Collaborative Research: Bentho-Pelagic Coupling on the West Antarctic Peninsula Shelf: The Impact and Fate of Bloom Material at the Seafloor

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OPP98-15823 P.I. Craig SmithOPP98-16049 P.I. David DeMasterPrimary production in Antarctic coastal waters is highly seasonal, yielding an intense pulse of biogenic particles to the continental shelf floor. This seasonal pulse may have major ramifications for carbon cycling, benthic ecology and material burial on the west Antarctic Peninsula (WAP) shelf. Thus, we propose a multii-disciplinary program to evaluate the seafloor accumulation, fate and benthic community impacts of bloom material along a transect of three stations crossing the Antarctic shelf in the Palmer LTER study area. Using a seasonal series of five cruises to our transect, we will test the following hypostheses: (1) A substantial proportion of spring/summer export production is deposited ont eh WAP shelf as phytodetritus or fecal pellets. (2) The deposited bloom production is a source of labile particulate organic carbon for benthos for an extended period of time (months). (3) Large amounts of labile bloom POC are rapidly subducted into the sediment column by the deposit-feeding and caching activities of benthos. (4) Macrobenthic detritivores sustain a rapid increase in biomass and abundance following the spring/summer particulate organic carbon pulse. To test these hypotheses, we will evaluate seabed deposition and lability of particulate organic carbon, patterns of particulate organic carbon mixing into sediments, seasonal variations in macrofaunal and megafaunal abundance, biomass and reproductive condition, and rates of particulate organic carbon and silica mineralization and accumulation in the seabed. Fluxes of biogenic materials and radionuclides into midwater particle traps will be contrasted with seabed deposition and burial rates to establish water-column and seabed preservation efficiencies for these materials. The project will substantially improve our understanding of the spring/summer production pulse on the WAP shelf and its impacts on seafloor communities and carbon cycling in Antarctic coastal systems.