Lentic environments from volcanic Deception Island (South Shetlands): Abiotic and diatomologic characterization.

VINOCUR, A.; MATALONI, G.; MADANES, N.

Curitiba, Brasil

Simposio; IX SCAR International Biology Symposium.; 2005

Scientific Committee of Antarctic Research (SCAR).

This work aims to characterize 10 waterbodies from Deception Island on the basis of abiotic parameters and the diatom flora.  During austral summer 2001-2002, water temperature, pH, conductivity and dissolved oxygen concentration were measured at each sampling site. Water samples were also collected for chemical analyses: phosphate, nitrate, ammonia, silicate and sulfate concentrations. Both phytoplanktonic and epilithic communities were qualitatively sampled, and permanent slides were prepared in order to identify the diatoms present. 76 specific and infraspecific diatom taxa were recorded, most of them belonging to the Order Pennatae. Among these, genera Navicula, Pinnularia, Nitzschia, Gomphonema, Fragilaria and Achnanthes showed the highest species richness. A better development of the epilithon was shown through a small proportion (13%) of euplanktonic taxa.  Also,  46 % of diatoms were typical from brackish and/or marine environments. Results of a Canonical Correspondence Analysis (CCA) ordinated sites ans species along the first axis according to conductivity, and along the second according to dissolved oxygen and phosphate. Three groups of waterbodies are thus seen:  Two of them nearby a lagoon, hosting most marine/brackish species, three eu- to hypereutrophic ponds inside a Chinstrap penguin rookery, and a group of deeper volcanic lakes with a less distinct diatom flora.