Is macroalgal distribution expanding in response to climate -induced glaciaer retreat at Potter Cove (South Shetland Islands)?

MARIA LILIANA QUARTINO; DOLORES DEREGIBUS; GABRIELA LAURA CAMPANA; GUSTAVO EDGAR JUAN LATORRE

Buenos Aires

Congreso; XXXI SCAR Open Science Conference; 2010

Instituto Antártico Argentino

Climate warming has been related to glacial retreat along the Western Antarctic Peninsula. Over the last years, a visible melting of Fourcade Glaciar (Potter Cove, South Shetland islands) has exposed new hard bottom ice-free areas available for benthic colonization. However, these sites are expected to present an alteration of the water column (due to an increase of sediment input and salinity changes) and on the ice disturbance patterns. Studies performed seventeen years ago showed that the coastal sites close to the glacier cliffs in the inner Cove, characterized by soft substratum, were practically devoid of macroalgae. Are the new ice free areas suitable for macroalgal colonization? To tackle this question, underwater video transects were performed at six new ice-free areas of the inner Cove, from the waterline down to 12-15 m. Macroalgae were found colonizing all studied areas, even in close proximity to the retreating glacier. Palmaria decipiens was one of the most abundant macroalgal species at the most disturbed sites. Himantothallus grandifolius was present at relatively shallow depths, where a decrease in light penetration caused by sediment input might have caused a shift in the vertical distribution of this species. Our results show an expansion of the macroalgal distribution in Potter Cove. As macroalgae are probably one of the main energy sources that support a large fraction of the secondary production of the benthos in the inner Cove, these results can be expected to affect the energy and matter flux in this ecosystem.