Deposit feeding: a novel mode of nutrition in the Antarctic colonial soft coral Gersemia antarctica

Abstract

The colonial nephtheid soft coral Gersemia antarctica is a deposit feeder in the soft sediment communities of McMurdo Sound, Antarctica. This feeding strategy involves coordinated bending of the entire colony against the substrate and is previously undescribed among soft corals. Gut content analyses indicate a mixed diet that includes benthic diatoms, foraminiferans, and particulate organic matter. Soft coral colonies move periodically in an 'inch worm' fashion, presumably to exploit undisturbed sediments. In fact, when colonies encounter previously grazed sediment they contract from the substrate almost immediately. This feeding strategy has likely evolved to supplement the capture of planktonic prey and is of particular importance in the Antarctic, and potentially the deep sea, where water column productivity is seasonally constrained.