Ecology of Neritic Marine Diatoms, Arthur Harbor, Antarctica

Publisher Website
Google Scholar
Abstract
The diatoms of Arthur Harbor, Antarctica (64.degree.46''S, 64.degree.06''W) were studied for 14 mo., from Dec. 1971-Jan. 1973. Phytoplankton standing crop was negligible during the winter, due to lack of sunlight, occasional sea ice cover and instability of the water column. Cryophilic diatoms released during the spring melting of sea ice served as an inoculum for later phytoplankton blooms. The temporal distribution of phytoplankton standing crop in Arthur Harbor during the austral summer was trimodal, resulting from disruption of intense vertical stability by offshore winds. Glacial runoff, melting sea ice and a well-developed thermocline were instrumental in stabilizing the water column during the austral summer. The end of the summer growing season in March and April coincided with vertical mixing and decreasing sunlight intensity and duration. Phytoplankton species diversity (richness) changed little during the year, but species equitability declined noticeably during blooms. Cluster analysis of phytoplankton samples revealed that there were 3 assemblages: a seed assemblage during the winter-spring months, a summer bloom assemblage and a fall boom assemblage. The seed assemblage gave rise to the other assemblages through the preferential growth of certain species. This preferential growth was responsible for the observed succession and distinctiveness of the phytoplankton assemblages. Intertidal and shallow subtidal phytochrobenthos attained an enormous standing crop during the austral summer and contributed many tychopelagic forms to the water column through the year.