K067 - Fate of the sea ice microbial community (SIMCO) in the benthic foodweb

The goal of the proposed project is 1) to test whether sea ice microbial communities are an important source of organic material supporting benthic communities in the Ross Sea and 2) resolve important sources of nutrient recycling in the system.  We will use bulk (13C, 15N and 34S) and compound specific isotopic composition of organic matter sources to trace their contribution to consumers across spatial gradients corresponding to different sea ice extent and persistence.  This will start with an in-depth sampling of SIMCO across the gradient of sea ice persistence between Scott Base and Cape Bird, and assessment of macro- (N, P) and micro (Fe, Zn) nutrient sources from land and ocean-based sources including recycled nutrients from sea birds.  Information on these two processes will be extended to a systems level modelling approach to understand organic matter flux is the Ross Sea benthic community. The project addresses two important unknowns for Antarctic communities: the connectivity between primary production within sea ice and availability of organic material for benthic consumers, and the role of sea birds in nutrient recycling. It will provide new understanding of the role of sea ice for ecosystem functioning in Antarctica. The outcomes will be important for understanding the link between changes to sea ice cover, and changes in sea bird populations for persistence of biodiversity patterns and fisheries productivity in the system.