AN ABSTRACT OF THE THESIS OF
Deborah L. Haapala for the degree of Master of Science in Fisheries Science presented
on November 18. 1996. Title: Pool Habitat Characteristics and Juvenile Anadromous
Salmonids in Two Oregon Coastal Streams.
Abstract approved:
Redacted for Privacy
Gordon H. Reeves
Relations between the diversity of juvenile anadromous salmonids and pool features
were examined in a managed and a pristine watershed in Oregon during the summer of
1990. There were no differences (p> 0.05) in pool depth, velocity or pool wood volumes
between streams. However, the pristine system had twice the number of pools within
similar lineal distances. Pools in the pristine system also had larger substrates (percent
dominant within pools) and smaller pool area (p=0.01). Fish diversity was found to be
greater in pools in the pristine system than in the managed system using the Simpson's
Diversity and Shannon Evenness indicies (p=0.01). The Shannon-Wiener Diversity
index did not show any differences between streams. The difference in assemblage
diversity was due to differences in relative abundance and not species richness. Relative
abundance of juvenile steelhead and cutthroat trout and coho salmon was more even in
Cummins Creek, the pristine system, than in Cape Creek, the managed system. Relative
abundance of coho increased in the managed system possibly due to a change in pool
habitat characteristics, whose conditions favored coho salmon, but this relationship was
ABSTRACT, Continued
not clear. This study emphasizes the importance of assessing communities of juvenile
anadromous salmonids as opposed to studies involving a single species. Past land
management activities have focused upon single species' with regards to a particular
habitat component, which has decreased biodiversity and changed stream habitat
characteristics through cumulative effects. Resource managers should examine
interactions between habitat characteristics and salmonid communities in order to
maintain biological diversity or risk creating favored habitat for a single species within
stream systems.
Pool Habitat Characteristics and Juvenile Anadromous Salmonids in Two Oregon
Coastal Streams
by
Deborah L. Haapala
A THESIS
submitted to
Oregon State University
in partial fulfillment of
the requirements for the
degree of
Master of Science
Completed November 18, 1996
Commencement June 1997
Master of Science thesis of Deborah L. Haapala presented on November 18. 1996
APPROVED:
Redacted for Privacy
r Professor, representing Fisheries Science
Redacted for Privacy
Chair of Department of Fis eries and Wildlife
Redacted for Privacy
Dean of Graduate.School
I understand that my thesis will become part of the permanent collection of Oregon State
University libraries. My signature below authorizes release of my thesis to any reader
upon request.
Redacted for Privacy
ACKNOWLEDGMENTS
There are many people who have given me support and advice while obtaining
this degree. I have learned a great deal from them, have met many people I will never
forget, and have made friendships to last a lifetime. I want to thank my family and
relatives; my parents, Bill and Nancy, and my brother, Kurt. They have always been a
phone call away with love and support and have never stopped believing in me. I also
wish to thank my major professor, Dr. Gordon Reeves and my committee members:
Drs. Deanna Olson, Stanley Gregory, Robert Beschta, and Allen Smith who have
encouraged, supported, and have been there to answer questions whenever I needed help.
I wish to thank all those who helped me collect my field data: Dede Olson, Gordie
Reeves, Debbie Urich, Dave Price, Greg Wiebe, and Eric Veach. I also wish to thank
the USDA Forest Service, Aquatic/Land Interactions Group for the use of their
equipment, technical expertise, thought provoking discussions, and financial support. I
also want to thank the Oregon State University Stream Team for the use of their velocity
meter and for providing informal discussions and presentations through which many
ideas were formed. Thanks goes to the McKibben/Veach Family for their support and
encouragement. Special thanks goes to my co-workers at the Mount St. Helens National
Volcanic Monument who supported, encouraged, and helped to continue my education,
especially: David Brown, Charlie Crisafulli, Peter Frenzen, Don Harm, Steve Kimball,
Mark Kreiter, Vaughan Marable, Darci Rivers-Pankratz, Rocky Pankratz, Jan Robbins,
Lynn Roberts, and Pete Sanda. Special thanks goes to my supervisor, Debbie Hollen, for
allowing me to flex my time and work schedule in order to complete this degree. But
ACKNOWLEDGMENTS, Continued
more importantly, for her friendship, support and the care she has shown to me. I also
appreciate the help of other USDA Forest Service employees/friends for reviewing my
thesis and for sitting on mock defense panels: David Brown, Charlie Crisafulli, Rhonda
Beckman, Chiska Derr, Debbie Hollen, Deborah Konnoff, Mark Kreiter, Steve Lanigan,
Nancy Fredricks, Steve Kimball, and Lynn Roberts.. Several OSU graduate students
provided a network of support, productive discussion and friendship: Jerry and Michelle
Cordova, Marty Fitzpatrick, Thraiin and Hugrun Gunnarsdottir, Mike and Joyce Joy,
Bob Steidl, and Choo-Guan Yeoh. I want to thank my "extended" family for putting up
with my odd hours, and who have given me needed hugs, encouragement, and support:
Vaughan, Ermalinda, Sean, Savanna, and Nyasha Marable. I want to thank Elena
Milashina, Deborah Konnoff, Angela Anderson, Debbie Buckhout, Mark Minturn,
Brenda Sims, Sara Wiley, and Tonya and Jeff Wheeler for their advice, friendship, and
encouragement. Thanks also goes out to Margaret & Barney Virgovic, Sandra and Fred
Schryver, Cheryl and Bruce Waller, Sandy and Jon Fink, and Mary Szekely for their
support, encouragement, and enthusiasm! Special thanks goes to Don Virgovic for his
strong support (and shoulder), advice, and friendship; for helping me see the light at the
end of the tunnel and for giving me "One of Those Days" when I needed it most!
TABLE OF CONTENTS
Page
INTRODUCTION
METHODS
Physical Features
Salmonid Assemblages
RESULTS
1
6
8
11
13
Physical Features
13
Salmonid Assemblages
27
DISCUSSION
49
CONCLUSIONS
63
BIBLIOGRAPHY
65
APPENDIX
73
LIST OF FIGURES
Figure
Page
1.
Location of Cape and Cummins Creeks on the Oregon Coast
7
2.
Pool depth and velocity profiles for transect data in Cape and Cummins
Creeks, OR, 1990
9
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
Means and standard error of physical pool habitat characteristics in Cape
and Cummins Creeks, OR, 1990
15
Means and standard error of wood within pools in Cape and Cummins
Creeks, OR, 1990
16
Percent of single wood diameter classes in pools in Cape and
Cummins Creeks, OR, 1990
19
Percent of single wood length classes in pools in Cape and
Cummins Creeks, OR, 1990
20
Means and standard error of substrate areas in pools in Cape and
Cummins Creeks, OR, 1990
21
Dominant substrate composition in pools in Cape and Cummins
Creeks, OR, 1990
23
Means and standard error of mean and maximum depth and velocity
in pools in Cape and Cummins Creeks, OR, 1990
24
Discriminant analysis of pool habitat characteristics in Cape and
Cummins Creeks, OR, 1990. Means and 95% confidence interval of
group scores are shown
25
Discriminant analysis of pool habitat characteristics in Cape and
Cummins Creeks, OR, 1990. Means and 95% confidence interval of
group scores are shown
26
Means and standard error of juvenile salmonids in pools in Cape and
Cummins Creeks, OR, 1990
29
Means and standard error of juvenile salmonid densities in pools
in Cape and Cummins Creeks, OR, 1990
31
LIST OF FIGURES (Continued)
Figure
14.
Page
Discriminant analysis of juvenile anadromous salmonid community in
pools in Cape and Cummins Creeks, OR, 1990. Means and 95%
confidence interval of group scores are shown
48
LIST OF TABLES
Table
Page
Total wood volumes and number of pieces of wood in pools per
kilometer (km) of stream in Cape and Cummins Creeks, OR, 1990
14
2.
Amounts of wood in pools in Cummins and Cape Creeks, OR, 1990
17
3.
Total wood volumes (m3) and number of pieces of wood in pools
per kilometer (km) of stream in Cummins and Cape Creeks, OR, 1990
18
Correlations relating pool habitat characteristics and fish diversity in
Cape and Cummins Creeks, OR, 1990
28
Correlations between fish species/age-class abundance in pools in
Cape and Cummins Creeks, OR, 1990
32
Correlations between density (number of fish/m2) of fish
species/age-classes in pools in Cape and Cummins Creeks, OR, 1990
33
Correlations between fish species/age-class abundance and pool
habitat characteristics for Cummins and Cape Creeks, OR, 1990
34
Correlations between density (number of fish/m2) of fish
species/age-classes and pool habitat characteristics in Cummins and
Cape Creeks, OR, 1990
36
Multiple regression models for cutthroat trout abundance in Cummins
and Cape Creeks, OR, 1990
38
Multiple regression models for 1+ steelhead trout abundance in
Cummins and Cape Creeks, OR, 1990
39
Multiple regression models for coho salmon abundance in Cummins
and Cape Creeks, OR, 1990
40
Multiple regression models for trout 0+ abundance in Cummins
and Cape Creeks, OR, 1990
41
1.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
Multiple regression models for cutthroat trout density in Cummins
and Cape Creeks, OR, 1990
43
LIST OF TABLES (Continued)
Figure
14.
15.
16.
17.
18.
Page
Multiple regression models for 1+ steelhead density in Cummins
and Cape Creeks, OR, 1990
44
Multiple regression models for coho salmon density in Cummins
and Cape Creeks, OR, 1990
45
Multiple regression models for trout 0+ density in Cummins
and Cape Creeks, OR, 1990
46
Comparison of salmonid species composition between Cape and
Cummins Creek pools and other Oregon coastal treams taken from
Reeves et al. 1993
51
Comparison of large woody debris data from Pacific Northwest
studies; data taken from Ursitti 1991
54
LIST OF APPENDIX TABLES
Appendix
A.1.
A.2.
Page
Correlations between pool habitat characteristics in Cummins Creek,
OR, 1990
74
Correlations between pool habitat characteristics in Cape Creek,
OR, 1990
75
Pool Habitat Characteristics and Juvenile Anadromous Salmonids in Two Oregon
Coastal Streams
Introduction
Diversity of biotic communities is influenced by habitat complexity. Positive
relations between habitat complexity and species diversity (species richness and/or
evenness) have been found for several taxa including birds (MacArthur and MacArthur
1961, Tomoff 1974, Roth 1976, Rafe et al. 1985), lizards (Pianka 1967), desert rodents
(Rosenweig and Winakur 1969), intertidal gastropods (Kohn and Leviten 1976)
invertebrates (Heck and Wetstone 1977, O'Conner 1991), coral reef fishes (Roberts and
Ormond 1987), benthic fishes (Macpherson 1989) and freshwater fishes (Crowder and
Cooper 1982, Tonn and Magnuson 1982, Eadie and Keast 1984). Habitat complexity
can influence biological communities by moderating predation-prey interactions
(Crowder and Cooper 1982), and population density (Kohn and Leviten 1976), and by
providing a greater array of microhabitat conditions (Heck and Wetstone 1977).
Habitat complexity, structural elements providing variety in habitat conditions
(Reeves et al. 1993, Pearsons et al. 1992, Faush and Bramblett 1992), can have a
significant influence on the structure and composition of biotic communities in lotic
ecosystems. Physical elements of stream habitats, such as water depth, wood, water
velocity and substrate composition, contribute to habitat complexity. A diverse array of
microhabitat areas within lotic systems can be formed by various flow regimes, substrate
types, depth profiles, and wood complexes; these attributes combine to create
complexity in instream habitat. In Australian streams, O'Conner (1991) found that
macroinvertebrate species richness was higher in complex systems than in less complex
2
systems. Corn and Bury (1989) found a greater species richness of amphibians in
Oregon streams with greater substrate complexity compared to streams where habitat
complexity was reduced.
Habitat complexity is a particularly important influence on species richness and
diversity of lotic fish communities (Shirvell 1990, Angermeier and Karr 1984, Schlosser
1982a, Gorman and Karr 1978). Gorman and Karr (1978) found that the species
richness was correlated with substrate diversity in streams in Indiana and Panama.
Species diversity differed with water velocities in the juvenile component of a
warmwater fish community in an Illinois stream (Schlosser 1985). In another Illinois
stream, Angermeier and Karr (1984) found that there was an increase in fish species and
fish abundance in areas where wood, increasing habitat complexity, was added to the
system.
Studies of habitat complexity conducted in warmwater systems led to the
development of a habitat diversity index by Schlosser (1982a). This index is a
combination of substrate composition, water depth, and water velocity, which
emphasizes the importance of assessing the complexity of relationships among habitat
elements. Although, the diversity index compiled habitat characteristics most important
in Illinois stream systems, the index does not address all habitat complexity components
which may be of concern in systems elsewhere. For example, Lewis (1969) found that
water depth, water velocity, surface area and volume explained 70-77% of the variation
in numbers of brown (Salmo trutta) and rainbow (Oncorhynchus mykiss) trout over 17.5
cm long. Also, instream wood may provide refuge areas for fish and has been related to
species abundances (Reeves et al. 1993, Angermeier and Karr 1984, Bisson et al. 1987).
