DOC
EPA
United States
Department of
Commerce
National Oceanic and Atmospheric
Administration
Seattle WA 98115
United States
Environmental Protection
Agency
Office of Environmental Engineering
and Technology
Washington DC 20460
EPA-600/7-80-032
February 1980
Research and Development
Plankton of the
Strait of
Juan de Fuca
1976-1977
Interagency
Energy/Environment
R&D Program
Report
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RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development, U.S. Environmental
Protection Agency, have been grouped into nine series. These nine broad cate-
gories were established to facilitate further development and application of en-
vironmental technology. Elimination of traditional grouping was consciously
planned to foster technology transfer and a maximum interface in related fields.
The nine series are:
1. Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental Studies
6. Scientific and Technical Assessment Reports (STAR)
7. Interagency Energy-Environment Research and Development
8. "Special" Reports
9. Miscellaneous Reports
This report has been assigned to the ECOLOGICAL RESEARCH series. This series
describes research on the effects of pollution on humans, plant and animal spe-
cies, and materials. Problems are assessed for their long- and short-term influ-
ences. Investigations include formation, transport, and pathway studies to deter-
mine the fate of pollutants and their effects. This work provides the technical basis
for setting standards to minimize undesirable changes in living organisms in the
aquatic, terrestrial, and atmospheric environments.
This document is available to the public through the National Technical Informa-
tion Service, Springfield, Virginia 22161.
-------
Replacement for Inside Cover
RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development, U.S. Environmental
Protection Agency, have been grouped into nine series. These nine broad cate-
gories were established to facilitate further development and application of en-
vironmental technology. Elimination of traditional grouping was consciously
planned to foster technology transfer and a maximum interface in related fields.
The nine series are:
1. Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental Studies
6. Scientific and Technical Assessment Reports (STAR)
7. Interagency Energy-Environment Research and Development
8. "Special" Reports
9. Miscellaneous Reports
This report has been assigned to the INTERAGENCY ENERGY-ENVIRONMENT
RESEARCH AND DEVELOPMENT series. Reports in this series result from the
effort funded under the 17-agency Federal Energy/Environment Research and
Development Program. These studies relate to EPA's mission to protect the public
health and welfare from adverse effects of pollutants associated with energy sys-
tems. The goal of the Program is to assure the rapid development of domestic
energy supplies in an environmentally-compatible manner by providing the nec-
essary environmental data and control technology. Investigations include analy-
ses of the transport of energy-related pollutants and their health and ecological
effects; assessments of, and development of, control technologies for energy
systems; and integrated assessments of a wide range of energy-related environ-
mental issues.
This document is available to the public through the National Technical Informa-
tion Service, Springfield, Virginia 22161.
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PLANKTON OF THE STRAIT OF JUAN DE FUCA, 1976 - 1977
by
Alexander J. Chester
David M. Damkaer
Douglas B. Dey
Gayle A. Heron
Jerry D. Larrance
Pacific Marine Environmental Laboratory
Environmental Research Laboratories
National Oceanic and Atmospheric Administration
7600 Sand Point Way N.E.
Seattle, Washington 98115
Prepared for the MESA (Marine Ecosystems Analysis) Puget Sound
Project, Seattle, Washington in partial fulfillment of
EPA Interagency Agreement No. D6-E693-EN
Program Element No. EHE625-A
This study was conducted
as part of the Federal
Interagency Energy/Environment
Research and Development Program
Prepared for
OFFICE OF ENERGY, MINERALS, AND INDUSTRY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
WASHINGTON, D.C. 20460
September 1979
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Completion Report Submitted to
PUGET SOUND ENERGY-RELATED RESEARCH PROJECT
MARINE ECOSYSTEMS ANALYSIS PROGRAM
ENVIRONMENTAL RESEARCH LABORATORIES
by
Pacific Marine Environmental Laboratory
Environmental Research Laboratories
National Oceanic and Atmospheric Administration
7600 Sand Point Way N.E.
Seattle, Washington 98115
This work is the result of research sponsored by the Environmental
Protection Agency and administered by the Environmental Research
Laboratories of the National Oceanic and Atmospheric Administration.
The Environmental Research Laboratories do not approve, recommend,
or endorse any proprietary product or proprietary material mentioned
in this publication. No reference shall be made to the Environmental
Research Laboratories or to this publication furnished by the
Environmental Research Laboratories in any advertising or sales
promotion which would indicate or imply that the Environmental
Research Laboratories approve, recommend, or endorse any proprietary
product or proprietary material mentioned herein, or which has as its
purpose an intent to cause directly or indirectly the advertised
product to be used or purchased because of this Environmental Research
Laboratories publication.
it
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CONTENTS
Figures ,v
Tables ! . ! ! ! vi
Abstract '.!."!!!!!!!!!!! vii
Acknowledgments i !!!!!!!!!!!!!! iviii
1. Introduction j
2. Conclusions 3
3. Sampling and Laboratory Methods 5
4. Results and Discussion 8
4.1. Physical Characteristics ...........'. 8
4.2. Oceanic Intrusions and Indicator Species .'!!.' 8
4.3. Phytoplankton Distribution ] 8
4.3.1. Phytoplanktonic Biomass '.'.'. 10
4.3.2. Phytoplankton Species Composition 14
4.4. Microzooplankton Distribution 20
4.5. Zooplankton Distribution . . . 21
4.5.1. Zooplanktonic Biomass ! ! ! ! 22
4.5.2. Zooplankton Species Composition 26
4.6. Ichthyoplankton Distribution 28
5. References 32
APPENDICES *
A. Pigment Distributions, Strait of Juan de Fuca,
February 1976 - October 1977 Al
B. Tabulated Phytoplankton Data, Strait of Juan de Fuca,
February 1976 - October 1977 Bl
C. Zooplankton Species and Major Groups, Strait of Juan de Fuca,
February 1976 - October 1977 Cl
D. Tabulated Zooplankton Data, Strait of Juan de Fuca,
February 1976 - October 1977 Dl
E. Tabulated Ichthyoplankton Data, Strait of Juan de Fuca,
February 1976 - October 1977 El
* Appendices on Microfiche inside back cover.
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FIGURES
1. Area chart and station locations for Strait of Juan de Fuca
cruises, February 1976 - October 1977 35
2. Chlorophyll a in the upper 50 m of the Strait of Juan de Fuca,
1976 - 1977 36
3. Diatom concentrations in the upper 1 m of the Strait of Juan de
Fuca, 1976 - 1977 37
4. Dinoflagellate concentrations in the upper 1 m of the Strait of
Juan de Fuca, 1976 - 1977 38
5. Concentrations of ciliates in the surface waters of the Strait
of Juan de Fuca, 1976 - 1977 39
6. Zooplankton settled volumes. Vertical tows, 211 ym mesh size;
total water column. Strait of Juan de Fuca, 1976 - 1977 40
7. Zooplankton settled volume. Vertical tows, 211 ym mesh size;
top 100 m. Strait of Juan de Fuca, 1976 - 1977 41
8. Zooplankton settled volumes, means of grouped stations. Oblique tows
(50-0 m), 333 ym mesh size. Strait of Juan de Fuca, 1976 - 1977 . 42
9. Copepod abundance from vertical hauls, Strait of Juan de Fuca,
February 1976 - October 1977; total number collected per total
water volume filtered, by cruise 43
10. Pseudoaalanus spp. (adults). Number of animals nr3. Station 2,
Strait of Juan de Fuca, 1976 - 1977 44
11. Pseudocalanus spp. (adults). Number of animals m~3. Station 5,
Strait of Juan de Fuca, 1976 - 1977 45
12. Pseudooalanus spp. (adults). Number of animals m"3. Station 8,
Strait of Juan de Fuca, 1976 - 1977 46
13. Pseudooalanus spp. (juveniles). Number of animals m~? Station 2,
Strait of Juan de Fuca, 1976 - 1977 47
14. Pseudooalanus spp. (juveniles). Number of animals m~3. Station 5,
Strait of Juan de Fuca, 1976 - 1977 48
iv
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15. Pseudoaalanus spp. (juveniles). Number of animals nf3. Station 8,
Strait of Juan de Fuca, 1976 - 1977 49
16. Acartia longiremis (adults). Number of animals nf3. Station 2,
Strait of Juan de Fuca, 1976 - 1977 50
17. Aaartia longivemis (adults). Number of animals m~3. Station 5,
Strait of Juan de Fuca, 1976 - 1977 51
18. Aeartia longiremis (adults). Number of animals m~3. Station 8,
Strait of Juan de Fuca, 1976 - 1977 52
19. Oithona simLlis (adults). Number of animals m~3. Station 2,
Strait of Juan de Fuca, 1976 - 1977 53
20. Oithona similis (adults). Number of animals nf3. Station 5,
Strait of Juan de Fuca, 1976 - 1977 54
21. Oithona similis (adults). Number of animals ra"3. Station 8,
Strait of Juan de Fuca, 1976 - 1977 55
22. Calanus nwshallae (adults). Number of animals m"3. Station 2,
Strait of Juan de Fuca, 1976 - 1977 56
23. Calanus marshallae (adults). Number of animals irf5. Station 5,
Strait of Juan de Fuca, 1976 - 1977 . 57
24. Calanus marshdllae (adults). Number of animals m~3. Station 8,
Strait of Juan de Fuca, 1976 - 1977 58
25. Sagitta elegans. Number of animals m"3. Station 2,
Strait of Juan de Fuca, 1976 - 1977 59
26. Sagitta elegans. Number of animals m"3. Station 5,
Strait of Juan de Fuca, 1976 - 1977 60
27. Sagitta elegans. Number of animals m"3. Station 8,
Strait of Juan de Fuca, 1976 - 1977 61
28. Number of ichthyoplankton taxa caught in surface and oblique
net hauls, Strait of Juan de Fuca, 1976 - 1977 62
»
29. Concentration of fish eggs caught in surface and oblique
net hauls, Strait of Juan de Fuca, 1976 - 1977 63
30. Concentration of fish larvae caught in surface and oblique
net hauls, Strait of Juan de Fuca, 1976 - 1977 64
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TABLES
1. Summary of sampling activities in the Strait of Juan de Fuca,
February 1976 - October 1977 6
2. Current reversals (intrusions) and presence of oceanic
surface-living plankton species, Strait of Juan de Fuca,
February 1976 - October 1977 9
3. Diatom species in upper 1 m, Strait of Juan de Fuca 11
4. Percentage Similarity values for phytoplankton in upper 1 m,
Strait of Juan de Fuca 16
5. Percentage Similarity values for station to station comparisons of
all phytoplankton populations during Strait of Juan de Fuca cruises,
1976 - 1977. PS values >_ 60 are underlined 18
6. Percentage Similarity values for station to station comparisons of
diatom populations during Strait of Juan de Fuca cruises,
1976 - 1977. PS values >_ 60 are underlined 19
7. Zooplankton settled volumes (ml m~3) from vertical tows (211 um mesh
size) taken in the Strait of Juan de Fuca, 1976 - 1977 23
8. Zooplankton settled volumes (ml rrf3) from oblique tows (333 \an mesh
size) taken in the upper 50 m of the Strait of Juan de Fuca,
1976 - 1977 25
9. Ichthyoplankton organisms caught in surface and oblique net hauls,
Strait of Juan de Fuca, 1976 - 1977 29
VI
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ABSTRACT
The exploitation of Alaskan oil deposits and anticipation of increased
oil transport through the Strait of Juan de Fuca to Washington State refin-
eries have generated concerns about the effects of petroleum spillage on
local marine communities. Although aspects of plankton research have been
actively pursued in Puget Sound and off the Pacific coast, virtually no pre-
vious quantitative investigations have been conducted in the Strait of Juan
de Fuca.
