CALIFORNIA STATE UNIVERSITY, NORTHRIDGE
DISTURBED MACROCYSTIS PYRIFERA HOLDFASTS:
WHO LEAVES; WHO STAYS
A thesis submitted in partial satisfaction of the
requirements for the degree of Master of Science in
Biology
by
Joseph Thomas Johnson
January, 1982
The Thesis of
Jos~ph
Thomas Johnson is approved:
Dr. Ross Pohlo
Dr. Earl Segal, Chai~an
California State University, Northridge
ii
ACKNOWLEDGMENTS
I wish to thank the many people who provided assistance
during this study.
Shelly Johnson helped with the con-
struction of the nets and provided lunches for those of us
that did not succumb to motion sickness,
Dan Warren
piloted the Southern California Ocean Studies Consortium's
Boston Whaler and supervised surface support,
After each
full day of collecting Dan donned his yellows and fearlessly rode the whaler, alone, a wet twenty miles from
Kings Harbor to Long Beach through the inevitable late
afternoon chop.
Surface support was also given by Steve
Blunt, Sam Johnson and Ted Johnson.
Ray Hartwig, Brian
Koneval and Jim Walker assisted me underwater despite
occasionally marginal diving conditions,
The isopods were
identified by Ernest Iverson, Melinda Thun and Barry
Wallerstein at the University of Southern Californials
Crustacean Lab.
Up to date kelp survey information was
provided by Kenneth Wilson of the California Department of
Fish and Game.
The illustrations were done by Phyllis
Johnson and Sam Johnson.
grams and appendix A .
Maureen Casey prepared the histoAs my advisor Dr. Earl Segal
cultivated my interests in marine biology through my undergraduate years and then helped me organise and execute each
aspect of this graduate study.
His aid was especially
valuable during the writing of the paper as he spent many
iii
hours correcting and polishing my writing technique. Many
helpful suggestions were also given by Dr, Jim Dole and
Dr. Ross Pohlo.
iv
TABLE OF CONTENTS
Page
Acknowledgements
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List of Tables .
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List of Figures
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Study site . . . . ,
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Gastropoda . .
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. 28
. 30
. 30
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Copepoda
'
. 17
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.
Pelecypoda
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....
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. . 14
t
Nematoda
Turbellaria
5
I
..
I
1
I
.
Natantia .
. . , ix
I
Isopoda
Ophiuroidea
t
t
1
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.
.
Polychaeta .
Mysidacea
f
...
Laboratory analysis
Garm:naridea
t
I
Collecting methods
Results
I
......
. . . . . . . .
Materials and Methods
. 32
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32
r
•
33
. . 33
. . . 33
34
Tanaidacea
...
Ostracoda
Nemertea .
Echinoidea
iii
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. . viii
Abstract . .
Introduction
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35
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o
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Caprellidea
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Reptantia
. . 36
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36
I
Cumacea
Pisces . .
37
. .
. .
'
'
'
'
.
38
Pycnogonida , Holothuroidea 1 Polyplacophora,
Asteroidea and Cephalopoda , , . . . . . , , , . . 38
Holdfast volume
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9
39
Uncontrolled conditions
Discussion .
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41
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Probable causes of exodus
. . 43
Mechanical disturbance ,
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Currents and acceleration
. 44
Light
Temperature
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Turbulence .
..
. . 45
'
.
45
.
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46
'
Desiccation
46
...
Pressure . .
. . 47
52
Size and composition of holdfast communities .
...
Research needed
. . . 55
Literature Cited
'
Appendix A
Appendix B
Appendix C
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...
.
vi
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. 57
. . 61
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. ' 74
• ' 76
LIST OF TABLES
Page
Table
1
2
Total na~bers of animals of various higher
taxa collected from 12 Macrocystis pyrifera
I
Average response of the animals from 12
holdfast cormnunities to the
tearloose-washup treatment . . . . .
Time course for animals leaving holdfast 12
4
Adjusted averages by taxon of animals leaving
all 12 holdfasts during each phase
of the treatment . .
I
I
•
•
•
•
•
•
•
16
17
3
5
•
•
I
,
•
Average response of the garnmarids from 12
holdfasts to the tearloose-washup treatment
I
I
•
18
19
20
6
Time course for gammarids leaving holdfast 12
7
Gastropoda collected during treatments .
. . 29
8
Isopoda collected during treatments
..
31
9
Natantia collected during treatments .
, . 34
10
Tanaidacea collected during treatments
35
11
Reptantia collected during treatments
37
12
Twelve holdfasts arranged by volume and
showing the total nu~ber of animals as well
as the number of gammarids polychaetes
gastropods and isopods collected with them .
39
13
, 23
Genera found in Macrocystis tyrifera holdfasts
at both Flat Rock and La Jol a . . . . , . . . . 54
vii
LIST OF FIGURES
Page
Figure
1
Map of the northwest section of
Palos Verdes Peninsula . . .
.
•
'
5
..6
. .
2
Mature Macrocystis pyrifera
3
Releasing a holdfast from the rock . .
4
Ascending net
5
Surface nets and wooden frame
6
Wave barrel
7
Anchored brace and bag net
8
Gammaridea collected during the treatment
of each of the 12 holdfasts . . . . . . . .
22
9
Sabellariidea (Polychaeta) collected during
the treatment of each of the 12 holdfasts
,25
10
..
'
'
.
. .
'
.
t
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t
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•
.•
. ..
I
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•
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8
9
,10
. ,11
'
. . ,12
Non-sabellariid polychaetes collected during
the treatment of each of the 12 holdfasts . . ,27
viii
ABSTRACT
DISTURBED MACROCYSTIS PYRIFERA HOLDFASTS:
WHO LEAVES; WHO STAYS
by
Joseph Thomas Johnson
Master of Science in Biology
Macrocystis pyrifera (12) were subjected to a
controlled shore wash-up treatment to determine which
animals leave from and which remain within holdfasts
detached from a rocky substrate.
The procedure encompassed
five phases: 1) separation from bottom and drift to surface
2) Drift at surface; 3) Wave wash in surf zone; 4) Out
of water on shore; 5) Recovery of the holdfast.
Among the
varieties of animals inhabiting M. pyrifera holdfasts,
amphipods and polychaetes make up the great majority (75%).
Most of the animals capable of leaving the holdfasts did so
during the ascension to the surface and during the early
part of the drift phase.
species.
Responses varied for groups and
Indirect evidence suggests that pressure change
may be primarily responsible for the exodus.
ix
INTRODUCTION
A diverse and abundant fauna lives within the holdfasts
of large brown algae.
The intertangled haptera, rock
interface and entrapped sand and debris provide a unique
combination of microhabitats that are colonized by a host
of filter feeders, grazers, detrital feeders and predators.
Darwin (1860) was one of the first to be impressed by the
profusion of holdfast dwellers when he examined giant kelp
from the beds off South America while on the voyage of the
Beagle:
"On shaking the entangled roots, a pile of small
fish, shells, cuttlefish, crabs of all orders, sea eggs,
starfish
beautiful Holuthuriae, Planariae
and crawling
nereidous animals of a multitude of forms all fall out
togeather."
Early investigators were chiefly concerned with
cataloging the fauna found on and around seaweeds (Andrews
1925, 1945, Colman 1940, Fosberg 1929, McLean 1962,
Scarratt 1961, Wieser 1952 1 Wing and Clendenning 1959,
1971) but, when the development of SCUBA brought formerly
inaccessible areas within easy reach 1 workers directed
their studies to specific aspects of kelp bed ecology.
Ghelardi (1960, 1971) discovered a recurring community
structure in the holdfasts of Macrocystis pyrifera at La
Jolla, California, U.S.A.
He used artificial holdfasts to
1
2
demonstrate how natural holdfasts fulfill the habitat
requirements of several nonherbivorous species,
Limbaugh
(1955) and Quast (197la,b1 c) examined species structure,
feeding habits and some behavior of kelp bed fishes off
California.
Food preferences and feeding habits of several
common herbivorous invertebrates from southern California
kelp beds were studied by Jones (1971) and Leighton (1971),
Jones worked with small crustacean amphipods and isopods
as well as gastropod molluscs.
Although some species were
of more importance as grazers than others, none compared in
destructive ability with bottom grazers.
Leighton examined
eleven large benthic grazer species including abalones,
snails) crabsJ urchins and a sea hare.
Macrocystis was a
highly preferred food for all species studied but the
urchins had the greatest effect.
In some instances the
urchins totally destroyed entire stands of Macrocystis and
its associated flora within a period of several weeks,
At Del Mar 1 California, Rosenthal et al. (1974) studied the
dynamics of benthic animals living on and around
Macrocystis pyrifera,
Most species there had aggregated
distribution patterns and the populations of most remained
reasonably constant over 4.25 yr.
Bernstein (1977)
analyzed some of the selective pressures on epiphytes
living on M. pyrifera in a bed near San Diego, California,
~
In spite of short term unpredictability1 broad patterns of
distribution were maintained by a sophisticated suite of
larval behaviors and settlement preferences,
3
When Coyer (1979) examined the mobile invertebrate
assemblage associated with the fronds of Macrocystis
pyrifera at Catalina Island} California, he discovered that
the fauna were vertically stratified,
On average 1 animal
lengths increased and number of species and individuals
decreased from the bottom to the canopy,
In a series of
papers contributed over the last decade Moore has added
immensely to our knowledge of British kelp fauna,
During
a recent study (1978) on the animals inhabiting Laminaria
hyperborea holdfasts off Wales and Southwest England1 he
found no significant difference in amphipod density with
differences in wave exposure or turbidity, but diversity
was lower in turbid waters due to the increased dominance
of a few species.
Andrews (1945) and Ghelardi (1960) noticed animals
leaving holdfast samples soon after removal from the bottom,
They suggested that many of these animals took refuge under
rocks or in other holdfasts when their plants were torn
loose during storms but failed to address the issue of
which segments of the community left before detached plants
washed ashore.
This study was performed to determine the composition of
Macrocystis pyrifera holdfasts off Palos Verdes 1
California: which of the resident fauna leave 1 when they
leave and possibly the stimulus for leaving when holdfasts
are removed from their substrates,
I designed a washup
experience for a series of holdfasts and devided it into
4
five phases 1 each defined by salient physical changes:
1) Separation from bottom and drift to surface; 2) Drift at
surface; 3) Wave wash in surf zone; 4) Out of water on
shore; 5) Recovery of holdfast.
Macrocystis pyrifera was selected because its large
holdfasts contain an extensive fauna 1 it is abundant and
easily available and it frequently tears loose and washes
ashore.
5
MATERIALS AND METHODS
Study Site
The study site was a :Hacrocystis pyrifera (Turner) bed
off Flat Rock Point (33.46'N, 118• 25'W) 1 Palos Verdes,
California, U.S.A. (Fig. 1).
Individual plants (Fig, 2)
N
0
'()
-----·
0
1 KILOMETER
Fig. 1. Map of the northwest section of Palos Verdes
Peninsula.
Point.
The study site is marked by an X off Flat Rock
The stippled areas offshore represent the kelp beds
as surveyed by the California Department of Fish and Game
in August 1979.
lower low water.
Depth curves are in feet,
Datum is mean
6
were attached to shallow, often parallel rock ridges protruding from a sandy bottom.
Most ridges rose less than
1 m from the bottom and were several meters in length but
Fig. 2. Mature Macrocystis pyrifera 1 X0.04.
(b) haptera.
(pneumatocyst).
(c) primary stipe.
(d) blade.
(a) holdfast.
(e) float
(f) frond (stipe with blades).
(g) canopy.
7
others included outcrops up to 3 m high.
An extensive kelp canopy covered nearly every suitable
rock at Flat Rock during 1979.
This bed was recently
restored through the efforts of the California Institute of
Technologys Kelp Habitat Improvement Project, directed by
Dr. Wheeler North, and the California Department of Fish
and Games Sport-fish-kelp Habitat Project.
No measurable
kelp canopy existed off Palos Verdes from 1967-1973 and
perhaps for much longer inasmuch as surveys were not taken
between 1958-1967 (Wilson et al
1978).
Most plants were
less than one year old at Flat Rock in March 1979 and the
location of suitably large holdfasts at that time was
difficult, but by september the plants had grown so large
that it was difficult to locate a holdfast small enough to
fit into the nets.
