Long-term benthic community change in a highly invaded estuary

Ecosystem-level changes in the San Francisco Estuary including reduction in phytoplankton and zooplankton biomass through competition and predation have been linked to the invasive bivalve Potamocorbula amurensis, first found in this estuary in 1986. My study assessed the competitive and other effects of P. amurensis on the benthic community at a long-term benthic monitoring site in Grizzly Bay, in the upper San Francisco Estuary during 1977-2000. Changes in the structure of the Grizzly Bay benthic community after the P. amurensis invasion included a significant decrease in the biomass of suspension feeding species and in species that spawn. There was no significant change in the biomass species that brood their young or in species that deposit feed, indicating that competitive effects of P. amurensis in the benthic community paralleled those documented for other biotic communities in the estuary.