The composition and distribution of phytoplankton, zooplankton, and
ichthyoplankton communities was studied during 13 cruises conducted in the
Strait of Juan de Fuca from February 1976 to October 1977. Phytoplankton was
numerically dominated by microflagellate species during late autumn and
winter months. During June 1976, a diatom bloom composed primarily of
Skeletonema oostatum was in progress, and chlorophyll concentrations as great
as 25 mg nr3 were measured. Diatoms were also dominant in the spring and
summer of 1977, but no bloom similar to that of 1976 was encountered.
Ciliates numerically dominated the microzooplankton community, with oligo-
trichs and tintinnids the most abundant. The settled volumes of net zoo-
plankton increased steadily through the late winter and spring. The highest
levels coincided with the June 1976 phytoplankton bloom. The most numerous
zooplankters were copepods, especially near-surface and surface-living
calanoids and cyclopoids. The sporadic occurrence of a group of oceanic
surface-living plankton species was associated with documented oceanic
intrusions and current reversals. The ichthyoplankton, composed principally
of fish larvae, were most abundant during the winter and early spring months.
This report was submitted to NOAA's Marine Ecosystem Analysis (MESA)
Office as part of the Puget Sound Energy-Related Project sponsored by the
U.S. Environmental Protection Agency.
vii
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ACKNOWLEDGMENTS
The authors are grateful to their colleague Mr. David A. Tennant for his
assistance during many of the cruises. We also wish to express appreciation
and thanks to Mr. Kenneth Waldron of the National Marine Fisheries Service
for providing data from the ichthyoplankton samples.
This study was supported by the U.S. Environmental Protection Agency
through an interagency agreement with the Environmental Research Laboratories
of NOAA.
viii
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1. INTRODUCTION
An important aspect of NOAA's Marine Ecosystem Analysis (MESA) Puget
Sound Energy-Related Project was to characterize the communities of the
inshore marine waters of Washington State. With respect to the plankton, the
least known major marine area is the Strait of Juan de Fuca, which separates
Puget Sound from the Pacific Ocean. The present study was conducted in the
Strait during 1976 and 1977 to describe the seasonal distribution and
composition of phytoplankton, zooplankton, and ichthyoplankton populations.
This information will add to MESA's overall biological baseline, and could aid
in monitoring and understanding the effects of possible petroleum discharges
associated with increased tanker transport through the Strait of Juan de Fuca.
Data and interpretations are presented concerning species composition, phyto-
plankton biomass as indexed by chlorophyll concentration, zooplankton densities
in the water column and at the surface, and distribution of ichthyoplankton.
The Strait of Juan de Fuca is a deep estuary connecting the inland marine
waters of Washington State with the Pacific Ocean (Fig. 1). It is character-
ized hydrographically as a two-layered system with an annual net westward flow
of relatively fresh water in the upper 30 m and more saline oceanic water
below. The Strait receives a large influx of fresh water from drainages into
Puget Sound and the Fraser River, which empties into the Strait of Georgia to
the north. There are two periods of high runoff. The major one occurs in late
spring when snowmelt is at a maximum in the Cascade and Olympic mountain
ranges. A smaller runoff period occurs during late fall and winter when pre-
cipitation is high.
Physical oceanographic characteristics of the Strait of Juan de Fuca have
been treated elsewhere (e.g. Herlinveaux and Tully, 1961; Cannon, 1978). In
general, salinity dominates the density structure throughout the year. During
the summer a thermocline coincides with the halocline to reinforce the stab-
ility of the upper layer. In the winter, waters are either isothermal or the
upper layers tend to be slightly colder than deeper layers. Tides and tidal
currents are considered to be important oceanographic components of the Strait
of Juan de Fuca system. During flood tide, dense ocean water enters the outer
Strait and flows beneath the upper zone. The inner Strait is a region of
exchange where brackish water contributed by the Strait of Georgia is mixed
to homogeneity and enriched with ocean water. Part of this water returns to
the deep zone of Georgia Strait, and part escapes seaward in the upper zone of
the Strait of Juan de Fuca during ebb tide. In addition to exchange with
Georgia Strait, Juan de Fuca water mixes vigorously with Puget Sound and Hood
Canal waters in the region of Admiralty Inlet during tidal flow. Because the
Strait of Juan de Fuca is a positive estuary where strong tides mix coastal
and inner basin waters, it is of interest to determine if the plankton com-
munities found there are mixtures of coastal and embayment populations, or are
1
-------
distinct from those in the source waters. The information obtained also pro-
vides a basis for comparing future plankton observations and for designing
future research efforts.
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2. CONCLUSIONS
Thirteen research cruises were conducted at about 6 to 8 week intervals
during 1976 and 1977 to provide information on the seasonal distribution and
abundance of planktonic organisms in the Strait of Juan de Fuca. Major
groups examined included phytoplankton, micro- and macrozooplankton, and
ichthyoplankton.
Phytoplankton, the major primary producers of organic matter in pelagic
ecosystems, were studied by biomass estimation (indexed by chlorophyll a
content) and by direct species count. Pigment concentrations were highest
during June 1976 at the time of a large spring phytoplankton bloom. No large
bloom was encountered in the Strait during 1977, but it is possible that a
bloom occurred between sampling periods. Major forms of phytoplankton included
diatoms, dinoflagellates, coccolithophorids, and miscellaneous microflagellates
in general, microflagellates were the dominant component of the phytoplankton
community during late autumn and winter months. Diatoms contributed the
major biomass portion during mid-spring to early summer; high concentrations
were also found during a fall bloom off Neah Bay in 1976. Dinoflagellates
reached their maximum numbers during late summer and early autumn, especially
at stations east of Neah Bay.- Coccolithophorids were rare except when intru-
sions of ocean water flooded into the Strait. An analysis of species similar-
ity showed the structure of diatom communities to be non-uniform from one
end of the Strait to the other during any one cruise. Often the variability
in percent species similarity during a single cruise was as great as variations
between cruises.
Microzooplankton is thought to be an important, and often overlooked,
trophic link between the smallest phytoplankton cells and the larger zooplank-
ton. in the Strait of Juan de Fuca, particle grazing ciliates such as oligo-
tncns and tintinnids were most numerous. Mesodinium rubrm, a ciliate that
may derive a major portion of its nutrition from photosynthetic endosymbionts,
was also present in significant numbers. Besides protozoans, metazoans such
as juvenile crustaceans, trochophore larvae, and rotifers occurred. Maximum
microzooplankton concentrations coincided with periods of high phytoplankton
concentration during spring aod summer.
Larger zooplankters are the major grazers of phytoplankton and as such
represent a critical trophic intermediary between primary producers and car-
7nnn^ni;tnnrtiCUlr^ ?ommercial1y valuable fish. In general, the biomass of
zooplankton closely followed the seasonal distribution of chlorophyll concen-
7nnni^nJn t- "PP6^50 m of the s^ait of Juan de Fuca. That is, maximum
zooplankton biomass levels were observed in the spring and summer. Copepods
were always the most abundant net-zooplankters, and these organisms showed the
same seasonal trends as total zooplankton volume. Three groups of "oceanic"
copepods not usually associated with coastal regions were identified in the
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Strait of Juan de Fuca. One group, composed of deep-living oceanic species,
is excluded from Puget Sound by the shallow entrance sill; a second group of
deep oceanic copepods found occasionally near the surface is present in Puget
Sound; and a third group of oceanic surface-living copepods was found in the
Strait during periods of ocean-water intrusions and current reversals.
In contrast to the zooplankton, the highest concentrations of fish eggs
and larvae were recorded in late winter and early spring, prior to the period
of greatest phytoplankton productivity. The number of fish larvae usually
exceeded the number of eggs present, probably because the most common larval
forms in the Strait of Juan de Fuca are demersal spawners. Most larval
species showed no particular preference for the surface waters, but one group,
Hexagrconmos spp., was pleustonic.
Of particular note is the unexpected presence of oceanic surface-living
phyto- and zooplankton species in the Strait. These species occurrences were
well correlated with times of independently documented oceanic intrusions.
These intrusions can at times influence even the eastern portion of the Strait,
and their presence suggests a reevaluation of ideas regarding pollution dis-
persement that are based on net water transport assumptions.
The Strait of Juan de Fuca is a dynamic estuarine system joining the
Pacific Ocean and the inland marine waters of Washington State and British
Columbia. The structure of the plankton community at any one time is influ-
enced by the complex physical exchanges between these bodies of water as well
as the biological characteristics of individual species and groups of species.
Seasonal cycles outlined in this report can only be considered approximations
of natural events. Short-term fluctuations could not be examined because of
the long periods between sampling. Future investigations might profitably
concentrate on the winter-spring transition period, stressing the increase in
primary production and the coupling of zooplankton species productivity to
phytoplankton biomass.
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3. SAMPLING AND LABORATORY METHODS
Thirteen sampling cruises to the Strait of Juan de Fuca were conducted
at intervals of approximately six weeks during 1976 and 1977. Sampling
activities are summarized in Table 1. In general, during each cruise three
transects of three stations apiece were made across the Strait at Port
Angeles, Pillar Point, and Neah Bay near Cape Flattery (Fig. 1). Only the
Port Angeles line was occupied during cruise SF7603 due to mechanical failure
of the vessel.
At every station occupied, an obliquely towed plankton net and a pleuston
sampler were used to sample the zooplankton. A double bongo net was used for
the initial three cruises for oblique tows, but because of handling difficult-
ies, this was replaced by a single net of similar configuration (333 urn mesh,
60 cm mouth diameter) suspended in a newly designed frame. Like the bongo net,
the new single net had no bridle or other obstruction in front, and the mouth
was free to swivel to maintain the net in a plane perpendicular to the towing
direction. The oblique net was towed from 50 m to the surface while being
slowly retrieved. For cruise SF7607 and all subsequent cruises, a digital
flowmeter (General Oceanics, Model 2030) was fitted to the net frame to more
accurately measure the volume of water filtered. The pleuston net, equipped
with a 333 ym net, was towed at the surface, away from the ship's wake, for
10 minutes. The zooplankton samples were preserved with sodium acetate
buffered 4% formaldehyde and returned to Seattle for analysis.
At each midchannel station (2, 5, and 8) only, a bottle cast and a series
of vertical closing-net hauls were made in addition to the oblique and
pleuston tows. Niskin bottles (1.5 1) were used to obtain water samples at
0, 10, 20, 30, 40, and 50 m. Subsamples were drawn directly to determine
chlorophyll and pheopigment content and the phytoplankton and microzooplankton
species assemblages. Phytoplankton and microzooplankton subsamples were
preserved in an acetate buffered 1.5% formaldehyde solution. These were later
analyzed in the laboratory using the inverted microscope technique described
by Uterm'ohl (1931). Pigment concentration was measured with a shipboard
fluorometer (Turner, Model 111) following the discrete sample method of
Lorenzen (1966). The vertical hauls were made with a 211 ym mesh, 60 cm
mouth diameter closing net. Usual depth strata sampled were: near bottom to
100 m, 100 m to 50 m, 50 m to 25 m, and 25 m to the surface. Sampling inter-
vals were adjusted for shallower stations.
