1314
-.3653E-01
-.2404E-01
-1 .8 6 5
4.189
-1 .1 7 8
-.5 0 8 5
1.939
2.826
2.882
1.891
- .9 6 1 9
1.482
-.4 0 8 7
- .2 6 8 9
- .3 8 5 6
-.3 2 6 5
.1585
.2689
.1475E-01
.1496
.5994E-01
-7 .6 2 9
-6 .3 0 5
3.043
5.184
.2616
2.803
1.141
1.633
1.633
1.696
1.661
1.586
1.657
1.700
-4 .6 7 2
-3 .8 6 2
1.794
3.121
.1649
1.692
.6713
.0000
.0000
.0000
-.69 93E -02
.0000
.0000
.0000
Iin e a r'
q u a d r a tic
c u b ic
S td .e rro r
re g r.c o e f.
.8175E-02 3787E-01
.3810
-.6 3 3 3
.4814
-.9 3 8 4
1.329
-.3558E-01
-.5 2 9 0
.1612
.2168
.1194
.8865E-02
^579E-02
-.1 4 0 7
-
9.538
117.9
1635
i n t e r c e p t = 0.9808E-01
Regr.
c o e f.
Computed
t v a lu e
Mean
R squared - 0.4553
std . e r ro r
M.S.
F Value
5112.45
300.732
6.14575
125
6116.67
48.9333
142
11229.1
d.f.
Due t o Regression
17
Residual
T o ta l
(n = 143)
S.S.
- .3 9 8 0
1.344
- 1 .5 8 9
(sy}x) - 6 . 9 9 5
ANALYSIS OF VARIANCE FOR THIS REGRESSION
Source
.2159
-1 .6 6 2
- 1 .9 4 9
-
119
-
Table 16 (con clu d e d )
m)
Optioservus sp.
C o le o p te ra :
= 186 .8 )
Independent
v a ria b le
Mean
P a rtia l
c o r re la tio n
A. noterophilum
R. nasturtiwn-jxquat.
Z. palustris
21.07
.4427
.1769
.1123
-.9628E-01
-.1 9 7 3
.8291
-7.1 43
-1 8 .7 8
.6564
6.605
8.345
1.263
-1.0 8 2
-2.251
0 .2 5 th
4.153
2.995
1.799
1.003
.1122
.3405E-01
-.9418E-01
.1273
42.45
18.66
-52 .8 3
47.03
33.62
48.99
49.95
32.78
1.263
.3809
-1 .0 5 8
1.435
.0000
- .3 6 8 9
.0000
.3044
-.2 4 1 8
.0000
-.6993E-02 -.2535E-01
.0000
-.1 6 2 3
.0000
.2631
.0000
-.1182E -02
-1 2 5 .6
101.1
-8 1 .8 9
-8 .1 6 4
-5 0 .5 6
87.56
-.3 8 9 2
28.31
28.30
29.40
28.79
27.50
28.72
29.46
-4.4 38
3.573
-2 .7 8 6
-.2 8 3 5
-1 .8 3 9
3.049
-.01321
p e r c e n t
i
g s
5 th
IO th
dummy v a r ia b le s f o r
stream s e c tio n
v a r ia b ility
tim e
9.538
117.9
1635
lin e a r
q u a d r a tic
c u b ic
S td .e rro r
re g r.c o e f.
Computed
t v a lu e
-8 .9 4 2
-.3469E-01
23.04
1.187
.3795E-01
2.795
- .4 8 1 7 E-Ol --.5215E-01 .9671 E-Ol
s td . e rro r
Il
R squared = 0.5849
I
i n t e r c e p t = 73.19
Regr.
c o e f.
-.3881
.4246
-.5 3 9 2
121.3
ANALYSIS OF VARIANCE FOR THIS REGRESSION
Source
d.f.
s.s.
Due t o Regression
17
.258942E+07
152319. . 10.3592
Residual
125
.183796E+07
14703.7
T o ta l
142
.442738E+07
(n = 143)
M.S.
F Value
LITERATURE CITED
A l l e n , K. R. 1959. The d i s t r i b u t i o n o f stream bottom fa u n a s.
New Zealand E c o l. Soc. 6: 5 -8 .
P ro c.
American P u b lic H e a lth A s s o c ia t io n .
