| A cold phase of the East Pacific triggers new phytoplankton blooms in San Francisco Bay. | |
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MedLine Citation:
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PMID: 18000053 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Ecological observations sustained over decades often reveal abrupt changes in biological communities that signal altered ecosystem states. We report a large shift in the biological communities of San Francisco Bay, first detected as increasing phytoplankton biomass and occurrences of new seasonal blooms that began in 1999. This phytoplankton increase is paradoxical because it occurred in an era of decreasing wastewater nutrient inputs and reduced nitrogen and phosphorus concentrations, contrary to the guiding paradigm that algal biomass in estuaries increases in proportion to nutrient inputs from their watersheds. Coincidental changes included sharp declines in the abundance of bivalve mollusks, the key phytoplankton consumers in this estuary, and record high abundances of several bivalve predators: Bay shrimp, English sole, and Dungeness crab. The phytoplankton increase is consistent with a trophic cascade resulting from heightened predation on bivalves and suppression of their filtration control on phytoplankton growth. These community changes in San Francisco Bay across three trophic levels followed a state change in the California Current System characterized by increased upwelling intensity, amplified primary production, and strengthened southerly flows. These diagnostic features of the East Pacific "cold phase" lead to strong recruitment and immigration of juvenile flatfish and crustaceans into estuaries where they feed and develop. This study, built from three decades of observation, reveals a previously unrecognized mechanism of ocean-estuary connectivity. Interdecadal oceanic regime changes can propagate into estuaries, altering their community structure and efficiency of transforming land-derived nutrients into algal biomass. |
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Authors:
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James E Cloern; Alan D Jassby; Janet K Thompson; Kathryn A Hieb |
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Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, Non-P.H.S. Date: 2007-11-13 |
Journal Detail:
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Title: Proceedings of the National Academy of Sciences of the United States of America Volume: 104 ISSN: 1091-6490 ISO Abbreviation: Proc. Natl. Acad. Sci. U.S.A. Publication Date: 2007 Nov |
Date Detail:
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Created Date: 2007-11-27 Completed Date: 2008-01-02 Revised Date: 2010-09-16 |
Medline Journal Info:
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Nlm Unique ID: 7505876 Medline TA: Proc Natl Acad Sci U S A Country: United States |
Other Details:
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Languages: eng Pagination: 18561-5 Citation Subset: IM |
Affiliation:
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United States Geological Survey, MS496, 345 Middlefield Road, Menlo Park, CA 94025, USA. jecloern@usgs.gov |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Cold Temperature* Ecosystem* Eutrophication* Pacific Ocean Phytoplankton / growth & development* San Francisco Seasons Time Factors Water* |
| Chemical | |
Reg. No./Substance:
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7732-18-5/Water |
| Comments/Corrections | |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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