MEPS 167:73-88 (1998)  -  doi:10.3354/meps167073

Spring in the California Current: the distribution of phytoplankton species, April 1993 and April 1995

E. L. Venrick*

Marine Life Research Group, Scripps Institution of Oceanography, La Jolla, California 92093-0227, USA

This study examines the distributions of 317 phytoplankton species from the survey area of the California Cooperative Oceanic Fisheries Investigations (CalCOFI). Samples were mixed-layer samples collected in April 1993 and April 1995. Both were periods of recent or active upwelling near Point Conception. There were 2 major groups of stations with similar flora, one inshore and one offshore. Effect of current flow on the boundary between the 2 regimes was evident. Stations in the southeastern portion of the area were more closely related to offshore stations in 1995; however, in 1993 there was influx of inshore flora from the north. Recurrent group procedure identified northern inshore and offshore groups of species, with similar composition in the 2 years. Northern inshore species were found throughout the CalCOFI study area, and their summed abundance was correlated with the concentration of 10 m chlorophyll. In 1995, no offshore group was formed unless the affinity level was relaxed. No recurrent group was endemic to the southeastern region. These diatom data were compared with diatom data of W. E. Allen, collected in April 1940. There were no marked differences in diatom abundance or species composition. However, in April 1940, an unusually well developed Southern California Eddy shifted the center of diatom abundance offshore.

Phytoplankton species · California Current · Spring bloom · Upwelling

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