S1-4 Saturday, Jan. 4 09:00 - 09:30 From Glaciers to Benthos: Fjord Ecosystem Processes in a Changing Climate ZIEGLER, AF*; HAHN-WOERNLE, L; POWELL, B; LUNDESGAARD, Ø; CAPE, M; SMITH, CR; University of Hawaii at Manoa, Honolulu, HI; University of Hawaii at Manoa, Honolulu, HI; University of Hawaii at Manoa, Honolulu, HI; University of Hawaii at Manoa, Honolulu, HI and Norwegian Polar Institute, Tromso, Norway; University of Washington, Seattle, WA; University of Hawaii at Manoa, Honolulu, HI email@example.com
Glaciomarine fjords of the West Antarctic Peninsula (WAP), e.g., Andvord Bay, form distinct hotspots of benthic biomass/diversity. Important drivers of these patterns may be 1) enhanced fjord primary productivity and export flux, and 2) limited larval dispersal from restricted fjord circulation. We found during our FjordEco Project that inner-middle Andvord Bay experiences limited meltwater/sediment input, high annual primary production, and high export flux, all of which support high benthic respiration and macro-/megafaunal abundance and biomass. Massive phytodetritus deposition mid-fjord in Jan 2016 led to rapid feeding by deposit-feeders yet still produced a substantial sediment food bank to sustain detritivory throughout the winter. To explore the influence of larval dispersal on benthic community structure, we used a high-resolution hydrodynamic/particle-tracking model to simulate larval transport. Larval dispersal between fjords is limited on ecological time and space scales due to weak circulation in most parts of the fjords. Occasionally, katabatic wind events may export near-surface larvae (<100 m depth) from the fjords. Our results suggest that self-recruitment and episodic, shallow dispersal are important drivers of community structure and diversity in WAP fjord benthos. Climate warming on the WAP may alter the timing, magnitude and composition of organic carbon flux to the seafloor which will directly influence biomass, abundance and function of benthic communities. Warming will also increase glacial melt and estuarine circulation which may alter connectivity and homogenize benthic communities across the WAP.