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

据预测，1998年春夏加利福尼亚海岸将出现一次主要的厄尔尼诺现象。1997 - 1998年厄尔尼诺现象的发展速度超过了近代历史上观察到的任何现象，包括1982 - 1983年的厄尔尼诺现象，当时被认为是本世纪最严重的事件。根据1992年至1993年厄尔尼诺现象的结果和1997年至1998年厄尔尼诺事件预测的前所未有的强度，我们预计进入深海的颗粒有机质通量（POM）将大幅下降，并对底栖边界层（BBL）群落产生伴随的影响。利用我们之前的长时间序列数据集进行比较，我们将通过这次厄尔尼诺事件在连续的基础上重新建立POM通量测量和海底摄影，并对沉积物群落活动进行季节性测量以检验三个假设。1)在过去7年中，深海POM通量作为食物供应的估算值将显著低于在相同深度测量的通量，同时表层水上升流和初级生产减少。2)沉积物群落耗氧量估算的沉积物群落活动将随着BBL中POM供应的减少而显著降低。3)移动的巨型底栖动物的活动将显著增加，同时减少对BBC的POM供应。我们预测，1997 - 1998年的厄尔尼诺事件将深刻影响底栖边界层群落，为评估深海生物过程的未来速率创造一个时间标记。这是一个前所未有的机会来研究自然大尺度现象对深海群落的影响，这种现象只发生在几十年到几百年的时间尺度上。

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.