SITTING ON A VOLCANO: SOIL ALGAL COMMUNITIES FROM DECEPTION IS., MARITIME ANTARTICA

MATALONI, GABRIELA; FERMANI, PAULINA; PETZ, WOLFGANG

Curitiba

Congreso; IX SCAR International Biology Symposium; 2005

Scientific Committee on Antarctic Research

During summer 2002, eighteen terrestrial sites representing a wide range of enviromental conditions from volcanic Deception Island were studied. Our aim was to characterize their algal communities. Abiotic parameters measured were: slope, % gravel, soil texture, temperature, pH conductivity, water and organic matter contents and nutrient concentrations (PO4, NO3 and NH4). Algal samples wereobserved both directly and after culturing under controlled conditions. Species richness before and after culturing and Chlorophyll-a concentration were measured, and presence and composition of microfauna was noted. Abiotic parameters varied widely among sites. All nutrient concentrations and conductivity were strongly correlated, with higher values in birds nesting areas. A Canonical Correspondence Analysis ordinated species and sites along the first axis in accordance with these parameters, while organic matter and water content+soil type influenced on the second and third axes, and cultures richness was 2 to 18 species. Chlorophyll-a concentrations were very low, and microfauna (mostly heterotrophic flagellates) was recovered only at 7 sites. Areas less influenced by recent sismic evets hosted well-developed communities, though with very different floristic compositions.