Sessile macro-epibiotic community of solitary ascidians, ecosystem engineers in soft substrates of Potter Cove, Antarctica

CLARA RIMONDINO; LUCIANA TORRE; RICARDO SAHADE; MARCOS TATIÁN

POLAR RESEARCH

WILEY-BLACKWELL PUBLISHING, INC

Año: 2015

0800-0395

The muddy bottoms of inner Potter Cove, King George Island (Isla 25 de Mayo),South Shetlands, Antarctica, show a high density and richness of macrobenthicspecies, particularly ascidians. In other areas, ascidians have been reported toplay the role of ecosystem engineers, as they support a significant number ofepibionts, increasing benthic diversity. In this study, a total of 21 sessile macroepibiotictaxa present on the ascidian species Corella antarctica Sluiter, 1905,Cnemidocarpa verrucosa (Lesson, 1830) and Molgula pedunculata Herdman, 1881were identified, with Bryozoa being the most diverse. There were differencesbetween the three ascidian species in terms of richness, percent cover anddiversity of sessile macro-epibionts. The morphological characteristics of thetunic surface, the available area for colonization (and its relation with the age ofthe basibiont individuals) and the pH of the ascidian tunic seem to explain theobserved differences. Recent environmental changes in the study area (increaseof suspended particulate matter caused by glaciers retreat) have been relatedto observed shifts in the benthic community structure, negatively affectingthe abundance and distribution of the studied ascidian species. Considering thediversity of sessile macro-epibionts found on these species, the impact ofenvironmental shifts may be greater than that estimated so far.