Spatial distribution and structure of benthic communities in Herve and Cardozo Coves (Admiralty Bay, King George Island, South Shetlands, Antarctica)

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In the last 50 years a significant climatic shift has been observed along Antarctic Peninsula (e.g. glacial retreat, temperature rise). Such changes may have a significant impact on the structure and diversity of benthic communities. Underwater photographic documentation of macrobentos was carried out in Cardozo and Herve Coves (Admiralty Bay, King George Island, Antarctica) during austral summers 2007–2008 and 2009–2010. Observations of bottom morphology and sediment type were done by scuba divers. Both coves are formed by retreating glaciers, but they differ in area, depth, isolation from the main waters of Admiralty Bay, and glacial input. Analysis of data revealed significant changes in the density, diversity, and species composition of benthic communities in both coves. Large, open Cardozo Cove supported more diverse macrofauna (35 species compared with 16 in Herve Cove). Areas recently freed from ice were colonized mostly by bivalves such as Laternula elliptica and Yoldia eightsi (Herve Cove) or ascidians such as Molgula pedunculata and Cnemidocarpa verrucosa (Cardozo Cove). Areas adjacent to open waters of Admiralty Bay were dominated by sea anemones (Edwardsia sp.) and amphipods (Cheirmedon femoratus) (Herve Cove) or sea urchins (Sterechinus neumayeri) and diverse sea stars (Cardozo Cove). In the last 15 years the macrofauna of Herve Cove has been enriched by species previously unknown or incidental there, such as isopods (Glyptonotus antarcticus), sea urchins (Sterechinus neumayeri), sea stars (Odontaster validus) and limpets (Nacella concinna). Changes in areas covered by Edwardsia sp. were observed. Collected data will be used in long‐term monitoring and mapping changes in benthic communities under environmental stress.