A total of twelve holdfasts,
approximately l-2 years old1 were collected from 8-10 m
depths during March, April, June and September 1979.
Collecting Methods
Plants 1-6 were treated in the following manner.
A
knife was inserted between the haptera and the rock to a
depth of approximately 5 em and the haptera were cut free
around the circumference of the holdfast (Fig. 3).
As the
plant was pulled upward from the rock the ascending net
(Fig· 4) was slipped under and around it until the mouth
was level with the apex of the holdfast.
Then the
ascending net and holdfast were brought to the surface at a
8
a
b
c
d
Fig. 3. Releasing a holdfast from the rock.
the haptera around the base of the holdfast.
the holdfast loose.
holdfast.
(a) cutting
(b) pulling
(c) slipping the net under the rising
(d) ascending to the surface.
9
controlled speed of 20-25 em/sec.
The holdfast was trans-
ferred to the surface net (Fig. 5) by slipping it over the
lowered edge of the net frame, keeping it totally immersed
during transfer.
No more than 1-2 min elapsed, including
swimming from the surfacing point to the boat (6-10 m) 1
between removal of the holdfast from the substrate and
transfer into the surface net.
The
n~~ber
of fronds on
each plant were then counted and removed with the primary
stipe.
After 2 h the holdfast was lifted out of the
surface net in a bucket of water and suspended in the wave
barrel (Fig. 6).
Sea water filtered through 0.5 mrn mesh
was poured over and around the holdfast:
two 10 liter
buckets of water every minute for 5 min, a pause for 3 min.
Fig. 4. Ascending net.
It is constructed of 0.5 mm mesh,
has a 0.5 m mouth and is 1.25 m long.
10
'f
:J!~
Fig. 5. Surface nets and wooden frame.
Constructed of
0.5 mm mesh, these nets are 60x60 em at the mouth and 1.1 m
deep.
A hook, suspended from the center of each net 1
supports the holdfast just below the waters surface.
weights keep the nets open.
Lead
ll
then 2 buckets every 15 sec for 7 min.
The holdfast was
then removed and placed in a white plastic tray (30x35xl6
em) for l h.
At the end of that time the holdfast and the
animals remaining in each of the containers (ascending net 1
surface net, wave barrel 1 tray) were preserved in 70 %
alcohol.
Fig. 6. Wave barrel.
The green plastic vessel is held
afloat by an automobile tire innertube and stabilized with
lead weights fastened around the bottom.
an apical haptera
A hook fixed to
supports the holdfast in the center of
the barrel just below the waters surface.
Three vents
(0.5 mm mesh) equalize water levels and a sleeve net
(0.5 mm mesh) with a glass reciever captures animals and
debris washed out the 3.5 em drain pipe.
~
12
~·.
Fig. 7. Anchored brace and bag net.
a 70 em steel pipe.
A cement base supports
Two brass rods 1 1 em thick 1 extending
from its top are bent into parallel hooks 3 em apart and
covered with clear plastic tubing.
A plant slipped between
these bars just above the holdfast is held in place by the
upward pull of the pneumatocysts and by a small hook
fixed to one of the apical haptera and tied by an elastic
band to a third brass rod.
When laid flat the bag net
(0.5 mm mesh) is 80 em wide and 95 em deep.
A 0.5 m brass
ring hand held at the mouth of the net is dropped to its
bottom when the net is pulled over the holdfast, thus
keeping the net from collapsing·
drawstring •
The net closes with a
13
While collecting holdfasts 1-6 crabs, snails and
amphipods were observed falling or swimming down the fronds
past the holdfasts and into the net.
Therefore 1 to
determine the extent of infiltration by non-holdfast
animals1 the primary stipe of holdfasts 8, 9 and 11 was cut
first, releasing it and the fronds which were then followed
to the surface by the ascending net.
Over the next 10 min.
the fronds were counted and discarded and the contents of
the net removed and preserved.
The holdfast was then cut
loose and followed as with holdfasts 1-6.
The process of separating the holdfasts from the rock
entailed some hapteral breakage and exposure of the
holdfast-rock interface.
Treatment of holdfasts 7 and 10
was modified to ascertain which animals left because of
this.
As the holdfast was pulled from the rock and placed
in the anchored brace the bag net was slipped under and
over it (Fig. 7).
The mouth of the bag net was then drawn
tight around the primary stipe.
Ten minutes later the
holdfast was slipped out of the anchored brace and removed
from the bag net.
The bag net was reclosed as the
ascending net was positioned under the holdfast.
Treatment
was otherwise identical to that for holdfasts 1-6
The number of animals observed leaving holdfasts 1-11
decreased rapidly with time while they were suspended in
the surface nets.
The procedure for holdfast 12 was
altered to check this.
Every 20 min. during the 2 h drift
holdfast 12 was transferred from one surface net to
14
another but it was otherwise treated in the same manner as
holdfasts 1-6.
On each day of collection water temperatures were
taken at each meter from the bottom to the surface (Martec
TDC).
Starting times for the treatment varied from
0920-1130 hours1 while finishing times were from 1237-1457
hours.
Laboratory Analysis
All holdfasts and animals were taken to the laboratory
where the volume of each holdfast was measured by wrapping
it in a clear plastic bag and submerging it in a bucket of
water that overflowed into a graduated cylinder.
Each
holdfast was then shredded with pliers and wire cutters.
The resulting slurry was rinsed in the ascending net to
remove fine sand and small animals.
Then all materials
collected were examined under a dissecting microscope.
The animals were removed with forceps 1 identified and
counted.
Since all nets were constructed of 0.5 mm mesh
only animals larger than this were retained.
However
some animals above 0.5 mrn were ignored because of their
low numbers and mode of attachment
(Porifera~
Ectoprocta,
Cirripedia, Urochordata).
The animals were grouped by Phylum, Class 1 Subclass 1
Order or Suborder.
Ideally every organism would have been
identified to species but the large numbers and wide
variety combined with time limitations dictated a more
15
selective approach.
Thus only about 10 % of the animals
were identified to species and these belonged to taxa that
were either extremely well documented in the literature or
were represented by very few species.
Size ranges have
been included to help define each animals place within the
community in relation to the other animals, to the holdfast
structure and to the exodus
16
Table 1.
Total numbers of animals of various higher taxa
collected from 12 Macrocyst is pyrifera.
SC:Subclass.
Phylum
Class
O:Order.
Crustacea
Annelida
Arthropoda
Crustacea
Mollusca
Anhropoda
Crustacea
C: Class.
SO: Suborder.
No. of
hold!asts
occupied
No. of
animals
collected
l2
25206
Po~haeta
so
c
l2
13461
Mysidacea
0
12
3363
Gastropoda
c
l2
2366
Isopoda
0
l2
1257
Nematoda
p
l2
926
Copepoda
12
774
l2
727
12
615
12
613
l2
434
Group
Taxon
ot
group
Arthropoda
P: Phylum.
Gammaridea
Arthropoda
Crustacea
Natantia
sc
c
c
c
so
Arthropoda
Crustacea
Tanaidacea
0
l2
422
Arthropoda
Crustacea
Ostracoda
sc
12
322
Nemertea
p
11
199
Echinoidea
l2
176
11
111
l2
98
Uthropoda
Crustacea
Mollusca
Pelecypod&
Echinodermata
Ophiuroidea
Platyhelminthes
Turbellaria
Arthropoda
Crustacea
Caprellidea
Arthropoda
Crustacea
Reptantia
c
so
so
Arthropoda
Crustacea
Cumacea
0
11
54
Chordata
Pisces
7
23
Arthropoda
Pycnogonida
4
l2
Echinodermata
Holothuroidea
c
c
c
sc
c
c
4
6
2
.3
1
2
1
1
Echinodermata
Mollusca
Amphineura
Polyplacophora
lchinodermata
Asteroidea
Mollusca
Cephalopoda
RESULTS
Over 51>000 animals belonging to 24 major groups were
collected with the holdfasts; 14 of the groups were
represented in all 12 collections while four were
represented in 11 (Table 1).
Since control modifications
(holdfasts 7-12) had no appreciable effect on the overall
Table 2.
Average response of the animals from 12 holdfast
communities to the tearloose-washup treatment.
Ascending
net
2 min
Surf'ace
net
l20 min
Wave
Tray
barrel
15 min
60 min
Animals collected
1057
789
164
10
1778
% bo1di'ast animals
26%
20%
4%
0.25%
44%
Animals/minute
529
7
ll
0.17
Remaining
in
holdi'ast
response other than isolating the desired portions of the
fauna, I assumed the figures for non-holdfast animals (6 %)
and for animals evidently disturbed by the removal of the
holdfast from the rock (in bag net, 5 %) were representative of all the holdfasts and deducted them from the
ascending net results prior to averaging them (Table 2).
The majority
(56 %) of the animals left the holdfasts
sometime during the collections.
Of those leaving almost
50 % appeared in the ascending net followed by progressively smaller percentages in the surface nets, wave barrel
17
18
and tray (Table 2).
Many animals actively left the
holdfasts but others) including some sessile forms 1 were
evidently dislodged (Appendix A contains complete response
data for each holdfast).
The exit rates probably give the best perspective on
the exodus because they eliminate some of the confusion
accompanying the use of a different time period for each
Exit rates for the
phase of the treatment (Table 2)
ascent were 32-149 times greater than those for
corresponding surface drifts.
Table 3.
Time course for animals leaving holdfast 12.
Ascending
Sur!ace
net.
nets
120 min
2 lllin
Wave
barrel
15
Tray
6o min
min
0-20 20-40 40-6o 6o-80 S0-100 100-120
Animals/min
min
min
min
6o
9
s
min
min
min
2
1
0.1
The collection from holdfast 12 corroborated the rapid
decrease in exit rates that was observed while holdfasts
1-11 were in the surface nets (Table 3).
The results for major groups were individually adjusted
prior to computing their average responses (Table 4).
Non-holdfast animals and some of those found in the bag net
(Gammaridea 1 Polychaeta, Mysidacea, Natantia) were deducted
from ascending net figures.
The deductions for others
19
represented in the bag net were split between the ascending
net and the surface nets (Ostracoda 80 % & 20 %; Isopoda
70 % & 30 %; Gastropoda 60 % & 40 %; Caprellidea and
Reptantia 50 % & 50 %i Ophiuroidea 30 % & 70 %) because
their limited mobility apparently prevented some of them
Table 4.
Adjusted averages, by taxon, of animals leaving
all 12 holdfasts during each phase of the treatment.
Bag
net
Ascending Surface
net
net
Wave
barrel
lS
Tray Remaining
in
6omin
Total
lO min
2 min
120 min
Guaaridea
126
79S
623
93
s
.374
2016
Polychaeta
22
16
1.8
1.8
1
l048
1123
M;ysidacea
2
222
2
s
Gastropoda
14
19
41
lO
Isopoda
13
37
23
3
holdtast
m1n
2.31
1
112
196
23
lOO
76
71
2
6
41
61
2)
)2
Nematoda
1
Copepoda
3
1
Pelecypoda
s
1
8
4
3
6
4
12
4
12
32
lO
lO
s
1
34
4
s
2
24
3S
4
8
s
1
27
1
14
16
Ophiuroidea
ll
Turbellaria
Natantia
2
Tanaidacea
Ostracoda
3
3
Nemertea
1
Echinoidea
1
l
2
ll
1S
3
10
Caprellidea
2
2
2
1
ReptanUa
1
.3
3
l
Cumacea
1
l
Pisces
Pycnogonida
8
l
2
3
2
1
1
20
from escaping during the brief ascent (see discussion).
Gamma ride a
Of all the animals collected gammarid amphipods
constituted the most numerous group (49 %).
Most of them
left the holdfasts soon after tearloose (Table 5 & Fig. 8).
Gammarids are generally good swimmers and they were the
most visible group in the burst of animals leaving the
holdfasts when they were approximately 1.3 m above the
rocks.
An average of 81 % left the holdfasts during the
various treatments (Table 5).
Table 5.
Exit rates during the ascent
Average response of the gammarids from 12
holdfasts to the tearloose-washup treatment.