To compare the catch efficiency of the bongo net with the single net
design and to examine the precision of these methods, a series of ten
alternating oblique tows was taken during cruise SF7705; five replicate
samples were obtained with each net. The total volume of plankton caught
per volume of water filtered was determined for each sample; no significant
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TABLE 1. Summary of sampling activities in the Strait of Juan de Fuca,
February 1976 - October 1977.
No. of Samples
Cruise
SF7601
SF7602
SF7603
SF7604
SF7605
SF7606
SF7607
SF7701
SF7702
SF7703
SF7704
SF7705
SF7706
Date
23-24 Feb
5-6 Apr
17-18 May
28-30 June
3-5 Aug
14-16 Sept
12-15 Nov
11-13 Jan
22-25 Feb
5-6 Apr
1-3 June
25-28 July
3-5 Oct
Vessel No. of
Stations
O)
_o
Commando
Commando
Hydah
Snow Goose
Snow Goose
Snow Goose
Snow Goose
Snow Goose
Snow Goose
Snow Goose
Snow Goose
Snow Goose
Snow Goose
8
9
7
9
9
9
9
9
9
9
9
9
9
o
8
9
7
9
9
9
9
9
9
9
9
18
9
leuston
o_
8
9
7
9
9
9
9
9
9
9
9
9
9
(O
o
4-»
Ol
11
11
11
11
11
11
11
11
11
11
11
19
11
c
o
c
to
'o.
o
4-J
.c:
ex
18
18
18
18
18
18
18
18
18
18
18
22
18
icrozooplankton
s:
2
5
4
3
4
3
3
3
3
3
3
3
3
5
o.
o
o
.c
o
18
18
18
18
18
23
18
18
18
18
18
30
18
heopigments
0.
18
18
18
18
18
23
18
18
18
18
18
30
18
-P
co
10
O
l_
o
0
3
0
3
3
3
3
1
3
3
3
3
3
Totals:
114
123 114 147 238 42 251 251 31
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difference (0.05 level) was found between the means of the two groups.
Settled volumes of all zooplankton samples were determined. Large or
otherwise conspicuous organisms were removed, counted, and identified at
least to major taxonomic group. Fish eggs and larvae were delivered to the
Northwest and Alaska Fisheries Center of the National Marine Fisheries
Service for further identification. Subsamples were obtained with a Folsom
plankton splitter (McEwen et al., 1954) and sorted entirely to major taxon-
omic groups. Principal species and copepods were identified and counted.
During cruises SF7602 and SF7604-SF7702, a hand-lowered CSTD (Inter-
ocean, Model 513A) was employed at the midchannel stations to collect salinity
and temperature information in the upper 100 m. During subsequent cruises, a
Plessey Environmental Systems CTD Model 4600 was used.
Data collected are archived on magnetic tape and are available at NOAA's
National Oceanographic Data Center in Washington, D.C.
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4. RESULTS AND DISCUSSION
4.1. PHYSICAL CHARACTERISTICS
CTD casts were made during 11 cruises. The vertical profiles of temper-
ature, salinity and density are generally consistent with the pattern describ-
ed by Herliveaux and Tully (1961). During April (SF7602), the deeper waters
tended to be slightly warmer than overlying layers. For all cruises the
surface salinity increased in a seaward direction. A well-developed pycnocline
with a distinct surface layer in late June (SF7604) coincided with a peak of
phytoplankton biomass and is probably an important factor influencing the
development of the bloom. Profiles obtained during later cruises clearly show
that salinity controls the density field. Although surface waters were warmed,
the lack of a well-defined halocline prevented the formation of a shallow
stable layer.
4.2. OCEANIC INTRUSIONS AND INDICATOR SPECIES
The sporadic occurrence in the Strait of Juan de Fuca of a group of
oceanic surface-living plankton species (Table 2) was unexpected, in view of
the quasi-constant surface outflow. In November 1976, a large bloom of phyto-
plankton occurred off Neah Bay (Station 8) and was accompanied by typically
offshore phytoplankton and zooplankton species. Physical parameters had been
independently monitored at that time and revealed an intrusion of relatively
warm ocean water in the Strait (Cannon, 1978). During two cruises in 1977,
there were no independent physical data available to supplement the occurrence
of some of these characteristically oceanic species. At other times these
oceanic species were present only at or near times of documented oceanic
intrusions and current reversals (Table 2). Thus, these species appear unique-
ly associated with oceanic intrusions and could act as "indicators" of surface
oceanic water masses, which at times influence even the easternmost limits of
the Strait. In light of the existence of these surface reversal events,
thoughts about contaminants rapidly flushing out to sea in the surface outflow
should be revised.
4.3. PHYTOPLANKTON DISTRIBUTION
There is little published information dealing directly with the seasonal
distribution of phytoplankton in the Strait of Juan de Fuca. The available
data are largely limited to the San Juan Archipelago (e.g. Gran and Thompson,
1930; Phifer, 1933; Phifer, 1934a; Thompson and Phifer, 1936) and Puget Sound
proper (e.g. Hirota, 1967; Booth, 1969; Munson, 1969; Winter et al., 1975;
Campbell et al., 1977). Phifer (1933) found two major diatom maxima in the
waters of the San Juan Islands. These occurred from late May to early June
and from mid-July to mid-August. Phifer (1934b) also studied the vertical
8
-------
TABLE 2. Current reversals (intrusions) and presence of oceanic
surface-living plankton species, Strait of Juan de Fuca,
February 1976 - October 1977.
ZOOPLANKTON PHYTOPLANKTON
ft
p
"C
11 8 I 1 1 -S
li II i 1 II ! 1 f 4 !l It 1 1 ll II Jl If
Reversals Cruises
Feb 16 - Feb 22 (1976) SF7601 (Feb 23-24)
Feb 28 - Mar 2
Mar 20 - Mar 30 SF7602 (Apr 5-6)
SF7603 (May 17-18)
SF7604 (Jun 28-30)
SF7605 (Aug 3-5)
SF7606 (Sep 14-16)
Nov 14 - Nov 19 SF7607 (Nov 12-15)
Dec 8 - Dec 9
Dec 14 - Dec 18
Dec 26 - Dec 28
Jan 1 - Jan 5 (1977) SF7701 (Jan 12-13)
Jan 14 - Jan 19
Feb 2 - Feb 3
Feb 5 - Feb 14 SF7702 (Feb 23-24)
SF7703 (Apr 7-8)
no
data
SF7704 (Jun 2-3)
SF7705 (Jul 26-27)
Aug 31 - Sep 2
Sep 6 - Sep 8
Sep 21 - Sep 25 SF7706 (Oct 3-5)
S3 '
X
X
X
X
^j <*j
O *4
X
X
X
X
X
X
X
5,8.
X
X
X
X
X
X
S
-------
distribution of diatoms in the Strait of Juan de Fuca for a single cruise
during July and reported that most diatoms were found in the upper 25 m.
Shim (1976) observed diatom populations in the Strait of Georgia, B.C. and the
eastern part of the Strait of Juan de Fuca and also reported two major diatom
maxima. He generally found a rapid increase in standing crop in April,
followed by a sharp decline in May. A second peak occurred during the early
summer months. Winter et al. (1975) noted that the annual pattern of phyto-
plankton growth in Puget Sound was dominated by several intense blooms between
early May and September and commented that the onset of blooms in the main
basin of Puget Sound is late for the latitude of 48°N. They stated that algal
concentrations changed drastically within time periods shorter than two weeks.
Munson (1969) found incident light, freshwater runoff, and tidal range to be
the three factors most useful in predicting the onset and disappearance of
blooms in Puget Sound. Campbell et al. (1977) identified wind stress as a
fourth important variable. These factors may also act to control phytoplankton
growth in the Strait of Juan de Fuca where tidal currents, thermohaline pro-
perties, and wind stress affect water column stability. The formation of a
stable upper layer is usually prerequisite to the occurrence of a phytoplankton
bloom because the average light intensity in a vigorously mixed water column
is insufficient for sustained growth.
4.3.1. Phytoplanktonic biomass
Chlorophyll a values integrated over the upper 50 m show that a large
spring bloom was in progress at all stations during late June 1976 (Fig. 2).
Point values as high as 25 mg Chi a nr3 were observed at that time (see
Appendix A for vertical profiles of chlorophyll and pheopigments at all
stations). By August, pigment concentrations had declined to prebloom levels.
Progressively lower levels were encountered at the two innermost stations (2 and
5) through January 1977. At these stations, moderately increasing chlorophyll
values were noted during the following spring and summer. The outermost station
(8) was the site of a distinct autumn phytoplankton bloom during November 1976,
coinciding with a strong oceanic intrusion. Winter chlorophyll concentrations
were significantly greater at station 8 than at stations 2 and 5 during both
1976 and 1977. No large phytoplankton bloom was observed in the Strait during
1977. Surface concentrations in the range of only 1-2 mg nr3 were commonly
measured. It is possible that a bloom did occur between sampling periods and
was therefore not detected.
Measuring the chlorophyll a content is the only rapid method for estimat-
ing the biomass of living phytoplankton cells in seawater. Statistical reli-
ability of the chlorophyll technique is very much dependent on the total amount
of pigment being analyzed, but precision (P) is better than 8% of any value
exceeding 0.5 mg m~3. The 95% confidence interval about a mean of n samples
is equal to ± P rr» (Strickland and Parsons, 1972).
Statistical variability was briefly examined during one cruise. Six
bottle casts were made in quick succession to sample surface seawater at one
location. A 95% confidence level of ± 0.07 about a mean of 0.81 mg nr3 was
calculated. This measure of variability includes errors in analysis as well as
patchiness in the imediate vicinity.
10
-------
TABLE 3. Diatom species in upper 1 m, Strait of Juan de Fuca.
Aatinoptyahus splendens
Aotinoptyohus undula^us
Amphiprora gigantea
v. suleata
Asterionella japonioa
Asteramphalus heptaotis
BaoteTiastrim d&ticatulwn
Be~L1e?ochea malleus
Biddulphia aurita
B-iddulphia longiaruris
Bi-ddulphia longiorupi-s
v. hyalina
Ceratulina bergcmii>
Chaetooeros affinis
Chaetoaeros approximatus
Chxetoaevos bvewis
Chzetoaeros compressus
Chaetoaeipos concavicoimis
Chaetoceros constrictus
Chaetooeros convolutus
Chaetooeros danicus
Chaetoeeros debilis
Chaetoceros deoipiens
Chaetoaeros didymus
Chaetoaeros gracilis
Chaetooeros laainiosus
Chaetoaeros lovenzianus
Chaetoaeros radicans
Chaetooeros aecwM&us
Chaetooeroe similis
Chaetooeros sooialis
Chaetoaeros subseeundus
Chaetooefos teres
Chaetooeros tortissimus
Chaetoceros vistulae
Cooaoneis
IO
r^
CT»
i— i
ca
LU
u_
X
X
X
a:
o.
<*:
X
>-
X
X
z
3
•-3
X
X
X
X
X
X
X
X
X
X
X
X
X
X
03
o:
X
X
X
X
X
X
Q.
LU
o
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
f-»
r^.
o>
I— 1
<
•-o
X
X
X
X
X
X
X
X
CQ
LU
u_
X
X
X
X
X
X
o:
CL
rs
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
H-
o
o
X
X
X
X
X
X
X
X
X
X
X
X
X
11
-------
TABLE 3. (Cont.)
