PHYTOGEOGRAPHY ASSOCIATED AT SPECTRAL ABSORPTION SHAPES IN THE SOUTHERN REGION OF THE CALIFORNIA CURRENT

The phytogeographic association of nano-microphytoplankton was characterized during April 2008 in the southern region of the California Current with 21 diatom and 11 dinoflagellate genera. Hierarchization of the diatom community (>5 mu m) revealed 12 persistent genera throughout the study area. Two bloom events were detected: one in San Quintin Bay dominated by Eucampia zodiacus (646 x 10(3) cells L-1) and another of lesser intensity off Punta Eugenia dominated by Pseudo-nitzschia spp. Both blooms were attributed to upwelling events in the region when the 25 sigma(theta). surface was inclined from between 80 and 30 m. The intrusion of two water masses was observed: high-nutrient low-chlorophyll Subarctic Water, influencing the stations off Ensenada and San Quintin Bay; and California Current water, influencing the stations off Punta Eugenia. The magnitude of the specific absorption coefficient of phytoplankton (a*(ph)) showed large variability in the blue Soret band (440 nm), while the blue/red ratio of absorption (a(ph)440/a(ph)674) ranged from 1.7 to 7.4, both with high values at offshore stations. Our a*(ph)440 and b/r ratio results indicated an inverse behavior in the community size distribution. The diatom community (>5 mu m) showed four phytogeographic provinces with six different pattern curves from normalized spectral absorption shapes (a(ph)n/440 nm). We concluded that the southern region of the California Current consists of a basic structure composed of smaller cells and few microphytoplankton cells that maintains a balanced community periodically, an extra diatom population is superimposed on the basic structure, resulting in high values of the absorption coefficient of phytoplankton and a better hierarchical phytoplankton structure in the upwelling system.