Bivalve metrics in the North San Francisco Bay and Sacramento-San Joaquin Delta

Phytoplankton is an important and limiting food source in the Sacramento-San Joaquin Delta and San Francisco Bay; the decline of phytoplankton biomass is one possible factor in the pelagic organism decline and specifically in the decline of the protected delta smelt. The bivalves Corbicula fluminea and Potamocorbula amurensis (hereafter Corbicula and Potamocorbula, respectively) have been shown to control phytoplankton biomass in several locations throughout the system, and their distribution and population dynamics are therefore of great interest. As one element of the Department of Water Resources' (DWR) and the Bureau of Reclamation?s (BOR) Environmental Monitoring Program (EMP), the benthic monitoring program examines the impact of water project operations on the estuary as prescribed by a series of Water Rights Decisions mandated by the State Water Resources Control Board (SWRCB). These impacts are determined by changes in benthic fauna presence, abundance and distribution of the benthos associated with physical factors in the estuary, and the detection of newly introduced species in the estuary.