Estructura y dinámica del fitoplancton estival de un lago antártico (Península Potter, Shetland del Sur)

UNREIN, F.

Ecología Austral

Asociación Argentina de Ecología

Año: 2000 vol. 10 p. 169 - 179

1667-782X

The structure and dynamics of the phytoplankton community of a lake from Potter Peninsula (SSSI N° 13, South Shetland Islands) were analyzed during the 1995-1996 summer together with the main limnological features of this system. The surface of the water body was partially coved by ice (60%) at the beginning of the study. Important changes in the abiotic parameters and in the phytoplankton composition were observed during the melting process. Temperature, pH, conductivity and phytoplankton density and biomass increased during the ice-free period. Chlorophyll a values were typical of oligo-mesotrophic lakes. SRP (soluble reactive phosphorus) values were always lower than 4 µg P l-1, while TP (total phosphorus) concentration fluctuated around 16 µg l-1.   Chlorophyta and Bacillariophyceae were the dominant groups in terms of density, biomass and species richness. Pseudodictyosphaerium jurisii (Hind.) Hind. (Chlorococcal) was the dominant species. A decrease in species equitability and diversity was observed as a consequence of the high density achieved by this species during the end of February. Other planktonic taxa of Chlorophyta were also present in low number. Bacillariophyceae mainly represented by tychoplanktonic species, showed a small peak just at the final phase of ice thawing. Thus, an increase in species richness and diversity, and a decrease in the similarity index (SIMI) applied to consecutives samples were observed during this period.