Corethron hystrix
Coscinodisous angstii
Coscinodisous asteromphalus
Coscinodiscus centralis
Coscinodiscus centralis
v. pacifica
Coscinodiscus concinnus
Coscinodisous curvatulus
Coscinodisous granii
Coscinodiscus lineatus
Coscinodiscus marginatus
Coscinodiscus nitides
Coscinodiscus oculus-iridis
Coscinodiscus radiatus
Coscinodiscus stellaris
Coscinodiscus wailesii
Cylindrotheca closterium
Ditylum brightwellii
Eucampia zoodiacus
Fragilariopsis spp.
Grammatophora marina
Lauderia borealis
Leptocylindrus danious
Leptocylindrus minimus
Licmophora abbreviata
Melosira sulcata
Navicula directa
Navicula distans
Nitzsahia deliaatissima
Nitzsohia longissima
Nitzsahia pungens
Nitzsahia seriata
Pleurosigma spp.
i— i
CQ
UI
U_
X
X
X
X
X
X
cc.
0.
**•
X
X
X
^f
^
X
X
X
X
X
X
X
X
ID
0
X
X
X
X
X
X
X
X
13
Z3
"^
X
X
X
X
X
X
X
X
X
d.
UJ
to
X
X
X
X
X
X
o
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
f— 1
^£
^
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
CQ
uu
Lj-
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
a:
Q.
«a:
X
X
X
X
X
X
X
X
X
X
X
X
X
ID
^
X
X
X
X
X
X
X
X
X
X
X
X
X
X
•""}
1-3
X
X
X
X
X
X
X
X
X
I—
o
o
X
X
X
X
X
X
X
X
X
X
X
X
12
-------
TABLE 3. (Cont.)
Rhisosolenia alata
Rhizosolenia alata
f. gracillima
Phizosolenia delioatula
Rhizosolenia fragilissima
Fthizosolenia hebetata
f. semispina
RhLzosolenia setigera
Rhizosolenia simplex
Rhizosolenia stoltevfothii
Rhoiaosphenia ourvata
Skeletonema oostatum
Stephanopyxis nipponica
Thalassionema nitzsohiodes
Thdlassiosira aestivalis
Thalassiosira bioculata
Thzlassiosira aondensata
Thalassiosiva decipiens
Thalassiosira exaentrica
Thalassiosira gravida
Thalassiosira lineata
Thalassios-ira nordenskioldii
Thalassioaira pao-ifica
Thalassios-ira polyohorda
Thalassiosira rotula
"Fhalassios-lva subtilis
Thalassiothrix fvausnfeldii
Thalaesiotkpix longissuna
Tropidoneis antaretiaa
polyahorda'
U3
r^
CD
r— 1
CO
LU
Ll_
X
X
X
X
X
X
0£
Q.
«c
X
X
>-
X
X
X
X
X
X
X
X
X
z
•-3
X
X
X
X
X
X
X
X
X
X
X
X
CD
<
X
X
X
X
X
Q.
bJ
00
X
X
X
X
X
X
X
X
X
X
>
o
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
r-~
r^
en
1— 1
<
•-3
X
X
X
X
X
X
X
X
X
X
X
X
X
CD
LU
LL.
X
X
X
X
X
X
X
X
X
X
X
a:
Q-
<
X
X
X
X
X
X
X
X
X
X
X
X
X
z
•-3
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
_l
ID
'O
X
X
X
X
X
X
X
X
X
X
X
o
o
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
13
-------
4.3.2. Phytoplankton species composition
Phytoplankton cells in the surface and 50 m water samples from the mid-
channel stations were enumerated to provide information on the spatial and
temporal distributions of algal populations in the Strait of Juan de Fuca.
Tabulated data from all stations are included in Appendix B. Chester et al.
(1977) commented on the statistical reliability of these data. Phytoplankton
groups found included diatoms, dinoflagellates, coccolithophorids, and mis-
cellaneous microflagellates. Unidentifiable microflagellates often dominated
a community in terms of absolute numbers, but their relative biomass was not
nearly as great since the size of individual cells was small (5-10 ym). Micro-
flagellates could not be identified to lower taxonomic categories because of
preservation distortions and the limitations of light microscopy.
Diatoms contributed much of the phytoplankton biomass, especially in the
spring, because the average cell size was large. Over the 2-year study, 93
species in 32 genera of diatoms were identified (Table 3). In general, diatoms
were most plentiful from mid-spring to early summer, but high concentrations
were also observed during the fall bloom off Neah Bay (Sta. 8) in 1976
(Fig. 3). During mid-winter, Melosiva suloata and Thalass-ionema nitzsoh-Lodes
were the most numerous diatoms encountered. M. suloata is a littoral species
that lives almost exclusively in association with nearshore substrates. Parts
of chains often break away and occur in plankton collections. Both M. suloata
and T. nitzsohiodes were present in the Strait throughout the year. By late
winter, species of Thalassiosira joined the plankton assemblage. The bloom
organism, Skeletonema costatum, first made a modest appearance during early
spring. A large bloom of S. costatum accompanied by high concentrations of
Chaetocevos spp. and Thalassiosira spp. was present in the early summer of 1976.
No massive bloom was encountered in 1977, but sizable quantities of S. costatum
were observed in late spring. By late summer, M. suloata and T. n-ltzsoh-Lod.es
were again im, ortant species.
Dinoflagellates are also important components of the phytoplankton commun-
ity in the Strait of Juan de Fuca. During the investigation, 23 species
representing 11 genera were identified. Dinoflagellates were usually not as
abundant as diatoms (Fig. 4). The seasonal cycle of abundance at stations 2
and 5 shows increased dinoflagellate populations during the late summer and
early autumn. This is consistent with the pattern commonly seen in Puget
Sound. Off Neah Bay (Sta. 8), however, no such pattern was discerned.
Coccolithophorids were infrequent members of the phytoplankton community,
but their very presence may be significant. These phytoplankters are abundant
in waters off the Washington coast, but they have not been observed in Puget
Sound. Therefore, the occurrence of coccolithophorids is probably indicative
of oceanic intrusions in the Strait of Juan de Fuca, and they are one of the
groups referred to earlier (Section 4.2.).
Phytoplankton count data are in part analyzed as comparisons of the
species composition of the samples. The Percentage Similarity (PS) index
(Whittaker, 1960) has proved to be the most useful approach to determine how
alike samples are with respect to species composition. The PS of two samples,
X and Y, is calculated as follows:
14
-------
PS
= 100 - 50 ( z |x. - y.| ) = z min (x., y.} ,
where x. and y. are the percents of total individuals that belong to the i
taxonomlc category in samples X and Y, and n is the total number of categories.
Miller (1970) used Monte Carlo computer techniques to show that PS is a down-
ward-biased estimator. This bias decreases with increasing sample size and
decreases with decreasing diversity of the population. That is, samples from
a population strongly dominated by one or a few categories will tend toward a
higher PS. PS is primarily sensitive to shifts in the more abundant groups.
Miller (1970) found that with sample sizes of 2000 and 1000 individuals, a PS
as low as 80% and 75%, respectively, could be obtained when comparing two
samples taken from the same populations. Because many of our samples contained
fewer than 1000 individuals and because not all phytoplankton classifications
were of equal taxonomic weight, the acceptance level required to consider two
samples identical should be lowered somewhat. The following criteria were
adopted:
if PS >_ 70, the samples showed excellent agreement and were consider-
ed to have the same population distribution;
if 60 £ PS < 70, agreement was fair and it was likely that popula-
tions were the same;
if PS < 60, agreement was poor and samples probably contained a
different phytoplankton community.
The complete PS matrix (Table 4) allows station-by-station intercompari-
sons for all surface samples counted. Values comparing stations 2, 5, and 8
from the same cruise can be useful indicators of the uniformity of phytoplank-
ton composition from along the east-west axis of the Strait (Table 5).
According to PS values, the algal composition was homogeneous during about half
the cruises. Large numbers of microflagellates, however, were often present,
and their influence far outweighed that of less abundant species on the PS
statistic. The result is an upwardly biased PS estimate. The microflagellate
category was necessarily a composite of many species because preservation tech-
niques and ordinary light microscopy made positive identification impossible.
It was therefore decided to calculate a PS matrix restricted to diatom species.
The results (Table 6) show that the structure of the diatom communities is not
uniform throughout the Strait during any one cruise. Rather, distinct spatial
variations exist with respect to the dominant species composition. Station 5,
located approximately midway along the longitudinal axis of the Strait, was
somewhat pivotal in that its diatom community sometimes resembled that at
station 2 and at other times resembled that at station 8. The lack of homo-
geneous phytoplankton distributions makes inter-cruise comparisons tenuous,
and in some cases one may say that the variation in PS during any one cruise
is as great as the variation between cruises. The observed variability is
probably linked to the circulation patterns and recent biological history of
various source waters (e.g. Pacific Ocean, Puget Sound, Strait of Georgia)
contributing to the Strait of Juan de Fuca.
15
-------
TABLE 4. Percentage Similarity values for phytoplankton in upper 1 m, Strait of Juan de Fuca.
Cruise
Station
SF7601
SF7601
SF7601
SF7602
SFZ602
SF7602
SF7603
SF7604
SF7604
SF7604
SF7605
SF7605
SF7605
SF7606
SF7606
SF7606
SF7607
SF7607
SF7607
SF7701
SF7701
SF7701
SF7702
SF7702
SF7702
SF7703
SF7703
SF7703
SF7704
SF7704
SF7704
SF7705
SF7705
SF7705
SF77D6
SF7706
SF7706
Z
5
$
Z
5
8
2
Z
5
8
~i
5
8
2
5
8
2
5
8
2
5
8
2
5
8
2
5
8
5
8
2
5
8
2
5
_fi
SF7601 SF7602 SF7603 SF7604 SF7605
258258 2 258 258
95 67 95 97 88 57 3 23 21 95 95
71 96 97 90 53 3 24 21 94 94
68 69 78 54 3 25 21 67 67
98 89 53 3 23 21 96 97
90 55 3 24 21 96 96
56 3 26 22 87 88
20 41 39 55 54
44 55 33
79 23 23
22 21
98
95
94
67
98
96
88
b4
3
23
21
9>
98
SF7606
258
42
39
40
39
41
42
54
13
44
30
41
40
40
83
83
68
83
83
86
66
5
27
23
83
83
83
50
88
88
67
89
89
89
61
4
25
23
do
90
89
47
91
SF7607
258
81
77
67
76
78
79
67
3
26
24
78
78
77
48
83
82
49
46
51
45
47
48
66
3
26
24
47
47
46
46
52
51
60
27
27
28
27
27
28
30
7
37
30
28
28
28
35
31
30
32
31
-------
TABLE 4. (cont.)
Cruise SF7701
Station 258
SF7601
SF7601
SF7601
SF7602
SF7602
SF7602
SF7603
SF7604
SF7604
SF7604
SF7605
SF7605
SF7605
SF7606
SF7606
SF7606
SF7607
SF7607
SF7607
SF7701
SF7701
SF7701
SF7702
SF7702
SF7702
SF7703
SF7703
SF7703
SF7704
SF7704
SF7704
SF7705
SF7705
SF77Q5
SF7706
SF7706
SF7706
2
5
8
2
5
8
2
2
5
8
2
5
8
2
5
8
2
5
8
2
5
8
2
5
8
2
5
8
2
5
8
2
5
9
2
5
8
65
62
62
61
62
64
70
4
26
23
63
62
61
46
64
63
/2
71
30
38
34
39
J4
36
37
b3
3
25
22
34
34
34
4b
40
39
48
63
33
66
59
59
69
59
59
61
b/
b
27
26
59
60
60
44
62
62
62
49
35
62
41
SF7702
258
34
32
36
30
32
34
50
3
25
23
32
31
31
43
37
36
44
59
29
63
85
38
20
17
18
Ib
18
19
3b
J
18
18
18
17
17
24
20
20
28
43
18
48
63
??
