Phytoplankton Community – Diatoms, Dinoflagellates, and Cryptophytes

Tara Schraga1, Jim Cloern1, Erica Kress1, Charles Martin1 and Misty Peacock2

1U.S. Geological Survey 2U.C. Santa Cruz

http://bayareanutrients.aquaticscience.org/goal

Science and Management Goals

n rc:swnsc to the apparent changes in the Bay's resilience to nutrient loading, the San Francisco Bay Regional Wntcr Quality Control Board and Bay Arca slllkeholders have been working collaboratively to develop the San Francisco Bay Nurricnt Strategy. The goal of lhe Nutrient Strategy is to lay out a well-reasoned and cost-effective progrum to gc..'llenuc the scientific undcr..tanding needed to fully support mujor management decisions.

The Nutrient Strategy hus 6 main goals:

Define the problem: develop conceptual models for Bay segments that characterize Important processes linking nutrient and

organic maller loading. biological responses. and indicators of adverse effects of nutrient over-enrich men

Establish guidelines (water quality objectives; I.e., assessment framework) for nuttienls, Jncludlng ammonium, focusing on the

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lm lement a monitoring program that supports regular assessments of the Ba ;

Develop and ut llze numcnt·toau response mo11e1s to s1.1pport nutrient management decisions;

Evaluate control strategies lo reduce nutrient Inputs from wastewater treatment plants and other sources; and

Consider alternative regulatory scenarios for how to move forward wtth nutrient management In SF Bay.

Why do we care about the phytoplankton community?

Nutrients

Phytoplankton Size

Lower South Bay

South Bay

Central Bay

San Pablo Bay

1992-2013 n=793

(4 subembayments)

• Preserved with acid Lugol’s solution

• 2-50 ml settled in chambers for 6 to 24 h

• All cells > 30 μm enumerated at 125× magnification

• The strip count method was used to detect cells < 30 μm at 1250x, with at least 100 cells of the most numerous taxon counted (APHA 1989)

• Diatom and dinoflagellate cell contents cleared in 30% H2O2

• Cell volumes (μm3) estimated for dominant taxa by measuring 10 to 100 cells and

applying standard geometric formulas (Hillebrand et al. 1999, Wetzel & Likens 1991)

• Total BIOVOLUME (μm3/ml) = abundance (# cells /ml) x cell volume (μm3)

Phytoplankton Taxonomy Methodology

Phytoplankton taxonomic groups in SF Bay

Diatoms (Bacillariophytes)

Chlorophytes

Chrysophytes

Cryptophytes

Cyanophytes

Dinoflagellates (Dinophytes)

Euglenophytes

Eustigmatophytes

Haptophytes

Prasinophytes

Raphidophytes

Diatoms (Bacillariophytes)

Chlorophytes

Chrysophytes

Cryptophytes

Cyanophytes

Dinoflagellates (Dinophytes)

Euglenophytes

Eustigmatophytes

Haptophytes

Prasinophytes

Raphidophytes Salty regions n=793

Diatom54%

Dino14%

Crypto27%

Other5%

Other 5%

Phytoplankton taxonomic groups in SF Bay

Diatoms Dinoflagellates Cryptophytes

• large cells

• fast growing

• rich in an EFA

• critical for food webs that are supporting fisheries

• one HAB species, Pseudonitzschia

• large cells

• rich in another EFA

• SFB copepods select dinos

• Some toxin producers

• small cells • highly enriched in in

both EFAs • No toxins!

these flagellates are

a primo food resource!

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Dinoflagellates Prasinophytes Others

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Carbon biomass proportion of dominant species

Chlorophytes Cryptophytes Cyanobacteria Diatoms

Dinoflagellates Prasinophytes Others

C

Global study of dominant phytoplankton groups in 86 estuarine-coastal sites > 30,000 samples

From: Carstensen, Klais and Cloern (almost submitted)

Carbon biomass proportion of dominant species

Check Suisun

Lower South Bay South Bay

Central Bay

Diatom 55% Dino

25%

Crypto 17%

Other 3%

Diatom 61%

Dino 6%

Crypto 24%

Other 9%

San Pablo Bay

Diatom 41%

Dino 15%

Crypto 38%

Other 6%

San Pablo Bay

Diatom 59%

Dino 8%

Crypto 28%

Other 5%

South Bay

Spring and fall partitioning

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Seasonal patterns

Spring = Feb through May Fall = Sept and Oct

1422864

Sample different times of year to capture seasonal variability

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Central Bay

San Pablo Bay

Increasing Importance of Dinoflagellates?

Sustained long term montioring

A new method for a nutrient based monitoring program

Pros: Inexpensive Fast Well correlated to microscopy Tiny cells detected

Pros: Detection to species level Detection of HAB organisms

Both plots = all SFB stations Nov 2011 – April 2014

Diatoms

56%

Dinoflagellates

13%

Cryptophytes

19%

Others

12%

Other 12%

Pigments

Cryptophyte 19%

Dinoflagellate 13%

Diatom 56%

Diatom58%Dinoflagellate

21%

Cryptophyte17%

Other4%

Microscopy

Diatom 58% Dinoflagellate

21%

Cryptophyte 17%

Other 4%

Poster #169 Melissa Peacock “What Does a Pigment-Based Analysis Tell Us About the Phytoplankton Community Composition in San Francisco Bay?”

http://bayareanutrients.aquaticscience.org/goal

What does all this mean for design of a monitoring program?

A phytoplankton taxonomic sampling regimen should include: ~ Spatially variable sampling ~ Seasonal variable sampling ~ Sustained sampling over the long term ~ Consideration of new, more efficient technologies

Photo of actual phytoplankton arranged on a microscope slide!