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

长期的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。我们在北太平洋东部的一个深海地点（4100米深）建立了一个长时间序列站，在过去三年中，一直在测量颗粒物质通量，同时用延时摄影监测海底。我们发现进入底栖边界层的颗粒物质通量与海底碎屑聚集体的到达和停留之间存在很强的时间关系。这些碎屑聚集体的停留时间长达6个月，与底栖巨型动物的丰度和活动增加相吻合。到目前为止，我们的结果表明，在近底部的上层海洋和底栖生物过程之间存在耦合。然而，最重要的问题仍然是深海中上层和底栖过程如何以及在什么时间尺度上耦合，特别是在我们过去三年观察到的年际变化的背景下。我们建议在连续监测底栖边界层的时间序列研究基础上，利用碎屑团聚体的原位测量来研究深海有机质供应与底栖生物群落利用之间的耦合关系。具体来说，我们建议解决三个问题。1)海底季节性观测到的碎屑聚集体的来源是什么？2)碎屑团聚体作为沉积物群落活动场所的重要性如何？3)碎屑聚集体作为底栖巨型动物活动的场所有多重要？这项研究将提高我们对上层海洋和底栖生物过程之间耦合的理解，并拓宽目前对深海生物地球化学循环年际时间尺度的认识。

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.