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Journal of Plankton Research Vol.22 no.5 pp.813-841, 2000
© Oxford University Press 2000
Summer in the Ensenada Front: The distribution of phytoplankton species, July 1985 and September 1988
Marine Life Research Group, Scripps Institution of Oceanography, University of California at San Diego, La Jolla, CA 92093–0227, USA
Two interdisciplinary cruises took place in the Ensenada Frontal region during July 1985 and September 1988. This paper discusses the distribution of phytoplankton species along one section from each cruise. Each year, the overall dominant species was Emiliania huxleyi. Although hydrography of the euphotic zone indicated the presence of water from three sources, the Central Pacific flora dominated the floral patterns. Recurrent group analysis identified two clusters of related groups of species, present in both years and separated by depth. These were similar to recurrent groups defined from the Climax area in the Central North Pacific. Similarity maps indicated the presence of the two-layered structure that is characteristic of the Central Pacific flora. The transition between flora corresponded to the depth of the chlorophyll maximum layer but also to the cool salinity minimum layer that marks California Current water and that is absent from the Central Pacific. The extensive entrainment and persistence of Central Pacific flora in the Ensenada Frontal region is unexpected.