3
Several physical attributes of stream habitat appear to influence lotic salmonid
populations in the Pacific Northwest. For example, Shirvell (1990) found that in a
British Columbia stream, juvenile coho salmon (Oncorhynchus kisutch) and steelhead
trout (O. mykiss) abundances increased in areas where wood had been added. Increasing
habitat complexity (wood and substrate) was found to increase rainbow and cutthroat
trout (0. clarki clarki) abundances in unconfined channels (Moore and Gregory 1989).
McMahon and Hartman (1989) found that during winter conditions, coho salmon
emigrated from outdoor stream channels when channel complexity (wood, shade and
water velocity) was low. Conversely, numbers of fish remaining in the stream channels
with higher complexity increased significantly.
In the Pacific Northwest, pool habitat is important for several species of juvenile
anadromous salmonids. Pools may contain the largest number of species or age classes
of any stream habitat type (Bisson et al. 1987). Pools may also contain the greatest
variation of habitat components (i.e., depth, velocity, substrate, wood) within stream
systems, providing cover from predators, high flow refugia and numerous microhabitat
areas (Bisson et al. 1987, Reeves et al. 1993). Altering pool features, such as decreasing
quantities of wood or pool depth, may decrease available habitat for a certain species and
affect species abundance or richness (Hartman 1987, Reeves et al. 1993). Bisson et al.
(1988) found that while coho salmon were found in most pool habitats, steelhead and
cutthroat trout only used deep pools with higher velocities. Although previous studies
have addressed species specific associations with pool habitat features, further
information is needed in order to relate salmonid assemblages to multiple components of
pool complexity.
4
Much of the freshwater habitat of juvenile anadromous salmonids in the Pacific
Northwest has been altered by human activities (see review in Thomas et al. 1993).
Stream habitat has been generally simplified as a consequence of human activities, such
as timber harvest, road construction, agriculture and livestock grazing (Hicks et al. 1991,
Bisson et al. 1992). This simplification includes the loss of habitat types, particularly
pools, decreases in amount of wood, and decreases in the range of substrates and water
velocities. Assemblages of juvenile anadromous salmonids have been simplified as a
consequence of human activities (Bisson and Sedell 1984, Scott et al. 1986, Reeves et al
1993). For example, Reeves et al. (1993) found that number of pools, amount of wood,
and juvenile anadromous salmonid diversity were lower in streams associated with
higher levels of timber harvest (i.e., >25% watershed harvested) compared to streams
with lower harvest (i.e., <25% watershed harvested).
Additional studies of the relationship between pool habitat complexity and
juvenile anadromous salmonids are needed in the Pacific Northwest (Reeves et al. 1993).
Previous studies primarily involve relationships between habitat features and single fish
populations. Studying a community of organisms is important because the response of a
community to environmental alterations may be very different from the way a single
species will respond to the same habitat alteration (Gorman and Karr 1978, Grossman et
al. 1982, Angermeier and Schlosser 1988). Integration of a community approach with an
investigation of multiple elements of pool habitats will allow researchers to gain further
insight into the complexity of relationships between stream habitat and juvenile
anadromous salmonids (Hartman and Brown 1987, Bisson et al. 1988, Shirvell 1990,
Reeves et al. 1993).
5
The purpose of this study was to examine the relationship between habitat
characteristics of pools and the structure and composition of the juvenile anadromous
salmonid assemblages in two streams that had experienced different levels of timber
harvest. Specific objectives were to: (1) compare pool habitat features (e.g., velocity,
depth, wood, substrate, pool area) between streams that differ in land management
histories; (2) compare species richness and abundance of the juvenile anadromous
salmonid assemblages; and (3) address associations of the juvenile salmonid
assemblages with elements of pool habitat features, and compare these results between
streams.
6
Methods
The study was conducted in Cummins and Cape Creeks, two Oregon coastal
streams (Figure 1) having similar basaltic geomorphology but different landmanagement histories. Cummins Creek has a basin area of 14.0 km2 and is located
primarily in a pristine old-growth forest (Cummins Creek Wilderness Area, Lincoln
county). Cape Creek has a basin area of 16.7 km2. Eighty percent of the watershed was
harvested between 1946 to 1986 (Hicks 1990) and the floodplain was mined for gravel
in the 1950's (USDA Forest Service 1978). Additionally, there has been a small amount
of cattle grazing along one bank of the lower portion of Cape Creek, but the impacts on
the stream from grazing appear to be minor due to the low number of cattle contained to
a small portion near the stream. Both streams are third-order streams within the Siuslaw
National Forest and drain directly into the Pacific Ocean. Mean channel gradient for
Cummins Creek is 2.5% (Hankin and Reeves 1985) and 2.1% for Cape Creek (Hicks
1990). The study area in Cape Creek had a sinuosity value of 1.44, while Cummins
Creek sinuosity was 1.27. The study area in Cummins Creek consisted of the lower 2
km of stream, starting at tidewater. Similarly, the Cape Creek study was conducted
along the lower 1.5 km, beginning at tidewater. Study areas were limited to the above
sections because of beaver dams in Cape Creek which act as a barrier to coho salmon
(USDA Forest Service 1978). Vegetation within the study area of Cummins Creek
consisted of Douglas fir (Pseudotsuga menziesii), red alder (Alnus rubra), and western
hemlock (Tsuga heterophylla). Vegetation within the study area in Cape Creek consisted
mainly of red alder and big leaf maple (Acer macrophyllum); (Hicks 1990).
7
Yachats
...
....
P
a
c
i
f
S.
...
S.
.
S.
,
Cummins Creek
%.
i
c
0
c
e
a
n
..,
Cape Creek ,-­
..
..,
...
..0
8 Kilometers
Figure 1
Location of Cape and Cummins Creeks on the Oregon Coast.
8
Physical Features
Selected pool features were measured once in each stream during low flow
conditions between July and October, 1990. Depth and velocity were measured at
selected intervals within a pool (Figure 2). Transects were established at 2 or 3 m
intervals beginning at the top of the pool and proceeding downstream. A minimum of 5
transects per pool was surveyed along the pool length. In long pools (i.e., > 20 m),
transects were at 2 m intervals near the tops of pools because depth and velocity changed
rapidly along pool lengths in this area; transect intervals were greater (4-6 m) through the
middle of pools because depth and velocity varied little. Depth measurements were
made at 1 m increments across transects, beginning at 1 m from the bank. At these
locations, current velocities were measured every 9 cm from the substrate to the water's
surface with an electronic current meter (Montedoro-Whitney Incorp., Model PVM-2).
Several pool features were determined from the transect data. Mean depth and
mean velocity in each pool were calculated by averaging all transect measurements.
Surface area was calculated as the summation of the distance between transects
multiplied by the mean width of successive transects. For pools >20 m in length,
transects conducted at >2 m intervals were weighted in this calculation to more
accurately estimate pool averages. Volume of a pool was estimated by partitioning the
pool into segments and summing the volume of each segment. A segment's volume was
the product of the surface area between two adjacent transects and the mean depth along
the transects.
Large instream woody debris was assigned to one of two categories, single pieces
and submerged wood influence zone (SWIZ). Only wood that was submerged
9
Water Surface
A1111111
4111111.111111.r
IN
9 cm
18
27
36
45
,,,,,
,,,,,,,,,
54
,
,
,
Figure 2
, , ,,
-
,, ,
Bottom
, , ,
,
63
,
Pool depth and velocity profiles for transect data in Cape and Cummins
Creeks, OR, 1990.
10
underwater was collected because it would have a direct impact upon the positioning or
distribution of juvenile salmonids during survey periods. Other studies in the Pacific
Northwest have assessed wood volumes that were in the channel, as well as the pieces
within bankfull width (Fausch and Northcote 1992; Bilby and Ward 1989) and
floodplain (Robison and Beschta 1990). Differing wood location assessments, along
with different minimum size criteria, makes it difficult to compare this study's wood
volume to other studies. Single pieces of wood included any solitary piece of wood with
a minimum length of >5 m and a minimum diameter of 30 cm. The SWIZ was any
submerged wood grouped together (e.g., a wood jam); therefore, the estimated volume
was the space occupied by both water and wood. Lengths and diameters of single pieces
of wood were visually estimated and volumes were calculated using the formula for a
cylinder (v= 1772), where 1= estimated length of wood piece, r = radius. Mean volume of
single wood pieces per pool per stream was calculated. Length, width and depth of the
SWIZ was visually estimated to calculate volume. These volumes usually consisted of
the space between wood pieces as well as the wood itself. Mean volume of SWIZ wood
per pool per stream was calculated. Total wood volume was the addition of the volume
of SWIZ and single wood volumes per pool. Mean total wood volume per pool per
stream was calculated. Percent wood in length and diameter categories were also
developed for single wood volume.
Substrate composition was visually estimated in each pool. Most of the substrate
categories were taken from USDA Forest Service Stream Survey protocol (USDA Forest
Service 1990) and included: 1) sand (1-3 mm); 2) medium gravel (3-7 mm);
gravel
(7-10
mm); 4) cobble
(100-300
3)
large
mm); 5) boulder (>300 mm); and 6) bedrock.
11
Organics, (fine organic material covering the bottom); clay; and silt (< 1 mm) were also
collected because they were found in abundance in the systems. The bottom mean
percent composition covered by each substrate category was estimated and the dominate
substrate identified in each pool.
Physical habitat characteristics between streams were compared using Student's
t-tests. Discriminant analysis was conducted to assess whether pool physical features
could be differentiated between the two streams. Discriminant analysis scores were
correlated with the physical habitat features to determine the order of importance of
habitat features. Student's t-tests were used to determine if the means of the
discriminant scores were significantly different.
Salmonid Assemblages
Salmonids examined in this study were age 0+ year coho salmon, age 1+ year
steelhead trout, and age 1+ year cutthroat trout. Age 0+ steelhead trout and cutthroat
trout could not be distinguished and were classified as trout 0+. Trout 0+ had a length of
5-7 cm, while a 1+ trout had a length of 8-14 cm. Other fish species present in Cummins
Creek included sculpins (Cottus spp.), while Cape Creek had sculpins and Pacific
lamprey (Lampetra tridentata).
Salmonid abundances were estimated by divers using a mask and snorkel. One
diver counted fish in pools in Cummins Creek. One to three divers (depending on pool
width) moving in parallel, assessed fish numbers in Cape Creek. Divers would enter a
pool at the downstream end and snorkel slowly upstream recording species abundance.
Divers counted species most sensitive to human presence first (i.e., cutthroat trout); other
species did not seek cover in the presence of divers and were counted secondly.
12
Mean number of a fish species or age-class in pools in each stream were
compared with a Student's t-test. The Shannon-Wiener Diversity index, H'=E(p, lnp,)
(where p,= the proportion of a fish species or age-class within each pool and lnp,= the
natural log of p,), the Shannon Evenness index, H' /lnS (where S= the number of species)
and the Simpson's Diverstiy index, D=E[ni(n,-1)/N(N-1)] (where n,= the number of
individuals in the ith species or age-class and N= the total number of individuals), were
used to measure diversity of the salmonid community in each pool. Different diversity
indicies were calculated in order to adjust for index bias towards either species richness
(Shannon-Wiener), evenness (Shannon's Evenness) or dominance (Simpson's index ).
A Student's t-test compared the diversity indices between streams. Additionally,
discriminant analysis assessed differences in the juvenile anadromous salmonid
communities between the two streams. Discriminant analysis scores were then
correlated with the salmonid community to determine the order of importance of
salmonid species. Student's t-tests were then used to determine if the means of the
discriminant scores were significantly different.
Relationships among salmonids and between the fish and the physical habitat
features of pools were assessed by correlation and multiple regression analyses.
Correlation analysis was also used to assess relationships between salmonid diversity
and pool physical features and relationships between fish diversity and habitat
characteriestics. Stepwise regression analysis determined a model for each species/age­
class abundance for both streams based on pool physical features and a combination of
pool physical features and fish abundances.
13
Results
Physical Features
Some pool features differed between Cape and Cummins Creek. Cape Creek had
more pool surface area and pool volume per meter of stream than Cummins Creek
(Table 1). There was more pools per meter in Cummins Creek than Cape Creek. Pools,
however, in Cummins Creek were shorter (Cummins x = 13.2 ± 8.6, Cape Creek x =
19.6 ± 14.0, p< 0.01) and narrower (Cummins x = 4.7 ± 2.0, Cape Creek >7( = 6.3 ± 2.1,
p< 0.01), and thus had a smaller surface area (Cummins x = 63.9 ± 50.7, Cape Creek x =
129.3 ± 101.0) and volume (Cummins x = 27.2 ± 23.2, Cape Creek x = 59.0 ± 45.0, p<
0.01; Figure 3). Total wood volumes per pool did not differ between streams (p> 0.05)
(Figure 4). Number of pieces of wood and volume of wood per pool, pool area, pool
volume, and pool length were similar between streams (Table 2). Cummins Creek
tended to have more single pieces of wood and single wood volume in pools per meter
of stream than Cape Creek, while Cape Creek tended to have more SWIZ and SWIZ
volume per meter of stream than Cummins (Table 3). Cummins Creek pools had more
wood in most of the single wood diameter classes (Figure 5). Cummins Creek pools
appeared to have more wood within length categories (Figure 6).