1965.
Standard method f o r th e
e xa m in a tio n o f w a te r and w astew ater i n c lu d in g bottom sediments
and s lu d g e s .
12th ed. Amer. P u b l. H e alth Assoc. I n c . , New York.
769 p.
A rm ita g e , K. B. 1958.
Ecology o f th e r i f f l e
R iv e r , Wyoming.
Ecology 39: 571-580.
in s e c t s o f th e F ir e h o le
A rm ita g e , K. B. 1961.
D i s t r i b u t i o n o f r i f f l e in s e c t s o f th e F ir e h o le
R iv e r , Wyoming. H y d ro b io lo g ia 17: 152-174.
B e l l , H. L.
1969.
E f f e c t o f s u b s t r a te types on a q u a tic in s e c t d i s t r i ­
b u t io n .
J. Minnesota Acad. S c i . 35: 79-81.
Buscemi, P. A.
1966. The im portance o f sedim e ntary o r g a n ic s in th e
d i s t r i b u t i o n o f b e n th ic organism s, p. 79-86. In K. W. Cummins,
C. A. T r y o n , J r . , and R. T. Hartman [ e d . ] .
O rg a n is m -s u b s tra te
r e l a t i o n s h i p s i n stream s.
Spec. P u b l. No. 4 , Pymatuning Labora­
t o r y o f E cology, U n iv . P it t s b u r g h .
145 p.
Cummins, K. W. 1962. An e v a lu a t io n o f some te c h n iq u e s f o r th e c o l l e c ­
t i o n and a n a ly s is of. b e n th ic samples w i t h s p e c ia l emphasis on
l o t i c w a te rs .
Amer. M id i. Nat. 67: 477-504.
Cummins, K. W. 1964.
F a cto rs l i m i t i n g th e m i c r o d i s t r i b u t i o n o f la r v a e
o f th e c a d d i s f l i e s Pycnopsyake lepida (Hagen) and Pyonopsyche
guttifer (W alker) in a M ichigan stream ( T r ic h o p t e r a : L im n e p h ilid a e ) .
E c o l. Monogr. 34: 271-295.
Cummins, K. W. 1966. A re v ie w o f stream ecology w i t h s p e c ia l emphasis
on o r g a n is m -s u b s tr a te r e l a t i o n s h i p s , p. 2-51. In K. W. Cummins,
C. A. T ry o n , J r . , and R. T. Hartman [ e d . ] .
O rg a n is m -s u b s tra te
r e l a t i o n s h i p s in streams.
Spec. P u b l. No. 4 , Pymatuning Labora­
t o r y o f Ecology, U n iv. P i t t s b u r g h .
145 p.
Cummins, K. W., and G. H. L a u f f . 1969. The i n f l u e n c e o f s u b s tr a te p a r ­
t i c l e s iz e on th e m i c r o d i s t r i b u t i o n o f stream macrobenthos.
Hydrob i o l o g i a 34: 145-181.
-1 2 1 -
Cushing, C. E . , J r .
1963.
F i l t e r - f e e d i n g in s e c t d i s t r i b u t i o n and
p la n k t o n ic food i n th e M ontreal R iv e r . T rans. Amer. F is h . Soc.
92: 216-219.
E g g lish aw , H. J .
1964. The d i s t r i b u t i o n a l r e l a t i o n s h i p between th e
bottom fauna and p l a n t d e t r i t u s in stream s. J . Anim . E c o l. 33:
463-476.
E g g lish aw , H. J .
1969. The d i s t r i b u t i o n o f b e n th ic in v e r t e b r a t e s on
s u b s t r a ta i n f a s t - f l o w i n g s tre a m s . J . Anim. E c o l. 38: 19-33.
E r ik s e n , C. H. 1963. The r e l a t i o n o f oxygen consumption t o s u b s t r a te
p a r t i c l e s iz e in two burrow ing m a y f l ie s .
J . Exp. B i o l . 40: 447453.
E r ik s e n , C. H. 1964. The in f l u e n c e o f r e s p i r a t i o n and s u b s t r a te upon
th e d i s t r i b u t i o n o f burrow ing m a y fly n a ia d s.
Verb. I n t e r n e t .
V e r e in. L im n o l. 15: 903-911.
E r ik s e n , C. H. 1966.
