Epibiosis on three ascidian species living on soft substrates at Potter Cove, South Shetland Islands

RIMONDINO, C.; SAHADE, R; TORRE L; TATIÁN, M

Barcelona

Congreso; XI SCAR (Scientific Committee on Antarctic Research); 2013

In the last two decades, it was reported at Potter Cove an evident retreat of the surrounding glaciers that produces an increase of suspended particulate matter and salinity lowering affecting the structure of benthic communities. The inner Potter Cove (characterized by muddy bottoms), showed a high density and species richness, particularly of ascidians, which support a community of epibiont organisms. These organisms were reported to be responsible for the tridimensional structure observed in benthic communities, contributing to the benthic diversity in other Antarctic areas. Intensity of epibiosis may depends on epibiont/basibiont species. It has been observed a high degree of specialization in epibiotic communities, according to physicochemical and morphological characteristics of the basibiont bodies where they develop, i.e. texture, shape and stability. In spite of its relevance, epibiotic communities were not still studied at Potter Cove. In this study, a total of 21 macroepibiont taxa were identified on the ascidians Corella antarctica Sluiter, 1905, Cnemidocarpa verrucosa (Lesson, 1830) and Molgula pedunculata Herdman, 1881, species characterized by a different tunic texture and pH values. Between these macroepibionts, Bryozoa was the most diverse taxa found. There were differences between the three ascidian species in terms of richness and percentage cover of macroepibionts. Besides chemical, physical and structural factors, the influence of the available area for settlement and their relation with the age of the basibiont individuals would produce the observed differences. The present results will allow to evaluating future changes in the macrobenthic community and, particularly, macroepibiotic ones at Potter Cove and other nearby Antarctic coastal areas. This work is supported by Agencia Nacional de Promoción Científica y Técnica (ANPCyT) Dirección Nacional del Antártico (DNA), Argentina and ECLIPSE , a three years project supported by the TOTAL foundation (France).