Antarctic Seabed Assemblages in an Ice-Shelf-Adjacent Polynya, Western Weddell Sea.

• Main Authors: Frinault, Bétina AV, Christie, Frazer DW, Fawcett, Sarah E, Flynn, Raquel F, Hutchinson, Katherine A, Montes Strevens, Chloë MJ, Taylor, Michelle L, Woodall, Lucy C, Barnes, David KA
• Format: Article in Journal/Newspaper
• Language: English
• Published: MDPI AG 2023
• Subjects: Antarctica; Larsen C Ice Shelf; Weddell Sea; benthic assemblages; benthic biodiversity; climate change; coastal polynya; continental shelf; functional groups; ice shelf; Antarctic; The Antarctic; Weddell; Antarc*; Ice Shelf; Ice Shelves
• Online Access: https://www.repository.cam.ac.uk/handle/1810/345725; https://doi.org/10.17863/CAM.93147

Ice shelves cover ~1.6 million km2 of the Antarctic continental shelf and are sensitive indicators of climate change. With ice-shelf retreat, aphotic marine environments transform into new open-water spaces of photo-induced primary production and associated organic matter export to the benthos. Predicting how Antarctic seafloor assemblages may develop following ice-shelf loss requires knowledge of assemblages bordering the ice-shelf margins, which are relatively undocumented. This study investigated seafloor assemblages, by taxa and functional groups, in a coastal polynya adjacent to the Larsen C Ice Shelf front, western Weddell Sea. The study area is rarely accessed, at the frontline of climate change, and located within a CCAMLR-proposed international marine protected area. Four sites, ~1 to 16 km from the ice-shelf front, were explored for megabenthic assemblages, and potential environmental drivers of assemblage structures were assessed. Faunal density increased with distance from the ice shelf, with epifaunal deposit-feeders a surrogate for overall density trends. Faunal richness did not exhibit a significant pattern with distance from the ice shelf and was most variable at sites closest to the ice-shelf front. Faunal assemblages significantly differed in composition among sites, and those nearest to the ice shelf were the most dissimilar; however, ice-shelf proximity did not emerge as a significant driver of assemblage structure. Overall, the study found a biologically-diverse and complex seafloor environment close to an ice-shelf front and provides ecological baselines for monitoring benthic ecosystem responses to environmental change, supporting marine management.