69
60
61
72
60
60
61
b4
3
24
22
60
60
60
40
61
60
60
49
28
62
38
77
37
18
SF7703
258
45
44
54
42
44
53
67
12
35
32
43
42
42
54
46
45
51
62
32
61
55
49
52
38
4?
43
41
44
39
41
45
62
13
36
31
40
40
39
56
46
45
51
55
31
49
48
44
47
32
40
73
94
94
67
9)
95
87
54
3
23
22
97
97
97
39
83
89
76
46
29
61
34
59
31
17
60
43
40
SF7704
258
39
35
36
3b
37
38
62
20
47
39
36
35
35
57
42
41
47
47
35
44
48
40
45
28
3f>
57
59
Ifi
92
92
66
92
92
86
b2
2
21
20
92
92
92
37
81
88
76
45
27
5$
32
58
29
15
59
40
38
9?
33
23
23
23
23
23
23
24
4
25
24
24
23
23
24
23
23
24
23
30
24
24
?5
24
16
?3
24
24
24
24
22
SF7705
258
56
55
56
55
57
57
57
9
37
33
57
57
56
47
59
58
59
51
37
60
36
63
34
19
57
46
44
Sfi
41
55
?5
87
87
fi7
8/
87
87
54
4
24
23
87
87
87
41
83
87
77
46
28
63
34
6?
37
18
60
44
40
87
36
86
?3
61
79
79
67
79
79
81
55
3
24
23
79
80
79
42
81
81
78
47
28
m u» en
10 <*> «o
38
19
fil
44
41
79
37
78
?3
63
90
SF7706
258
86
86
67
86
86
87
56
5
26
23
86
87
86
44
84
88
80
49
31
64
36
64
34
20
60
45
42
Rfi
39
85
?3
66
90
85
62 94
62 93
63 66
62 97
62 95
62 86
53 52
5 2
25 21
23 20
62 96
62 97
62 98
40 38
64 81
64 88
63 76
46 45
33 27
61 60
35 32
62 58
30 29
17 16
60 59
42 40
39 37
62 96
35 33
62 91
25 23
60 56
64 87
65 79
65 85
62
-------
TABLE 5. Percentage Similarity values for station to station comparisons of
all phytoplankton populations during Strait of Juan de Fuca cruises,
1976-1977. PS values > 60 are underlined.
CRUISE
SF7601
SF7602
SF7603
SF7604
SF7605
SF7606
SF7607
SF7701
SF7702
SF7703
SF7704
SF7705
SF77Q6
STATION COMPARISONS
2X5
95
98
—
44
98
50
60
66_
69
73
33
6J,
65
5X8
67_
90
--
79
97
91
31
41
18
40
22
90
62
2 X 8
n
89
—
55
98
47
32
62
37
43
24
63
85
18
-------
TABLE 6. Percentage Similarity values for station to station comparisons of
diatom populations during Strait of Juan de Fuca cruises, 1976-1977.
PS values > 60 are underlined.
CRUISE
SF7601
SF7602
SF7603
SF7604
SF7605
SF7606
SF7607
SF7701
SF7702
SF7703
SF7704
SF7705
SF7706
STATION COMPARISONS
2X5
28
65
--
52
59
37
53
80
79
61
4
26
30
5X8
77
62
__
75
58
74
7
19
11
46
1
69
17
2X8
24
86
__
69
47
29
14
16
29
41
4
21
28
19
-------
4.4. MICROZOOPLANKTON DISTRIBUTION
The term microzooplankton embraces a large variety of protozoan and
metazoan organisms which are too small to be adequately sampled by conven-
tional plankton nets. Although they are small (generally < 200 um), their
specific metabolic rates (reproduction, ingestion, nutrient recycling, etc.)
far exceed those of the larger zooplankton. Their ecological role may there-
fore be significantly greater than biomass alone indicates, and they may be
an important trophic link between the smaller phytoplankton and larger zoo-
plankton.
In the Strait of Juan de Fuca, ciliates numerically dominate the micro-
zooplankton community. Oligotrichs and tintinnids, active phytoplankton
grazers, are usually the most abundant ciliate taxa. A total of 26 tintinnid
species and 12 oligotrich species were identified from the surface waters during
the 2-year study. The population peaks of most of these species (e.g.
tintinnids -- HeHcostomella subulatas Eut-intinnus spp.; oligotrichs —
Strombidium aon-icum, S. strobilus) usually coincided with periods of highest
biological activity during the spring and summer (Fig. 5). However, certain
species, such as the tintinnid Stenosemella ventriaosa, were most abundant
during the winter months. The distribution of S. ventvieosa may be related to
some combination of temperature preference, lorica building requirements, and
nutritional needs. Besides the particle-grazing ciliates, large concentrations
of Mesodinium rubrum were often present, especially at the innermost sites.
M. -cub-rum, derives its nutrition from photosynthetic endosymbionts and as such
occupies a distinctly different position in the pelagic food web of neritic
waters than do other ciliates. Protozoans other than ciliates include the
heterotrophic dinoflagellate Noetiluea mil-Loris and various foraminiferan and
radiolarian species. These were seen infrequently during the study. Metazoan
organisms were also recorded. Juvenile crustaceans, trochophore larvae,
mitraria larvae, and juvenile larvaceans were recognized. Adult rotifers were
also fairly frequently encountered. In general, metazoans followed a pattern
similar to the protozoans. That is, they were usually most abundant during the
periods of high phytoplankton production.
The data gathered verify the volatile "boom or bust" nature of many of
these species and reinforce the view that microzooplankton may react quickly
to increased phytoplankton concentrations in such a way as to limit and
control blooms of at least the smaller photosynthetic organisms. Although
the general trends are clear, the rapid variation in community composition and
size limits the possible interpretations . A better picture of the distribu-
tion of specific organisms as well as an understanding of interspecies rela-
tionships requires a more comprehensive sampling schedule in terms of both
time and space. A more detailed report on the distribution of the microzoo-
plankton in the Strait of Juan de Fuca has been published (Chester, 1978).
20
-------
4.5. ZOOPLANKTON DISTRIBUTION
Zooplankton are important components of the environment in terms of their
biomass, their roles in the ecosystem, and their probable sensitivity to the
kinds of petroleum industry development and transport activity anticipated in
the Puget Sound region. Zooplankton are the major grazers of phytoplankton
and as such are a critical trophic link between primary producers and carni-
vores, particularly commercially valuable fish. Zooplankton include a variety
of commercially important fish and shellfish as larval forms, and the remaining
fractions are directly or indirectly food sources or predators. Many marine
organisms are planktonic for their entire life cycle, but even organisms not
usually thought of as plankton pass through early planktonic life stages.
Most benthic and nektonic organisms tave planktonic eggs and/or larval stages
and are, therefore, especially vulnerable to contaminants throughout the water
column (Moore et al., 1973). Zooplankton provide important mechanisms, other
than ocean currents, for redistributing pollutants, especially by daily and
seasonal vertical migrations and through significant repackaging of suspended
materials into rapidly sinking fecal pellets.
In general, the distribution (particularly the vertical distribution) of
Zooplankton is not narrowly fixed, but varies with season, location, illumina-
tion, time, hydrographic conditions, and endogenous factors. Because of pre-
vious irregular space/time investigations, there is not much information on the
dynamics of plankton populations within the Strait of Juan de Fuca, including
seasonal cycles of species, species successions, recruitment, and vertical dis-
tributions and migrations of Zooplankton. Much is known about the kinds of
plankton organisms in the Strait of Juan de Fuca, and, except for larval stages
and a few large and important groups like cyclopoid copepods, the general tax-
onotnic problems are manageable.
Compared to warm-water plankton communities, the fauna of the Strait of
Juan de Fuca region is not particularly diverse. Nevertheless, the net-zoo-
plankton community here undoubtedly comprises several hundred species. The
zooplankton of the Strait has been regarded as a simple mixture of species,
oceanic forms becoming less important eastward, being replaced by coastal
species doing well under estuarine conditions. This species mixture is govern-
ed by complex factors, giving the Strait a unique quasi-permanent zooplankton
community which differs from that of the nearby Strait of Georgia as well as
from Puget Sound. Relatively few species can be considered principal components
on the basis of numbers and mass, or their critical roles in the transfer and
conversion of matter and energy within the ecosystem.
It is of value to determine the natural zooplankton populations and levels,
and ultimately to be able to detect changes in these as they occur, and then to
predict serious modifications in the ecosystem. However, this is always an
extremely difficult task and especially so in such a complex area as the Strait
of Juan de Fuca. This is primarily because the Strait has water-mass components
mixing rapidly between Puget Sound, the Strait of Georgia, and the open ocean.
Pelagic populations cannot be followed and resampled, especially between time
frames of several weeks. Even within stable water bodies such as lakes, it is
difficult to track single planktonic populations. Along the Strait, at any one
21
-------
time, an investigator may encounter the same basic plankton populations, but at
each locality these may be at a different stage of community and individual
development. Superimposed on this time variability is variability in depth.
Species have broad depth preferences that often change with age, season, or
even time of day. Mixing water layers and lenses obscure these depth rela-
tions, but also add complexity to the space-time relationships that are the
basis of the present study.
A 2-year study at 6-8 week intervals is not adequate to describe the limits
of abundance of the zooplankton species in the Strait. We have, however, out-
lined the basic yearly cycle, although highs and lows of short duration may have
been missed. We can also describe a typical zooplankton population, and suggest
envelopes of abundance with depth and season for many species. Unless catas-
trophic, changes in abundance would be difficult or impossible to detect using
the data of this survey. The presence or absence of species may imply a funda-
mental change in the environment, and we have noticed such "indicators" on a
small scale during winter current reversals (see Table 2); warm-water oceanic
species were unexpectedly found then in the Strait. A climatic shift could
give the Strait a very different zooplankton population, but this would be
accompanied by changes in physical characteristics.
4.5.1. Zooplanktom'c biomass
Zooplankton samples collected during the 13 cruises in the Strait of Juan
de Fuca have been processed and analyzed in the laboratory. Sampling times
varied; these are given in Appendix D. Settled plankton volumes were used as
an index of zooplankton biomass (Tables 7 and 8). These volumes (Fig. 6-8)
followed fairly closely the seasonal cycle of chlorophyll concentration in the
upper 50 m, as might be expected, since the bulk of this zooplankton volume is
composed of herbivores directly dependent upon phytoplankton. Zooplankton
volumes in the oblique tows (Fig. 8) tended toward a fall-winter minimum
(7 months, September through March) with values below 1 ml m"3, and usually
less than 0.5 ml m~3. Maximum zooplankton volumes were found in spring and
summer (5_months, April through August) with values above 1 ml m~3 and as high
as 2 ml m"3. In the finer-mesh vertically hauled net (Fig. 6 and 7) the volumes
were somewhat higher, although the trends were the same.
Zooplankton volume data are useful to show fundamental cycles, but they
do not provide much insight into ecosystems. Populations under stress are often
replaced by other populations, and a measure of volume would not detect this
change; different species of equal volume may have very different roles and
impacts.