B e n th ic in v e r t e b r a t e s and some s u b s t r a t e - c u r r e n t
oxygen i n t e r r e l a t i o n s h i p s , p. 98-115. In K. W. Cummins, C. A.
T ry o n , J r . , and R. T. Hartman [ e d . ] .
O rg a n is m -s u b s tra te r e l a t i o n ­
s h ip s i n stream s.
Spec. P u b l. No. 4 , Pymatuning L a b o ra to ry o f
E co log y, U n iv . P i t t s b u r g h .
145 p.
E r ik s e n , C. H. 1968. E c o lo g ic a l s i g n i f i c a n c e o f r e s p i r a t i o n and sub­
s t r a t e f o r b u rro w in g Ephemeroptera. Can, J . Z o o l . 46: 93-103.
H e n d ric k s , A . , W. M. Parsons, D. F r a n c is c o , K. D ickso n , D. Henley, and
J . K. G. S i l v e y .
1969. Bottom fauna s tu d ie s o f t h e lo w e r S a lin e
R iv e r . Texas J . S c i . 21: 175-187.
Hughes, D. A.
1966a. Mountain streams o f th e B a rb e rto n a re a . E a s te rn .
T r a n s v a a l.
P a rt I I .
The e f f e c t o f v e g e ta t io n a l shading and
d i r e c t i l l u m i n a t i o n on th e d i s t r i b u t i o n o f stream fa u n a . H y d r o - •
b i o l o g i a 27: 439-459.
Hughes, D. A.
19666. The r o l e o f responses t o l i g h t i n th e s e l e c t i o n
and maintenance ^of m ic r o h a b it a t by th e nymphs o f two species o f
m a y fly . Anim. Behctv,. 14: 17-33.
Hunt, J . S. 1930.
Bottom as a f a c t o r i n animal d i s t r i b u t i o n i n small
stream s. J . Tennessee Acad. S c i . 5: 11-18.
-1 2 2 -
Hynes1 H. B. N. 1970. The e c o lo g y o f ru n n in g w a te rs .
P re ss, T o ro n to . 555 p.
U n iv. Toronto
I d e 1 F. P. 1935. The e f f e c t o f te m p e ra tu re on th e d i s t r i b u t i o n o f th e
m a y fly fauna o f a stream .
U n iv. T oro n to S t u d . , B i o l . S e r. 39:
9-76.
Jaag1 O. , and H. Ambtihl. 1964. The e f f e c t o f th e c u r r e n t on th e com­
p o s i t i o n o f biocoenoses in f lo w in g w a te r stream s.
I n t . C o nf.
Water P o l l u t . R e s ., London, S ept. 1962.
Pergammon Press, New
Y ork.
p. 31-49.
Kamler1 E. 1965. Thermal c o n d it io n s in mountain w a ters and t h e i r i n ­
f lu e n c e on t h e d i s t r i b u t i o n o f P le c o p te ra and Ephemeroptera la r v a e .
E k o l. P o ls k . 13: 378-414.
Kamler1 E . , and W. R ie d e l.
1960. A method o f q u a n t i t a t i v e stu d y o f
th e bottom fauna o f T a tr a stream s.
P o ls k . A rch . H y d r o b io l.
21: 95-105.
L a u f f 1 G. H ., K. W. Cummins, C. E r ik s e n 1 and M. P a rke r.
1961. A
method f o r s o r t i n g bottom fauna samples by e l u t r i a t i o n .
L im n o l.
Oceanogr. 6: 462-466.
L a v a n d ie r 1 P ., and J . Dumas. 1971. M i c r o r e p a r t i t i o n de quelques
especes d 'i n v e r t e b r e s ben thique s dans des ru is s e a u x des Pyrenees
c e n tra le s .
[ M i c r o d i s t r i b u t i o n o f b e n th ic i n v e r t e b r a t e s i n streams
o f th e C e n tra l P yre n e e s .] Ann. L im n o l. 7: 7 -2 3 .
[ I n French,
E n g lis h summary].
L in d u s k a 1 J . P. 1942.
Bottom typ e s as a f a c t o r in f l u e n c i n g th e lo c a l
d i s t r i b u t i o n o f m a y fly nymphs. Can. Entom ol. 74: 26-30.
