Bioavailability of organic matter in a highly disturbed estuary: The role of detrital and algal resources
- *U.S. Geological Survey, MS-496, 345 Middlefield Road, Menlo Park, CA 94025; and ‡Department of Environmental Science and Policy, University of California, Davis, CA 95616
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Edited by Stephen R. Carpenter, University of Wisconsin, Madison, WI, and approved April 18, 2002 (received for review November 18, 2001)
Abstract
The importance of algal and detrital food supplies to the planktonic food web of a highly disturbed, estuarine ecosystem was evaluated in response to declining zooplankton and fish populations. We assessed organic matter bioavailability among a diversity of habitats and hydrologic inputs over 2 years in San Francisco Estuary's Sacramento–San Joaquin River Delta. Results show that bioavailable dissolved organic carbon from external riverine sources supports a large component of ecosystem metabolism. However, bioavailable particulate organic carbon derived primarily from internal phytoplankton production is the dominant food supply to the planktonic food web. The relative importance of phytoplankton as a food source is surprising because phytoplankton production is a small component of the ecosystem's organic-matter mass balance. Our results indicate that management plans aimed at modifying the supply of organic matter to riverine, estuarine, and coastal food webs need to incorporate the potentially wide nutritional range represented by different organic matter sources.
Footnotes
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↵ † To whom reprint requests should be addressed. E-mail: wsobczak{at}usgs.gov.
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This paper was submitted directly (Track II) to the PNAS office.
- Abbreviations:
- DOC,
- dissolved organic carbon;
- POC,
- particulate organic carbon;
- BDOC,
- bioavailable DOC
- Copyright © 2002, The National Academy of Sciences