(see text)
As in Table 2
frond gammarids (4 % of those collected with
holdfasts 8 1 9 and 11) and those apparently disturbed by
the removal of the holdfasts from the rocks (6 % of those
collected with holdfasts 7 and 10) were deducted from the
ascending net figures prior to averaging.
net
2 min
Surface
net
120 min
79S
623
~scending
Animals collected
%holdfast aniJnals
Animals/minute
Wave
Tray
Remaining
barrel
60 min
15 min
in
holdfast
93
374
3U
398
0.25%
6
0.08
19%
21
Fig. 8. Gammaridea collected during the treatment of each
of the 12 holdfasts.
plant (2 min.).
(2 min.).
AN-E: ascending net with entire
AN-F: ascending net with fronds only
AN-H: ascending net with holdfast only (2 min. ).
SN: surface net (120 min.).
SN 1 -sN 6 : surface nets for
holdfast 12 (consecutive 20 min. periods).
barrel (15 min.).
holdfast.
T: tray (60 min.).
BN: bag net (10 min. ).
given for each non-zero entry.
WB: wave
RH: remaining in
A minimum of l % was
22
66"
1
1
39%27%
21"
II~!!=
2230 733 123
28% 23%
2
49%
111~~1
9
360 291 103 25 514
li
~~~~!!~
57 673 459 290 9 228
40%
50%
3
8
6 353
!!
983 507 53
!!.
11
1 426
~
1I
25%
~!!. 1~
50 674 349 62
!!
83
4
li
~
1234 633 32
37%45%
5 716
11~
884 70
.!!.
8%
161
15%
4
285
29%
487 304 94
390
·~!!4
31"
111~1!11
6 1142
747 102 8 886
AN-E
SN WB
T
RH
T
I
RH
40%36%
7 229
~~~~~
13911232123 5
54%
10
~
1
26%
II~
14%
•
483
-
1% 10%
36 373 182 27 2
72
BN AN-E SN WB
40% 28%
236
36%
122%
AN-F AN-H SN WB
60%
2
48%121%
T
RH
12
~~~~~~1!1!.1!.=
49 22 18 33
1 431
1372881131 81
AN-E SN1 SN2 SN3 SN4 SN5 SN6 WB
T
RH
23
averaged 80 times that for the surface nets.
Seventy five
percent of the gammarids from holdfast 12 that left during
the 2 h surface drift were captured during the first 20 min.
(Table 6).
This is six times the rate during the second
20 min. but still only 1/12 of the exit rate during the
ascent.
The garmnarids \.Vere 1-24 mm long but most fell
within the 2-6 mm range.
Although I was unable to identify
all the gammarids I did follow one species, Corophium
baconi, throughout the study.
C. baconi 1 a tube building
species of distinctive appearance, constituted 0.5 %of the
gammarids collected.
Most (92 %) were captured outside the
holdfast: 43 % in the ascending net, 46 % in the surface
nets
and 3 % in the wave barrel.
Table 6.
Time course for gammarids leaving holdfast 12.
Ascending
net.
Surtace
net.s
2 min
120 min
Wave
barrel
15 min
Tray
60
min
o-20 20-ba 40-60 60-Bo Bo-100 100-12o
Animals/min
537
min
min
43
7
min
min
min
min
2
l
l
2
0.02
Polychaeta
The polychaetes comprised the second most numerous
group (26 %).
They were 1.5-85 rnm long but most fell
24
Fig. 9.
Sabellariidea (Polychaeta) collected during the
treatment of each of the 12 holdfasts.
net with entire plant (2 min. ).
fronds only (2 min.).
only (2 min.).
AN-E: ascending
AN-F: ascending net with
AN-H: ascending net with holdfast
SN: surface net (120 min.).
SN 1 -sN 6 :
surface nets for holdfast 12 (consecutive 20 min.
periods).
WB: wave barrel (15 min.).
RH: remaining in holdfast.
T: tray (60 min.).
BN: bag net (10 min.).
minimum of 1 % was given for each non-zero entry.
A
25
1
~I
1%
-1%.
2 -1 -2
1%
760
100%1
8
9
99%
2
-1%1
91%
I
- I
I
I
I
!!I • - I
I --72
9
-3
-2%5 1%
5%
202
12
99%
3
-1%2
1%
1
-1%4
995
92%
11
3%
-
29
99%
4 -1%2
246
2% 3%
18 22
790
AN-F
7
- -
2% 1% 1% 1%
6
6
14 2
850
97%
69%
5 - - 1%
4
1% 1%
7 4
1 492
17%
10
73
99%
BN
2% 4% 7%
10 19 31
AN-E
SN
WB
292
T
~%1
12
6
1%
11
AN-E
-1%5
1%
13
SN
WB
9% 3% 1% 1% 1% 1%
3310 118 41 4
7 12 3
T
RH
SN,
SN
2
SN
3
SN
4
- -1%6
2%
22
SN6
WB
SNs
RH
-1%1 1177
T
RH
~
.
26
Fig. 10.
Non-sabellariid polychaetes collected during the
treatment of each of the 12 holdfastsnet with entire plant (2 min.).
fronds only (2 min.).
only (2 min.).
AN-E: ascending
AN-F: ascending net with
AN-H: ascending net with holdfast
SN: surface net (120 min.).
SN -sN
1
6~
surface nets for holdfast 12 (consecutive 20 min.
periods).
WB: wave barrel (15 min.).
RH: remaining in holdfast.
T: tray (60
BN: bag net (10 min.).
minimum of l % was given for each non-zero entry.
mi~).
A
27
93%
1
2
6%
25
85%
I
I
- -
1" 1"
2
3
8
393
98%
-
1%
2
1"
1
9
165
1%
1
-
I
-·•
4%
12%
1
3
22
68%
I
6% 17% 5%
6
16
5
65
91%
93%
3
-1%3 -2%
13
-3%17
~I
--- I
11
4 495
3% 2% 4%
15 9 23
AN-F AN-H SN WI
475
T
70%
4
• -- I
19%
18
7
1% 4"
7
4
68
- - ---
5
67%
I
- 4
~
1
10
9%
46
5
I -8%2%
l ! !!.
20
12
AN-I SN WI
780
T
-
38
9
I
•
7%
4%
1
IN AN-I
93%
6 -3%24
I~
3% 1% 5% 3% 1%
14 3 23 17 1 443
82%
7%
RH
22%
2
6
SN
WI
18
T
~I
12
-1%1
-1% 1%
1
2
RH
-1%2
IH ~ ~ SN2 ~ SN4 SNs SN6 WI
407
T
RH
28
within the 3-35 mm range.
Most of the animals (93 %)
failed to leave the holdfasts.
A few were observed
swimming from the holdfasts but most of those found in the
nets~
tubes.
wave barrel and tray remained inside their broken
Colonies of sandtube building worms, Sabellariidae,
were present in every holdfast and comprised 72 % of the
polychaetes collected.
These were principally
Phragmatopoma sp. but at least two other unidentified
sabellariid species were present.
An overwhelming majority
(95 %) of the sabellariids remained within the holdfasts
(Fig. 9).
The balance of the polychaetes, including some
mobile species, also stayed largely (90 %) within the
holdfasts (Fig. 10).
Mysidacea
Mysids (opossum shrimp) comprised 7 % of the collection.
They were 3-15 mm long with most falling within the 3-4 mm
range.
The ascending net accounted for most captures
(96 %) 1 but they also appeared in the surface nets, wave
barrel and bag net.
Only three individuals remained with
the holdfasts at the end of the treatments.
Twenty animals
or fewer were collected with five of the holdfasts even
though mysids were the third most numerous group.
Over
two thirds of them (2339) were taken with holdfast 7.
Eighteen percent (from plants 81 9 & 11) came from the
fronds while less than 1 % (from holdfasts 7 & 10) were
captured in the bag net.
These percentages may be suspect
29
because of the high mobility of these animals and the way
they sometimes congregate in swarms.
Table 7.
Gastropoda collected during treatments.
Nudibranch lengths are for unrelaxed specimens.
J.lla (Mitrella) carinata
19
Crepipatella Ungulata
2
Caecidae
1
12
8
Tricolla ep.
11
i:arleeia ep.
1
Crepidula sp.
1
134 269 67
1
843 1345 56%
2-7
10
16
94 13
lOS
230 10%
1-3
11
12
19
9
135
184
8%
1-3
9
80S6S
21
179
8%
o.s-2 10
19
l4
1
82
123
S%
o.S-1
8
20
30
3
27
87
4%
l.S-5
6
49
55
2%
3-22
10
1
4
1
Amphissa versicolor
1
12
20
s
Conua californicus
4
s
19
1
Sinezona riMuloides
36
2%
4-9
1
3
32
1%
2-14
6
22
22
1%
o.S-1
8
Vol.arina taeniolata
4
s
2
5
16
1%
J-S
6
~lip.
1
2
s
1
15
1%
l.S-2
6
s
1
1
13
1%
l-2
4
s
10 0.4%
1-3
2
1
8 0.3%
1-2
3
1
1 0.3%
l-5
3
6
1 0.3%
1-4
6
Turbon11la sp. B
4
4 0.2%
0.5-2
2
!!ll!!!! sp.
2
2 0.1%
3
1
Carthiopeis sp.
2
2 0.1%
2-5
1
Odostomia ep. (eucollmia?)
Lirularia sp.
Turbon11la sp. J.
4
1
Doridella steinbergae
6
1
4
Lacuna uni!'asciata
Nudibranchia (unidentified)
1
1
1
2
2 0.1%
2
2
Odost.oada ep. (navisa?)
2
2
o.l%
2
1
Bittiua interfossa
1
1 0.04%
3
1
1 0.04%
30
1
1 0.04%
l
1
lorrisia norrisi
1
30
Gastropoda
Gastropod molluscs made up 5 % of all animals collected.
Two percent of the gastropods collected with plants 8 1 9
and 11 came from the fronds.
The majority (57 %) of the
animals stayed within the holdfasts while 43 % appeared
7 %in the bag net (from holdfasts 7 & 10)) 10%
outside:
in the ascending
net~
21 % in the surface
wave barrel and 0 04 % in the tray.
nets~
5 % in the
Species responses
varied from 100 % leaving to 100 % staying (Table 7).
Isopoda
The fifth largest
group~
the isopod crustaceans) made
up 2.5 %of the total catch.
They ranged from 1-35 mm in
length but most were 2-7 mrn long.
Five percent of the
isopods collected with plants 8 1 9 and 11 came from the
fronds.
Over 3/4 of the isopods were caught outside the
holdfasts:
13 % (from holdfasts 7 & 10) in the bag netJ
38 %in the ascending net 1 23 %in the surface nets, 3 %in
the wave barrel and 0 7 % in the tray.
with the species (Table 8).
(94 %) left the holdfasts.
Responses varied
Most Paracerceis cordata
Seventy percent of them were
caught in the ascending net.
The majority of Limnoria
algarum left and most of those were found in the surface
nets.
More than 3/4 of the L. algarum captured in the
surface nets of holdfast 12 were taken during the initial
20 min. of the surface drift.
Just 40 % of the Cyathura
I
•
31
Table 8.
Isopoda collected during treatments .
.l'
~
# ~~ ...
..j
~
~
~
Paracerceia cordata
"' ~~
o!or
g.4f
~
fb'b
&!
.,f
~
.....
e~
..f'"'<b
~ .rt' ~
c."'
.... cf
-.$'
g.
#.I:,..o.Y
.,o?
#
#
"'
....
~.f ..
,.,~
4
283
78 14
2
25 406 32%
11
127 318 25%
8
r.e
'II
35 149
lS
sp. (jUYani1e)
#
~~
q,.lli
Lilmoria (Phycollmnori.a) a1garwn
C;[!thura m\Ulcla
.,
5
16
7
16 10
5
"Y
6t
93 155 12%
9
9%
8
8%
9
57
5%
1
26
2%
1
102
9
116
4
19 lOS
Jaeroesill dubia
s
S6
21
Cirolana parva
3
37
13
2
14
8
1
lO
2
6
18
1%
8
Mesanthura occ1danta11s
1
6
l
14
1%
6
Ianiro£s1s tridans
9
2
l
13
1%
5
lO
l
13
l%
l
6
o.S%
3
3
2
Idotea resecata
~lip.