The two streams also differed significantly (p < 0.05) in their substrate
composition (Figure 7). For example, Cummins Creek also had more area covered by
larger substrate per pool, such as boulder (Cummins x = 10.0 ± 3.0, Cape 5:: = 2.9 ± 2.0,
p< 0.01) than did Cape Creek while Cape Creek had more area covered by large gravel
(Cummins )7( = 11.9 ± 3.8, Cape x = 33.5 ± 14.5, p< 0.01), silt (Cummins T< = 4.2 ± 2.1,
Cape x = 25.6 ± 14.3, p< 0.01) sand (Cummins x = 9.9 ± 2.9, Cape x = 17.9 ± 8.9,
14
Table 1
Total wood volumes and number of pieces of wood in pools per
kilometer (km) of stream in Cape and Cummins Creeks, OR, 1990.
Cummins Creek
Cape Creek
29
20
Total pool area (m2)/km
1822
2587
Total pool volume (m3)/km
775
1181
Number of pools/km
15
* p < 0.05
** p < 0.01
30
150­
-20
100­
c
i
as
a)
2 5 0
1
I
i
0
.
Volume**
(m3)
Figure 3
i
ig
Cummins, n = 57
Cape, n = 30
1
Surface
Area**
(m2)
.
1
Length*
Width**
(m)
(m)
0
Means and standard error of physical pool habitat characteristics in Cape
and Cummins Creeks, OR, 1990.
16
Cummins, n=56
0 Cape, n=30
7
6
5
4
3
2
1
0
0
Total
Wood
Figure 4
SWIZ
Single
Wood
Means and standard error of wood in pools in Cape and Cummins
Creeks, OR, 1990.
17
Table 2
Amounts of wood in pools in Cummins and Cape Creeks, OR, 1990.
Cape Creek
Cummins Creek
Habitat Features
Single
Wood
SWIZ
Total
Wood
Single
Wood
SWIZ
Total
Wood
Mean No./Pool
0.6
1.1
1.7
0.3
2.0
2.3
Mean No./Pool Area (m2)
0.02
0.02
0.04
0.01
0.02
0.03
Mean No./Pool Volume (m3)
0.04
0.07
0.1
0.03
0.04
0.07
Mean No./Pool Length (m)
0.08
0.09
0.2
0.03
0.1
0.13
Mean Total Wood Volume/Pool
0.5
3.5
4.0
0.4
5.8
6.2
Mean Total Wood Volume/Pool Area (m2)
0.01
0.05
0.06
0.007
0.06
0.06
Mean Total Wood Volume/Pool Volume
0.03
0.1
0.1
0.02
0.1
0.12
0.05
0.2
0.3
0.03
0.4
0.43
(m)
Mean Total Wood Volume/Pool Length (m)
18
Table 3
Total wood volumes (m3) and number of pieces of wood in pools per
kilometer (km) of stream in Cummins and Cape Creeks, OR, 1990.
Cummins Creek
Cape Creek
Single
Wood
SWIZ
Total
Wood
Single
Wood
SWIZ
Total
Wood
Total wood volume
(m3) in pools/km of
stream
14
101
115
7
117
124
No. pieces and/or
SWIZ wood in
pools/km of stream
18
32
50
6
41
47
45
40
35
30
"E 25
Cummins
cv
c.)
a)
p.,
Cape
20
15
10
0
0.31­
0.40
0.41­
0.50
0.51
0.6
0.61
0.7
0.71
0.8
0.81
0.9
0.91
1.0+
1.0
Diameter Classes (m)
Figure 5
Percent of single wood diameter classes in pools in Cape and Cummins
Creeks, OR, 1990.
100
90
80
70
60
Cummins
Cape
40
30
20
10
0
O
O
(-1
ri
71­
vl
.10
/I
O
kr;
00
(--1
kr1
r-­
eI
/
00
cr
n-1
11
00
CI
e
Length Classes (m)
Figure 6
Percent of single wood length classes in pools in Cape and Cummins
Creeks, OR, 1990.
21
50
Cummins, n = 57
Cape, n = 30
40
"E 30
* p < 0.05
** p < 0.01
cu
2 20
<
.
0
10
i
4
0
1
1
Cobble
Bedrock
I
Med gravel
I
Boulder**
Figure 7
Lg gravel**
4
Silt**
I
Sand*
I
Org debris**
Means and standard error of substrate areas in pools in Cape and
Cummins Creeks, OR, 1990.
22
p< 0.05) and organic debris (Cummins x = 5.8 ± 1.2, Cape x = 12.2 ± 5.0, p< 0.01) than
did pools in Cummins Creek. Pools in Cummins Creek had a trend towards a broader
range of dominant substrate types than pools in Cape Creek, and Cummins Creek had a
higher percentage of pools which were dominated by larger substrates than in Cape
Creek (Figure 8).
Other pool features did not differ significantly (p> 0.05) between the two creeks.
These included depth and velocity (Figure 9), and some substrate categories (Figure 7).
Correlation coefficients for various habitat features are presented in Appendix A.
Pools in the two streams were separated using discriminant analysis (p< 0.001;
Figure 10). Pools in Cummins Creek had more area of boulder, lower pool width, lower
area covered by silt, lower area of large gravel, lower pool length, and lower maximum
depth than the pools in Cape Creek. Based on pool habitat characteristics, locations of
87.7% of the pools in Cummins Creek and 73.3% of the pools in Cape Creek were
correctly classified. The mean of the discriminant scores was statistically different
between streams (Cummins x = -0.05 ± 0.67, Cape x = 0.96 ± 1.4, p< 0.01). Because of
the large difference in width and length of pools between streams, discriminant analysis
was also performed without substrate mean percent compositions and pools in the two
streams were separated (p< 0.001; Figure 11). Pools in Cummins Creek had lower pool
widths and lengths, lower maximum depths and higher mean velocities than pools in
Cape Creek. Based on pool habitat characteristics, locations of 72% of the pools in
Cummins Creek and 70% of the pools in Cape Creek were correctly classified. The
mean of the discriminant scores was statistically different between streams (Cummins
= -0.39 ± 0.84, Cape x = 0.73 ± 1.3, p< 0.01). In both cases, 100% of the variation in
pools was explained by these pool habitat characteristics.
23
Cape Creek
Bedrock ­
n = 28
Cummins Creek
n = 56
Boulder ­
Cobble Lg gravel
Med gravel ­
Sand
Silt
Clay
Org debris
0
Figure 8
10
10
20
20
0
30
Percent Dominant Substrate
30
Dominant substrate composition in pools in Cape and Cummins Creeks,
OR, 1990.
24
Mean
Depth
(m)
Figure 9
Max
Depth
(m)
Mean
Velocity
(m/sec)
Max
Velocity
(m/sec)
Means and standard error of mean and maximum depth and velocity in
pools in Cape and Cummins Creeks, OR, 1990.
25
Cape Creek
Cummins Creek
1f1111111
-1.0
-0.5
0.5
0
1-0
1.0
I
1.5
DA Scores
Low <
Pool Width
> High
Low <
Area of Silt
> High
Low <
Area Large Gravel
> High
High<
Area of Boulder
> Low
Low <
Pool Length
> High
Low <
Maximum Depth
> High
Figure 10
Discriminant analysis of pool habitat characteristics in Cape and
Cummins Creeks, OR, 1990. Mean and 95% confidence interval of
group scores are shown.
26
Cape Creek
Cummins Creek
I
I
-1.0
1
-0.5
I
0
I
I
I
0
I
I
0.5
I
I
I
1.0
DA Scores
Low <
Pool Width
> High
Low <
Pool Length
> High
Low <
Maximum Depth
> High
High<
Mean Velocity
> Low
Figure 11
Discriminant analysis of pool habitat characteristics in Cape and
Cummins Creeks, OR, 1990. Mean and 95% confidence interval of
group scores are shown.
27
Salmonid Assemblages
The population surveyed in Cummins Creek was composed of 37% steelhead
trout, 20% cutthroat trout and 43% coho salmon (trout 0+ are excluded from these
numbers due to lack of species identification). The community surveyed in Cape Creek
pools was composed of 21% steelhead trout, 9% cutthroat trout and 70% coho salmon.
Difference in the diversity of the salmonid assemblages in Cummins Creek and
Cape Creek varied with diversity indicies. Pool assemblage diversity was greater (p<
0.01) in Cummins Creek than in Cape Creek for Simpson's Diversity (Cummins Creek )7;
= 0.47 ± 0.22, Cape Creek x = 0.33 ± 0.23) and for the Shannon Eveness index
(Cummins Creek x = 0.50 ± 0.20, Cape Creek x = 0.30 ± 0.19 (p<0.01). However,
there was no difference in pool assemblage diversity (p< 0.05) between streams for the
Shannon-Wiener Diversity index (Cummins s = 0.77 ± 0.36, Cape )-( = 0.66 ± 0.32).
Community diversity, using all three indicies, was correlated with pool features
(Table 4). In Cummins Creek, salmonid diversity is significantly correlated with
maximum depth (p<0.01), and correlated with mean depth, maximum velocity, pool
length, pool width, surface area, area of organics, area of sand, area of boulder, and total
volume of wood (p<0.05). There were no significant (p> 0.05) correlations between fish
diversity and pool habitat characteristics in Cape Creek.
Salmonid populations differed (p< 0.05) between Cape and Cummins Creeks
(Figure 12). Coho abundance (Cummins )-< = 7.6 ± 6.9, Cape x = 43 ± 54, p< 0.01),
cutthroat abundance (Cummins x = 3.6 ± 3.5, Cape x = 5.6 ± 5.4, p< 0.05), steelhead 1+
abundance (Cummins s = 6.5 ± 5.5, Cape x = 13 ± 12.6, p< 0.01), and trout 0+
abundance (Cummins )7( = 2.1 ± 2.4, Cape )7( = 14.3 ± 19.8, p< 0.01) were greater in
Table 4
Correlations relating pool habitat characteristics and fish diversity in Cape and Cummins Creeks, OR, 1990.
Cummins Creek
Cape Creek
Habitat Feature
Simpson's
Diversity
Shannon
Evenness
Shannon­
Wiener
Simpson's
Diversity
Shannon
Evenness
ShannonWiener
Mean Depth (m)
0.32*
0.33*
0.32*
0.30
0.26
0.20
Maximum Depth (m)
0.48**
0.46**
0.48**
0.34
0.29
0.26
Maximum Velocity (m/s)
0.26*
0.26*
0.33*
-0.00
-0.04
0.05
Length (m)
0.32*
0.30*
0.33*
0.29
0.26
0.15
Organics (m2)
0.31*
0.28*
0.32*
-0.01
-0.02
-0.04
Width (m)
0.29*
0.29*
0.28*
0.29
0.26
0.25
Surface Area (m2)
0.31*
0.29*
0.31*
0.28
0.25
0.15
Sabd (m2)
0.33*
0.32*
0.33*
0.09
0.10
-0.01
Boulder (m2)
0.28*
0.23
0.29*
0.30
0.28
0.21
Total Wood Volume (m3)
0.24*
0.20
0.26*
-0.06
-0.05
0.05
*p< 0.05
**p< 0.01
29
Cummins, n=56
Cape, n=30
50
*p<0.05
**p<0.01
40
30
20
10
0
Coho**
Figure 12
Cutthroat*
Steelhead 1+**
Trout 0+**
Means and standard error of juvenile salmonid abundances in pools in
Cape and Cummins Creeks, OR, 1990.
30
pools in Cape Creek. When the fish abundances were standardized for pool area, only trout
0+ pool abundances were significantly higher in Cape Creek (7( = 0.129, ± 0.17, p< 0.01;
Figure 13).
There were various significant relationships among the species/age-classes within
pools of the two streams (Table 5). In Cummins Creek, cutthroat trout abundance was
positively correlated with coho (p< 0.01) and steelhead 1+ (p< 0.01) abundances, trout 0+
abundance was positively correlated with steelhead 1+ (p< 0.01), and steelhead 1+ abundance
was correlated with coho salmon (p< 0.01) abundance. In Cape Creek, cutthroat abundance
was positively correlated with both coho (p< 0.01) and steelhead 1+ (p< 0.01) abundances,
and steelhead 1+ was positively correlated with trout 0+ (p< 0.01) and coho (p< 0.01)
abundances. Positive relationships were also found between densities (mean number per 100
m) of fish species/age-classes (Table 6). In Cummins Creek, cutthroat trout density was
positively correlated with densities of coho and steelhead 1+ (p<0.01). Density of trout 0+
was positively correlated with the density of steelhead 1+ trout. In Cape Creek, coho density
was positively correlated with the densities of cutthroat and trout 0+ (p< 0.01). Density of
trout 0+ was positively correlated with steelhead 1+ density (p< 0.01).
