PHYSIOLOGICAL RESPONSE OF ANTARCTIC SOLITARY ASCIDIANS TO INCREASED SEDIMENTATION EROSION

TORRE L; ABELE, D; MOMO F; TATIÁN, M; SAHADE, R

Buenos Aires

Congreso; SCAR XXXI & Open Science Conference; 2010

SCAR-DNA

Over the last 15 years, changes in distribution and species abundances were observed in the coastal areas of Potter Cove (King George Island, South Shetlands, Antarctica), especially with regard to ascidians. The time course of population changes correlate with the retreat of the coastal land glaciers and the increase of near-shore sediment discharge, suggesting a possible linkage between these processes. Dry mass of three ascidian species, simulating the in-situ sedimentation conditions. To compare their physiologycal capacity, as a response to sediment effect, aerobic (citrate synthase (CS) activity) and anaerobic capacities (lactate (LDH) and opine dehydrogenases (ODH) activity were measured in these species as well as their energetic resources (glycogen content). All ascidians displayed a rise of metabolic rate up to a species-specific critical sediment concentration of: 200 mg•l. Ascidia challengeri, 100 mg•l for Cnemidocarpa verrucosa and 15 mg•l for M. pedunculata, respectively.Because of the lack of any rejection system and the low anaerobic capacity, M. pedunculata, seems to be the most affected to sedimentation. Contrary, C. verrucosa shows an strategy to avoid the sedimentation effect, cleaning actively their branchial basquet. The higher glycogen contents found in this species could help them to survive under high sedimentation.On the other hand, the low metabolism observed in A. challengeri could be an adaptation to survive to high regimes of sediment loads.