The seasonal cycle and magnitude of zooplankton volumes appear similar to
those from other years observed by somewhat different methods off the Washing-
ton coast and in the main basin of Puget Sound. These comparisons are based on
the very few observations in each region (Hebard, 1956; Frolander, 1962).
22
-------
TABLE 7. Zooplankton settled volumes (ml nr3) from vertical tows (211 pm mesh
size) taken in the Strait of Juan de Fuca, 1976-1977.
Cruise Date
SF7601 23-24 Feb
SF7602 5- 6 Apr
SF7603 17-18 May
SF7604 28-30 Jun
SF7605 3- 5 Aug
SF7606 14-16 Sep
SF7607 12-15 Nov
SF7701 11-13 Jan
SF7702 22-25 Feb
Interval
Depth (m)
0-25
25-50
50-100
100-bottom
0-25
25-50
50-100
100-bottom
0-25
25-50
50-100
100-bottom
0-25
25-50
50-100
100-bottom
0-25
25-50
50-100
100-bottom
0-25
25-50
50-100
100-bottom
0-25
25-50
50-100
100-bottom
0-25
25-50
50-100
100-bottom
0-25
25-50
50-100
100-bottom
Station 2
(100 m)
0.9
1.0
0.3
2.9
1.6
0.8
4.1
2.8
0.8
16.6
9.4
5.9
1.7
1.4
1.8
1.0
0.9
2.2
0.6
0.4
1.2
0.3
1.0
1.7
1.3
0.6
0.5
Station 5
(180 m)
2.0
2.4
0.4
0.7
1.3
0.4
0.7
0.7
. 3.0
7.4
4.5
3.2
0.6
0.7
0.9
0.9
0.7
0.7
1.7
2.5
0.7
1.4
1.3
2.5
0.3
0.5
0.4
1.1
1.0
0.6
0.4
0.6
Station 8
(250 m)
1.0
1.1
1.0
3.2
1.3
1.1
0.8
0.4
36.4
1.9
3.0
3.4
0.6
0.7
0.7
1.2
0.1
0.1
0.6
0.5
2.0
0.1
0.3
0.9
1.0
0.5
0.3
0.03
2.0
0.6
0.7
0.6
23
-------
TABLE 7. (Cont.)
Cruise Date
SF7703 5- 6 Apr
SF7704 1- 3 Jun
SF7705 25-28 Jul
SF7706 3- 5 Oct
Interval
Depth (m)
0-25
25-50
50-100
100-bottom
0-25
25-50
50-100
100-bottom
0-25
25-50
50-100
100-bottom
0-25
25-50
50-100
100-bottom
Station 2
(100 m)
0.7
0.9
0.2
1.0
1.4
2.5
3.7
1.7
2.1
1.3
1.0
1.7
Station 5
(180 m)
0.4
0.4
0.8
0.8
3.1
0.4
1.3
2.4
1.1
0.4
0.7
0.7
2.4
0.7
1.4
6.4
Station 8
(250 m)
2.4
0.4
0.6
0.7
4.3
0.3
1.8
1.0
1.0
0.3
0.6
0.8
0.7
0.4
0.5
0.7
24
-------
TABLE 8. Zooplankton settled volumes (ml m"3) from oblique tows (333 ym mesh
size) taken in the upper 50 m of the Strait of Juan de Fuca,
1976-1977.
Cruise
SF7601
SF7602
SF7603
SF7604
SF7605
SF7606
SF7607
SF7701
SF7702
SF7703
SF7704
SF7705
SF7706
Date
23-24
5- 6
17-18
28-30
3- 5
14-16
12-15
11-13
22-25
5- 6
1- 3
25-28
3- 5
Station No.
Feb
Apr
May
Jun
Aug
Sep
Nov
Jan
Feb
Apr
Jun
Jul
Oct
4
0.6
1.0
0.8
1.2
1.2
1.1
0.2
0.2
0.9
0.4
1.2
0.9
0.7
2
0.5
1.0
1.1
1.7
0.8
0.4
0.2
0.1
0.4
0.2
0.7
1.1
0.7
3
0.3
1.1
0.6
1.9
1.2
0.3
0.4
0.8
0.2
0.3
0.8
1.1
0.6
4
0.4
1.9
2.8
1.1
0.4
2.1
0.2
0.4
0.4
1.5
0.4
0.8
5
1.2
1.7
2.4
0.5
0.2
0.1
0.1
0.4
0.1
1.5
0.2
1.3
6
1.2
1.2
0.8
0.4
0.2
0.1
0.1
0.2
0.2
1.7
0.1
1.9
7
1.4
1.7
1.2
0.3
0.1
0.1
0.2
0.3
1.9
0.3
0.3
8
0.5
1.1
1.3
0.6
0.2
0.4
0.2
0.3
0.3
1.5
0.2
0.3
9
0.5
1.3
2.4
0.3
0.2
0.2
0.2
0.4
0.4
1.9
0.2
0.2
25
-------
4.5.2. Zooplankton species composition
Zooplankton volumes are obtained relatively quickly and simply, but inter-
pretations are complicated by the irregular occurrence of phytoplankton. Some
phytoplankters form long intertwining chains and do not settle from the sample,
but entangle Zooplankton to give the appearance of a large plankton volume. A
better characterization of the zooplankton is given by the identification and
counting of specimens. There was a substantial variety of taxonomic groups
represented in the samples. The most common groups were Copepoda, Chaetognatha,
Polychaeta, Medusae, Siphonophora, Cladocera, Ostracoda, Amphipoda,
Euphausiacea, Decapoda, Chordata, and larval fishes. See Appendix B for a list
of species and major groups.
The zooplankton of the Strait of Juan de Fuca and Puget Sound are a mixture
of cold-temperate species and (warm) transition-water species. From the zoo-
plankton retained by nets, there are more than 100 species. None of these
species is found only in the inland marine water system. That is, all of these
zooplankton species are also found offshore in the open ocean. In addition, a
great many species found offshore cannot enter or go beyond the Strait of Juan
de Fuca, or cannot maintain populations there for one reason or another.
There is a group of 16 species (marked * in Appendix C) of large, deep-
living "oceanic" copepods, which in most cases were persistent components of
Strait zooplankton. As expected, these copepods were most abundant in the
deeper samples and occurred most commonly at the westernmost stations. These
species do not occur above 50 m, and they are unable to cross the shallow sill
at Admiralty Inlet; therefore, they are not found to the southeast in Puget
Sound, Hood Canal, or Dabob Bay. Apparently, this is a strictly mechanical
phenomenon, with the vertical distribution of a number of important oceanic
species limiting their horizontal distribution.
Five other species (marked ** in Appendix C) of "oceanic" copepods, with
a similar preference for depth but which are occasionally found at or near the
surface, can cross the Admiralty Inlet sill and are found, generally as juven-
iles, in Puget Sound and/or Dabob Bay (Hood Canal). It is not known if these
populations are entirely dependent upon periodic immigration, or if they can
breed in the inland marine areas.
A third group is of five "oceanic" surface-living copepods (Table 2);
their sporadic occurrence in the Strait was unexpected in view of the quasi-
constant surface outflow. Initially, these specimens were believed to be deep
strays entering the Strait at depth, but they were not seen in deep samples,
nor were they found in summer when they can be very abundant offshore. Recent
physical evidence (Cannon, 1978) suggested winter ocean-surface intrusions and
periodic current reversals. The occurrence of the surface oceanic species was
associated with or close to these reversals (see Section 4.2.).
The Copepoda of the Strait of Juan de Fuca were represented by about 60
species. Copepods were always the most abundant net-zooplankton, and copepod
numbers showed the same seasonal trends as zooplankton volumes (Fig. 6-9). The
fall-winter period was characterized by a large number of zooplankton species,
26
-------
but each species was in small numbers. This period of high species diversity
was in contrast to the lower diversity of spring and summer, where about the
same number of species was present (not always the same species as in fall and
winter), but where a few species were very abundant. Zooplankton diversity,
therefore, shows an inverse relationship to zooplankton volume. During the
spring-summer zooplankton volume increase, over 80% of the numbers were of a
single copepod type (Pseudooalanus species), while during the fall, winter, and
early spring volume lows, this same copepod type often amounted to less than
50% of the numbers (Fig. 9).
In addition to Pseudooalanus spp. (Fig. 10-15), the most abundant copepods
include the calanoid Aoartia long-iremis (Fig. 16-18) and the cyclopoid Oithona
similis (Fig. 19-21). These animals can be present in high concentrations
(hundreds to thousands nr3) and probably play a key role in the conversion of
plant material to animal substance. Moreover, they are an important food web
link because of their high metabolic rates and energy turnover potential. Of
the larger, common species of copepods, Calanus marshallae, a key grazer
(Frost, 1974), is most abundant during the spring and summer months; the adult
form virtually disappears from the water column in late fall and winter in the
Strait of Juan de Fuca (Fig. 22-24). The highest concentrations of this species
were found at station 8, with a maximum in April 1977 of 368 nr3 in the upper
25 m.
Euphausids were not nearly as abundant as copepods, yet euphausids are a
critical link between lower trophic levels and the large carnivores (Parsons
and LeBrasseur, 1970). Five species were found: Euphausia pacif-iaa, Thysanoessa
inermis, T. longipes, T. rasahii., and T. spinifera. For the most numerous,
Euphausia pacifiaa, the data suggest a maximum or near-maximum during the late
spring-early summer months: 51 m~3 in the upper 25 m, station 2, May 1976; and
123 m"3 at 100-50 m, station 2, June 1977. Nevertheless, the 6-8 week time
intervals between cruises make it difficult to generalize.
Four species of chaetognath were identified: Sagitta elegans, the most
abundant, S. lyra, S. sori.ppsaet and Eukpohn-La hamata. While almost always
present, Sagitta elegans was highly variable in abundance throughout the 2-year
sampling period (Fig. 25-27). The highest concentrations for this species were
found during the spring and summer months (> 100 m~3) and in the surface layer.
A number of amphipods were collected including species representing the
families: Calliopiidae, Lysianassidae, Hyperiidae, Lycaeidae, Oxycephalidae,
Phronimidae, Paraphronimidae, and Phrosinidae (see Appendix C). No species
was found to be present in great numbers, but Parathemisto paaifiaa was con-
sistently the most abundant, reaching concentrations of 25-50 m~3 in the fall
of 1976 and 1977.
The seasonal cycle, as outlined in this report, is only an approximation
of natural and variable events. Short-term fluctuations (weekly/biweekly) were
not examined at all, and between-year trends were not fairly examined. Future
investigations of this type in the Strait of Juan de Fuca might look intensive-
ly at the winter-spring transition, noting particularly the increase in primary
production and the coupling of zooplankton species to chlorophyll. Also, to
assess the impact of zooplankton in the ecosystem, there is a need to examine
27
-------
more closely the detailed depth distributions of species, especially daily
vertical migrations.
The most abundant zooplankton species are essentially the same in all three
principal inland marine areas: the Strait of Juan de Fuca, the Strait of Georgia,
and Puget Sound. However, the proportions of some of these vary with region,
giving each area a characteristic zooplankton community. This is clear with
the various Calanus species, all of which are important herbivores. In the
Strait of Georgia, the most numerous of all net-zooplankton species is the
large Calanus plimahrus, a cornerstone of the ecosystem. In contrast, C.
plumohrus is rare in the Strait of Juan de Fuca and Puget Sound. This is prob-
ably a mechanical phenomenon, since C. plumahrus seems to require depths in
excess of 300 m to complete its life cycle.