Juvenile salmonid species/age-classes were also correlated with physical features
within the pools (Table 7). In Cummins Creek, coho salmon were significantly correlated (p<
0.01) with mean and maximum depth, pool length and surface area, area of organics, silt, sand
and large gravel, and negatively correlated (p< 0.01) with mean velocity. Coho salmon were
also significantly correlated (p< 0.05) with pool width and volume, and area of clay, cobble,
and boulder. Cutthroat trout were correlated (p< 0.01) with mean and maximum depth, pool
length, volume, and surface area, and area of
31
0.5
Cummins, n = 57
Cape, n = 30
N
0.4 ­
** p < 0.01
.--: 0.3­
o
Z
co
co
-
0.2
a)
2
0
0.1
I
Coho
Figure 13
Cutt
St 1+
Tr 0+
**
Means and standard error of juvenile salmonid densities in pools in Cape
and Cummins Creeks, OR, 1990.
Table 5
Correlations between fish species/age-class abundance in pools in Cape and Cummins Creeks, OR,
1990.
Cummins Creek
Fish Species/AgeClass Abundance
Coho
Cutthroat
Steelhead 1+
Trout 0+
*p < 0.05
**p < 0.01
Coho
Cape Creek
Cutthroat
Steelhead 1+
Trout0+
0.62**
0.38**
-0.04
0.59**
0.18
0.47**
Coho
Cutthroat
Steelhead 1+
Trout 0+
0.65**
0.48**
0.36
0.53**
0.17
0.69**
Table 6
Correlations between density (number of fish/m2) of fish species/age-classes in pools in Cape and Cummins Creeks,
OR, 1990.
Cummins Creek
Density of Fish
Species/Age-Class
Coho
Cutthroat
Steelhead 1+
Trout 0+
*p < 0.05
**p < 0.01
Density
of Coho
Cape Creek
Density of
Cutthroat
Density of
Steelhead 1+
Density of
Trout 0+
0.69**
0.14
-0.07
0.37**
-0.02
0.33**
Density
of Coho
Density of
Cutthroat
Density of
Steelhead 1+
Density of
Trout 0+
0.53**
-0.00
0.53**
0.11
0.16
0.42*
Table 7
Correlations between fish species/age-class abundances and pool habitat characteristics in Cummins and Cape
Creeks, OR, 1990.
Curium's Creek
Cape Creek
Habitat Feature
Coho
Cutthroat
Steelhead 1+
Trout 0+
Coho
Cutthroat
Steelhead 1+
Trout 0+
Mean Depth (m)
Maximum Depth (m)
Mean Velocity (m/s)
Maximum Velocity (m/s)
Length (m)
Width (m)
Surface Area (m2)
Volume (m3)
Aggregate Wood Volume (m3)
Single Wood Volume (m3)
Total Wood Volume (m3)
Organics (m2)
0.39**
0.56**
0.27*
0.52**
-0.30*
-0.03
0.48**
0.30*
0.50**
0.27*
0.09
-0.05
0.08
-0.06
-0.03
0.16
0.31*
0.23
0.12
0.05
-0.23
0.07
0,51**
-0.34
-0.07
0.75**
0.27
0 78**
0 66**
-0.06
-0.02
-0.06
0.37*
0.15
0.50**
-0.22
0.15
0.48**
0.29
0.50**
0.45*
-0.21
0.13
-0.21
0.02
0.34
0.55**
-0.06
0.32
0.63**
0.09
0.55**
0.58**
-0.13
0.27
-0.10
0.27
0.26
0.26
-0.04
0.25
Clay (m2)
Silt (m2)
Sand (m2)
Medium Gravel (m2)
Large Gravel (m2)
Cobble (m2)
Boulder (m2)
0.39**
0.45**
-0.36**
-0.06
0.46**
0.30
0.49**
0.35*
-0.06
0.07
-0.05
0.52*
0.33*
0.43**
0.34**
0.18
0.41**
0.27*
0.31*
+
+
+
+
0.49**
-0.08
0.06
0.34
0.58**
0.38*
0.47**
0.47**
0.12
0.19
0.56**
0.71**
0.18
0.64**
Bedrock (m2)
0.15
0.13
0.33
0.12
*p<0.05
"p<0.01
+Cape Creek did not contain clay
-0.31 *
0.05
0.40**
0.32*
0.45**
0.34**
0.06
-0.14
0.04
0.49**
0.42**
0.41**
0.19
-0.21
0.01
0.10
0.26
0.37**
0.40**
0.06
0.48**
0.31*
0.40**
0.14
0.08
0.33*
0.43**
0.47**
0.05
0.44**
0.34*
0 84**
0.30
0.44*
0.40*
0.49**
0 34
0.01
0.14
-0.18
0.26
0.06
0.28*
0.17
-0.07
-0.01
0 39*
0.19
0.38*
0.38*
0.06
0.39*
0.10
0.25
0.34
0.10
0.28
0.36
35
organics, clay, silt, cobble, and boulder. Cutthroat trout also were correlated (p< 0.05)
with pool width, and negatively correlated with mean velocity. Steelhead 1+ in
Cummins Creek were correlated (p< 0.01) with maximum depth, pool length and surface
area, area of organics, silt, cobble and boulder. Steelhead 1+ were also correlated (p<
0.05) with mean depth, pool width and volume, area of clay, and large gravel, and
negatively correlated with mean velocity. Trout 0+ in Cummins Creek pools were
correlated (p< 0.01) with area of cobble. Trout 0+ were also correlated (p< 0.05) with
pool width, area of clay and boulder. In Cape Creek, coho salmon were correlated (p<
0.01) with maximum depth, pool length, surface area, volume, and area of silt and
cobble. Coho salmon were also correlated (p< 0.05) with area of organics, medium
gravel and large gravel. Cutthroat trout were correlated (p< 0.01) with maximum depth,
pool length, surface area, and area of silt and cobble. Cutthroat trout were also
correlated (p< 0.05) with pool volume and area of boulder. Steelhead 1+ in Cape Creek
were correlated (p< 0.01) with maximum depth, pool length, surface area and volume,
and area silt, sand, cobble and boulder. Trout 0+ were correlated (p< 0.01) with area of
sand. Trout 0+ were also correlated (p< 0.05) with pool length, surface area, and
volume, and volume of single wood.
Densities of juvenile salmonid species/age-classes also were correlated with physical
features within the pools (Table 8). In Cummins Creek, density of coho was correlated
(p< 0.01) with single wood volume. Density of cutthroat trout was correlated (p< 0.01)
with mean depth, and correlated (p< 0.05) with maximum depth. Density of steelhead
1+ was negatively correlated (p< 0.05) with area of sand. Density of trout 0+ was
negatively correlated (p< 0.05) with area of organics and sand. In Cape Creek, density
of cutthroat trout was correlated (p< 0.05) with maximum velocity. Density of steelhead
Table 8
Correlations between density (number of fish/m2) of fish species/age-classes and pool habitat
characteristics in Cummins and Cape Creeks, OR, 1990.
Cummins Creek
Habitat Feature
Cape Creek
Density
Density of
Density of
Density of
Density
Density of
Density of
Density of
of Coho
Cutthroat
Steelhead 1+
Trout 0+
of Coho
Cutthroat
Steelhead 1+
Trout()+
Mean Depth (m)
0.29
0.42**
0.20
-0.09
0.04
-0.07
-0.18
-0.04
Maximum Depth (m)
0.04
0.31*
0.17
-0.15
0.18
-0.01
-0.17
-0.05
Mean Velocity (m/s)
-0.24
-0.26
-0.16
0.16
-0.23
0.19
0.42*
0.13
Maximum Velocity (m/s)
-0.20
-0.01
-0.06
-0.01
0.07
0.38*
0.52**
0.30
Aggregate Wood Volume (LW)
-0.09
0.002
0.04
0.09
0.05
-0.27
-0.37*
-0.05
Single Wood Volume (m`)
0.44**
0.26
-0.08
-0.19
0.15
0.08
0.16
0.36
Total Wood Volume (m3)
-0.02
0.04
0.03
0.06
0.06
-0.26
-0.36
-0.02
Organics (m)
0.01
-0.00
-0.11
-0.31*
-0.02
-0.31
-0.39*
-0.10
Clay (m2)
-0.03
-0.01
-0.07
-0.05
+
Silt (m2)
-0.09
-0.09
-0.16
-0.20
0.13
-0.13
-0.21
-0.13
Sand (m')
-0.09
-0.15
-0.27*
-0.32*
0.16
-0.16
-0.14
0.19
Medium Gravel (m2)
-0.02
0.02
0.04
-0.10
0.02
-0.12
-0.17
-0.05
Large Gravel (m2)
-0.11
-0.14
-0.16
-0.22
-0.15
-0.02
-0.26
-0.22
Cobble (m)
-0.18
-0.08
-0.19
-0.03
0.07
0.03
-0.06
0.04
Boulder (m2)
-0.14
-0.09
-0.15
-0.13
-0.03
0.00
0.15
0.15
Bedrock (m2)
-0.08
-0.12
-0.13
-0.20
0.12
-0.05
-0.02
-0.04
*p<0.05
"p<0.01
+Cape Creek does not contain clay
+
37
1+ was correlated (p< 0.01) with maximum velocity and (p< 0.05) with mean velocity.
Density of steelhead 1+ was negatively correlated with SWIZ volume and area of
organics. Neither density of coho nor density of trout 0+ was correlated with any
physical characteristics in Cape Creek.
Forward stepwise multiple regression was used to create a model for the
abundance of each species/age-class from physical habitat parameters (maximum depth,
mean velocity, pool length and width, area of silt, large gravel, cobble and boulder, and
volume of SWIZ and single wood) and from pool physical and biological parameters
(maximum depth, mean velocity, pool length and width, area of silt, large gravel, cobble
and boulder, volume of SWIZ and single wood and abundance of salmonid species/age­
classes). Different models were developed for each stream and some consistencies were
found (Tables 9-12). Maximum depth in both streams explained a portion of the
variation in abundances of cutthroat trout (Table 9) and steelhead 1+ trout (Table 10).
There were no similar physical habitat variables that explained coho salmon (Table 11)
or trout 0+ (Table 12) abundances in the two streams.
Consistencies also were found between fish species/age-class abundances between
sites. Cutthroat trout (Table 9) abundances were explained by coho salmon abundances
in both streams. Steelhead trout 1+ (Table 10) abundances were explained by cutthroat
trout and trout 0+ abundances. Coho salmon (Table 11) abundances were explained by
cutthroat trout abundances in both streams. Trout 0+ (Table 12) abundances were
explained by steelhead 1+ trout abundances in both streams. Interestingly, only trout 0+
(Table 12) abundances in Cummins Creek retained one of the same physical habitat
features after the biological components were added to the stream model.
Forward stepwise multiple regression was used to create a model for the density
38
Table 9
Site
Cummins
Creek
Multiple regression models for cutthroat trout abundance in Cummins
and Cape Creeks, OR, 1990.
Model
Physical
Physical +
Biological
Cape
Creek
Physical
Independent
Variables
R2
r
F
p
Maximum Depth
Pool Length
Coho Salmon
Steelhead 1+
Area Cobble
0.34
0.58
15.50
0.00
0.52
0.72
30.60
0.00
Maximum Depth
0.48
0.69
9.90
0.00
0.41
0.64
20.84
0.00
S WIZ
Physical +
Biological
Coho Salmon
39
Table 10
Site
Cummins
Creek
Multiple regression models for 1+ steelhead trout abundance in
Cummins and Cape Creeks, OR, 1990.
Model
R2
r
F
p
Maximum Depth
Pool Length
Trout 0+
Cutthroat Trout
Pool Length
Maximum Depth
Area Boulder
0.35
0.59
16.00
0.00
0.54
0.73
17.30
0.00
Physical
Maximum Depth
0.49
0.70
15.10
0.00
Physical +
Biological
Trout 0+
Cutthroat Trout
Area Bouder
0.70
0.84
23.90
0.00
Physical
Physical +
Biological
Cape
Creek
Independent
Variables
Table 11
Site
Cummins
Creek
40
Multiple regression models for coho salmon abundance in Cummins and
Cape Creeks, OR, 1990.
Model
Physical
R2
r
F
p
Pool Length
Maximum Depth
Cutthroat Trout
Area Large Gravel
Area Silt
0.29
0.54
12.30
0.00
0.43
0.66
21.60
0.00
Physical
Area Large Gravel
0.70
0.84
34.90
0.01
Physical +
Biological
Area Silt
Cutthroat Trout
0.73
0.85
40.30
0.00
Physical +
Biological
Cape
Creek
Independent
Variables
41
Table 12
Site
Cummins
Creek
Cape
Creek
Multiple regression models for trout 0+ abundance in Cummins
and Cape Creeks, OR, 1990.
