The epibenthic megafaunal and benthic infaunal invertebrates of Port Foster, Deception Island (South Shetland Islands, Antarctica)

Abstract

Abstract Otter trawl and grab samples (0.3 mm sieve) collected in Port Foster, Deception Island, from March 1999 to November 2000 as part of the ERUPT Antarctic ecosystem study were used to assess the status of the epibenthic megafaunal and benthic infaunal communities, which were heavily impacted by the volcanic eruptions of 1967–1970. Additional otter trawls were collected in coastal waters off Livingston and King George Islands to compare the epibenthic megafauna community of Port Foster with that of open coastal Antarctic environments. The epibenthic and infaunal communities of mid-bay Port Foster have significantly recovered since 1967 when mid-bay dredge and grab samples yielded a total of four individuals in two dredge hauls and an infaunal abundance of 40 individuals m −2 . Port Foster trawls from this study yielded an average of 26.2 taxa for the five sampling dates, with a cumulative total of 68 taxa. The epibenthic community at Port Foster was primarily composed of deposit feeding taxa with the ophiuroid, Ophionotus victoriae the dominant organism. Livingston and King George trawls yielded a total of 99 and 135 taxa, respectively, with a dominant suspension-feeding community of sponges and tunicates supporting a more diverse rich epibenthic fauna. Benthic infaunal abundance and biomass averaged 85,566.3 individuals m −2 and 121.951 g m −2 . Foraminifera, nematodes, and polychaetes were the most abundant infauna in Port Foster sediments representing 59.05%, 17.48% and 16.38% of total abundance, respectively. Bivalve mollusks and polychaetes were the major contributors to the biomass, with 48.375% and 45.294% of total wet weight, respectively. Abundant populations of microbiota (foraminiferans) and meiofauna (nematodes) suggest that, as in other benthic habitats, these small but numerous organisms play a key role in carbon utilization and the food web. Sediment type and food resources are major factors controlling the benthic community structures of Port Foster and Livingston and King George Islands. The accumulation of sediments in Port Foster from wind and melt-runoff associated with past volcanic activity limits the suspension feeding community and is a possible source of metals contamination. Warming of the Antarctic polar environment will likely increase sedimentation at Port Foster and open coastal areas as glaciers melt and land surfaces are exposed to wind and rain.