~
2
urotorna
Ancinua S!anulatus
6
l
2
l
Idotea rutescans
2
3
5
o.4:C
Kunna (UromlUln&) sp,
l
l
2
0.2%
2
l
l
O.l:C
l
l
0.}.%
l
l
O.l:C
l
Cal11'anthura squamosissillla
Clnathia crenulatifrons
l
S1lophasma geminatum
l
munda left during the treatments.
J>
The only isopod
remaining mainly within the holdfasts 1 Cyathura munda
probably lives at or near the rock interface since it was
prominant in the bag net catch.
Idotea sp. were just out
of the brood pouch and were too small to identify to
species.
rufescens.
They were probably Idotea resecata or Idotea
These two highly active species'are usually
found on fronds but some were definitely on or in the
holdfasts.
Idotea urotoma was taken only with holdfast 8.
32
No one of the remaining groups (11 % of the total) made
up more than 2 % of all the animals collected from the 12
holdfasts.
Nematoda
Ninety eight percent of the nematods were taken from
the preserved holdfasts.
This figure is of dubious
significance because the nematods were so small they could
leave the nets at will.
Just 21 individuals were recovered
outside the holdfasts and those may have emerged from
pieces of debris when the samples were preserved.
Copepoda
The copepod crustaceans were all about 0.5 mm long.
Control results showed the majority (91 %) apparently came
from the fronds.
Most (98 %) of the copepods were
harpacticoids, consisting of an unidentified species (54 %)
and Porcellidium sp
(44 %).
The remainder were calanoids
made up of at least three unidentified species.
Pelecypoda
The pelecypod molluscs were 1-6 mm long.
were caught outside the holdfasts:
One third
8 % in the ascending
net, 12 % in the surface nets and 13 % in the wave barrel.
Although at least six species were present only three were
identified- Lima hemphilli
Hiatella artica.
1
Leptopectin latiauratus and
Most of the clams (85 %) were H. artica.
33
Ophiuroidea
Just over half (52 %) of the ophiuroids (Echinodermata)
left the holdfasts.
They ranged in size from 2-70 mm.
Their responses were inconsistent from one treatment to the
next and followed no particular pattern,
Each phase of the
treatment accounted for the majority of the exiting
ophiuroids at least twice (except the fronds only ascending
net which captured no ophiuroids).
Turbellaria
The flatworms ranged in size from 2-15 mm.
figures showed many (39 %) came from the fronds.
Control
Most
(63 %) of those from the holdfasts were recovered in the
ascending net (11 %) 1 surface nets (38 %) 1 wave barrel
(13 %) and tray (0 25 %).
These were the only animals
other than idoteid isopods observed climbing up from the
bottom of-the surface nets during the 2 h drift.
Natantia
The response of the Natantia (Crustacea) was similar
to that of the gammarids.
the holdfasts:
Most (79 %) of these shrimp left
6 % in the bag net (from holdfasts 7 & 10)/
29 % in the ascending net 1 29 % in the surface nets, 15 %
in the wave barrel and 0 24 % in the tray.
Three percent
of the animals collected with plants 8, 9 and 11 came from
34
the fronds.
As with all groups examined in detailJ the
responses varied with the species (Table 9).
Although
Hippolyte clarki was the only species captured from the
fronds during the control treatments, the presence of
Heptacarpus palpator in a few casual samples taken from
adjacent plants revealed that they can also occur on fronds.
Table 9.
Natantia collected during treatments .
....,
~
q•
~·
.....
#.;
..$'
.}
'1:1
~
0
,.,~
,/
".
;'
~·
;;-
... :; .......
"f-..
~
.....
1
45
46
41
HeJ2taCa!l!us 2!1J2!tor
4
67
)8
l4
~
33
8
3
3
3
Betaeus
c larlci
4
~i1is
HeJ2t&C&!l!US tay1ori
HeJ2t&C!!l!WI J2iCtUS
l
~~
~ap.
""...
1
~l'
-<?
~
.} -§"4,
.t! ..,..,e
"' !)>
c.e
-<1'
.t1 c.e~ .§-~· ..!' 'II:.\
~
""
..
5...
S'
~,
.A.1pheus c1lllll&tor
HiJ2~:!z!:!
'!t
-..$"
if
§~
~-..$" .;qf
86
"'0
.;§<
<-c.
0
I'
.:r.t:;o
,$
"<:'~~
~
~4,
-v"'
':'.§
~0
220 Sl%
1-39 12
28%
8-21 12
12)
75 17%
8-17
7
8
2%
4-8
2
l
4
l.
ll-14
2
l
2
O.S%
21
2
l
1
0.2%
lS
1
l
0.2%
- 7
l
2
l
...........
Tanaidacea
The tanaid crustaceans were 1-3 mm long.
Approximately
1/3 left the holdfasts and were captured in the ascending
net (11 %), surface nets (15 %), wave barrel (6 %) and tray
(0 24 %).
Three species are listed in Table 10.
The
majority (83 %) of Leptochelia sp. were found in the
holdfasts;
the remainder were distributed among the
ascending net (4 %); surface nets (7 %)
and wave barrel
35
(6 %).
Synapseudes intumescens was the only tanaid
occurring mainly (62 %) outside the holdfasts:
17 %in the
ascending net; 35 %in the surface nets; 9 % in the wave
barrel; 0 9 % in the tray.
They left throughout the
surface drift of holdfast 12 but more were captured during
the initial 20 min. than during any other phase of the
drift.
A third species) unidentified, stayed mainly (60 %)
inside the holdfasts.
Those that left the holdfasts
appeared in the ascending net (24 %)) surface nets (13 %)
and wave barrel (3 %).
Table 10.
Tanaidacea collected during treatments.
Lept.oche11a sp.
9
17
14
Synapaeudes intumescens
19
38
10
Tanaid (unidentified)
lB
10
2
197 237
1
56% 12
42
110 26%
7
45
75 18%
9
Ostracoda
The majority (74 %) of the ostracods were captured
outside the holdfasts:
10 % in the bag net. (from holdfasts
7 & 10), 16 % in the ascending netJ 31 % in the surface
nets and 17 % in the wave barrel.
Most (81 %) of those
taken during the surface drift of holdfast 12 left during
the initial 20 min.
At least 3 species were present.
36
They were all less than 2 mm long.
Nemertea
The nemertean worms (=Rhynchocoela) were 4-40 mm long.
Most (85 %) remained within the holdfasts and those that
did not were usually recovered in pieces.
Echinoidea
Most of the urchins were about 1 mm across although a
few measured 6 mm .
Only 22 % of the holdfast urchins were
caught outside the holdfasts:
4 %in the ascending net,
5 % in the surface nets and 13 % in the wave barrel.
Three
percent of those collected with plants 8) 9 and 11 came
from the ·fronds.
Caprellidea
The caprellid amphipods varied between 2-10 mm in
length.
Most (71 %) were collected outside the holdfasts:
17 % in the bag net (from holdfasts 7 & 10) 1 19 % in the
ascending net, 24 % in the surface nets and 11 % in the
wave barrel.
Just one of the caprellids collected with
plants 8, 9 and 11 came from the fronds.
At least four
species, unidentified, were present.
Reptantia
Most (95 %) of the crabs were captured outside the
holdfasts:
18 % in the bag net (from holdfasts 7 & 10),
37
35 % in the ascending netJ 33 % in the surface nets and
9 % in the wave barrel (Table 11).
They were 2-70 mrn. long
but most fell within the 3-15 mm range.
Even though no
crabs came from the fronds during the control treatments
three Pugettia producta were deducted from the totals
because they were observed decending from the fronds of
holdfast 3.
Table 11.
Reptantia collected during treatments .
.
fb~
~
§
~·
~
c}
"'
~
...." ' .t,o~~
.,•
§
~
-co
~...
.....
~~
}
...
~
.,_D:>
Loxorhynchus crisE:!tus
2
9
17
Paraxanthias tallori
l
14
1
8
2
2
4
Pagurus sp.
5
2
Megalopa larva
1
3
Cancer sp.
1
l
Pugettia Eroducta
3
Pachlcheles rudis
Lo2ho~o~us
bellus
l
(I'll
Talie2us nuttalli
'
.,.OJ
,
'::'t
~ ..~~
Cj
411J
~"
""\
~~
-<?
-.$'
qf
.....,
.r;-46
~
"CJe
,§r.;
9.?
.qf
~
.'j
-#~
~
~
§ ~·
.#
.;-
qf~
~0
~
31
32%
8
22
22~
6
12
12%
5
l
8
8%
4
l
8
8%
5
1
7%
4
6
6%
5
3
3~
1
l
l%
l
2
3
4
l
l'
0
~
~~·
~
3
.
¥
"CJ
Cumacea
The cumacean crustaceans were 2-6 mm long.
The
majority (74 %) left the holdfasts and most of them were
found in the ascending net.
38
Pisces
Five species of fish and some unidentified larva were
captured in the ascending net and surface nets (Appendix A
& B).
Their size range was 6-90 rnm.
Rimicola muscarum is
mainly a canopy species and was taken from the fronds of
plant 8.
Most of the other fish were probably from the
holdfasts but the coloration of some Paraclinus
integripinnis and of the lone Ulvicola sanctaerosae
indicated these may have come from the fronds.
Pycnogonida 1 Holothuroidea 1 Polyplacophora1
Asteroidea and Cephalopoda
These five groups were represented by few individuals
(12 or less).
Their responses are given in Appendix A.
Holdfast Volume
Although large holdfasts generally contain more animals
than small holdfasts factors other than volume appear to
influence population size.
Table 12 ranks all holdfasts
by volume and shows the total number of animals as well as
the number of gammarids 1 polychaetes 1 gastropods and
isopods colle.cted with each holdfast.
Some holdfasts
contained inordinately large or small populations (see
discussion).
~
.
39
Table 12.
Twelve holdfasts arranged by volume and showing
the total number of animals) as well as the number of
gammarids) polychaetes) gastropods
and isopods collected
with them.
Hold!ast
Volume
Jill
No. of
animals
No. of
gammarids
7
4300
8604
3463
1
4200
5193
12
3900
ll
No. of
No. of
gastropods
No. of
isopods
1379
511
207
3450
1188
96
194
6377
2966
1852
1.34
361
3300
.3699
1362
1361
193
62
6
2100
6108
2882
4175
65
8J
3
1900
4052
1970
1534
92
71
9
1700
2174
1373
315
87
S5
lO
1300
1639
692
452
95
13
2
1100
2198
1293
241
42
61
4
Boo
2914
206o
.345
44
79
s
700
2921
1959
564
25
21
8
600
3353
1n6
35
942
30
po~chaetes
Uncontrolled Conditions
Tides varied considerably during the study.
The
lowest low of the day occurred near the middle of the
surface drift of holdfasts 1-6.
Holdfasts 7-11 were cut
loose 1.5-2.5 h after the days lowest low.
Holdfast 12
was taken out of the tray 1 h befor low tide on a day when
the low tides were nearly equal.
40
Temperatures did not vary more than 4°C from the sea
surface to the bottom and the differences were usually less
than 3aC.
The lowest surface temperature (13.5.C) was
recorded March 7 and the highest (21.5.C) september 22.
Underwater visibility fluctuated from a few centimeters
to 7-8 mJ some times on the same day.
Winds) surface chop,
swells and cloud cover all changed many
a collection was in progress.
times~
often while
DISCUSSION
The animals of the holdfast community 1 living in
various microhabitats and possessing.a broad range of
sensory capabilities 1 were presented with a common 1
potentially catastrophic,situation.
Their reactions varied
from group to group but most animals capable of leaving the
holdfasts did so within a few minutes of a holdfasts
separation from the rocks.
Development of this expeditious
behavior is critical to holdfast dwellers.
Although some
holdfasts die in situ as a result of being stripped of
their fronds by urchins, by disease or by unseasonably warm
wate~
most of those that live long enough to anchor fronds
reaching the surface begin their dissolution by tearing
loose from the bottom.
A Macrocystis pyrifera free of attachment is pulled to
the surface by its buoyant fronds.
At the surface it may
become entangled with neighboring plants.
Holdfasts
hanging beneath a canopy of attached plants are a common
sight.