Model
Independent
Variables
R2
r
F
p
Physical
Area Cobble
0.18
0.42
12.80
0.00
Physical +
Biological
Steelhead Trout 1+
Pool Length (-)
0.30
0.55
8.80
0.00
Physical
Single Wood
Volume
0.27
0.52
6.30
0.01
Physical +
Biological
Steelhead Trout 1+
0.45
0.67
25.20
0.00
42
of each species/age-class from pool physical habitat parameters and from physical and
biological parameters. Different models were developed for each stream and some
consistencies were found (Tables 13-16). Neither stream showed consistencies between
physical habitat and fish species/age-class densities. No physical variables entered the
model to explain the variation in densities of cutthroat (Table 13) or trout 0+ (Table 16)
in Cape Creek.
Consistencies were found between fish species/age-class densities between sites.
Density of coho entered the model in both Cape and Cummins Creek as one of the
variables to explain the density of cutthroat trout (Table 13). Density of trout 0+ entered
the model in both streams as one of the variables to explain steelhead 1+ density (Table
14). Density of cutthroat trout entered the model in both streams as one of the variables
explaining density of coho salmon (Table 15). Steelhead 1+ density entered the models
for both streams as one of the variables explaining density of trout 0+ (Table 16). In
Cummins Creek, cutthroat trout (Table 13) and coho salmon (Table 15) density retained
maximum depth and single wood volume in both physical and physical/biological
models, respectively. In Cape Creek, steelhead 1+ density (Table 14) retained pool
width in both physical and physical/biological models.
Salmonid diversity was used as a dependent variable in multiple regression
analysis. Fish diversity was significantly correlated with pool habitat characteristics only
in Cummins Creek. There were no significant correlations between any diversity
measure and physical attributes in Cape Creek pools (Table 4). When Simpson's
Diversity (SD) index Shannon Evenness (SE) and Shannon-Wiener (SW) indicies were
the dependent variables, 21%, 20%, and 22% of the variation in diversity was explained
by maximum depth, respectively (SD, R2 = 0.21; p< 0.01; SE, R2 = 0.20; p< 0.01; SW,
43
Table 13
Site
Cummins
Multiple regression models for cutthroat trout density in Cummins and
Cape Creeks, OR, 1990.
Model
Physical
Creek
Physical +
Biological
Cape
Creek
Independent Variables
R2
r
F
P
Maximum Depth
Single Wood Volume
Area Silt
Density of Coho
Salmon
Maximum Depth
Density of Steelhead 1+
0.21
0.46
6.00
0.00
0.59
0.77
27.40
0.00
0.33
0.57
8.00
0.00
Physical
Physical +
Biological
*
Density of Coho
Salmon
Mean Pool Velocity
*No variables entered into the model.
44
Table 14
Site
Cummins
Creek
Cape
Creek
Multiple regression models for 1+ steelhead density in Cummins
and Cape Creeks, OR, 1990.
Model
Physical
Independent
Variables
R2
r
F
p
0.12
0.35
4.80
0.00
Physical +
Biological
Pool Length (-)
Maximum Depth
Density of Cutthroat
Density of Trout 0+
0.22
0.47
8.80
0.00
Physical
Pool Width (-)
0.27
0.52
11.50
0.00
Physical +
Biological
Pool Width (-)
Density of Trout 0+
0.43
0.66
11.40
0.00
45
Table 15
Site
Cummins
Creek
Multiple regression models for coho salmon density in Cummins and
Cape Creeks, OR, 1990.
Model
Physical
Physical +
Biological
Cape
Creek
Independent
Variables
R2
r
F
p
Single Wood Volume
Mean Pool Velocity (-)
Density of Cutthroat
Density of Trout 0+
0.26
0.51
10.50
0.00
0.54
0.73
32.80
0.00
0.58
0.76
13.90
0.00
Physical
Physical +
Biological
*
Density of Cutthroat
Density of Trout 0+
Mean Pool Velocity (-)
*No variables entered into the model.
46
Table 16
Site
Cummins
Creek
Multiple regression models for trout 0+ density in Cummins and
Cape Creeks, OR, 1990.
F
p
0.12
0.35
4.90
0.01
0.09
0.30
6.40
0.01
0.41
0.64
10.80
0.00
Independent
Variables
R2
Physical
Pool Length (-)
Single Wood
Volume (-)
Density of
Steelhead 1+
Physical +
Biological
Cape
Creek
r
Model
Physical
Physical +
Biological
*
Density of
Coho
Density of
Steelhead 1+
*No variables entered into the model.
47
R2 = 0.22, p< 0.01).
Assemblages of salmonids in pools in the two streams differed (Discriminant
analysis, p <0.01; Figure 14). Pools in Cummins Creek had higher proportions of
cutthroat and steelhead 1+ and lower proportions of trout 0+ and coho than pools in
Cape Creek. Seventy percent of the pools were correctly classified in Cummins Creek
and 73% in Cape Creek. One hundred percent of the variation was explained by this
discriminant function.
48
Cape
Cummins
I
-0.5
-1.0
0.5
0.0
DA Scores
1.0
1.5
Low <
% Coho 0+
> High
High <
% Steelhead 1+
> Low
Low <
% Trout 0+
> High
High <
% Cutthroat 1+
> Low
Figure 14
Discriminant analysis of juvenile salmonid community in pools in Cape
and Cummins Creeks, OR, 1990. Mean and 95% confidence interval of
group scores are shown.
49
Discussion
Pool habitat characteristics did not vary greatly between streams, while diversity
of the assemblage of juvenile anadromous salmonids were greater in pools in Cummins
Creek, the less disturbed system, than in Cape Creek, a watershed that had been
subjected to timber harvest. Other studies examining the impact of land management
activities on stream habitats and biotic assemblages have found different physical
responses (Kaufmann 1987, Hicks et al. 1991, McIntosh et al. 1994, Ralph et al. 1994)
while others have found similar biological responses (Li et al. 1987, Hicks 1990, Reeves
et al. 1993) elsewhere in the Pacific Northwest. Corn and Bury (1989) reported the
diversity of amphibians in the Oregon Coast Range was greater in streams in uncut
forests compared to streams in logged stands. Scott et al. (1986) found a more diverse
fish assemblage in a pristine stream compared to one altered by urbanization. Simplified
habitat and associated fish assemblages have been observed in streams in other regions
as a consequence of land management impacts such as timber harvest (Grant et al. 1986,
Rutherford et al. 1987) and agriculture (Schlosser 1982b, Berkman and Rabeni 1987).
In this study, diversity of the salmonid assemblage between the two streams
differed because of differences in relative abundance rather than species richness.
Species/age-class abundances were greater in Cape Creek than in Cummins Creek;
abundance of coho salmon was disproportionately higher than the other salmonid species
abundances in Cape Creek. The Shannon-Wiener index, which is biased towards species
richness, did not show any differences in diversity between streams. The Simpson's
Diversity index, which is biased towards dominance, was higher in Cummins Creek.
The Shannon Evenness Index, which is biased towards community evenness, was higher
50
in Cummins Creek than in Cape Creek. Relative abundances among the three salmonid
species were more even in Cummins Creek. Salmonid species composition in both
streams were comparable to other studies on the Oregon coast (Reeves et al., 1993)
(Table 17). Even though this study used a different dominance index than Reeves et al.
(1993) and looked at juvenile salmonids in pools only, there is a similar trend wherein
streams through unmanaged stands have higher diversity. Even if this study had
assessed juvenile salmonids in riffles as well as in pools, trout numbers would have
increased, lessening the dominance and reducing my values, to more closely match those
found in Reeves et al. (1993). Changes in relative abundance and not a loss of species
were responsible for the differences in assemblage diversity. In Carnation Creek, British
Columbia, numbers of coho salmon smolts increased following timber harvest (Holtby
1988) while cutthroat and steelhead trout (Hartman 1987) and chum salmon (0. keta)
declined (Scrivener and Brownlee 1989). Numbers of Dolly Varden (Salvelinus malma)
declined following removal of wood from an Alaskan stream (Elliot 1986). Gurtz and
Wallace (1984) observed a differential response by benthic macroinvertebrates to
clearcut logging in a second order stream in the southeastern United States.
In contrast, this study, fish densities were similar between streams, with the
exception of trout 0+ fish which were higher in Cape Creek pools. Similar results were
found by Reeves et al. (1993). They found that densities of juvenile anadromous
salmonids did not significantly differ between basins subjected to different harvest
levels.
Mechanisms responsible for the change in relative abundance of the different
species and for the increase in trout 0+ density are unclear. One explanation is that
changes in the physical conditions of Cape Creek were more favorable to coho salmon
51
Table 17
Comparison of salmonid species composition between Cape and
Cummins Creek pools and other Oregon coastal streams taken from
Reeves et al. 1993.
Harvest Level & Stream
Species Composition
> 1 year
>1 year
old
old
steelhead cutthroat
(%)
(%)
0
2.9
4.7
4.0
2.3
0
3.2
4.8
Coho
salmon
(%)
Diversity
95.3
93.1
85.1
38.8
27.2
62.7
48.4
43
1.05
Low Harvest Level (>25%)
Upper Flynn Creek
South Fork Drift Creek
Franklin Creek
Red Cedar Creek
Lower North Fork Elk River
Cummins Creek
Lower Panther Creek
Cummins Creek 1990
12.5
61.2
59.0
35.5
47.5
0.1
37
20
0
0.9
0
2.3
1.8
0.3
2.7
2.1
91.7
93.1
8.3
15.9
1.2
21
9
1.07
1.18
1.63
1.69
1.59
2.07
1.05
High Harvest Level (> 25%)
Needle Branch Creek
Deer Creek
Canal Creek
Knowles Creek
Bald Mountain Creek
Butler Creek
Cape Creek
Cape Creek 1990
3.6
99.1
98.2
97.3
95.1
0
0
82.8
70
1.01
1.02
1.03
1.05
1.09
1.09
1.21
0.797
52
and trout 0+ than to older trout. Schlosser (1991) found that decreased habitat
components may selectively benefit species that are able to exploit new conditions while
resulting in the decline of others, thus resulting in a reduction in community diversity.
Coho salmon are more surface-oriented (Hartman 1965), and use areas of slower
velocities (Bisson et al. 1988) in pools compared with trout. Trout 0+ also prefer areas
of slower velocities and shallow depths (Moore and Gregory 1989). Pools in Cape
Creek were larger and had relatively high proportions of homogeneous slow velocities
(as suggested by the lower standard deviation of maximum velocities) and shallower
depth, particularly in the downstream halves. These areas were almost exclusively used
only by coho salmon or trout 0+. Older trout were found in the deeper, faster portions at
the heads of pools. Such conditions were a relatively small proportion of the available
habitat in pools in Cape Creek compared to pools in Cummins Creek due to the large
differences in pool size. Cummins Creek pools had larger (percent dominant) substrate.
It is possible that smaller pools, which have larger substrates could lead to a change in
relative abundance as seen in Cummins Creek. Increased abundance of salmonids in
Cape Cape could be due to the open vegetation condition. Cutthroat trout were found to
capture drift more efficiently in open areas of stream that those adjacent to old-growth
forests where the canopy shaded the stream (Wilzbach et al. 1986). Differences in
habitat conditions between Cape and Cummins Creeks may have affected the relative
abundances of salmonids, but there is no definitive answer from these results.
Changes in the outcome of interactions between the trout and coho salmon for
space in these pools also may have influenced the relative abundances of the species.
Coho salmon use mid-water and slow velocity areas of pools, while trout use deep, faster
velocity areas (Bisson et al. 1988). Body morphologies of the species appear to be
53
adapted to these specific habitat conditions. Coho salmon have longer anal fins and a
laterally compressed body which allowed them to maneuver better than trout in slower
areas. Steelhead body morphologies are more cylindrical with large paired fins which
seemed to allow them to hold position in swift water (Bisson et al. 1988). Trout were
typically found at the head of pools in Cape Creek, while coho and trout 0+ were located
towards the middle and back of pools. Swanston (1991) state that woody debris and
boulders created varied velocities in channels. Increased tail portions of pools, which
typically had little to no wood and finer substrates, along with increased pool area and
volume would suggest pools in Cape Creek had less varied velocities. A decrease in
velocity variability could allow velocities to slow which would be preferred habitat for
coho salmon who respond more favorably to slow water habitat than would trout.
Woody debris has been studied in streams throughout the Pacific Northwest and
has been recognized as an important component of the channel and for aquatic habitat
(Robison and Beschta 1990, Bilby and Ward 1989, Sedell and Swanson 1984). Several
studies have examined wood in several influence zones, ranging from in-stream wood to
wood above bankfull (Ursitti 1991, Table 18). Using these studies as a basis for
comparison to wood volumes found in Cummins and Cape Creeks, differences are
noticed. Most of the studies used a minimum size of 10cm in diameter and looked at
wood within the active channel, and in all habitat units. This study only assessed wood
that was submerged in pools and pieces of wood that composed the SWIZ. Estimates of
volume for individual pieces were not made for the SWIZ. Large woody debris volumes
(m3/hectare) for Cummins and Cape Creeks were 628.8 and 479.2, respectively. These
are towards the high end of the range reported in other studies (Table 18). The primary
reason for this may be the way in which the estimates for the current study were derived.