Macan1 T. T.
1961. A re v ie w o f ru n n in g w a te r s t u d ie s .
V e r e in. L im n o l. 14: 587-602.
Verb. I n t e r n e t .
Moon1 H. P.
1939. Aspects o f th e e c o lo g y o f a q u a tic i n s e c t s .
B r i t . Entom ol. Soc. 6: 3 9 -4 9 ,
Trans.
Mundie1 J . H. 1971.
Sampling benthos and s u b s t r a te m a t e r i a ls down
t o 50 m icrons i n s i z e , i n s h a llo w stream s. 0. F is h . Res. Bd.
Canada 28: 849^860.
12 3 -
Need ham, P. R ., and R. L. U s in g e r . 1956. V a r i a b i l i t y i n th e macro­
fauna o f a s i n g l e r i f f l e i n P rosser Creek, C a l i f o r n i a , as i n d i ­
cated by th e Surber sam pler.
H i l g a r d i a 24: 383-409.
Pennak, R. W. 1953.
F re s h -w a te r i n v e r t e b r a t e s o f th e U nited S ta te s .
Ronald Press C o ., New York. 769 p.
Pennak, R. W., and E. D. Van Gerpen. 1947. Bottom fauna p ro d u c tio n
and p h y s ic a l n a tu re o f th e s u b s t r a t e i n a n o r th e r n Colorado
stream .
Ecology 28: 42-48.
P e r c i v a l , E ., and H. Whitehead.
1929. A q u a n t i t a t i v e s tu d y o f th e
fauna o f some typ e s o f stream -bed. J . E c o l. 17: 282-314.
R ic k e r , W. E.
stream s.
1934. An e c o lo g ic a l c l a s s i f i c a t i o n o f c e r t a i n O n ta rio
U n iv . Toro n to S t u d . , B i o l . S e r. 37: 7-114.
S c o t t , D. 1958.
E c o lo g ic a l s t u d ie s on th e T r ic h o p t e r a o f th e R iv e r
Dean, C h e sh ire . A rch . H y d r o b io l. 54: 340-392.
Snedecor, G. W., and W. G. Cochran.
1967. S t a t i s t i c a l methods.
ed.
Iowa S ta te U n iv . P ress, Ames. 593 p.
6 th
S p ru le s , W. N!. 1947.. An e c o lo g ic a l i n v e s t i g a t i o n o f stream in s e c ts in
A lg o n q u in P ark, O n ta r io .
U n iv . T o ro n to S t u d . , B i o l . S e rv . 56:
1-81.
S ta d n yk, L.
1971.
F a cto rs a f f e c t i n g th e d i s t r i b u t i o n o f s t o n e f l i e s in
th e Y e llo w s to n e R iv e r , Montana.
Unpublished Ph.D. d i s s e r t a t i o n ,
Montana S ta te U n iv . , Bozeman. 36 p.
Thorup, J .
19 6 6 . - S u b s tra te ty p e and i t s v a lu e as a b a s is f o r th e de­
l i m i t a t i o n o f bottom fauna com munities i n ru n n in g w a te r s , p. 59-74.
In K. W. Cummins, C. A. T ry o n , J r . , and R. T. Hartman [ e d . ] . Organ­
is m - s u b s t r a t e r e l a t i o n s h i p s i n stream s. Spec. P u b l. No. 4 , Pymat u n in g L a b o ra to ry o f Ecology, U n iv. P i t t s b u r g h .
145 p.
U l f s t r a n d , S. 1967. M i c r o d i s t r i b u t i o n o f b e n th ic sp e cie s (Ephemeropt e r a , P le c o p te r a , T r i c h o p t e r a , D i p t e r a : S im u li i d a e ) in Lapland
stream s. Oikos 18: 293-310.
U l f s ta n d , S. 1968. L i f e c y c le s o f b e n th ic in s e c ts i n Lapland streams
(Ephemeroptera, P le c o p te r a , T r i c h o p t e r a , D ip t e r a : S im u li i d a e ) .
Oikos 19: 167-190.
-1 24-
Wene
G ., and E. L. W ic k li f f .
1940. M o d i f i c a t i o n o f a stream bottom
and i t s e f f e c t on th e in s e c t fa u n a . Can. Entom ol. 72: 131-135.
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