Aquatic Sciences Meeting, Albuquerque 2001

CS09 Climate Change, Interannual/Interdecadal Variation and Global Change

Date: Wednesday, February 14, 2001, Time: 3:45:00 PM

Location: Ruidoso/Pecos

Hyrenbach , K, D, Scripps Institution of Oceanography, La Jolla, USA, khyrenba@coast.ucsd.edu

Veit, R, R, CSI-CUNY, Staten Island, USA, veit@postbox.csi.cuny.edu

McGowan, J, A, Scripps Institution of Oceanography, La Jolla, USA, jmcgowan@ucsd.edu

CHANGING MARINE BIRD COMMUNITY STRUCTURE IN THE CALIFORNIA CURRENT SYSTEM (1987-98): IMPORTANCE OF PREY PATCHINESS AND FLIGHT COST

In recent decades, the productivity of the California Current has declined in response to a long-term warming trend. We surveyed seabird and macrozooplankton abundance off southern California to determine if marine bird communities have shifted in response to changes in the abundance and patchiness of their prey. Our analyses revealed that onshore and offshore seabird assemblages have responded to the drop in ocean productivity differently. Onshore, we detected a decrease in seabird abundance and a long-term shift in community composition, concurrent with a decline in the overall abundance and aggregation of macrozooplankton biomass. We detected no such changes offshore. Additionally, we found that onshore and offshore seabird assemblages have become progressively more similar through time. We hypothesize that flight costs and prey patchiness modulate the response of bird species to decreasing secondary productivity. During this study, coastal species with high energetic requirements decreased in abundance and pelagic taxa with low-cost lifestyles became more numerous. These results suggest that specific life-history adaptations influence community-level responses to climatic change.

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Aquatic Sciences Meeting, Albuquerque 2001

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