August 1, 2013.
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 organism, including bivalves, crustaceans, and fish. Little is known about the microplankton community in the San Francisco Estuary, and information on their abundance and distribution will help scientists better understand their role in local foodwebs. This research quantified the abundance and distribution of microplankton in the San Francisco Estuary from 2010 to 2012. Microplankton were collected from the Sacramento and San Joaquin Rivers and preserved with iodine. They were then identified, measured, and counted on an inverted microscope. Over small spatial scales (~30 km), microplankton abundance (number per liter) varied significantly; however, the composition of the microplankton assemblage did not. Microplankton abundance in the Sacramento River was dominated by diatoms, and total abundance did not vary significantly. Microplankton abundance in the San Joaquin River was dominated by cyanobacteria, and total abundance was extremely variable. As a result, the Sacramento River might provide a more stable food source for higher trophic levels, including crustaceans and fish.
Ecology and Evolutionary Biology
Romberg Tiburon Center for Environmental Studies (RTC)
This material is based upon work supported by the S.D. Bechtel, Jr. Foundation and by the National Science Foundation under Grant No. 0952013. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the S.D. Bechtel, Jr. Foundation or the National Science Foundation. This project has also been made possible with support of the National Marine Sanctuary Foundation. The STAR program is administered by the Cal Poly Center for Excellence in Science and Mathematics Education (CESaME) on behalf of the California State University (CSU).