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Trophic interactions and direct physical effects control phytoplankton biomass and production in an estuary

Limnology and Oceanography

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Abstract

San Francisco Bay has recently been invaded by the suspension-feeding clam Potamocorbula amurensis. Previous work has shown that phytoplankton biomass in the upper estuary is low (2-3 mg Chl a m-3) during seasonal periods of high river flow and short residence time and it is usually high (peak >30 mg Chl a m-3) during the summer-autumn seasons of low river flow and long residence time. However since P. amurensis became widespread and abundant in 1987, the summer phytoplankton biomass maximum has disappeared, presumably because of increased grazing pressure by this newly introduced species. For 1977-1990, mean estimated primary production was only 39 g C m-2 yr-1 during years when bivalve suspension feeders were abundant (>2000 m-2), compared to 106 g C m-2 yr-1 when bivalves were absent or present in low numbers. These observations support the hypothesis that seasonal and interannual fluctuations in estuarine phytoplankton biomass and primary production can be regulated jointly by direct physical effects (eg river-driven transport) and trophic interactions (episodes of enhanced grazing pressure by immigrant populations of benthic suspension feeders). -from Authors

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Trophic interactions and direct physical effects control phytoplankton biomass and production in an estuary
Series title:
Limnology and Oceanography
Volume
37
Issue:
5
Year Published:
1992
Language:
English
Publisher:
American Society of Limnology and Oceanography
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Limnology and Oceanography
First page:
946
Last page:
955