Sitting on a volcano: soil algal communities from Deception Is., Maritime Antarctica

MATALONI, G.; FERMANI, P.; PETZ, W.

Curitiba

Simposio; IXº SCAR International Biology Symposium; 2005

Scientific Committee on Antarctic Research (SCAR)

Abstract: During summer 2002, eighteen terrestrial sites representing a wide range of environmental conditions from volcanic Deception Island were studied. Our aim was to caracterize their algal communities and to discover de main biotic and abiotics parameters shaping such communities. Abiotics parameters meseaure were: slope, % gravel, soil texture, temperature, pH, conductivity, water and organic matters contens, and nutrients concentrations (PO4, NO3 and NH4). Algal samples were observed both directly and after culturing under controled conditions. Species richness before and after culturing and Chlorophyll-a concentrations were meseaured 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 nestings areas. A Canocial Correspondence Analysis ordinated species and sites along the first axis in accordance with these parameters, while organics matter and waters contens soils type influenced on the second and third axes, respecthly.Uncultured species richness at individual sites varied to 0 and 9 taxa, and cultured richness was to 2 to 18 species. Chlorophyll-a concentrations were very low and microfauna (mostly heterotrophic flagellates) was recovery only at 7 sites. Areas less influenced by recents sismics events hosted well- developed communities, thougt with very different floristic composition.