Carbon flow and trophic structure of an Antarctic coastal benthic community as determined by δ13C and δ15N

Stable isotopes of carbon and nitrogen were used to determine the different carbon pathways and trophic assemblages amongst coastal benthic fauna of the Windmill Islands, East Antarctica. Macroalgae, pelagic POM, sediment POM and sea ice POM had well-separated delta C-13 signatures, which ranged from -36.75 parts per thousand, for the red alga Phyllophora antarctica, to -10.35 parts per thousand for sea ice POM. Consumers were also well separated by delta C-13, ranging from -21.42 parts per thousand for the holothurian Staurocucumis sp. up to -7.47 parts per thousand, for the urchin Sterechinus neumayeri. Analysis of delta C-13 and delta N-15 revealed distinct groups for suspension feeders, grazer/herbivores and deposit feeders, whilst predators and predator/scavengers showed less grouping. Consumers spanned a delta N-15 range of 8.71 parts per thousand, equivalent to four trophic levels, although delta N-15 ratios amongst consumers were continuous, rather than grouped into discrete trophic levels. The study has built a trophic model for the Windmill Islands and summarises three main carbon pathways utilised by the benthos: (1) pelagic POM; (2) macroalgae/epiphytic/benthic diatoms and (3) sediment POM/benthic diatoms. The movement of carbon within the coastal benthic community of the Windmill Islands is considered complex, and stable isotopes of carbon and nitrogen were valuable tools in determining specific feeding guilds and in tracing carbon flow, particularly amongst lower-order consumers. (C) 2011 Elsevier Ltd. All rights reserved.