The hapteral growth of these trapped holdfasts
indicate some plants survive in this condition for many
days 1 perhaps weeks during calm weather but eventually the
fronds come loose or the entangled neighbor tears loose and
the plant, like those that never tangled, drifts away from
the kelp bed.
Wind and water conditions determine where the plants
41
42
will go.
They may drift out to open sea where growth may
cease because of nutrient depletion.
They may remain at
the surface until the pneumatocysts loose buoyancy and the
plants sink into deeper water.
Sooner or later many1
probably most 1 drift towards the coastline where they are
dashed about in the surf and deposited on the shore.
While
beached the plants are exposed. to dehydration 1 temperature
extremes and the birds, crabs, amphipods 1 isopods 1 insects,
raccoons and small children that forage along the shore.
Plants may remain on shore for moments or months, but most
are washed out again on the next tide (Zobell 1959).
Deterioration, accelerated by dehydration and abrasion,
destroys the buoyancy of the floats and the plants sink to
the bottom.
Complete dissolution may occur in shallow
water but drifting kelp has been observed in submarine
canyons and in deep water on the continental shelf 1 carried
there by bottom currents (North 1971).
Animals that do not leave the holdfasts have poor
prospects for survival.
They share the fate of the plant1
dislocation and eventual death by either dehydration
mechanical distruction> predation or extreme hydrostatic
pressure.
The sooner the animals escape from the drifting
holdfast the higher the probability they will reach a rocky
bottom of suitable depth.
A prompt getaway also decreases
the amount of open water they must cross to reach bottom
and helps them avoid the opportunistic fish that arrive
43
soon after tearloose.
Probable Causes of Exodus
Tidal height, temperature, water visibility, surge,
current, cloud cover, swells, surface chop and all aspects
of water chemistry fluctuated naturally during the study.
Although these factors may have had some
influence~
the
striking similarity in responses (easily seen in Fig
8)
suggests that the exodus is governed by conditions
faithfully reproduced for all 12 holdfasts.
Mechanical Disturbance.
When a holdfast is plucked from a
rock its haptera either pull free or break 1 exposing the
rock interface.
Some animals are crushed or dislodged and
these 1 along with sand and debris, rain down beneath the
holdfast.
Other holdfast dwellers, disturbed but not
dislodged, swim or crawl out.
Small holdfasts can be very
disordered by this but the effect on larger holdfasts,
those over one year old, is very localized.
The inter-
tangled haptera and the debris and worm tubes incorporated
between them make the mature holdfast a very strong
structure.
The disorder is usually limited to the area near the
rock interface and is probably responsible for only a small
part of the exodus.
When holdfasts 7 and 10 were cut loose
and held at the bottom for 10 minutes barely 5 % of their
inhabitants appeared in the ·bag net.
Debris and sessile
44
animals were found throughout the collections but the
ascending net usually caught the largest part.
Most of the
· debris and sedentary animals collected with holdfasts 7 and
10 appeared in the bag net. evidently as a direct result of
holdfast detachment.
Currents and Acceleration.
Water easily circulates through
the porous holdfast structure.
Interhapteral water move-
ments caused by surge or prevailing currents are
effectively cancelled when a holdfast is drifting free but
new currents result when the holdfast accelerates upward}
pulled by the pneumatocysts.
Eventually it slows, usually
stopping within 1 m of the surface.
While it drifts there
it is moved up and down by swells and chop·
Many of the groups represented here (especially the
filter feeders) can detect currents but 1 except for the
animals abruptly exposed at the interface 1 sudden current
changes are a normal occurrence. and not a dependable
indication that the plant is unanchored.
Although acceleration is not a regular part of the
benthic environment and most holdfast species have
statocysts (balance organs,· some possibly capable of
detecting the changes following a holdfast tearloose) it is
an unreliable criterion for holdfast abandonment
b~cause
the strength and duration vary with the weight of the
holdfast 1 the number of fronds and the nmnber of
pneumatocysts.
Several holdfast species are also found on
45
fronds where accelerations accompany surge as a normal part
of the habitat and they may consequently be insensitive to
it.
Light.
Although light increases in intensity and wave-
length range as water depth decreases and nearly every
member of the holdfast community has some form of photoreceptor it probably has little effect on the exodus.
Water visibility, cloud cover and the thickness and
configuration of the canopy change unpredictably and even
intense aberrations may be undetectable to creatures living
deep within the holdfasts.
Increased light may have contributed to the exodus of
the ophiuroidsl a generally photonegative group, and of
some groups possessing highly discriminating photoreceptors
(malacostracans)J but the widely varying natural light
conditions strongly suggest that light changes did not
effect the community response.
Temperature.
Water temperatures are usually higher at the
sea surface than at the bottom.
The greatest difference
encountered here was 4•c and Quast (197ld) found
temperature changes greater than 6°C occurred normally over
a fairly short time in kelp beds.
Holdfasts rising from
deeper water could be subjected to larger changes and in
these cases temperature may affect the exodus but it
probably had little or no effect during this study.
46
Turbulence.
When a plant drifts into the surf zone it is
in imminent danger of washing ashore.
The intermittently
turbulent, highly oxygenated water conditions usually
found there could conceivably release some escape behavior
since the capture rate increased when the holdfasts were
put into the wave barrel (Tables 2 and 3) but it is more
likely that any active surf zone exits are prompted by
mechanical disturbance of haptera and debris caused by
knocking about in the waves and contacting the bottom or
other obstacles.
Surf-like conditions are an unreliable
sign of an impending washup because they can occur anywhere
on the sea surface and plants may drift ashore at sheltered
locations or be left on the beach by a receding tide during
relatively calm periods.
Storm induced wave turbulence can
sometimes be felt several meters below the surface1 even
reaching holdfasts still attached to rocks in the
shallowest parts of the kelp beds.
Desiccation.
Very few animals left the holdfasts when they
were taken out of the water and most of those that did were
the larger amphipods and ophiuroids.
Water} held by
capillary attraction throughout the holdfasts 1 evidently
was both refuge and trap for the vast majority of the
remaining holdfast dwellers who did not leave the water
pockets·
Water surface tension and the air itself are
formidable barriers to small marine animals.
Natural beach washups usually include a period when the
47
holdfast is exposed to air near the waters edge where it is
occasionally doused with wavewash.
Animals attempting to
leave might be washed out at that time.
Pressure.
The change in hydrostatic pressure during the
drift up to the surface is the best candidate for prime
releaser of the exodus.
compelling.
The evidence is indirect but
Within a few seconds of pulling free from the
bottom every animal in the holdfast is exposed to a
decrease in hydrostatic pressure of a magnitude and
duration very unlikely to occur while the plant is still
attached to the substrate.
Pressure variations caused by
the tidal cycle are much slower and fairly regularized
and those accompanying large swells oscillate rapidly.
Just 5 % of the animals from holdfasts 7 and 10 left
during the 10 min. they were held at the bottom in the bag
net.
When the holdfasts were taken to the surface and run
through the remainder of the treatment the results were
similar to those of the other 10 holdfasts.
A great many
animals left soon after the holdfasts started their ascent
and the percentage captured during each subsequent phase
of the treatment was comparable to the other ten treatments.
Perhaps the most impressive evidence were the sudden
outflows of animals that occurred when the holdfasts had
risen a short distance above the rocks.
After a holdfast
was pulled loose, sand> debris and just a few animals fell
or swam from it until it had ascended slightly more than
48
1m,
At that point a cloud of animals swam out and down
from all over the holdfast.
They continued to stream down
as the plant drifted to the surface.
These abrupt
departures were most easily observed when a holdfast rose
slowly, they were obscured during
e~tremely
fast ascents.
I am unaware of any studies involving the pressure
sensing abilities of holdfast species but the capability
of detecting small hydrostatic pressure changes has been
demonstrated for many marine animals, both pelagic and
benthic, and it is clearly a widespread attribute.
Many planktonic marine animals living in shallow water
or near the sea surface-respond to pressure changes of the
order of 0.01 atm by movement up or down in the direction
appropriate to depth regulation (Knight-Jones and Morgan
1966, Kitching 1972).
Hydrostatic pressure increases by
approximately 1 atm, roughly 15 lb/in 2 , for each 10m water
depth.
Knight-Jones and Qasim (1955) demonstrated
sensitivity to pressure change in polychaetes) copepods
isopods) decapods and fish.
results.
Digby (1967) obtained similar
Rice (1961) found a mysid that responded to
changes as small as 15 mbar (one mbar equals 1000 dy/cm
2
and is approximately equivalent to the pressure exerted by
a column of seawater 1 em high.
One atmosphere equals
1 0132 bars) .
Some benthic species have also demonstrated pressure
sensitivity.
Naylor and Atkinson (1972) and Morgan (1967)
found adult crabs, Carcinus maenas and Macropipus holsatus
49
respectively, sensitive to changes of less than 0.1 atm .
Activity
rhyt~~s
partially based on pressure change were
reported by Jones and Naylor (1970) for the isopod Eurydice
pulchra, by Enright (1961) 1962) for the amphipod
Synchelidium sp. and by Morgan (1965) for the amphipod
Corophium volutator.
Hydrostatic pressure change serves as a releaser for
several types of behavior.
list four;
1) Depth regulation;
exploration and navigation;
cycle;
Knight-Jones and Morgan (1966)
2) Hyperbenthic
3) Control of the spawning
4) Detection of pressure fronts and pulses caused
by approaching objects or animals.
The main part of the exodus from the detached
Macrocystis pyrifera holdfasts was apparently a bottomoriented escape behavior released by the sudden decrease
in pressure.
The sense organs involved in pressure sensitivity have
not been located) nor has the mode of action been
determined but Digby (1972) suggests that the receptors may
reside somewhere in the crustacean cuticle.
He also
suggests some general mechanism may be responsible because
sensitivity to small pressure changes is found in such a
great variety of animals.
Not all marine animals are sensitive to small pressure
changes.
Enright (1962) found the isopod Excinolana
chiltoni and a mysid, Archaeomysis maculata) did not react
appreciably to pressure changes up to 100 mbar.
50
Knight-Jones and Morgan (1966) list known response
thresholds for a wide variety of marine animals.
Responses
to pressure changes corresponding to depth changes of 1 m
or less were found for some isopods, copepods
1
amphipodsJ
polychaetes, cmnaceans 1 mysids 1 decapods, fish (with and
without swim bladders) and molluscs.
One
amphipod~
Synchelidium
spo~
apparently responded to
pressure change rather than absolute levels and quickly
accomodated to new pressures (Enright 1961, 1962).
Its
response threshold increased as the rate of pressure change
decreased.
The response thresholds also increased after
the animals had experienced several pressure changes.
This
amphipod lives in the surf zone of La Jolla sandy beaches
and responds to a sudden increase in pressure by a sharp
burst of activity.
The intensity of the response decreases
exponentially with time and the animals apparently return
to prechange activity fairly quickly.
Even though this
species does not live in holdfasts and responds to
increases in pressure rather than decreases it demonstrates
the dual abilities of pressure sensitivity and accomodation
to pressure change that would be needed in order to detect
the pressure decrease accompanying holdfast detachment in
the midst of normal tidal and swell fluctuations.
(1960) collected a few
Synchelidi~~
Ghelardi
sp. from La Jolla
holdfasts but these evidently represented one of the
subtidal species.
Knight-Jones and Morgan (1964, 1966) noted a good deal
~
.
51
of variation in the readiness with which animals respond to
pressure change, not only between species but between
individuals and between different physiological states of
the same individual.
This may partially account for the
portions of apparently pressure sensitive groups that
failed to leave the holdfasts.
The sudden pressure decrease appears to be responsible
for most of the exits by the following groups:
Garnmaridea,
Mysidacea, Isopoda, NatantiaJ Caprellidea and Reptantia.
All belong to the Crustacea and are highly mobile animals.
Most of these left the holdfast soon after it began to rise
toward the surface and were subsequently caught in the
ascending net and surface nets.
Cumacea and Pisces may
also leave because of the pressure change but their low
nmnbers obscure the issue.
The probable cause or causes of the escape behavior of
some species of the other mobile groups are not as easily
seen because many of these slow moving animals lived deep
within the holdfast and would still be in the process of
crawling out sometime after they initiated their decampment.
