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Does the benthos control phytoplankton biomass in South San Francisco Bay?

January 1, 1982

South San Francisco Bay, USA, is a shallow coastal embayment that receives large inputs of nutrients (N. P, Si) and small local inputs of freshwater. Phytoplankton dynamics are typically characterized by a spring bloom when surface chlorophyll a increases from < 5 to > 40 mg m-3. The bloom persists for 2 to 4 wk, and then dissipates. Phytoplankton biomass remains low (chlorophyll a < 5 mg m-3) from May through December, although light and nutrient availability are sufficient to sustain growth rates of 1 to 1.5 divisions d-1 in the expansive shallows. Transport processes apparently exert a small influence on phytoplankton biomass, and calculated zooplankton grazing accounts for only a small reduction in net rate of phytoplankton population growth in the shallows. However, suspension-feeding bivalves are sufficiently abundant to filter a volume equivalent to the volume of South Bay at least once daily. These observations suggest that grazing by benthos is the primary mechanism controlling phytoplankton biomass during summer and fall.

Publication Year 1982
Title Does the benthos control phytoplankton biomass in South San Francisco Bay?
Authors James E. Cloern
Publication Type Article
Publication Subtype Journal Article
Series Title Marine Ecology Progress Series
Index ID 70156387
Record Source USGS Publications Warehouse
USGS Organization San Francisco Bay-Delta; Toxic Substances Hydrology Program; Pacific Regional Director's Office