Salinity Distribution of Microplankton in the San Francisco Estuary

Microplankton are a diverse group of planktonic organisms ranging from 0.02 to 0.2 millimeters. Since the group is defined solely by size, it spans numerous taxonomic groups, including both heterotrophs and autotrophs. Microplankton are abundant in all aquatic ecosystems and are important prey for many organisms, including bivalves, crustaceans, and fish. The San Francisco Bay is truly an estuary as saltwater enters the estuary under the Golden Gate Bridge and freshwater flows in from the Sacramento and San Joaquin Rivers. Thus, there is a gradient of salinity from freshwater (0) in the rivers to saltwater by the Golden Gate Bridge (30). This research quantified the abundance and distribution of microplankton in the San Francisco Estuary from 2010 to 2013. Microplankton were collected from nine sites within the estuary and preserved with iodine. They were then identified, measured, and counted on an inverted microscope. The data was then evaluated to determine if the distribution of microplankton was related to the salinity levels