This lack of speed was probably the reason several species
which were obviously disposed to leave appeared mainly in
the surface nets.
Several gastropod species (Table 7) 1
the tanaid Synapseudes intumescens and the various
ostracods and turbellarians may fit this catagory.
One
isopod) Limnoria algarumJ also showed a somewhat delayed
response (Table 8).
This species carves tunnels in haptera
".
52
deep within the holdfasts and even though they are capable
of swimming they seldom do (Jones 1971).
Most (78 %) of
the L. algarwn caught in the surface nets of holdfast 12
were taken during the initial 20 min. of the surface drift.
Size and Composition of Holdfast Communities
Evidently factors other than displacement volume
can
influence the number of animals in a holdfast community.
Although the larger holdfasts generally held the most
animals) the relative sizes of the various population
components differed considerably (Table 12).
A large
sabellariid colony enabled holdfast 6 to support twice as
many polychaetes as did any other even though the volume of
the holdfast was average.
It was one of two holdfasts in
which polychaetes outnumbered garmnarids.
The smallest
holdfast, number 8, was half buried by sand .
The black
haptera beneath the sand continued to hold the plant firmly
to the rock while newer haptera stopped short of entering
the sand.
shape.
This gave the holdfast a slightly mushroom-like
It held very few
polychaetes~
one ophiuroid and
one tanaid and it was the only holdfast where the isopod
Idotea urotoma appeared.
Further, holdfast 8 contained
more gastropods (942) than any of the larger holdfasts.
Eighty seven percent of these were Alia carinata.
10 held fewer animals than any other
holdfast~
Holdfast
It was
unusually loose, lacking the more densely interwoven
haptera found in most others.
Even though it was eighth
53
largest in volume it had relatively little surface area
contained only small amounts of debris and provided few
really protected areas.
The sabellariid colony near the
apex of this holdfast was disrupted when the holdfast was
pulled loose, seventeen percent appeared in the bag net
and 31 % ended up out of the holdfast, by far the largest
percentage dislodged from any of the holdfasts.
The same types of animals (amphipods, isopods,
polychaetes, crabs. Table 1) that I collected at Flat Rock
have been reported from the holdfasts of large marine algae
off Tasmania (Cribb 1954), South America (Darwin 1860) and
England (Moore 1972
1973 a, b, c, Scarratt 1961) as well
as the west coast of the U.S.A. (Andrews 1925
Ghelardi 1960).
1945
Some wide ranging holdfast dwellers have
been collected from several algal species in diverse
locations (Appendix B).
The holdfast fauna collected from the Macrocystis
pyrifera at Flat Rock had many similarities to that taken
by Ghelardi (1960) 20 years earlier and 100 miles to the
southwest in a La Jolla kelp bed.
Comparisons are fairly
general because his methods were so different. He took
144 cores. approximately 100 cm3 each) from 39 M. pyrifera
holdfasts over a one year period.
The plants ranged in
age from less than a year to several years old and the
cores were separated into live haptera and dead or
senescent haptera.·. When a plant is about two years old
the haptera at the bottom center of the holdfast become
54
Table 13.
Genera found in Macrocystis pyrifera holdfasts
at both Flat Rock and La Jolla (incomplete
see materials
and methods).
Genus
Pol.n>lacophora
Gastropoda
Pelecypod&
Polychaeta
Tanaidacea
Isopoda
Callistochiton
Cyanoplax
.A.lia
crassieostatus
hartwegii
carina.ta
A!l!phissa
Caecum
Cerithiopsis
Conus
Crepidula
Crepipatella
Norrisia
Tricolia
LeptoEecten
Lima
versicolor
sp.
sp.
cali!ornicus
sp.
lingulata
norrisi
sp.
latiauratus
hemphilli
sp.
sp.
intumescens
sguamosissima
parva
munda
erenulatifrons
sp.
dubia
algarum
sp.
baconi
clamator
palpator
sp.
bellus
product&
Phra~topoma
Leptochelia
SynaEseudes
Califanthura
Cirolana
Cyathura
Gnathia
Jaeropsis
Limnoria
Munna.
Gammaridea
Natantia
Reptantia
Flat Rock
species
Corophium
AlEheus
Heptaca!:Eus
Cancer
LophOp!!!O~US
Pugettia
senescent and die.
La Jolla
species
E!lmulatus
sp.
carinata
sausaEata
versicolor
sp.
sp.
californicus
sp.
li~lata
norrisi
sp.
latiauratus
sp.
calif'ornica
sp.
intumescens
S9,U&IIlOSiSSima
pam
sp.
eristata
dubia
algarum
ubiquita
sp.
bellimanus
palpator
anthonyi
bellus
sp.
As a holdfast increases in size the
dead portion enlarges until there is only a thin layer of
living haptera anchoring the plant.
None of the Flat Rock
holdfasts contained an appreciable amount of dead haptera
except for the portion of holdfast 8 that was buried by
the sand.
The nine most numerous groups from La Jolla
55
were the Nematoda, PolychaetaJ Gamrnaridea, Isopoda)
CaprellideaJ Chelifera (Tanaidacea)J
Gastropoda~
Pelecypoda
and Ophiuroidea which comprised 97 % of the fauna from live
haptera and 91 % of that from dead haptera.
These same
nine groups comprised 88 % of the animals collected at Flat
Rock and were found in every holdfast, except for the
Caprellidea which was absent from holdfast 2.
At La Jolla
Ghelardi found that gamrnarids made up 44 % of the live
haptera inhabitants; at Flat Rock they made up 49 % .
Twenty nine percent from the dead sections and 11 % from
the live sections were polychaetes at La Jolla versus 26 %
at Flat Rock.
Seventeen percent of the live and 16 % of
the dead section inhabitants at La Jolla were isopods
although they comprised only 2 5 % of the holdfast dwellers
at Flat Rock.
Several genera common to both locations are listed in
Table 13.
This comparison is extremely incomplete because
nearly 90 % of the Flat Rock fauna was not identified in
detail.
A comparison of all species collected at the two
sites would probably reveal more species in common .
Research Needed
This study was the initial step of the inquiry into the
behavior of holdfast dwellers after their homes become
detached from the substrate.
The results suggest that
pressure sensitivity is widespread among the animals that
live in Macrocystis pyrifera holdfasts.
Since the holdfast
56
fauna at a given location are a partial reflection of the
surrounding fauna and the same types of animals are found
in holdfasts at various sites around the world pressure
sensitivity may be more common among shallow water benthic
faunas than previously suspected.
areas that need clarification:
The following are a few
1) Colonization and
microhabitat selection in holdfasts; 2) Factors affecting
growth and comformation of holdfasts; 3) Pressure
sensitivity in holdfast animals: Laboratory and in situ
studies;
4) Pressure tolerance in holdfast animals; 5)
Faunal changes in holdfasts entangled at the surface with
attached neighboring plants;
6) Post exodus survival;
7) Tearloose-washup treatment of large brown algae other
than Macrocystis pyrifera;
Where do they go ?;
8) Naturally drifting holdfasts:
9) Animals feeding on beached
holdfasts; What do they eat ? ;
10) Utilization of deep
drift kelp: Which deep sea animals eat kelp and the
accompanying holdfast animals ?
LITERATURE CITED
Andrews, H. L. (1925). Animals living on kelp. Puget Sound
Biol. Sta. Publ.J 5:25-27.
Andrews, H. L. (1945). The kelp beds of the Monterey region
Ecology, 26:24-3~
Bernstein, B. B. (1977). Selective pressures and
coevolution in a kelp canopy community in Southern
California. Ph. D. ThesisJ Univ. of Calif~ San Dieg~
146 pp.
Colman, J. (1940). On the faunas inhabiting intertidal
seaweeds. J. Mar. Biol. Assoc. U.K., 24:129-183.
Coyer1 J. A. (1979). The mobile invertebrate assemblage
associated with the giant kelp, Macrocystis pyrifera,
Western Society of Naturalists: Abstracts of symposia
and contributed papers. Western Society of Naturalists
60th annual meeting, Pomona, California• Dec. 26-30,
1979.
Cribb, A. B. (1954). Macrocystis pyrifera in Tasmanian
waters. Aust. J. Mar. Fw. Res., 5~1-34.
Darwin, C. R. (1860). The voyage of the Beagle. Doubleday,
New York 1 . 1962) 524 pp.
P. S. B. (1967). Pressure sensitivity and its
mechanism in the shallow marine invironment. Symp. Zool.
Soc. Lond. 19:159-188.
Digb~
P. s. B. (1972). Detection of small changes in
hydrostatic pressure by crustacea and its relation to
electrode action in the cuticle. Symp. Soc. exp. Biol.
26:445-472.
Digb~
Enright, J. T. (1961). Pressure sensitivity of an amphipod.
Science, 133:758-760.
Enright, J. T. (1962). Responses of an amphipod to pressure
changes. Comp. Biochem. Physiol. 7:131-145.
Fosberg 1 F. R. (1929). Preliminary notes on the fauna
of the giant kelp. J. Ent. Zool. 21:133-135.
Ghelardi/ R. J. (1960). Structure and dynamics of the
animal community found in Macrocystis pyrifera holdfasts.
Ph. D. Thesis., Univ. of Calif., La Jolla. 183 pp.
57
58
Ghelardi~
R. J. (1971). Species structure of the holdfast
communities. In: W J. North (ed.), The biology of giant
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APPENDIX A
Animals collected during the treatment of each of the
twelve holdfasts.
Major groups are given on the left
(see Table 1) and species are listed on the right.
Unidentified zoea larva collected with holdfasts 4, 5, 7
and 8 were included after the last major group.
ascending net with entire plant (2 min.).
net with fronds only (2 min.).
holdfast only (2 min.).
AN-E:
AN-F: ascending
AN-H: ascending net with
SN: surface net (120 min.).
SN 1 -sN 6 : surface nets for holdfast 12 (consecutive 20 min.
periods).
WB: wave barrel (15 min.).
RH: remaining in holdfast.
total.
T: tray (60
BN: bag net (10 min.).
*:unidentified.
61
min~.
TO:
AN-E
forophium baconi
/
HOLDFAST 1
Gammaridea
Poly chaeta
lsopoda
Mysidacea
Gastropoda
Copepoda
Nemertea
Natantia
Ostracoda
Ophiuroidea
Cum ace a
Nematoda
Turbellaria
Pisces
Pelecypoda
Tanaidacea
Reptantia
Caprellidea
Echinoidea
Cephalopoda
AN-E
SN
WB
T
RH
2230
27
163
130
45
14
2
8
7
2
9
733
3
25
123
5
1
6
358
1153
5
13
5
1
4
1
4
3
1
1
1
2
6
1
3
3
2
1
34
5
10
3
5
10
2
9
5
4
3
1
1
~:y
1188
194
130
96
24
16
15
14
12
12
10
7
6
5
!~
Paracerceis cordata
Jaeropsis dubia
Gnathia sp.
Mesanthura occidentalis
l!gotea resecata
I
Tricolia sp.
Alia carinata
Crepidula sp.
Crepipatella Jingulata
SN
2
2
157
2
2
1
1
25
14
12
13
RH
TO
1
4
1
187
3
2
1
1
1
6
2
3
1
11
21
17
16
11
11
6
6
2
2
1
1
1
1
WB
4
3
10
Caecidae
Amphissa versicolor
Lirularia sp.
Cerithiopsis sp.
Sinezona rimuloides
Conus californicus
Triopha grandis
Lacuna unifasciata
5
T
1
1
5
2
2
1
1
1
1
7
4
3
Alpheus clamator
Heptacarpus palpator
Betaeus sp.
5
2
1
Paraclinus integripinnis
Liparis mucosus
5
1
12
9
3
3
10
4
1
5
2
2
5
1
2
*
:J
Ioxorhynchus crispatus
Lophopanopeus bel/us
5
3
1
2
1
4
3
1
0\
N
AN-E
HOLDFAST 2
SN
WB
1
2
4
8
1
5
11
55
4
1
1
1
Gammaridea
Mysidacea
Poly chaeta
lsopoda
Gastropoda
Nematoda
Tanaidacea
Natantia
Nemertea
Turbellaria
Pelecypoda
Copepoda
Ostracoda
Ophiuroidea
Cum ace a
Pisces
Reptantia
Echinoidea
AN-E
SN
WB
T
RH
360
422
3
35
3
291
103
6
1
5
25
514
1
11
2
1
1
1
1
1
9
34
1
237
12
5
39
12
2
10
10
9
7
1
1
1
1
5
3
1
2
1
1
1
1
2
2
31
3
1
RH
1
3
16
7
4
5
2
Heptacarpus palpator
B~ipheu•da~'"'
8
Hippo/yte clarki
7
4
1
1
Harpacticoida
*
Porcellidium sp.
