Antarctic benthic organisms at the shallow waters of Deception Island (South Shetland Islands, Antarctica): the recovery after a volcano eruption

BLANCA FIGUEROLA; AMELIA GOMEZ; CARLOS ANGULO-PRECKLER; LAURA NÚÑEZ-PONS; SERGI TABOADA; JUAN MOLES; ANA RIESGO; JAVIER CRISTOBO; JORDI RULL; CONXITA AVILA; MARIA BAS

Congreso; V Simposio Internacional de Ciencias del Mar; 2016

Deception Island is an active volcano with an internal bay, Port Foster. After the last eruption in 1970, an abundant epibenthic fauna has been established there with a significant increase in abundances of echinoderms (Odontaster validus, Ophionotus victoriae, and Sterechinus neumayeri), as dominant epifauna within the caldera, together with sediment-feeding communities. The ACTIQUIM cruises have helped to describe the megabenthos of the shallow subtidal areas of Deception Island, from the entrance to far inside the caldera, including algal communities. In particular, during the austral summers of 2008-2010 and 2011-2013, sampling was carried out mainly inside the bay, and to a lesser extent, outside the bay. Epifauna was qualitative scored as presence vs. absence, mainly due to the different sampling efforts done in the different localities and over the years. A total of 16 phyla and 115 species were collected, including an important macroalgae diversity (more than 20 species), out of ca. 900 samples. Moreover, our data showed more epifaunal species than previously reported in all sites surveyed, with a dramatic decline pattern in biodiversity as the distance increased from the bay entrance. However, we suggest here that the distance to the open sea, related to a recolonization from external waters, may not be the only reason for this pattern. In fact, sediment flux rates and substrate instability seem likely to be common disturbances largely conditioning the benthic community assemblages in Deception Island, forcing these communities to a dominance of sediment-feeding organisms at the most internal locations.