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Extramural Research

Grantee Research Project Results

Grantee Research Project Results

Influences of the Invasive Clam, Potamocorbula amurensis, on San Francisco Bay Phytoplankton Abundance, Nutrient Availability and Trophic Shifts: Has an Invader Enhanced Conditions for Seagrass Recovery?

EPA Grant Number: FP916312
Title: Influences of the Invasive Clam, Potamocorbula amurensis, on San Francisco Bay Phytoplankton Abundance, Nutrient Availability and Trophic Shifts: Has an Invader Enhanced Conditions for Seagrass Recovery?
Investigators: Huntington, Brittany E.
Institution: San Francisco State University
EPA Project Officer: Just, Theodore J.
Project Period: January 1, 2004 through December 31, 2006
Project Amount: $68,869
RFA: STAR Graduate Fellowships (2004)
Research Category: Academic Fellowships , Aquatic Ecosystems , Fellowship - Aquatic Ecology and Ecosystems



Although research of anthropogenic effects typically addresses a single environmental problem—eutrophication, increased sedimentation, or species invasion—I am interested in investigating the impacts when multiple human stressors interact. I propose to examine how nutrient levels and invasive species may function in concert to affect the benthic estuarine community in San Francisco Bay and lead to a shift in trophic structure. There are several introduced species of bivalves in the Bay, including the Asian clam, Potamocorbula amurensis. Now extremely common, P. amurensis is capable of filtering large volumes of the estuarine water. The objective of this study is to examine the increased levels of dissolved nutrients in the water column that are associated with this invasion and the potential impacts on trophic structure. I hypothesize that phytoplankton biomass and total suspended solids will decrease, leading to an increase in dissolved nutrients in the water column and greater light penetration to the benthos. In the absence of P. amurensis, phytoplankton and seagrass (Zostera sp.) are in direct competition for light. Increased water clarity and freed nutrients available for tissue assimilation, however, may result is favorable conditions for Zostera growth.


The study will include extensive field surveys of invaded and noninvaded sites. Mesocosm habitats will be created to compare changes in phytoplankton biomass as a result of P. amurensis presence and to determine the relationship between P. amurensis and Zostera. Lastly, competition between macroalgae and seagrass will be explored by conducting a final mesocosm experiment. By examining the impact of P. amurensis presence in conjunction with nutrient levels, results will provide insight into impact on water column productivity and seagrass recovery caused by this dominant filter feeder. This research will provide an important analysis on two human-induced stressors acting in conjunction. Understanding their impacts will lead to improved habitat management and preservation of existing communities facing over-competition.

Supplemental Keywords:

fellowship, invasive species, clam, San Francisco Bay, benthic community, trophic structure, estuary, seagrass, nutrient availability, competition, stressors, habitat management,, RFA, Scientific Discipline, Geographic Area, ECOSYSTEMS, Ecosystem Protection/Environmental Exposure & Risk, Aquatic Ecosystems & Estuarine Research, Environmental Chemistry, State, Aquatic Ecosystem, Aquatic Ecosystems, Environmental Monitoring, Ecological Risk Assessment, Ecology and Ecosystems, nutrient dynamics, trophic levels, aquaculture, ecosystem monitoring, biotic complexity, nutrients, phytoplankton, bidoveristy, invasive species, California (CA)

Relevant Websites:

2004 STAR Graduate Fellowship Conference Poster (PDF, 1p., 133KB, about PDF)

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The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.

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