~c.lono;"'
Liparis mucosus
6
3
2
TO
2
2
1
18
12
5
5
2
12
12
1
1
3
1
T
2
6
1
6
5
2
6
~:,/inu• /ntegrip/~1•
Larva
Lophopanopeusbellus
0"\
w
forophium baconi
Crepipatella lingulata
Barleeia sp.
AN-E
SN
11
3
3
3
6
2
1
5
6
4
WB
T
/
HOLDFAST 3
Gammaridea
Polychaeta
Gastropoda
Ophiuroidea
Nematoda
Isopod a
Copepoda
Turbellaria
Tanaidacea
Ostracoda
Pelecypoda
Nemertea
Natantia
Pycnogonida
Reptantia
Caprellidea
Mysidacea
Echinoidea
Pisces
Cumacea
AN-E
SN
WB
T
RH
983
5
17
8
507
14
24
21
1
4
426
1490
46
38
37
33
10
1
2
2
13
12
5
4
12
1
53
21
5
11
2
3
3
1
5
2
3
2
2
2
3
2
2
12
5
2
5
2
3
1
4
72
1
1
17
1
23
24
4
14
10
2
3
2
3
2
1
TO
1970
1534
92
82
74
71
46
Conus californicus
Triopha grandis
~r~~~~-;*
6
2
Volvarina taeniolata
Doto sp.
TO
7
17
11
1
20
20
11
8
7
6
6
6
3
14
4
Caecidae
IAlia carinata
RH
3
3
1
1
2
Nudibranchia
Lirularia sp.
Sinezona rimuloides
Cyatnura munda
ldotea sp. (juvenile)
Paracerceis cordata
Limnoria algarum
Cirolana parva
ldotea resecata
Gnathia sp.
Ancinus granulatus
*
Harpacticoida
Porcellidium sp.
Leptochelia sp.
Synapseudes intumescens
Tanaid
*
1
2
18
8
3
1
1
1
5
1
2
1
1
14
4
4
1
2
1
1
29
4
1
12
1
3
1
2
23
2
5
2
1
Alpheus clamator
!:feptacarpus palpator
1
2
Pugettia producta
Lophopanopeus bellus
Cancer sp.
.J:.araxanthias taylori
3
2
1
1
21
18
9
8
4
4
3
2
1
1
41
5
28
2
1
10
2
3
2
1
1
[Z'imicola muscarum
Ulvico/a sanctaerosae
~
+:--
HOLDFAST 4
Gammaridea
Polychaeta
Nematoda
lsopoda
Pelecypoda
Gastropoda
Ophiuroidea
Copepoda
Mysidacea
Ostracoda
Natantia
Reptantia
Tanaidacea
Turbellaria
Caprellidea
Cumacea
Echinoidea
Holothuroidea
Zoea larva
/
AN-E
SN
WB
1234
20
3
35
4
3
3
17
13
3
8
7
3
4
6
3
633
7
32
4
21
4
7
15
4
1
7
2
2
6
3
2
1
12
2
T
RH
TO/
161
314
190
22
50
34
4
1
2060
345
193
79
58
44
24
21
13
11
10
1
~g ~
3
10
1
8
1
1
3
2
1
12
Uimnoria algarum
ldotea sp. (juvenile)
Cyathura munda
ldotea rescata
Jaeropsis dubia
Cirolana parva
laniropsis tridens
Mesanthura occidentalis
AN-E
SN
8
10
2
18
3
4
17
4
2
1
1
2
WB
T
RH
TO
20
40
18
7
4
4
3
1
1
1
18
1
2
1
1
1
2
3
3
26
5
2
Harpacticoida
*
Alpheus clamator
~.,,.,,,., palpa""
1
17
4
21
7
1
2
9
1
Pachycheles rudis
Loxorhynchus crispatus
Pagarus sp.
3
2
1
1
P!lr~v.::Jnthi!:lr
1
1
1
2
5
1
t-!lulnri
30
5
5
2
3
2
2
2
1
6
3
1
0\
Ln
'HOLDFAST 5
AN-E
Gammaridea
Poly chaeta
Turbellaria
Mysidacea
Pelecypoda
Gastropoda
Tanaidacea
Isopod a
Natantia
Copepoda
Ostracoda
Ophiuroidea
Reptantia
Nemertea
Nematoda
Echinoidea
Caprellidea
Cumacea
Zoea larva
SN
AN-E
SN
WB
T
RH
2
1
716
8
884
8
36
1
3
17
7
9
3
3
5
4
3
1
70
9
21
48
1
4
1
285
538
•9
1
17
4
7
64
10
1
5
9
5
10
3
1
3
3
1
10
1
1
2
3
1
1
T
RH
TO
5
1.
23
1
1
3
1
51
7
10
2
2
1
4
1
5
5
4
1
WB
3
5
5
19
5
1
2
7
6
4
2
1
1
1
3
9
7
6
5
5
4
3
1
Cyathura munda
Paracerceis cordata
ldotea sp. (juvenile)
Jaeropsis dubia
3
1
1
1
Hippolyte clarki
Alpheus clamator
Heptacarpus palpator
4
1
Harpacticoida
Porcel/idium sp.
10
*
Pachycheles rudis
Loxorhynchus crispatus
2
5
1
1
3
1
8
2
2
1
11
3
3
3
1
2
15
3
2
1
5
2
0\
0\
ynapseudes intumescens
Leptochelia sp.
/
HOLDFAST 6
/
Lianaid
AN-E
SN
WB
11
22
3
7
43
2
9
3
2
5
3
28
32
25
44
38
27
14
4
5
1
5
4
4
1
3
12
5
1
1
23
18
13
11
6
5
2
2
1
1
1
16
11
5
2
6
16
16
8
7
6
*
ri.;»Prnn~i~ rl11hi::~
Limnoria algarum
Poly chaeta
Gammaridea
Turbellaria
Pelecypoda
Nematoda
Tanaidacea
Ophiuroidea
lsopoda
Ostracoda
Gastropoda
Nemertea
Natantia
Mysidacea
Copepoda
Cumacea
Reptantia
Caprellidea
Echinoidea
Pisces
Polyplacophora
Pycnogonida
AN-E
SN
WB
35
1142
82
1
25
747
38
6
25
102
3
2
2
13
30
8
13
14
8
23
16
4
3
12
5
33
4
7
7
2
1
10
3
2
5
8
9
7
6
1
2
20
1
4
1
3
1
T
6
15
1
RH
4090
885
19
123
114
85
57
22
47
49
59
12
12
.:~,~
2882
142
132
114
109
102
83
77
Cirolana parva
Mesanthura occidentalis
Paracerceis cordata
Gnathia sp.
/dotea resecata
/do tea rufescens
Ancinus granulatus
Califanthura squamosissima
Crepipatella lingulata
Barleeia sp.
Tricolia sp.
Conus californicus
Triopha grandis
Amphissa versicolor
Bittium sp.
2
1
1
3
2
RH
1
2
1
1
1
4
3
1
1
4
3
TO
3
1
B
2
5
4
1
4
2
T
2
1
2
1
1
2
2
2
1
1
Lirularia sp.
Volvarina taeniolata
1
Alpheus clamator
Heptacarpus palpator
8
4
3
2
20
12
43
6
4
2
4
4
5
14
5
3
3
Harpacticoida ..¥
Porcel/idium sp.
falanoida
Paraxanthias ray/on·
Loxorhynchus crispatus
Pachvcheles rudis
eagurus sp.
4
1
:f. iparis mucosus
5
Catlistochiton crassicostatus
4
6
8
7
1
1
1
1
5
2
2
0"\
-....)
BN
bacon'
Alia carinata
foropi1JUf11
Caecidae
Barleeia sp.
Tricolia sp.
Triopha grandis
AN-E
5
1
7
6
5
6
36
115
9
3
4
Crepipatella lingulata
1
2
1
1
Amphissa versicolor
Gammaridea
Mysidacea
Polychaeta
Gastropoda
lsopoda
BN
AN-E
SN
WB
T
RH
229
17
28
32
24
1391
2320
5
44
110
1232
123
1
23
17
7
5
22
2
28
1
3
31
40
27
30
23
17
4
483
1
1293
329
40
115
22
45
26
39
7
29
148
23
1
1
3
Nematoda
Natantia
Ophiuroidea
Turbellaria
Pelecypoda
Ostracoda
12
1
3
Copepoda
Tanaidacea
Nemer tea
Echinoidea
Aeptantia
Caprellidea
Cumacea
Polyplacophora
Pycnogonida
Zoea larva
3
3
1
1
1
2
8
1
11
6
6
8
1
4
1
2
5
1
1
4
1
26
27
19
2
1
1
Crepida/a sp.
I
HOLDFAST 7
/Jconus californicus
~:,y
2339
1379
571
207
115
96
96
90
64
38
Sinezona rimuloides
Turbonilla sp. A
[olvarma taemolata
Doto sp
Turbomlla sp
1
6
8
2
WB
T
RH
TO
12
1
1
209
48
22
9
15
13
380
64
31
21
16
15
8
8
7
5
5
3
3
2
7
2
1
1
5
3
1
1
2
1
B
Orlostom1a sp (eucosm1a~)
(juvenile)
Cyathura munda
61
15
1
5
3
Cirolana parva
28
2
8
5
4
12
5
2
3
3
1
2
24
2
7
1
5
Ancinus granulatus
!!~
i\ ~
4
4
Lacuna unifasciata
SN
1
4
2
!dotea rafescens
61
48
46
20
13
6
5
4
2
Limnoria algarum
Alpheus clan1ator
Heptacarpus palpator
Hippo/yte clarki
16
6
Betaeus gracilis
~ ~arpacticoicla
Porcel/~dium
*
10
22
5
2
10
1
19
3
1
9
sp.
r:alan01da
20
2
3
1
1
5
2
2
1
41
39
11
4
22
11
3
1
3
eptochelia sp.
oxorhynchus crispatus
Lophopanopeus bel/us
1
25
28
2
1
8
4
2
2
1
1
1
1
0\
00
HOLDFAST 8
Gammaridea
Gastropoda
Mysidacea
Copepoda
Turbellaria
Natantia
Echinoidea
Polychaeta
lsopoda
Pelecypoda
Nemertea
Reptantia
Caprellidea
Ostracoda
Asteroidea
Nematoda
Pisces
Cumacea
Ophiuroidea
Tanaidacea
Zoea larva
AN-F
AN-H
SN
WB
T
RH
TO
57
25
43
134
27
673
103
262
5
16
37
1
1
22
3
459
105
290
60
3
9
228
649
1716
942
308
146
50
49
40
35
30
11
6
4
1
3
7
2
2
3
2
1
5
1
29
31
1
4
6
9
9
3
1
4
2
2
2
1
1
1
2
2
1
Alia carinata
Crepidula sp.
Tricolia sp.
Caecidae
Crepipatella lingulata
Triopha grandis
Barleeia sp.
Nudibranchia
Doto sp.
Conus californicus
.II.N-F
AN-H
SN
WB
15
7
73
6
16
6
2
79
14
4
49
3
4
2
1
1
2
*
*
Harpacticoida
Porcellidium sp.