Table 18
Comparison of large woody debris data from Pacific Northwest studies; data from Ursitti 1991.
Basin Area
(ha)
Active Channel Width
(m)
Stream Gradient
(%)
LWD Volume
(m`/ha)
LWD Density
(# pieces/100 ni)
mean (range)
mean (range)
mean (range)
mean (range)
mean (range)
5.1 (2.1-14.3)
7.8(4.9-12.8)
193(55-300)
5
466(72-1140)
1.9(1 1-2.5)
185(140-250)
4
12
5540
25.9
0.8
240
1
12
792(330-1680)
5
2
Forest Type and
Location
Picea sitchensis/ Tsuga
heterophylla
Southeast Alaska
Southeast Alaska
Coastal B.C., Canada
Olympic Nat. Pk., WA
Coast Range, OR
Picea sitchensis
Coast Range, OR
Tsuga heterophylla
Coast Range, OR
Coast Range, OR
Coast/Cascades, OR
Cascade Range, OR
Cascade Range, OR
Cascade Range, WA
Age
300-500
200
860(850.-900)
100+
701(520-850)
271(114-536)
80-140
50+
1.2(0.8-1.5)
3
4
4.5(2.0-7.3)
9.0(2.8-22.6)
293(201-422)
42(36-55)
4
5
4.1(1.3-10.7)
1.2(0.4-2.0)
42(26-80)
58(47-81)
29(11-62)
9
6
6
6
3.9(1.3-8.9)
190(86-363)
382(258-582)
210(30-430)
9
7
78(47-133)
17(5-44)
4
7
44(25-72)
5
8
5
9
5
I, 10
100-150
281(50-640)
5.2(2.7-7.1)
7.7(4.6-11.2)
4.6(2.5-7.1)
1075(600-1900)
9(4-13)
1.2(0.4-3.0)
4
12.7(3.6-23.6)
Old
365(40-1810)
3130(750-6800)
7
5
896(287-1629)
315(114-645)
60
61(37-124)
507(142-1012)
Old
Reference
375(194-584)
80-150
250-500
(I)
Size
4.5(3.5-8.3)
290-410
Old
Sample
6.5(4.5-9.0)
6.5(3.6-9.7)
15 3(10 1-19.7)
10.8(6-17)
61(23-87)
684(320-780)
11.2(2-18)
42
14
I1
3 3(1-10)
14
8
II
Continued on next page
Table 18 (Cont'd)
Comparison of large woody debris data from Pacific Northwest studies; data from Ursitti 1991.
Active Channel Width
(m)
Stream Gradient
MD Volume
(ha)
(%)
(m'/ha)
LWD Density
(# pieces/100 m)
mean (range)
mean (range)
mean (range)
mean (range)
mean (range)
Basin Area
Forest Type and
Location
Pseudotsuga nienziesii
Cascade Range, OR
Klamath Nits.. CA
Age
500
600
12.0
570
300-500
3415(1200-6000)
296(110-640)
18.8(15.5-24.0)
240(150-340)
352(18-1200)
300
4 70 8-7 21
Sample
(I)
Size
Reference
3
6
(I) Data adapted from the following authors includes lwd size, category, and channel area surveyed (if available).
I . Harmon et al. 1986
>10 cm diam
2. Toews and Moore 1982
>3 m long
3. Grette 1985
>10 cm diam., >3 m long
4. Heimann 1988
to 4.5 m each side of channel centerline (probably includes zones 1-4)
>10 cm diam.
5. Long 1987
to 5.0 m each side of channel centerline
>10 cm diam., >1 in long
6. Ursitti 1991
>10 cm diam., >1 m long
within active channel
7. Veldhuisen 1990
>15 cm diam., >2 m long
within active channel
8. Summers 1983
>10 cm diam., >stream width
in and above the active channel
9. Franklin et al. 1981
>10 cm diam.
10. Froehlich 1973
>10 cm diam., >0.3 m long
to 4.5 m each side of channel centerline
11. Bilby and Ward 1989
>10 cm diam., >2 m long
12. Robison and Beschta 1990 >20 cm diam., >1.5 in long
within active channel
56
I expanded the number from my study reaches to the entire watershed area. It appears
that the study reaches may not have represented wood distribution for the watershed as a
whole. They were high and consequently, expanded estimates fell into the higher end of
the range reported in other studies. Large woody debris densities (# pieces/100 m) for
Cummins and Cape Creeks were 5.0 and 4.7, respectively. These are outside of the
range reported in other studies (Table 18) because the calculation for the current study
only included single wood volumes and not the SWIZ. Although Cummins and Cape
Creeks have comparable woody debris volumes, the data from this study can only
evaluate the importance of wood at low flow conditions; the studies in Table 18 are able
to address the importance of the role woody debris plays in winter high flow conditions.
McMahon and Hartman (1989) found that woody debris was influenced the
abundance of coho salmon within stream habitats in winter, and that the complexity of
the wood was also important. Location of wood was important in a study done by Ralph
et al. (1994). They found that the location of wood shifted towards the stream margins
in harvested streams. Factors such as woody debris at low flow and high flow conditions
and location within the stream may be as important to assess when addressing habitat
conditions.
One difference between streams was the number of pools within similar lineal
distances of stream. Large wood is more effective in forming pool habitat, causing bed
scour from flow deflections (Bilby 1985), which may be why there were twice the
number of pools in Cummins Creek than in Cape Creek within the same longitudinal
distance. Wood in streams also provides a physical obstruction to water flow (Bisson et
al. 1987), which may explain the trend towards greater mean and maximum velocity
observed in pools in Cummins Creek. Kaufmann (1987) found that larger amounts of
57
wood provided a greater array of velocitiescompared to less amounts. Reasons why
differences in velocites were not seen between Cummins and Cape Creeks could be due
to the similar volumes of wood within pools.
Differences in geomorphology between the two creeks could have been the
reason seen for differences in habitat characteristics. Cape Creek has a higher channel
sinuosity than Cummins Creek, while Cummins Creek has a higher gradient than Cape
Creek. A lower gradient, more sinuous and wider channel would provide areas of
deposition, which could be why there were smaller substrates found in Cape Creek.
Both physical and biological factors can influence the structure and composition
of lotic fish communities. However, the influence of each on community structure is
subject to much debate (Grossman et al. 1982, Yant et al. 1984). Some studies have
found that biological interactions, including predation and interspecific competition, are
important in determining the structure and composition of stream fish communities
(Kalleberg 1958, Heck and Wetstone 1977, Faush and White 1981, Crowder and Cooper
1982, Moyle and Vondracek 1985). Others suggest that physical conditions are more
important (Moyle and Li 1979, Schlosser 1982a, Angermeier and Karr 1984, Shirvell
1990). Some studies (Baltz et al. 1982, Schlosser 1985, Reeves et al. 1987, De Staso
and Rahel 1994, Nielsen et al. 1994) have found that changes in environmental
conditions can alter the outcome of interactions between lotic fishes. Everest and
Chapman (1972) suggested that pattern of habitat use in sympatric populations of
juvenile chinook salmon (O. tshawytscha) and steelhead trout in Idaho streams was
based on selective, rather than interactive, segregation. Selective segregation is based
upon a genetic difference as an explanation for species habitat use (Everest and
Chapman 1972). In this study, I believe that a shift in relative abundance of coho
58
salmon resulted from an increase in habitat conditions favored by coho salmon rather
than changes in interactions.
Examination of individual species or total fish numbers may ignore community-
level effects of land management activities. Studies examining the impact of land
management practices often consider a single species (e.g., Holtby 1988, Scrivener and
Brownlee 1989) instead of a community. Assessing land management effects upon one
species, although valuable, does not consider the range of responses of community
members. For example, Swartz (1991) found that cutthroat trout populations in streams
with coho salmon adjacent to areas that had been clearcut, remained lower than pre-
harvest populations 25 years after harvest. In this study, individual species were related
to physical habitat characteristics, as well as other salmonid species, both of which could
affect community structure. Finer substrates explained a portion of the variation in coho
abundance in Cape Creek for both multiple regression models. Finer substrates typically
settled out of the water column near the middle to end portions of pools because less
wood occurred and velocities were slower. Coho salmon were generally found in the
back portions of pools. In Cummins Creek, pool length and maximum depth explained a
portion of the variance in coho abundance when physical factors alone were considered.
Volume of single wood was related to coho density in Cummins Creek for both models.
Single wood could have created a variety of flows and provided for visual isolation
(Do lloff 1986). Cutthroat trout abundance and density was important to coho salmon in
both streams. Reasons for this are unclear since other studies have shown a negative
relationship between these two species (Schwartz 1991, Trotter 1989, Glova 1986). It is
possible that in these coastal systems, cutthroat trout and coho salmon have little
interaction due to differences in habitat, and this relationship is a statistical anomaly.
59
Trout 0+ abundance was related to pool length and volume of single pieces of
wood in Cape Creek, while these characteristics were negatively related to trout 0+
density in Cummins Creek. The larger pool length in Cape Creek may have provided
trout 0+ with preferred habitat. Moore and Gregory (1989) found that trout 0+ were
associated with stream margins where the water velocities were slower. Single pieces of
wood may provide trout 0+ with protection from predators and provide backwater areas
of slower water velocity. In Cummins Creek, area of cobble was important to trout 0+ in
both models, possibly providing protection and slow velocity areas as well. Steelhead
1+ explained a high proportion of the variation trout 0+ abundance and density in both
streams for the second model. Reasons for this is unclear, but this relationship could be
due to individuals of the same species associating with one another, or similar habitats.
Cutthroat trout abundances and densities were related to maximum depth in both
streams; pool length was also important to cutthroat trout abundances in Cummins
Creek. Maximum depth also explained a portion of the variation of steelhead 1+ trout
abundance in both streams and steelhead 1+ density in Cummins Creek. Bisson et al.
(1988) has shown that steelhead and cutthroat trout prefer deeper sections of pools and
use larger substrates and wood for cover. For most of the salmonid species/age-classes
and densities in the second multiple regression model, at least one physical habitat
characteristic, as well as another salmonid species, explained a portion of the variation of
species abundance. This emphasizes the importance of examining both physical and
biological factors regulating structure and composition of salmonid communities.
There may be other biological consequences of habitat differences due to
management that were not manifested in this study. This study examined associations
between pool habitat and juvenile salmonids during low flows in 1990. During this
60
time, coho relative abundance and trout 0+ density was greater in the managed system
compared to the pristine system. Other studies also have seen similar effects, but found
decreased survival at later seasons or in different life history stages. Holtby (1988)
observed an increase in abundance of coho salmon smolts in Carnation Creek, British
Columbia, following timber harvest. However, this did not translate into an increase in
adult returns. Holtby (1988) speculated that the reason for this was a change in the
timing of ocean entry caused by increased growth rates. Hall et al. (1987) observed a
slight decrease in average numbers of coho migrating from managed streams compared
to a reference system, but timing of this migration was earlier than normal and coho
numbers continued to decline. Murphy et al. (1986) found coho abundance increased in
summer in Alaskan streams after timber had been harvested, leaving no buffer zones,
but, abundance declined in the next year because of reduced overwinter survival.
Additional considerations for the Cummins and Cape Creeks study would be the
consideration of associations between habitat components and other life history stages
and seasonal changes within the pools and pool assemblages.
Results from this study may provide insight into habitat components which could
be important for maintaining diverse juvenile salmonid assemblages. This study
suggests that assessing wood in relationship to high and low flow conditions, as well as,
its role in pool formation may provide an additional component when examining the
effect of woody debris. Wood provides pools with a variety of velocities (Swanston
1991), and salmonids use wood for cover (Bisson et al. 1987). A variety of habitats
could be created from an increased amount of wood within habitat units and where it is
located (Dolloff 1986) which may enhance salmonid diversity. Larger pools which lack
61
wood throughout, may provide increased habitat for one species and thus may affect
species abundance.
Several physical attributes of stream habitat have been studied and combined in
various ways to address habitat complexity (e.g., Shirvell 1990, Schlosser 1982a,
McMahon and Hartman 1989, Moore and Gregory 1989). Physical elements of stream
habitats, such as water depth, wood, water velocity and substrate composition, contribute
to habitat complexity. A diverse array of microhabitat areas within lotic systems can be
formed by various flow regimes, substrate types, depth profiles, and wood complexes;
these attributes combine to create complexity in instream habitat. Habitat complexity
has also been related to fish species diversity (Reeves et al. 1993). Complexity in
Cummins and Cape Creeks was not addressed in enough detail to relate habitat
complexity to fish species diversity. Complexity components assessed, such as woody
debris, needed to be assessed for both high and low flow conditions and for other habitat
units.
Higher numbers of fish were found in the managed system, while diversity of the
community was higher in the pristine system. Reeves et al. (1993) found similar results
in salmonid community structure. Diversity was higher in unmanaged systems, while
densities did not differ between streams with different harvest levels. Steelhead and
cutthroat densities in this study were lower than in the streams assessed by Reeves et al.
(1993), while the coho densities were comparable. This could be due to the lower
number of sampling sites in this study and because this study only assessed pool habitat.