In Puget Sound, a smaller Calanus species, C. paaificus, is among the
most abundant zooplankton. Very few C. plumchrus or C. paoif-iaus were found in
the Strait of Juan de Fuca, but a third species, c. marshallae, of intermediate
size is one of the most numerous zooplankton species.
Because of these regional communities, it may continue to be necessary to
examine separately the zooplankton of each principal area. Also, because of
the physical interchanges between the Strait of Juan de Fuca, the Strait of
Georgia, and Puget Sound, the responses of the zooplankton of one region will
not be fully understood without an understanding of the distribution and abun-
dance of the zooplankton in the adjacent regions.
4.6. ICHTHYOPLANKTON DISTRIBUTION
Fish eggs and larvae are particularly sensitive to oil pollution because
many forms aggregate at the surface. Also, since reproductive intervals are
long relative to those of other planktonic organisms, the population recovery
rates may be correspondingly slower. Several species spawn only during one
short period of the year. The recruitment of such species might be seriously
disrupted by a single coincidental pollution episode. The results of fish eggs
and larvae analyses are tabulated in Appendix E.
During the study, a total of 49 taxa, representing 21 fish families, were
identified. Fifteen of these taxa have commercial value (Hart, 1973; Clemens
and Wilby, 1949). They include salmon, sole, smelt, greenling, herring, cod,
and ling cod (Table 9). The greatest number of taxa occurred during late
winter and early spring (Fig. 28) in both the pleuston and oblique samples.
The greatest population densities of fish eggs and larvae were also recorded
in late winter and early spring; they mark this period as one of active spawn-
ing and recruitment (Fig. 29 and 30).
It is evident from the large number of eggs captured by the pleuston
sampler that many fish eggs aggregate in the extreme upper water layer. For
the 13 cruises, the average abundance of pleustonic fish eggs in the open water
of the Strait of Juan de Fuca was estimated to be 100 million. The greatest
density of fish eggs was observed in April 1977, when there were an estimated
one-half billion pleustonic eggs in the Strait. Estimates of the total number
of fish eggs in the upper 50 m of the Strait of Juan de Fuca, based on oblique
28
-------
TABLE 9. Ichthyoplankton organisms caught in surface and oblique net hauls,
Strait of Juan de Fuca, 1976-1977.
TAXON
COMMON NAME
COMMERCIAL
VALUE (X)
LARVAE
Agonidae
Ammodytes hexacpterus
Artedius spp.
Bathylagus stilbius
Bathymasteridae
Cithariohthys spp.
Clinidae
Clicpea harengus pallasii,
Cottidae
Cyclopteridae
Gadidae
Gadus spp.
Gasterosteus aouleatus
Gibbons-la spp.
Hemilepidotus spp.
Eexagvamnos spp.
Hexagraimos deaagramrus
Hexagrammos lagocephalus
Hexagrammos stelleiH,
Hexagrarmos supero-iliosus
loelinus spp.
Isopsetta isolepis
Lepidopsetta bilineata
Leptoeottus armatus
Lumpenus maculatous
Lyopsetta ex-LZ-is
Micvogadus proximus
Ophidon elongatus
Osmeridae
Parophrys vetulus
Pholis spp.
Pleuronectidae
Platioht'hys stellatus
Plei&onic'hthys decumene
pyotcmyotophim thompson-i
Pset'bic'kt'hyB melanostictus
Psyohpolutes spp.
Salmonidae
Soorpaenioht'hys marmoratue
Sea-poacher
Sand-lance
Sculpin
Black smelt
Ronquil
Sand dab
Kelp-fish
Pacific Herring
Sculpin
Lump-sucker
Cod
Cod
Three-spined stickleback
Kelp-fish
Irish lord
Green!ing
Kelp greenling
Rock greenling
Whitespotted greenling
Fringed greenling
Sculpin
Butter sole
Rock sole
Cabezon
Eel-blenny
Slender sole
Tom cod
Ling cod
Smel t
Lemon (English) sole
Blenny
Flounder
Starry flounder
Curl-fin sole
Bigeye lanternfish
Sand sole
Sculpin
Salmon
Giant marbled sculpin
X
X
X
X
X
X
X
29
-------
TABLE 9. (Cont.)
TAXA
COMMON NAME
COMMERCIAL
VALUE (X)
Sebastes spp.
Stichaeidae
Theragra ehaleogrcama
Zaniolepis latipinnis
OVA
Engraulis mordax
Hippoglossoides spp.
M-icrostamus paei-f-Lcus
Plewconioh-fhys spp.
Pleui'onie'hthys deourrens
Pleuronichthys ooenosus
Tvaahypterus spp.
Rock-fish
Northern lampfish
Northern blenny
Whiting
Long-spined green!ing
Anchovy
Sole
Dover sole
Sole
Curl-fin sole
C-0 sole
Ribbon fish
X
X
30
-------
net catches, averaged 1.3 billion. Similar calculations for total fish larvae
gave average values of about 100 million pleustonic juveniles for the entire
Strait of Juan de Fuca (maximum of 650 million during February 1977), and
estimates from the oblique net data showed an overall average of 31 billion
larvae in the upper 50 m.
There are apparently far greater numbers of larvae than eggs in the upper
waters of the Strait. This conclusions seems contradictory, but knowledge of
the life cycles of the dominant fish populations makes it more plausible. Most
of the common larval taxa found in the Strait of Juan de Fuca are demersal
spawners {e.g. smelt, greenling, sculpin, herring, cod, blennies, ling cod);
others (e.g. rockfish) are live bearers. The only major group which produces
pelagic eggs is the sole. Therefore, the relative paucity of eggs in the open
waters of the Strait is understandable because the common larvae encountered
represent species that do not release pelagic eggs.
The number of fish taxa present as eggs or larvae throughout the year and
their abundances clearly show that the major spawning season in the Strait of
Juan de Fuca is winter and early spring (Fig. 28-30). The osmerids (smelt) were
overwhelmingly the most abundant larval type found in the upper 50 m, especially
during late winter and spring. Population densities approximating 2 m"3 were
recorded during both 1976 and 1977. The osmerids were captured primarily by
the oblique net, indicating that they had no great preference for the extreme
surface layer. Other common species showing no particular depth pattern
included Amnodytes hexapterus> Sebastes spp., Hemilepidotus spp., and members
of the Cottidae, Gadidae, and Cyclopteridae.
One other group merits attention. Hexagrconmos spp. (greenlings) were the
most numerous larvae taken in the pleuston sampler. They were only rarely seen
in any oblique net samples, however. Hexagrammids were only observed during
the months of October through April. According to Hart (1973), adults of the
family Hexagrammidae are common bottom fish in shallow waters. The diet of
young fish taken from British Columbian waters during spring included copepods,
amphipods, oikopleurans, and smaller fish. The genus Eexagrammos provides an
excellent example of demersal organisms whose larval stages are closely coupled
to the surface and may be particularly susceptible to pollution by oily slicks
and films.
31
-------
5. REFERENCES
Booth, B.C., 1969. Species differences between two consecutive phytoplankton
blooms in Puget Sound during May, 1967. M.S. thesis, Univ. of Wash.,
Seattle, 28 pp.
Campbell, S.A., W.K. Peterson, and J.R. Postel, 1977. Phytoplankton production
and standing stock in the main basin of Puget Sound. Final Report to
Municipality of Metropolitan Seattle, 132 pp.
Cannon, G.A., ed., 1978. Circulation in the Strait of Juan de Fuca: some
recent oceanographic observations. NOAA Tech. Report ERL-399-PMEL 29:1-49.
Chester, A.J., 1978. Microzooplankton in the surface waters of the Strait of
Juan de Fuca. NOAA Tech. Report ERL-403-PMEL 30.
Chester, A.J., D.M. Damkaer, D.B. Dey, and J.D. Larrance, 1977. Seasonal
distributions of plankton in the Strait of Juan de Fuca. NOAA Tech. Memo.
ERL MESA-24, 71 pp.
Clemens, W.A., and G.V. Wilby, 1949. Fishes of the Pacific Coast of Canada.
Fish. Res. Board Can. Bull., 68, 368 pp.
Frolander, H.F., 1962. Quantitative estimations of temporal variations of zoo-
plankton off the coast of Washington and British Columbia. J. Fish. Res.
Board Can., 19: 657-675.
Frost, B.W., 1974. Calanus marshallae, a new species of calanoid copepod
closely allied to the sibling species C. finmarehiaus and C. glacial-is.
Mar. Biol., 26: 77-99.
Gran, H.H., and T.G. Thompson, 1930. The diatoms and the physical and chemical
conditions of the seawater of the San Juan Archipelago. Publ. Puget Sound
Biol. Sta., 7: 169-204.
Hart, J.L., 1973. Pacific Fishes of Canada. Fish. Res. Board Can., Ottawa,
740 pp.
Hebard, J.F., 1956. The seasonal variation of zooplankton in Puget Sound.
M.S. thesis, Univ. of Wash., Seattle, 64 pp.
Herlinveaux, R.H., and J.P. Tully, 1961. Some oceanographic features of the
Juan de Fuca Strait. J. Fish. Res. Board Can., 18: 1027-1071.
32
-------
Hirota, J., 1967. Use of free-floating polyethylene cylinders in studies of
Puget Sound phytoplankton ecology. M.S. thesis, Univ. of Wash., Seattle,
83 pp.
Lorenzen, C.J., 1966. A method for the continuous measurement of in vivo
chlorophyll concentration. Deep-Sea Res., 13: 223-227.
McEwen, G.F., M.W. Johnson, and T.R. Folsom, 1954. A statistical analysis of
the Folsom plankton splitter, based on test observations. Arch. Meteorol.
Geophys. Bioklimatol. Ser. A, 7: 502-527.
Miller, C.B., 1970. Some environmental consequences of vertical migration in
marine zooplankton. Limnol. Oceanogr., 15: 727-741.
Moore, S.F., R.L. Dwyer, and A.M. Katz, 1973. A preliminary assessment of the
environmental vulnerability of Machias Bay, Maine to oil supertankers.
Mass. Inst. Technol. Rep. No. MITSG 73-6, 162 pp.
Munson, R.E., 1969. The horizontal distribution of phytoplankton in a bloom in
Puget Sound during May, 1969. Non-thesis master's report, Univ. of Wash.,
Seattle, 13 pp.
Parsons, T.R., and R.J. LeBrasseur, 1970. The availability of food to different
trophic levels in the marine food chain. In: Marine Food Chains, J.H.
Steele, ed., Oliver and Boyd, Edinburgh, 325-343.
Phifer, L.D., 1933. Seasonal distribution and occurrence of plankton diatoms
at Friday Harbor, Wash. Univ. Wash. Publ. Ocean., 1: 39-81.
Phifer, L.D., 1934a. Phytoplankton of East Sound, Wash., Feb. to Nov. 1932.
Univ. Wash. Publ. Ocean., 1: 97-110.
Phifer, L.D., 1934b. Vertical distribution of diatoms in the Strait of Juan de
Fuca. Univ. Wash. Publ. Ocean., 1: 83-96.
Shim, J.H., 1976. Distribution and taxonomy of planktonic marine diatoms in
the Strait of Georgia, B.C., Ph.D. thesis, Univ. British Columbia,
Vancouver, Canada, 252 pp.
Strickland, J.D.H., and T.R. Parsons, 1972. A practical handbook of seawater
analysis. Fish. Res. Board Can. Bull., 167: 310 pp.
