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Pasulka, A. P., Scripps Institution of Oceanography, UCSD, La Jolla, USA, apasulka@ucsd.edu
Landry, M. R., Scripps Institution of Oceanography, UCSD, La Jolla, USA,
Taniguchi, D. A., Scripps Institution of Oceanography, UCSD, La Jolla, USA,
Taylor, A. G., Scripps Institution of Oceanography, UCSD, La Jolla, USA,
Church, M. J., Department of Oceanography, University of Hawai’i at Manoa, Honolulu, USA,

TEMPORAL DYNAMICS OF PHYTOPLANKTON AND HETEROTROPHIC PROTISTS AT STATION ALOHA

Understanding the coupled temporal and spatial variability of primary producers and their consumers is essential for developing a comprehensive understanding of the trophic relationships at the base of the food web in the North Pacific Subtropical Gyre (NPSG). Based on epifluoresence microscopy, we assessed the abundances and biomasses of autotrophs and heterotrophic protists at Station ALOHA over 4.5 years from June 2004 to January 2009. Autotrophic size structure and community composition varied seasonally. In addition, there is evidence that zooplankton trophic linkages may impact the structure of lower trophic levels in the NPSG on both seasonal and interannual timescales. Higher ratios of autotrophic to heterotrophic protists (A:H ratio) and a shift in the size structure of eukaryotic autotrophs (A-EUKS) during winter suggest a seasonal release from grazing pressure. Anomalous patterns of A:H variability during summer 2006 (low mesozooplankton, high A-EUKS and H-dinoflagellates) reveal that top-down forcing may also contribute to interannual variability of lower trophic levels. Continued studies of protistan abundances and biomasses are essential for developing a predictive understanding of community response in the NPSG to a changing climate.

Session #:039
Date: 2/23/2012
Time: 09:00
Location: Ballroom B

Presentation is given by student: Yes