Many resource managers are using habitat characteristics, such as number of
pools, number of pools per mile, pool to riffle ratios, pool depth and number of pieces of
large woody debris, to determine the condition of a stream. The latter two characteristics
62
are similar between Cape and Cummins Creeks, but there is a difference between the
fish communities in these two systems. Relying on a few broad habitat characteristics to
assess pool habitat condition may not be detailed enough to pick up discrepancies
between similar systems. Pool size, and number of pieces of woody debris per pool area
and salmonid diversity, may provide resource managers with further knowledge in order
to assess pool habitat conditions.
Coastal salmonids are the subject of much focus within the Pacific Northwest
because of declining populations. Many populations could be listed as threatened or
endangered in the near future (Nehlsen et al. 1991). One of the threats for juvenile
anadromous salmonids is the decline of the quantity and quality of their freshwater
habitat. Much of their freshwater habitat has been altered as a consequence of past land
management activities (Hicks et al. 1991). Much more information is needed to assess
the effects of land management activities on juvenile anadromous salmonid
communities. This study was confined to low flow conditions and only assessed
juvenile salmonids. Further studies on communities during high flows, different life
stages, as well as assessing complete vertebrate communities, could give resources
manager a more complete picture of habitat differences between pristine and managed
systems.
63
Conclusion
This study found similarities and differences in pool habitat characteristics and
juvenile salmonid assemblages between two streams with different land management
histories. Although these streams had some similar pool habitat characteristics, the
structure of the juvenile salmonid assemblages differed. There were no significant
differences (p> 0.05) between depth, velocity or wood volumes within these two
streams. This could be due to the focus on a single type of habitat unit or the fact that
the features examined did not respond to possible effects of land management activities.
Perhaps analysis of other variables, such as residual pool depth, depth and velocity
profiles in each pool, or estimation of wood within the active channel, may have shown
differences such as have been found in other studies (Ralph et al. 1994, Carlson et al.
1990, Ursitti 1991).
Several pool habitat characteristics that were assessed in this study are currently
used by resource managers to assess stream conditions. Despite the difference in land
management activities many of these characteristics were found to be similar between
Cape and Cummins Creeks. Caution is needed when evaluating stream systems; number
of pieces of woody debris has been shown to be important for channel morphology
(Sedell and Swanson 1984), but the location of that wood (Dolloff 1993) may be other
important components in pools. Size and depth of pools is also used to assess stream
condition. Large deep pools are considered to be good habitat. This study suggested
that larger pools tended to offer habitat for one species. An increase in one species
could affect species diversity. Pool depth, velocity or volume of wood did not differ
between streams of differing land management activity. These habitat characteristics, if
64
assessed on their own without considering seasonal variations or the types of
measurements taken, may provide misleading information for resource managers.
Addition of fish community information, such as diversity or evenness, may provide
resource managers with further insight into habitat conditions when assessing stream
habitat conditions.
65
BIBLIOGRAPHY
Angermeier, P.L. and J.R. Karr. 1984. Relationships between woody debris and fish habitat
in a small warmwater stream. Transactions of the American Fisheries Society.
113:716-726.
Angermeier, P.L. and I.J. Scholsser. 1988. Species-area relationships for stream fishes.
Ecology. 70(5):1450-1462.
Baltz, D.M., P.B. Moyle, and N.J. Knight. 1982. Competitive interactions between benthic
stream fishes, riffle sculpin, Cottus gulosus, and speckled dace, Rhinichthys osculus.
Canadian Journal of Fisheries and Aquatic Sciences. 39:1502-1511.
Berkman H.E. and C.F. Rabeni. 1987. Effect of siltation of stream fish communities.
Environmental Biology of Fishes. 18(4): 285-294.
Bilby, R.E. 1985. Influence of stream size on the function and characteristics of large
organic debris. p. 1-14. In: Prodeedings: West Coast meeting of the National
Council of the Paper Industry for Air and Streams Improvement, Tech. Bull. 466,
Portland, Oregon.
Bilby, R.E. and J.W. Ward. 1989. Changes in characteristics and function of woody debris
with increasing size of streams in western Washington. Transactions of the American
Fisheries Society, 118:368-378.
Bisson, P.A. and J.R. Sedell. 1984. Salmonid populations in streams in clearcut vs. OldGrowth forests of Western Washington. In: W.R. Meehan, T.R. Merrell, Jr., and J.W.
Matthews, editors. Fish and Wildlife Relationships in Old-Growth Forests.
Proceedings of a symposium. pp. 121-140. American Institute of Fishery Research
Biologists.
Bisson, P.A., R.E. Bilby, M.D. Bryant, C.A. Dolloff, G.B. Grette, R.A. House, M.L.
Murphy, K.V. Koski and J.R. Sedell. 1987. Large woody debris in forested streams
in the Pacific Northwest: Past, present, and future. In: E.O. Salo and T.W. Cundy,
editors. Streamside Management: Forestry and Fishery Interactions. College of
Forest Resources, University of Washington, Seattle, Washington. Contribution No.
57. pp. 143-190.
Bisson, P.A., K. Sullivan and J.L. Nielsen. 1988. Channel hydraulics, habitat use, and body
form of juvenile coho salmon, steelhead, and cutthroat trout in streams. Transactions
of the American Fisheries Society 117:262-273.
66
BIBLIOGRAPHY, Continued
Bisson, P.A., T.P. Quinn, G.H. Reeves and S.V. Gregory. 1992. Best management practices,
cumulative effects, and long-term trends in fish abundance in Pacific Northwest river
systems, p. 189-232. In: R.J. Naiman, editor. Watershed management: balancing
sustainability and environmental change. Springer-Verlag, New York, N.Y.
Carlson C.J., C.W. Andrus, and H.A. Froehlich. 1990. Woody debris, channel features, and
macroinvertebrates of streams of logged and unlogged riparian timber in northeastern
Oregon, U.S.A. Canadian Journal of Fisheries and Aquatic Sciences 47:1103-1111.
Corn P.S. and R.B. Bury. 1989. Logging in Western Oregon: Responses of headwater
habitats and stream amphibians. Forest Ecology and Management. 29:39-57.
Crowder, L.B. and W.E. Cooper. 1982. Habitat structural complexity and the interaction
between bluegills and their prey. Ecology. 63(6):1802-1813.
De Staso III, J. and F.J. Rahel. 1994. Influence of water temperature on interactions between
juvenile Colorado River cutthroat trout and brook trout in a laboratory stream.
Transactions of the American Fisheries Society. 123:289-297.
Dolloff, C.A. 1986. Effects of stream cleaning on juvenile coho salmon and Dolly Varden in
southeast Alaska. Transactions of the American Fisheries Society. 115:743-755.
Eadie, J.McA. and A. Keast. 1984. Resource heterogeneity and fish species diversity in
lakes. Canadian Journal of Zoology. 62:1689-1695.
Elliot, S.T. 1986. Reduction of a Dolly Varden population and macrobenthos after removal
of logging debris. Transactions of the American Fisheries Society. 115:392-400.
Everest, F.H. and D.W. Chapman. 1972. Habitat selection and spatial interaction by juvenile
chinook salmon and steelhead trout in two Idaho streams. Journal of the Fisheries
Research Board of Canada. 29:91-100.
Fausch, K.D. and R.G. Bramblett. 1991. Disturbance and fish communities in intermittent
tributaries of a western Great Plains river. Copeia. 3:659-674.
Fausch, K.D. and T.G. Northcote. 1992. Large woody debris and salmonid habitat in a small
coastal British Columbia stream. Canadian Journal of Fisheries and Aquatic
Sciences. 49:682-693.
Fausch, K.D. and R.J. White. 1981.Competition between brook trout (Salvelinus fontinalis)
and brown trout (Salmo trutta) for positions in a Michigan stream. Canadian Journal
of Fisheries and Aquatic Sciences. 38:1220-1227.
67
BIBLIOGRAPHY, Continued
Glova, G.J. 1986. Interaction for food and space between experimental populations of
juvenile coho salmon (Oncorhynchus kisutch) and coastal cutthroat trout (Salmo
clarki) in a laboratory stream. Hydrobiologia, 132:155-168.
Gorman O.T. and J.R. Karr. 1978. Habitat structure and stream fish communities. Ecology.
59(3):507-515.
Grant, J.W.A., J. Englert, and B.F. Bietz. 1986. Application of a method for assessing the
impact of watershed practices: Effects of logging on salmonid standing crops. North
American Journal of Fisheries Management. 6:24-31.
Grossman, G.D., P.B. Moyle, and J.O. Whittaker, Jr. 1982. Stochasticity in structural and
functional characteristics of an Indiana stream fish assemblage: A test of community
theory. American Naturalist. 120:423-454.
Gurtz, M.E. and J.B. Wallace. 1984. Substrate mediated response of stream invertebrates to
disturbance. Ecology. 65:1556-1569.
Hall, J.D., G.W. Brown, and R.L. Lantz. 1987. The Alsea watershed study: A retrospective.
Pages 399-416. In: E.O. Salo and T. W. Cundy, editors. Streamside management:
Forestry and fishery interactions. University of Washington, Institute of Forest
Resources Contribution 57, Seattle, WA.
Hankin, D.G. and G.H. Reeves. 1985. Estimating total fish abundance and total habitat area
in small streams based on visual estimation methods. Canadian Journal of Fisheries
and Aquatic Sciences. 45(5):834-844.
Hartman, G.H. 1987. Some preliminary comments on results of studies of trout biology and
logging impacts in Carnation Creek. Pages 175-180 In: W. Chamberlin, editor.
Proceedings of the workshop applying 15 years of Carnation Creek results. Pacific
Biological Station, Carnation Creek Steering Committee, Nanaimo, British
Columbia.
Hartman, G.F. and T.G. Brown. 1987. Use of small, temporary, floodplain tributaries by
juvenile salmonids in a west coast rain-forest drainage basin, Carnation Creek,
British Columbia. Canadian Journal of Fisheries and Aquatic Sciences. 44:262-270.
Hartman, G.F. 1965. The role of behavior in the ecology and interaction of underyearling
coho salmon (Oncorhynchus kisutch) and steelhead trout (Salmo gairdneri). Journal
Fisheries Research Board if Canada. 22(4):1035-1081.
68
BIBLIOGRAPHY, Continued
Heck, Jr., K.L. and G.S. Wetstone. 1977. Habitat complexity and invertebrate species
richness and abundance in tropical seagrass meadows. Journal of Biogeography.
4:135-142.
Hicks, B.J. 1990. The influence of geology and timber harvest on channel morphology and
salmonid populations in Oregon Coast Range streams. Doctoral dissertation. Oregon
State University.
Hicks, B.J., J.D. Hall, P.A. Bisson and J.R. Sedell. 1991. Responses of salmonids to habitat
changes. Pages 483-518. In: W.R. Meehan, editor. American Fisheries Society
Special Publication 19.
Holtby, L.B. 1988. Effects of logging on stream temperatures in Carnation Creek, British
Columbia, and associated impacts on the coho salmon (Oncorhynchus kisutch).
Canadian Journal of Fisheries and Aquatic Sciences. 45:502-515.
Kalleberg, H. 1958. Observations in a stream tank of territoriality and competition in
juvenile salmon and trout (Salmo salar L. and S. trutta L.). Institute of Freshwater
Research Drottningholm Report. 39:5-98.
Kaufmann, P.R. 1987. Channel morphology and hydraulic characteristics of torrentimpacted forest streams in the Oregon Coast Range, U.S.A. Doctoral dissertation.
Oregon State University, Corvallis, Oregon.
Kohn, A.J. and P.J. Leviten. 1976. Effect of habitat complexity on population density and
species richness in tropical intertidal predatory gastropod assemblages. Oecologia
(Berlin). 25:199-210.
Lewis, S.L. 1969. Physical factors influencing fish populations in pools of a trout stream.
Transactions of the American Fisheries Society. 98(1):14-19.
Li H.W., C.B. Schreck, C.E. Bond, and E. Rexstad. 1987. Factors influencing changes in
fish assemblages of Pacific Northwest streams. Pages 193-202 In: W.J. Matthews
and D.C. Heins, editors. Community and evolutionary ecology of North American
stream fishes. University of Oklahoma Press, Norman.
MacArthur, R.H. and J.W. MacArthur. 1961. On bird species diversity. Ecology. 42:594­
598.
Macpherson, E. 1989. Influence of geographical distribution, body size and diet on
population density of benthic fishes off Namibia (South West Africa). Marine
Ecology Progress Series. 50:295-299.
69
BIBLIOGRAPHY, Continued
McIntosh, B.J., J.R. Sedell, J.E. Smith, R.C. Wissmar, S.E. Clarke, G.H. Reeves, L.A.
Brown. 1994. Historical changes in fish habitat for select river basins of Eastern
Oregon and Washington. Northwest Science. 68:36-53.
McMahon, T.E. and G.F. Hartman. 1989. Influence of cover complexity and current velocity
on winter habitat use by juvenile coho salmon (Oncorhynchus kisutch). Canadian
Journal of Fisheries and Aquatic Sciences. 46:1551-1557.
