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GEOPHYSICAL RESEARCH LETTERS, VOL. 32, L14608, doi:10.1029/2005GL023321, 2005

Climate anomalies generate an exceptional dinoflagellate bloom in San Francisco Bay

James E. Cloern

U. S. Geological Survey, Menlo Park, California, USA


Tara S. Schraga

U. S. Geological Survey, Menlo Park, California, USA


Cary B. Lopez

U. S. Geological Survey, Menlo Park, California, USA


Noah Knowles

U. S. Geological Survey, Menlo Park, California, USA


Rochelle Grover Labiosa

Department of Geophysics, Stanford University, Stanford, California, USA


Richard Dugdale

Romberg Tiburon Centers, San Francisco State University, Tiburon, California, USA


Abstract

We describe a large dinoflagellate bloom, unprecedented in nearly three decades of observation, that developed in San Francisco Bay (SFB) during September 2004. SFB is highly enriched in nutrients but has low summer-autumn algal biomass because wind stress and tidally induced bottom stress produce a well mixed and light-limited pelagic habitat. The bloom coincided with calm winds and record high air temperatures that stratified the water column and suppressed mixing long enough for motile dinoflagellates to grow and accumulate in surface waters. This event-scale climate pattern, produced by an upper-atmosphere high-pressure anomaly off the U.S. west coast, followed a summer of weak coastal upwelling and high dinoflagellate biomass in coastal waters that apparently seeded the SFB bloom. This event suggests that some red tides are responses to changes in local physical dynamics that are driven by large-scale atmospheric processes and operate over both the event scale of biomass growth and the antecedent seasonal scale that shapes the bloom community.

Received 28 April 2005; accepted 17 June 2005; published 20 July 2005.

Index Terms: 0442 Biogeosciences: Estuarine and nearshore processes (4235); 1616 Global Change: Climate variability (1635, 3305, 3309, 4215, 4513); 3339 Atmospheric Processes: Ocean/atmosphere interactions (0312, 4504); 4262 Oceanography: General: Ocean observing systems; 4855 Oceanography: Biological and Chemical: Phytoplankton.

Subscriber Access to Full Article (Nonsubscribers may purchase for $9.00, Includes print PDF, file size: 291198 bytes)

Citation: Cloern, J. E., T. S. Schraga, C. B. Lopez, N. Knowles, R. Grover Labiosa, and R. Dugdale (2005), Climate anomalies generate an exceptional dinoflagellate bloom in San Francisco Bay, Geophys. Res. Lett., 32, L14608, doi:10.1029/2005GL023321.