Calanoida
1
107
24
3
Heptacarpus palpator
Hippolyte clarki
Alpheus clamator
Heptacarpus taylori
5
20
15
2
11
10
1
1
2
2
608
22
824
52
24
17
11
6
2
2
2
2
118
25
3
30
15
2
2
15
13
1
1
2
2
2
8
6
2
2
1
2
1
1
1
2
1
TO
9
1
1
RH
2
6
1
1
2
1
6
T
1
(j\
\..0
AN-F
I
HOLDFAST 9
Gammaridea
Poly chaeta
Gastropoda
Natantia
Echinoidea
Isopod a
Ophiuroidea
Mysidacea
Copepoda
Pelecypoda
Nematoda
Turbett aria
AN-F
AN-H
SN
WB
T
RH
TO
50
1
5
4
674
11
18
18
349
19
27
35
4
21
11
15
1
8
62
17
4
2
2
236
267
33
1373
315
87
59
56
55
53
48
34
27
23
14
8
3
4
19
28
2
2
3
5
1
5
7
23
1
Nemertea
Reptantia
Ostracoda
Caprellidea
Tanaidacea
Cumacea
Holothuroidea
24
17
11
5
7
49
3
18
6
1
3
2
1
1
1
1
3
4
4
1
2
1
1
2
6
1
2
1~
Caecidae
Alia carinata
Barleeia sp.
Amphissa versicolor
Crepipatella lingulata
Tricolia sp.
Crepidula sp.
Doto sp.
Conus ca/ifornicus
4
AN-H
SN
WB
4
2
5
2
7
4
1
7
2
2
3
1
1
3
2
T
RH
TO
8
8
6
21
20
12
9
7
6
3
3
1
1
1
1
1
1
7
2
1
1
1
Sinezona rimuloides
Triopha grandis
Volvarina taeniolata
Hippolyte clarki
Heptacarpus plapator
Alpheus clamator
Heptacarpus picrus
Paracerceis cordata
ldotea sp. (juvenile)
1
1
1
4
15
3
17
2
Cirolana parva
25
7
2
1
29
24
5
1
2
7
8
1
2
1
2
1
1
1
2
6
Limnoria algarum
/dotea resecata
2
ldotea rufescens
*
Harpacticoida
Porcellidium sp.
Calanoida
6
1
18
9
1
2
3
28
10
1
4
3
2
1
1
1
21
12
1
2
1
3
2
1
-....J
0
~
HOLDFAST 10
Gammdridea
Polychaeta
Pelecypoda
Copepoda
Gastropoda
Caprell idea
Turbellaria
Ophiuroidea
lsopoda
Echinoidea
Natantia
Nemertea
Reptantia
Nematoda
Ostracoda
Pisces
Tanaidacea
BN
-
BN
AN-E
SN
WB
T
RH
36
74
373
10
2
40
7
5
19
1
6
182
21
11
70
45
13
12
1
3
27
37
41
2
72
310
88
1
18
18
8
15
5
1
11
3
10
4
3
1
7
6
1
1
3
1
5
1
1
1
2
1
1
1
1
L!..VILJ:IIIUIUHI
:.p.
Alia carinata
5
Crepipatel/a lingulata
Tricolia sp.
Barleeia sp.
Triopha grandis
5
2
Caecidae
Amphissa versicolor
Doto sp.
"=-----r~,·=<>·
,~_,.,.,....
13
10
~
Heptacarpus pictus
Hippo!yte clarki
1_~oxorhynchuscrispatus
Cancer sp.
SN
15
25
65
5
2
1
3
1
25
16
1
3
WB
4
5
1
T
RH
TO
1
80
31
1
10
2
2
2
2
1
1
3
!dotea sp. (juvenile)
laniropsis tridens
Jaeropsis dubia
'~'-"~~
2
1
AN-E
2
4
4
1
1
8
3
2
1
1
6
5
4
1
1
1
1
1
37
32
11
1
1
1
2
Leptochelia sp.
-....J
,_....
....
AN-F
/
HOLDFAST 11
Polychaeta
Gammaridea
Gastropoda
Ophiuroidea
Pelecypod a
Nematoda
Isopod a
Copepoda
Ostracoda
Turbellaria
AN-F
AN-H
SN
WB
83
44
487
21
27
304
55
15
7
45
94
13
35
28
9
1
7
7
1
1
6
7
2
63
18
Tanaidacea
Echinoidea
Caprellidea
Nemertea
Natantia
Reptantia
Holothuroidea
Mysidacea
Cumacea
Pycnogonida
1
22
12
2
18
3
20
4
1
2
10
3
4
2
6
2
23
10
5
3
3
1
1
T
4
5
1
RH
1265
390
104
87
50
R6
45
12
14
41
20
7
19
5
2
2
1
1
TO/
1381
1362
193
164
97
88
AN-H
SN
WB
2
2
1
3
3
29
7
3
4
6
4
1
1
1
2
4
2
2
2
1
forophium baconi
3
Caecidae
I
Alia carinata
Bar/eeia sp.
Crepipatella lingulata
Sinezona rimuloides
Tricolia sp.
Turbonilla sp. A
Volvarina taeniolata
Amphissa versicolor
Triopha grandis
Conus californicus
Crepidula sp.
Data sp.
Odostonia sp. (navisa?)
Turbonilla sp. 8
Nudibranchia lll<
Odostomia sp. (eucosmia?)
Teinostoma sp.
4
7
Limnoria a/garum
Cirolana parva
2
2
1
3
2
2
2
2
6
1
1
2
4
1
1
1
6
1
38
1
6
1
2
2
11
2
1
*
1
Atpheus clamator
1
1
Heptar.arpus taylori
tfippo/yte clarki
1
2
I.oxorhynchus crispatus
Paraxanthias taylori
1
1
52
40
22
20
8
7
7
7
6
6
5
3
3
2
2
53
8
7
3
3
3
2
2
55
12
1
5
35
3
3
41
4
3
3
2
1
3
5
12
2
2
2
2
1
§_vnapseudes in rumescens
Heptacarpus palpator
TO
3
43
9
14
11
8
2
52
eptochelia sp.
Tanaid
RH
2
2
Cyathura munda
/aniropsis tridens
Jaeropsis dubia
Paracerceis cordata
!dotea sp. (juvenile)
Mesanthura occidentalis
T
4
1
-.....!
N
Dmnoria algarum
Gammaridea
Polychaeta
Isopoda
Nematoda
Copepoda
Tanaidacea
Gastropoda
Pelecypoda
Natantic:
Ostracoda
Ophiuroidea
Turbellaria
Nemertea
Mysidacea
Reptantia
Cum ace a
sN1
SN2
SN3
SN4
SNs
SN6
WB
T
RH
1372
157
100
8
209
31
40
23
20
21
7
861
50
112
3
34
21
45
10
12
26
5
4
138
4
20
61
8
10
49
14
6
22
4
3
18
6
1
33
24
4
1
1
1
431
1594
104
250
1
2
4
2
2
6
3
3
6
4
1
1
1
2
1
2
5
8
9
,
1
6
3
3
1
1
2
1
5
2
1
1
1
1
3
y
I
TO
AN-E
2
2
7
6
4
2
JCyarhura munda
I
HOLDFAST 12
82
33
51
39
6
32
15
12
2
1
1
/
Gnarhia sp.
Mesanthurd occidentalis
Grldthia crenulatifrons
1, ______________ , __
245
147 ..
134
Calano•da
mproche~a '"·
Tanaul V:
105~
86\
SN1
11
17
1
30
23
31
11
91
7
8
5
15
4
1
SN2
SN3
SN4
SNs
7
2
1
3
3
1
2
SN6
WB
T
1
2
1
RH
TO
89
237
29
1
1
2
5
6
1
2
1
50
47
17
2
2
2
U!fop/wsm.s gem;narum
~~~~ ~'ceih<lhun
w
Harp~ct•couJ;• "~
361
261
AN-E
27
7
1
1
230
13
2
7
13
6
Synapseudes mwmescens
11
7
2
1
1
3
1
Crep11fl!teJfa tmgulata
31
4
4
23
21
1
5
1
2
4
1
Barlee1a sp.
Alpheus clam~tor
Beraeusaracilis
16
3
9
4
3
4
1
[:wo/iJ;p
62
202
5
2
8
2
2
1
77
62
14
6
36
34
9
8
57
45
12
39
79
51
21
18
16
14
9
Pisces
Echinoidea
Caprellidea
Holothuroidea
<
2
1
1
\ \ 'i
3
'-.I
w
APPENDIX B
Species list (incomplete
see materials and methods).
Some of these species were also reported by Andrews (1945)
(A), Ghelardi (1960) (G) 1 McLean (1962) (M), North (1971)
(N)
and Rosenthal et al (1974) (R).
Polyplacophora
Callistochiton crassicostatus Pilsbry, 1893
Cyanoplax hartwegii (Carpenter, 1855)
Gastropoda
Alia (Mitrella) carinata (Hinds, 1844) (A,G,M,N,R)
AffiPhissa versicolor Dall, 1871 (A,G,M,N)
Barleeia sp.
Bittium interfossa (Carpenter, 1864) (M)
Bittium sp.
Cerithiopsis sp.
Conus californicus Reeve, 1844 (G,R,N)
Crepidula sp.
Crepipatella lingulata (Gould, 1846) (G,N)
Doridella steinbergae (Lance, 1962)
Doto sp.
Lacuna unifasciata Carpenter, 1857 (N)
Lirularia sp.
Norrisia norrisi (Sowerby, 1838) (G,N,R)
Odostomia sp. (eucosmia ? )
Odostomia sp. (navis a ? ) .
Sinezona rimuloides (Carpenter, 1865)
Teinostoma sp.
Tricolia sp.
Triopha grandis MacFarland, 1905
Turbonilla sp. A
Turbonilla sp. B
Volvarina taeniolata Morch, 1860
Pelecypoda
Hiatella artica (Linnaeus, 1767) (M,N)
Leptopecten latiauratus (Conrad, 1837) (G,N)
Lima hemphilli Hertlein & Strong, 1946 (G,M,N,R)
Polychaeta
Phragmatopoma sp.
Copepoda
Porcellidium sp.
Tanaidacea
Leptochelia sp.
Synapseudes intumescens Menzies, 1949 (G,N)
74
75
Isopoda
Ancinus granulatus (Holmes & Gay)
Califanthura squamosissima (Menzies 1 1951) (G,N)
Cirolana parva Hansen, 1890 (G,N)
Cyathura munda Menzies, 1951
Gnathia crenulatifrons Monod, 1926
Gnathia sp.
Ianiropsis tridens (Menzies, 1952)
Idotea resecata Stimpson, 1857 (A,N,R)
Idotea rufescens Fee, 1926 (N)
Idotea urotoma Stimpson, 1864
Idotea sp. (juvenile)
Jaeropsis dubia (Menzies, 1951) (G,N)
Limnoria (Phycolimnoria) algarum Menzies, 1956 (G,N)
Mesanthura occidentalis (Menzies & Barnard, 1959)
Munna (Uromunna) sp.
Paracerceis cordata (Richardson, 1899) (N)
Silophasma geminatum (Menzies & Barnard, 1959)
Amphipoda
Corophium baconi (Shoemaker, 1949)
Natantia
Alpheus clamator Lockington, 1877
Betaeus gracilis Hart, 1964
Betaeus setosus Hart, 1964
Betaeus sp.
Heptacarpus palpator (Owen, 1839) (A,N)
Heptacarpus pictus (Stimpson, 1871)
Heptacarpus ta~lori (Stimpson, 1857)
Hippolyte clar i Chace, 1951
Reptantia
Cancer sp.
Lophopanopeus bellus (Stimpson, 1860) (A,G,N)
Loxorh~nchus crispatus Stimpson, 1857 (M,N)
Pachyc eles rudis Stimpson 1 1859 (A,N,R)
Pagurus sp·
Paraxanthias taylori (Stimpson, 1860) (A,N)
Pugettia producta (Randall, 1839) (A,M,N)
Taliepus nuttalli (Randall, 1839) (N,R)
Pisces
Hypsoblennius sp.
Liparis mucosus Ayres, 1855 (N)
Paraclinus integritinnis (Smith, 1880) (N)
Rimicola muscarum Meek & Pierson, 1895) (N)
Ulvicola sanctaerosae Gilbert & Starks, 1897 (N)
APPENDIX C
Collection date and the number of fronds for each holdfast.
HOLDFAST
DATE COLLECTED
FRONDS
1
3/7/79
25
2
3/7/79
19
3
3/22/79
42
4
3/22/79
16
5
4/7/79
9
6
4/7/79
21
7
6/2/79
38
8
6/2/79
11
9
6/2/79
16
10
6/3/79
14
11
6/3/79
15
12
9/22/79
24
76