Thompson, T.G., and L.D. Phifer, 1936. The plankton and properties of the
surface waters of the Puget Sounf region. Univ. Wash. Publ. Ocean.,
1: 115-134.
Utermb'hl, H., 1931. Neue Wege in der quantitativen Erfassung des Planktons.
Verh. Intern. Ver. Limnol., 5: 567-597.
Whittaker, R.H., 1960. Vegetation of the Siskiyou Mountains, Oregon and Cali-
fornia. Ecol. Monogr., 30: 279-338.
33
-------
Winter, D.F., K. Banse, and G.C. Anderson, 1975. The dynamics of phytoplankton
blooms in Puget Sound, a fjord in the northwestern United States.
Mar. Biol., 29: 139-176.
34
-------
...
SAN JUAN ISLANDS
WASHINGTON
Figure 1. Area chart and station locations for Strait of Juan de Fuca
cruises, February 1976 - October 1977.
-------
500 r
400 -
300 -
O = STA 2
D = STA 5
A= STA 8
co
01
ot
jE
o
100 -
M A M J
J A S 0 N D J
1976 |
F M A
1977
M Jo J
0 N D
Figure 2. Chlorophyll a in the upper 50 m of the Strait of Juan de Fuca,
1976-1977.
-------
ce
LU
t-
co
5
o
o
O STATION 2
A STATION $
Q STATION 8
J F M A U J J AS3 :JDJ FflA.MJJASONO
1976 11977
Figure 3. Diatom concentrations in the upper 1 m of the Strait of Juan de
Fuca, 1976-1977.
-------
co
CD
u.
o
o
o
J F M A r1 J AS
O STATION 2
A STATION 5
Q STATION 8
OJF.1AMJJASOND
'•97C. 1077
Figure 4. Dinoflagellate concentrations in the upper 1 m of the Strait of
Juan de Fuca, 1976-1977.
-------
£(10,500)
CO
10
8000 r
7000 -
O = STA 2
Q = STA 5
A= STA 8
0
Figure 5. Concentrations of ciliates in the surface waters of the Strait of
Juan de Fuca, 1976-1977.
-------
ml/in
FMAHJJASONDJ
Figure 6. Zooplankton settled volumes. Vertical tows, 211 ym mesh size;
total water column. Strait of Juan de Fuca, 1976-1977.
-------
ml/m'
M A
Figure 7. Zooplankton settled volume. Vertical tows, 211 ym mesh size;
top 100 ra. Strait of Juan de Fuca, 1976-1977.
-------
ml/rn
ro
Figure 8. Zooplankton settled volumes, means of grouped stations. Oblique
tows (50-0 m), 333 urn mesh size. Strait of Juan de Fuca, 1976-1977.
-------
] Pseudoaalanus spp. (juveniles;
Pseudbaalanus spp. (adults
&g| Oithona similis
"alanus marshallae
\j Aeartia longiremis
MetT-idia luaens
other copepods
500-
MAMJJASONDJFMAMJJASO
Figure 9. Copepod abundance from vertical hauls, Strait of Juan de Fuca,
February 1976 - October 1977; total number collected per total
water volume filtered, by cruise.
-------
= 500 / irT
Depth (m)
— 25
— 50
1976
— 100
1977
Depth (m)
0 -,
25 _
50 -
100 -J
Jan
Feb
Mar
Aor
May
June July
Aug Sept
Oct
Nov
Figure 10. Pseudocalanus spp. (adults). Number of animals nf3. Station 2,
Strait of Juan de Fuca, 1976-1977.
-------
= 500 / m"
Depth (m)
— 0
_ 25
_ 50
_ 100
— 180
1976
Ol
1977
Depth (m)
0 _
25
50 -
100 _
180 _
Jan
Feb
Mar
Apr
May
June
July
Auq
Sept
Oct
Figure 11. Pseudoealanus spp. (adults). Number of animals nr3. Station 5,
Strait of Juan de Fuca, 1976-1977.
Nov
-------
= 500 / m~
Depth (m)
— 25
. 50
_ 100
T
1976
250
1977
Depth (m)
0 —
25
50
100
250 -J
Jan Feb
Mar Apr
May
June Jun
Aug Sept
Oct
Nov
Figure 12, Pseudocalanus spp. (adults). Number of animals m"3. Station 8,
Strait of Juan de Fuca, 1976-1977.
-------
= 400 / m3
Depth (m)
r- 0
— 25
— 50
1976
_ 100
1977
Deoth (m)
0 -
25
50
100 J
Jan
Feb
Mar
Apr
May June
Jul v
Auci
Sent
Oct
Mov
Figure 13. Pseudocalanus spp. (juveniles). Number of animals m~3,
Strait of Juan de Fuca, 1976-1977.
Station 2,
-------
= 400 / m3
Depth (m)
0
_ 25
— 50
_ 100
L_ 180
1976
T
1977
CO
Depth (m)
0
25 _
50 -
100 -
180 _
Jan
Feb
Mar
Apr
May
June
July
Auq
Sept
Get
Nov
Figure 14. Pseudocalanus spp. (juveniles). Number of animals m~3,
Strait of Juan de Fuca, 1976-1977.
Station 5,
-------
= 400 / m3
Depth (m)
— 0
25
— 50
100
1976
f T
1— 250
10
1977
T
Depth (m)
0 .
25 -
50 _
100 _
250 J
Nov
Jan
—l—
Feb
Mar
Aor
May
June
July
Aug
Seot
Oct
Figure 15. Pseudocalanus spp. (juveniles). Number of animals m"3. Station 8,
Strait of Juan de Fuca, 1976-1977.
-------
= 150 / m3
Depth (m)
. 0
1976
— 25
— 50
_ 100
en
1977
Depth (m)
0 .
25 .
50 .
100 -J
Jan
Feb
Mar
Apr
May
June
July
Aun
Seot
Oct
Nov
Figure 16. Aeartia longiremis (adults'). Number of animals m"3. Station 2,
Strait of Ouan de Fuca, 1976-1977.
-------
= 150 / m3
Depth (m)
— 0
— 25
— 50
100
_ 180
1976
1977
T
Depth (m)
0 -|
25 -
50 -
100 -
180
Jan Feb
Mar
Apr
May
June July
Aun
Sent
Oct
Nov
Figure 17. Aeartia longiremis (adults). Number of animals m~3. Station 5,
Strait of Juan de Fuca, 1976-1977.
-------
= 150
Depth (m)
_ 25
• 50
— 100
1976
— 250
T T
1977
en
ro
T T
Depth (m)
0 —
25 _
50 -
100 -
250
,lan
Feb
Mar
Anr
May
June
July
Auo
Sent
Get
Nov
Figure 18. Aoartia Zongirem-is (adults). Number of animals m"3. Station 8,
Strait of Juan de Fuca, 1976-1977.
-------
= 100 / m3
Depth (m)
r— 0
— 25
— 50
1976
— 100
I
tn
CO
1977
Denth (m)
25 _
50 _
100 _J
Jan
Feb
Mar
Apr
May
June
July
Auq
Sept
Get
-\—
NOV
Figure 19. Oithona similis (adults). Number of animals m"3. Station 2,
Strait of Juan de Fuca, 1976-1977.
-------
100 / m3
Depth (m)
i— 0
— 25
_ 50
— 100
I— 180
1976
en
1977
Deoth (m)
0 _
25
50 -
100 -
180
—I—
Nov
Jan
Feb
Mar
Apr
May
June
July
Auq
Sept
Oct
Figure 20. Oithona similis (adults). Number of animals m~3. Station 5,
Strait of Juan de Fuca, 1976-1977.
-------
= 100 / m3
Depth (m)
- 0
_ 25
— 50
— 100
1976
L_ 250
1977
en
Denth (rr>)
0 -,
25 -
50 -
100 _
250 -J
Jan l:eb
Mar Anr
May
June July
Aun Sent
Oct
Nov
Figure 21. Oithona similis (adults). Number of animals m~3. Station 8,
Strait of Juan de Fuca, 1976-1977.
-------
= 125 / nT
en
Depth (m)
r— 0
— 25
— 50
— 100
no
adults
1976
Tno no
adults adults
1977 Depth (m)
0 — ,
25 -
no no 5n
adults adults
100 -
Jan
Feb
Mar
Apr
May
June July
Aug
Sept
Oct
Nov
Figure 22. Calanus marshallae (adults). Number of animals m~3. Station 2,
Strait of Juan de Fuca, 1976-1977.
-------
= 125 / m°
Depth (m)
_. 0
. 25
- 50
_ 100
L_ 180
1976
no
ad ill ts
no
adul ts
en
-vj
1977
no
adul ts
Depth (m)
0
25 _
50 -
100 _
180 J
Feb Mar Apr May June July Aun Sent Oct
Hov
Figure 23. Calanus marshallae (adults). Numbers of animals m~3. Station 5,
Strait of Juan de Fuca, 1976-1977.
-------
= 125 / nT
Depth (m)
— 0
— 25
_ 50
_ 100
1976
L- 250
no
adults
no
adul ts
en
00
1977
Depth (m)
0 -i
25 -
50 _
100 -
250 -J
Jan
Feb
Mar
Aor
May
June July
Auq
Sept
Oct
Nov
Figure 24. Calanus marshallae (adults). Number of animals m"3. Station 8,
Strait of Juan de Fuca, 1976-1977.
-------
= 50 / m°
Depth (m)
r~ o
_ 25
_ 50
1976
_ 100
1977
en
Depth (m)
0 —|
25 _
50 _
100
Jan Feb Mar Apr May June July Aug Sept
Oct Nov
Figure 25. Sagitta elegans. Number of animals nr3,
Strait of Juan de Fuca, 1976-1977.
Station 2,
-------
= 50 /
Depth (m)
_ 0
. 25
— 50
~ 100
l_ 180
1976
1977
I
Depth (m)
0 _
25
50 _
100 -
180 _
Jan Feb Mar Apr
May
June July Aun Sept Oct
Nov
Figure 26. Sagitta elegans. Number of animals m"3
Strait of Juan de Fuca, 1976-1977.
Station 5,
-------
= 50 / m~
Depth (m)
__ 0
. 25
. 50
— 100
1976
L_ 250
1977
Depth (m)
0 —|
25 _
50 -
100 -
250 —I
—i
Nov
Jan
Feb
Mar
Apr
May
June
July
Auq
Sept
Oct
Figure 27. Sagitta elegans. Number of animals m~3
Strait of Juan de Fuca, 1976-1977.
Station 8,
-------
0 PLEUSTON
Q OBLIQUE
20
18
16
<
x
12
o
CD
ro
00
z
3
z
10
8
6
4
2
0 J F
1976 I 1977
Figure 28. Number of ichthyoplankton taxa caught in surface and oblique
net hauls, Strait of Juan de Fuca, 1976-1977.
-------
CT>
CO
80
O PLEUSTON
Q OBLIQUE
a.
z
o
20
J F MAMJ J AS ONDJFMAMJ JAS 0
1976
1977
Figure 29. Concentration of fish eggs caught in surface and oblique
net hauls, Strait of Juan de Fuca, 1976-1977.
-------
CT>
3(116)
O PLEUSTON
OBLIQUE
JFMAMJJASONDJFMAM
0.8
0.6
CD
O
<
l/>
•^
UJ
0.2
J J A S 0
Figure 30. Concentration of fish larvae caught in surface and oblique
net hauls, Strait of Juan de Fuca, 1976-1977.
------- |