Moore, K.M.S. and S.V. Gregory. 1989. Geomorphic and riparian influences on the
distribution and abundance of salmonids in a Cascade mountain stream. USDA
Forest Service Gen. Tech. Rep. PSW-110. pp. 256-261.
Moyle, P.B. and H.W. Li. 1979. Community ecology and predator-prey relationships in
warmwater streams. Pages 171-180 In: H. Clepper, editor. Predator-prey systems in
fisheries management. Sport Fishing Institute, Washington, D.C.
Moyle, P.B. and B. Vondracek. 1985. Persistence and structure of the fish assemblage in a
small California stream. Ecology. 66(1):1-13.
Murphy, M.L., J. Heifetz, S.W. Johnson, K.V. Koski and J.F. Thedinga. 1986. Effects of
clear-cut logging with and without buffer strips on juvenile salmonids in Alaskan
streams. Canadian Journal of Fisheries and Aquatic Sciences. 43:1521-1533.
NeWsen, W., J.E. Williams, and J.A. Lichatowich. 1991. Pacific salmon at the crossroads:
stocks at risk from California, Oregon, Idaho, and Washington. Fisheries (Bethesda).
16(2):4-21.
Nielson, J.L., T.E. Lisle, and V. Ozaki. 1994. Thermally stratified pools and their use by
steelhead in Northern California streams. Transactions of the American Fisheries
Society. 123:613-626.
Newcombe, C. 1981. A procedure to estimate changes in fish populations caused by
changes in stream discharge. Transactions of the American Fisheries Society.
110:382-390.
O'Connor, N.A. 1991. The effects of habitat complexity on the macroinvertebrates
colonizing wood substrates in a lowland stream. Oecologia. 85:504-512.
Pianka, E.R. 1967. On lizard species diversity: North American flatland deserts. Ecology.
48(3):333-351.
70
BIBLIOGRAPHY, Continued
Pearsons T.C., H.W. Li, and G.A. Lamberti. 1992.Influence of habitat complexity on
resistance to flooding and resilience of stream fish assemblages. Transactions of the
American Fisheries Society. 121:427-436.
Rafe, R.W., M.B. Usher and R.G. Jefferson. 1985. Birds on reserves: The influence of area
and habitat on species richness. Journal of Applied Ecology. 22:327-335.
Ralph, S.C., G.C. Poole, L.L. Conquest, and R.J. Naiman. 1994. Stream channel
morphology and woody debris in logged and unlogged basins of Western
Washington. Canadian Journal of Fisheries and Aquatic Sciences. 51:37-51.
Reeves, G.H., F.H. Everest, and J.D. Hall. 1987. Interactions between the redside shiner
(Richardsonius balteatus) and the steelhead trout (Salmo gairdneri) in western
Oregon: the influence of water temperature. Canadian Journal of Fisheries and
Aquatic Sciences. 44:1602-1613.
Reeves, G.H., F.H. Everest, and J.R. Sedell. 1993. Diversity of juvenile anadromous
salmonid assemblages in coastal Oregon basins with different levels of timber
harvest. Transactions of the American Fisheries Society. 122(3):309-317.
Robison, L.G. and R.L. Beschta. 1990. Characteristics of coarse woody debris for several
coastal streams of southeast Alaska, USA. Canadian Journal of Fisheries and Aquatic
Sciences. 47:1684-1693.
Roberts, C.M. and R.F.G. Ormond. 1987. Habitat complexity and coral reef fish diversity
and abundance on Red Sea fringing reefs. Marine Ecology Progress Series. 41:1-8.
Rosenzweig, M.L. and J. Winakur. 1969. Population ecology of desert rodent communities:
Habitats and environmental complexity. Ecology. 50(4):558-572.
Roth, R.R. 1976. Spatial heterogeneity and bird species diversity. Ecology. 57:773-782.
Rutherford, D.A., A.A. Echelle, and O.E. Maughan. 1987. Changes in the fauna of the Little
River drainage, southeastern Oklahoma, 1948-1955 to 1981-1982: a test of the
hypothesis of environmental degradation. Pages 178-183 In: W.J. Matthews and
D.C. Heins, editors. Community and evolutionary ecology of North American stream
fishes. University of Oklahoma Press, Norman.
Schlosser, I.J. 1982a. Fish community structure and function along two habitat gradients in a
headwater stream. Ecological Monographs. 52(4):395-414.
71
BIBLIOGRAPHY, Continued
Schlosser, I.J. 1982b. Trophic structure, reproductive success, and growth rate of fishes in a
natural and modified headwater stream. Canadian Journal of Fisheries and Aquatic
Sciences. 39:968-978.
Schlosser, I.J. 1985. Flow regime, juvenile abundance, and the assemblage structure of
stream fishes. Ecology. 66(5):1484-1490.
Schlosser, I.J. 1991. Stream fish ecology: a landscape perspective. BioScience. 41(10):704­
712.
Scott, J.B., C.R. Steward, and Q.J. Stober. 1986. Effects of urban development on fish
population dynamics in Kelsey Creek, Washington. Transactions of the American
Fisheries Society. 115:555-567.
Scrivener, J.C., and M.J. Brownlee. 1989. Effects of forest harvesting on gravel quality and
incubation survival of chum salmon (Oncorhynchus keta) and coho salmon (0.
kisutch) in Carnation Creek, British Columbia. Canadian Journal of Fisheries and
Aquatic Science. 46:681-696.
Sedell, J.R., and F.J. Swanson. 1984. Ecological characteristics of streams in Old-Growth
forests of the Pacific Northwest. Pages 9-16 In: W.R. Meehan, T.R. Merrell, Jr., and
T.A. Hanley, editors. Fish and wildlife relationships in Old-Growth forests:
Proceedings of a symposium held in Juneau, Alaska, 12-15 April 1982. American
Institute of Fishery Research Biologists.
Shirvell, C.S. 1990. Role of instream rootwads as juvenile coho salmon (Oncorhynchus
kisutch) and steelhead trout (0. mykiss) cover habitat under varying streamflows.
Canadian Journal of Fisheries and Aquatic Science. 47:852-861.
Schwartz, J.S. 1991. Influence of geomorpology and land use on distribution and abundance
of salmonids in a coastal Oregon basin. Master's thesis. Oregon State University,
Corvallis.
Swanston D.N. 1991. Natural processes. Pages 139-179. In: W.R. Meehan, editor.
American Fisheries Society Special Publication 19.
Thomas, J.W.and the Forest Ecosystem Management Assessment Team. 1993. Forest
ecosystem management: an ecological, economic, and social assessment. Report of
the Forest Ecosystem Management Assessment Team. USDA Forest Service,
Portland, OR.
Tomoff, C.S. 1974. Avian species diversity in desert scrub. Ecology. 55:396-403.
72
BIBLIOGRAPHY, Continued
Tonn, W.M. and J.J. Magnuson. 1982. Patterns in the species composition and richness of
fish assemblages in northern Wisconsin lakes. Ecology. 63(4):1149-1166.
Trotter, P.C. 1989. Coastal cutthroat trout: A life history compendium. Transactions of the
American Fisheries Society. 118:463-473.
Ursitti, V.L. 1991. Riparian vegetation and abundance of woody debris in streams of
southwestern Oregon. Master's thesis. Oregon State University, Corvallis.
USDA Forest Service. 1978. Cape Creek Stream Survey. Waldport Ranger District, Siuslaw
National Forest. pp. 1-35.
USDA Forest Service. 1990. Stream Survey Methodology. Pacific Northwest Region,
Portland, OR.
Wilzbach, M.A., K.W. Cummins, and J.D. Hall. 1986. Influence of habitat manipulations on
interactions between cutthroat trout and invertebrate drift. Ecoloav 67:898-911.
Yant, P.R., J.R. Karr, and P.L. Angermeier. 1984. Stochasticity in stream fish communities,
an alternative interpretation. American Naturalistist. 124:573-582.
73
APPENDIX
Table A.1 Correlations between pool habitat characteristics in Cummins Creek, OR, 1990.
NA=Not
Mean
Maximum
Mean
Maximum
Applicable
Depth
Depth
Velocity
Velocity
Length
Width
Surface
Volume
SW1Z
Area
'p<0 05
Single
Thal
Area
Area
Area
Area
Area
Area
Area
Area
Area
Wood
Wood
Organic
Clay
Silt
Sand
Mai
Large
Cobble
Boulder
Bea, xi
Vol.
Vol.
Gravel
Gravel
"p<0 01
Mean Depth
Max.Depth
Mean Vel.
Max Vel
Length
Width
Surface
Volume
SW IZ
Sng. Wood
Total Wok.'
Organics
Clay
Silt
Sand
Med. Gravel
Lg Gray
Cobble
Madder
Bcdrrx k
NA
1385
(111 **
-0.09
0.07
0.27.
0 15
NA
0.07
(0(19
0.08
0.31
0.06
1334
0.06
4308
-1.02
0.12
NA
0.11 **­
-0.03
0131*
044.*
040 **
NA
-0.01
-0.11
-0.03
0.41 **
009
0 49..
0.21
0.04
0.20
0.23*
0.34."
0.10
NA
NA
-0.10
-0.33.*
-0.19
-(118
018
0.12
0.19
-0.32*
-0.10
-0.36*
-0.16
-0.09
-0316
-0.14
-0 10
0.13
NA
0.03
0.040.*
0 051
-0.04
-0.03
41.03
-0.03
-0.04
-0.03
-01118
0.07
-03/2
-0.07
0.05
0.21
0 (Si
NA
0.18
NA
NA
-0.1(2
4319
-0B5
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
-0.11
-0,16
-0.13
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
3305
-0.20
-0.08
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
0.01
al IN
-(0)!
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
0.11
NA
-0.05
0.02
-0.08
-0 12
0.01
0.15
-000
-0.10
-0 20
NA
NA
0.01
-0.09
-0.08
-030
-0.02
-0.15
-0.29*
-0 15
-0.17
NA
-0315
(101
-0.09
-0.13
(081
0.12
-0 04
0.12
3322
NA
0.52.*
0.73*.
(171.*
0.07
0.385.
0.27.
0.51**
1H I
NA
((47 **
0.38*.
-0.09
0 40**
0.29*
0 35.*
-0.)12
NA
0.53*.
-0.03
041.*
1333*
UV"
0.19
NA
0.08
0.41.*
0 16
0 425"
0.40*.
NA
(1.22
-0.15
0 16
NA
0.32*
0107
0.40
NA
0 57­
0.16
NA
0.23
18
.0 6
-(0(2
NA
Table A.2 Correlations between pool habitat characteristics in Cape Creek, OR, 1990.
NA=Not
Mean
Maximum
Mean
Maximum
Applicable
Depth
Depth
Velocity
Velocity
Length
Width
Surface
Volume
SWIZ
Area
.p<0.05
Single
Tool
Area
Area
Area
Area
Area
Area
Area
Area
Wood
Wood
Organics
Silt
Sand
Med.
Large
Cobble
Boulder
Bedrock
Volume
Volume
Gravel
Gravel
**TKO 01
Mean Depth
Max. Depth
Mean yel.
Max.Vel.
Length
Width
Surface
Volume
SWIZ
Sng.Wood
Taal Wood
Organics
Silt
Sand
Med. Gravel
L g.firav
Cobble
Boulder
Bednx:k
NA
NA
-0.27
-0.10
0.27
0.29
((.26
NA
0.45°'
0.06
0.46°'
029
0.20
029
-.11.05
000I
0 16
0.24
0 40'
NA
B.43.
-0.01
0.49*.
0.39.
0 50
NA
0.17
0.11
0.18
0.25
0.60**
0.17
-0.02
0 09
0.35
0.34
0 (,0."
NA
NA
-0.26
-0.58..
-0.36
-0.40'
4429
-0.09
-0.30
-0.40.
-0.28
-0.13
-0.09
-024
-0.12
0.16
-0.06
NA
-0.20
-0.50°
-0.31
-0.32
-0.42'
0.42*
-0.38'
-046..
-020
-0.17
-11.19
-0.14
-0.04
0.07
0.09
NA
0 25
NA
NA
0.09
4403
0.08
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
0.25
-0ft5
0.24
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
0.10
-0.06
0.09
NA
NA
NA
NA
NA
NA
NA
NA
NA
0.28
-0.01
0.28
NA
NA
NA
NA
NA
NA
NA
NA
NA
-006
NA
0.41'.
0.11
0.36
-0.14
-009
ILLS
-0.07
.0 08
NA
NA
0.11
-0.10
-0.00
-0.11
-008
0 20
((.07
-008
NA
048.*
0.10
0.36
-0.15
0.09
0.17
-0.06
-0.09
NA
043'
0.63'
029
0 15
((.24
0.20
NA
0.25
0.29
0 20
0.51."
041.
0.50..
NA
0.43.
0.14
0.12
0.27
011
NA
0 63*.
.0.05
-0.07
-0.03
NA
0.21
0.02
-0.02
NA
0.06'.
-01/5
NA
0.09
NA