Temporal Variation in Deep-Sea Benthic Boundary Layer Communities: Long Time-Series Measurements

长时间序列研究已经广泛地改变了我们对深海生物过程的基本理解。我们在东太平洋(4100米深)的一个深海站点建立了一个长时间序列观测站，在过去三年里，我们一直在测量颗粒物通量，同时用延时摄影技术监测海底。我们发现，进入海底边界层的颗粒物通量与碎屑聚集体在海底的到达和停留之间存在着很强的时间关系。这些碎屑集合体的停留时间跨度为6个月，与底栖大型动物丰度和运动的增加相吻合。到目前为止，我们的结果表明，近底浮游和海底过程之间存在耦合。然而，关于深海中上层和底栖生物过程如何以及在何种时间尺度上耦合，尤其是在我们在过去三年中观察到的年际变化的背景下，最重要的问题仍然存在。我们建议利用叠加在监测海底边界层的持续时间序列研究上的碎屑聚集体的现场测量来研究远洋有机质供应与底栖生物群落利用有机物质之间的耦合。具体地说，我们建议解决三个问题。1)在海底季节性观察到的碎屑聚集体的来源是什么？2)碎屑聚集体作为沉积物群落活动场所的重要性有多大？3)碎屑聚集体作为底栖大型动物活动场所的重要性有多大？这项研究将增进我们对远洋和海底过程之间的耦合的理解，并扩大目前对深海年际时间尺度上的生物地球化学循环的认识。

Long time-series studies have extensively altered our basic understanding of biological processes in the deep ocean. We have established a long time-series station at an abyssal site in the eastern N. Pacific (4100 m depth) and, over the past three years, have been measuring particulate matter flux while concurrently monitoring the sea floor with time-lapse photography. We have found a strong temporal relationship between the flux of particulate matter entering the benthic boundary layer and the arrival and residence of detrital aggregates on the sea floor. The residence of these detrital aggregates spans a six-month period and coincides with increased abundance and movements of the epibenthic megafauna. Our results to date suggest coupling exists between near-bottom pelagic and benthic processes. However, the most important questions still remain regarding how and on what time scales the pelagic and benthic processes are coupled in the deep sea, especially in the context of the interannual variability we have observed over the past three years. We propose to study the coupling between the pelagic supply of organic matter and its utilization by the benthic community using in situ measurements of detrital aggregates superimposed on a continuing time-series study of monitoring the benthic boundary layer. Specifically, we propose to address three questions. 1) What is the source of detrital aggregates observed seasonally on the sea floor? 2) How important are detrital aggregates as sites of sediment community activity? 3) How important are detrital aggregates as sited of epibenthic megafaunal activity? This study will improve our understanding of the coupling between pelagic and benthic processes and broaden current perceptions of biogeochemical cycling over interannual time scales in the deep ocean.