Our data reveal some key features about plankton communities in theGFNMS near the Farallon Islands compared to the San Francisco Bayestuary. The data in Figures 3 and 4 indicate that lower trophic levelshave a greater number of individuals at both locations. Phytoplankton,as primary producers, must be more abundant than consumers at thenext trophic level. The greater abundance of phytoplankton at the oceanlocations than the estuary locations may be due to upwelling nutrientsthat concentrate around the Farallones (Anderson and Lucas 2008).Data in Figure 6 indicate that plankton species diversity vary across timeand location, which may be linked to seasonal weather changes, nutrientfluctuation, and grazing zooplankton communities.
While much of the North Central California coast has been protectedas Marine Protected Areas (19.97%, 152.41 km2) and three large areas asNational Marine Sanctuaries, very little of the San Francisco Bay hasbeen designated as protected areas (PISCO 2007). However, estuarineecosystems are vital to many marine organisms, especially juveniles. Inthe San Francisco Bay estuary alone, more than 90% of the tidal marshesthat once lined the estuary’s shores have been altered and nearly half ofthe water that once fed the estuary has been diverted (Cohn 2000).Creating reserves within this critically stressed environment is crucial.
Understanding variability in plankton abundance and diversity overthe long-term will provide insight to future interannual predictions ofecosystem productivity. We hope our collective results from this projectwill inform the GFNMS management to help ensure our coast willprotect marine life diversity and abundance, restore depletedpopulations, and ensure the integrity of the ecosystem.
Plankton Species Diversity and AbundanceA Comparative Study in San Francisco Bay and the Greater Farallones National Marine Sanctuary
Fadwa Bouhedda, Viktoria Kuehn, John Damascus, Gretchen Coffman, PhD
•Sampling Locations: Plankton tows were performed at three estuarine sites(Point Bonita, Shipping Channel, and Clipper Yacht Harbor) and two upwellingmarine sites (Farallon Islands West and East).
•Plankton Net Tow: A 325-µm mesh plankton net was towed at 2 knots for 10minutes along the surface of the water. The net was deployed at the stern of theboat, and contents were immediately fixed with a solution of 50% aqueouspropylene glycol and 1% formaldehyde. The jars were then sealed and analyzed in alaboratory at University of San Francisco with Leica light microscopes.
The number of cubic meters of water sampled per site was calculated based on:
𝑉𝑜𝑙𝑢𝑚𝑒 = ᴨ𝑟2𝐿Where length of tow:
𝐿 =𝑚
ℎ𝑟𝑡
•Abiotic Factors: GPS coordinates and time were measured with an eTrex GPS.Air temperature and wind speed were measured with a Kestrel 4500 PocketWeather Meter. Water temperature, conductivity, salinity, dissolved oxygen, andpH data were measured with a Hach HQ40d portable multiparameter meter withthree different probes (conductivity, dissolved oxygen, and pH). Salinity was alsodetermined with a Reichert Goldberg Salinity Refractometer. A Secchi disc wasused to sample water clarity.
Introduction Methods
Results
Study Location
Discussion and Management
Figure 1. Various plankton identified at 40x magnification from tows in 2015 and 2016. Pictured are (A) Dinoflagellates-Phylum: Dinophyta - ceratium; (B) Chrysophyta- coscinodiscus (C) Skeletonema sp. (D). Coscinodiscus sp.(Photos by USG authors)
Citations• Anderson, T.R. and M.I. Lucas. 2008. Upwelling Ecosystems. Pages 450 – 460 in S.E. Jørgensen, editor. Ecosystem Ecology. Elsevier, Amsterdam,
North Holland, The Netherlands.
• Cohen, A. 2000. An Introduction to the San Francisco Estuary. San Francisco Estuary Institute, San Francisco Estuary Project, and Save the Bay,
Oakland and Richmond, California, United States.
• Karl, H.A., J.L. Chin, E. Ueber, P.H. Stauffer, and J.W. Hendley II. 2001. Beyond the Golden Gate – Oceanography, Geology, Biology, and Environmental
Issues in the Gulf of the Farallones. U.S. Department of the Interior, U.S. Geological Survey, Reston, Virginia, USA.
• Partnership for Interdisciplinary Studies of Coastal Oceans (PISCO). 2007. The Science of Marine Reserves (2nd Edition, United States Version).
www.piscoweb.org. 22 pages.
Figure 5. Sampling methods of (A) Secchi disk and (B) plankton net tow taken in duration of Farallon Islands transect, 2015.
