Biogeochemistry of the Darwin Mounds, NE Atlantic

The Darwin Mounds are a series of small (<=5 m high, 75-100 m diameter) sandy features located in the northern Rockall Trough. They provide a habitat for communities of Lophelia pertusa and associated fauna. Suspended particulate organic matter (sPOM) reaching the deep-sea floor, which could potentially fuel this deep-water coral (DWC) ecosystem, was collected during summer 2000. This was relatively \"fresh\" (i.e. dominated by labile lipids such as polyunsaturated fatty acids) and was derived largely from phytoplankton remains and faecal pellets, with contributions from bacteria and microzooplankton. Labile sPOM components were enriched in the benthic boundary layer (~10 m above bottom (mab)) relative to 150 mab. The action of certain benthic fauna that are exclusively associated with the DWC ecosystem (e.g. echiuran worms) leads to the subduction of fresh organic material into the sediments. The mound surface sediments are enriched in organic carbon, relative to off-mound sites. There is no evidence for hydrocarbon venting at this location.达尔文丘（Darwin Mounds）是分布于罗卡尔海槽（Rockall Trough）北部的一系列小型沙质地貌，其高度不超过5米，直径介于75至100米之间。该地貌为多枝笠珊瑚（Lophelia pertusa）群落及其伴生生物提供了栖息环境。2000年夏季，研究人员采集了抵达深海海底的悬浮颗粒有机物（sPOM）——这类物质可为该深水珊瑚（DWC）生态系统提供潜在的能量补给。这类悬浮颗粒有机物相对“新鲜”，即以多不饱和脂肪酸等易分解脂质为主要组成，其来源主要为浮游植物残体与粪粒，另有细菌及微型浮游动物的贡献。相较于150 mab处，易降解悬浮颗粒有机物组分在底栖边界层（距底约10米，mab，即meters above bottom）中更为富集。仅与深水珊瑚生态系统伴生的部分底栖生物（如螠虫（echiuran worms））的活动，会促使新鲜有机质向沉积物内搬运埋藏。相较于丘外站位，达尔文丘表层沉积物中的有机碳含量更为富集。该区域未发现烃类泄溢的相关证据。