SGER: Impact of the 1997-98 El Nino Event on Abyssal Benthic Boundary Layer Communities in the NE Pacific

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A major El Nino event is predicted along the California coast in Spring and Summer 1998. The rate of development of this 1997 98 El Nino exceeds anything observed in recent history, including the 1982 83 El Nino which was then considered the event of the century. Based on previous results during the 1992 93 El Nino and the unprecedented magnitude predicted for the 1997 98 event, we expect a major decline in particulate organic matter flux (POM; food supply) into the deep sea and a concomitant impact on benthic boundary layer (BBL) communities. Using our previous long time series data set for comparison, we will re establish our POM flux measurements and sea floor photography on a continuous basis through this El Nino event and make seasonal measurements of sediment community activity to test three hypotheses. 1) The flux of POM, as an estimate of food supply, at abyssal depths will be significantly lower than fluxes measured at the same depths over the past 7 years in conjunction with a decline in upwelling and primary production in surface waters. 2) Sediment community activity, as estimated from sediment community oxygen consumption, will be significantly lower in conjunction with decreasing POM supply to the BBL. 3) Activity of the mobile epibenthic megafauna will significantly increase in conjunction with decreasing POM supply to the BBC. We predict that the major El Nino event of 1997 98 will profoundly influence the benthic boundary layer community, creating a time mark from which to evaluate future rates of biological processes in the deep sea. This is an unprecedented opportunity to study the effects of a natural large scale phenomenon, which only occurs on time scales of decades to centuries, on deep sea communities.