The plankton community of oceans and estuaries is comprised ofall aquatic organisms that are free-floating and carried bycurrent. Organisms classified as plankton thus range in size andvariety, from unicellular diatoms to large jellyfish. Plankton can bebroadly divided into phytoplankton (producers) and zooplankton(consumers). The University of San Francisco is conducting a 30year study of species diversity and abundance comparing planktoncommunities of the San Francisco Bay estuary with those of thePacific Ocean within the Greater Farallones National MarineSanctuary (GFNMS). The southern edge of the GFNMS is borderedby the Monterey Bay National Marine Sanctuary, which protect thecoastline from Marin County towards Monterey Bay. There is a~200 square mile gap in protection from Point Bonita to Pacifica, inwhich samples were collected (Karl et al., 2001). Data were collectedalong transects on boat expeditions in 2012, 2013, and 2015 as partof the USF California Ecosystems course. It was hypothesized thathigher abundance and species diversity of plankton would be foundin samples from the Ocean compared to Bay samples. To test thishypothesis, plankton tows were conducted at two estuarine and twoocean sites along a 30 mile transect (see Figure 2). Abiotic factorswere also surveyed at sampling locations for correlation purposes.
Results (continued)
Abiotic water quality results are depicted in Table 1. The twoestuarine samples, had lower wind speeds at 0.6 m/s and 1.1 m/s, alower pH (7.95 and 7.87) and lower visibility (2.25m and 1.45)respectively. Compared to the ocean samples, estuarine sites hadhigher temperatures (16.0-17.2 °C), lower salinity (30.3-30.5 ppt),and slightly lower levels of dissolved oxygen (9.06-9.70 mg/L). Theocean sites had wind speeds of 4.2 and 6.1m/sec, a more basic pH of8.10 and 8.14, and greater visibility (5.78 and 8.75). Ocean watersamples compared to Bay samples had lower water temperatures(14.5-15.6 °C), more saline water (31.4-31.8ppt), and slightly higherdissolved oxygen levels (9.63-10.10 mg/L).
Figure 4. Abundance of phytoplankton and zooplankton betweenSan Francisco Bay and Ocean sites (number of plankton per m3 ofocean water) from data collected by USF students in 2015.
Figure 3. Abundance of phytoplankton and zooplankton (number/m3) for Bay sites (Point Bonita and the Shipping Channel) compared to ocean sites (West Side and East Side of the Farallones) sampled in 2015.
Table 1. Abiotic and water quality measurements along a transect from San Francisco Bay at Fisherman's Wharf tocontinental shelf October 2015.
Figure 6. Number of plankton species observed in the Estuary, Ocean and along the continental shelf in 2012 and 2013 samples.
Figure 2. The route taken and sampling locations from the 2015 data collection. This route began and ended in the Clipper Yacht Harbor, Sausalito.
A B
DC
A B
Site
SampledTime
Tide
Heigh
t (m)
Long/Lat
Air
Temp.
(°C)
Wind
Speed
(m/sec)
Depth
Sample
d (m)
Water
Temp.
(°C)
Salini
ty
(ppt)
Conduc-
tivity
(mS/cm)
DO
(mg/L)
DO
(%)pH
Sec
chi
(m)
Point
Bonita9:00 0.54
N
37°49’14.2”
W122°30’29.
1”
13.4 0.6
1 16.2 30.4 38.8 9.70 97.8
7.95 2.255 16.0 30.5 38.6 9.47 95.6
Fisherman
’s Cove
Farallones
West
12:24 1.82
N
37°42’0.02”
W122°59’53.
3”
13.5 4.2
1 15.6 31.5 39.8 10.10 101.4
8.10 5.78
5 15.3 31.8 39.6 10.09 100.9
Mirounga
Bay
(Farallone
s East)
13:20 1.31
N
37°41’40.5”
W123°00’52.
8”
13.2 6.1
1 15.0 31.4 39.2 9.82 98.6
8.14 8.75
5 14.5 31.8 39.0 9.63 95.8
Clipper
Yacht
Harbor
16:55 0.48
N
37°48’29.3”
W122°25’1.9
”
19.3 1.1
1 17.2 30.3 39.8 9.22 95.6
7.87 1.455 17.1 30.3 39.6 9.06 93.9
Estuary Ocean
Various plankton were observed from collected water samples at Sites 1-4(Fig.6). Figure 1 shows specific organisms observed and identified. A total of 71species of phytoplankton and 27 species of zooplanktons were found. Among theplankton observed are dinoflagellates, diatoms, larval stages of arthropods,macroalgae, copepods, copepod nauplii, and amphipods.
USF students identified and analyzed plankton individuals from ocean andestuarine water samples collected in October of 2012, 2013 and 2015. The data inFigures 3 and 4 indicate there is a higher abundance of plankton in the ocean thanin the estuary. Plankton species diversity was highest 28 miles offshore, near theFarallones Islands, and lowest in the estuary.
