PHYTOPLANKTON SPECIES COMPOSITION AND ABUNDANCE OFF RIO DE LA PLATA (URUGUAY)

Results are presented on phytoplankton species and abundance from bott le samples collected in November, 1989, off Rio de La Plata, over the Uruguay continental shelf. The phytoplankton assemblages were dominate d by dinoflagellates and coccolithophores. The mixture of typical warm water species with subantarctic species reflected the water mixing ch aracteristics of the studied region. Phytoplankton abundance (Fraction > 5 mu m) was in general low, cell densities varied from 0.8 x 10(3) to 24.3 x 10(3) cells per litre with the exception of one of the stati ons, situated about 50 km from the shelf break. Here a bloom of the co ccolithophorid Emiliania huxleyi (Lohmann) Hay and Mohler was found wi th cell numbers reaching 6 x 10(5) per litre.