UK Atlantic Margin Environmental Survey: Introduction and overview of bathyal benthic ecology
UK Atlantic Margin Environmental Survey: Introduction and overview of bathyal benthic ecology
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DOI：
10.1016/s0278-4343(00)00119-9
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发表时间：
2001-05-01
影响因子：
2.3
通讯作者：
Bett, BJ
中科院分区：
文献类型：
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作者：
Bett, BJ
石油和天然气工业最近向英国大西洋前沿的深水沃茨扩张，促使该行业及其监管机构重新评估环境监测的需求和手段。深海学者、专业承包商、监管机构和业界通过大西洋前沿环境网络（AFEN）协调一致，设计并实施了对苏格兰北部和西部深海沃茨的大规模环境调查。由澳大利亚海洋环境研究所资助的调查于1996年和1998年夏季进行，包括两个步骤：首先对调查区进行侧扫声纳测绘，然后通过取芯和摄影进行直接海底调查。本文论述了后一步骤。采集了海底样本，以评估沉积物类型、有机物含量、重金属、碳氢化合物和大型底栖生物。采用摄影和录像观测，以提供“常规”海底评估，并调查值得注意的特殊侧扫特征。虽然基本上是作为一项“基线”环境调查，但在所调查的地区，人为影响已经很明显。经常发现深海拖网影响的迹象（海底拖网痕迹和沉积物扰动区），几乎在所有研究区都有，水深超过1 000米。还发现了钻井泥浆对海床局部污染的证据，尽管背景碳氢化合物污染主要来自陆地或来自航运。英国大西洋边缘的底栖生态主要由法罗群岛-设得兰海峡（FSC）和罗卡尔海槽（RT）的水文地理的显著差异决定。相对温暖的北大西洋水在这两个地区都很常见;然而，在FSC，寒冷（零度以下）的沃茨占据了海峡的较深部分（> 600 m）。西设得兰群岛斜坡的极端温度梯度对大型底栖动物的分布和多样性有很大的影响。虽然动物群随深度不断变化，但暖水和冷水动物群却相当不同。边界区域，集中在400米水深，可能是最好的特点作为一个生态交错带，有一个混合的温暖和冷水动物的明显增强的多样性。Wyville-Thomson海岭在很大程度上阻止了FSC深层的冷水沃茨进入RT（它们当然不会影响勘测期间评估的Malin/Hebrides斜坡区域）。因此，海脊北部和南部的深水动物群非常不同。也有一个非常显着的差异，在两个动物群的多样性：多样性下降，在FSC的深度，但增加在RT的深度。在RT的大型底栖动物的分布基本上是连续的深度，很少有迹象表明当地的变化，但一些证据表明，在1200米左右的变化率增强，可能与拉布拉多海水的存在。在调查过程中进行的其他观察包括：（a）在斜坡中部深度（约100米）出现海绵为主的群落（“ostebund”）。500米）的北部和西部的设得兰群岛; Cb）的沉积物表面居住的enteroclasts人口的发现与砂质等深岩存款在西设得兰群岛斜坡（约500米）的基础。900米）;（c）广泛和丰富的植物碎屑发生在RT，但不是FSC;和fd）的“达尔文土丘”的发现在约。RT北方1000米处，一片由众多小型海底土丘组成的区域，支持珊瑚Lophelia pertusa的显著生长。这些土丘还具有“声学可见的尾巴”，具有密集的异生植物种群（Syringammina fragilissima），这是RT其他地方常见的物种。（C）2001 Elsevier Science Ltd.保留所有权利。
The recent expansion of the Oil and Gas Industry in to the deep waters of the UK Atlantic Frontier prompted the industry and its regulator to reappraise the needs and means of environmental monitoring. In concert, deep-sea academics, specialist contractors, the regulator and the Industry, through the Atlantic Frontier Environmental Network (AFEN), devised and implemented a large-scale environmental survey of the deep waters to the north and west of Scotland. The AFEN-funded survey was carried out during the summers of 1996 and 1998, and involved two steps; an initial sidescan sonar mapping of the survey areas, followed up with direct seabed investigations by coring and photography. This contribution deals with the latter step. Seabed samples were collected to assess sediment type, organic content, heavy metals, hydrocarbons and macrobenthos. Photographic and video observations were employed to provide both 'routine' seabed assessments and to investigate particular sidescan features of note. Although essentially intended as a 'baseline' environmental survey, anthropogenic impacts are already evident throughout the areas surveyed. Indications of the effects of deep-sea trawling were frequently encountered (seabed trawl marks and areas of disturbed sediments), being present in almost all of the areas studied and extending to water depths in excess of 1000 m. Evidence of localised contamination of the seabed by drilling muds was also detected, though background hydrocarbon contamination is predominantly of terrestrial origin or derived from shipping. The benthic ecology of the UK Atlantic Margin is dominated by the marked differences in the hydrography of the Faroe-Shetland Channel (FSC) and the Rockall Trough (RT). Comparatively warm North Atlantic Water is common to both areas; however, in the FSC, cold (subzero) waters occupy the deeper parts of the channel ( > 600 m). The extreme thermal gradient present on the West Shetland Slope has a substantial influence on the distribution and diversity of the macrobenthos. While there is continuous variation in the fauna with depth, warm and cold water faunas are nonetheless quite distinct. The boundary region, centred on 400m water depth, may be best characterised as an ecotone, having a mixed warm and cold water fauna with a distinctly enhanced diversity. The Wyville-Thomson Ridge largely prevents the cold waters of the deep FSC from entering the RT (they certainly do not influence the areas of the Malin/Hebrides Slope assessed during the survey). Consequently, the deep-water faunas north and south of the ridge are highly distinct. There is also a very marked difference in the diversity of the two faunas: diversity declines with depth in the FSC but increases with depth in the RT. The distribution of macrobenthos in the RT is largely continuous with depth, with little indication of local variations but some evidence of enhanced rates of change at around 1200 m, possibly associated with the presence of Labrador Sea Water. Other observations made during the course of the survey include: (a) the occurrence of sponge dominated communities ('ostebund') at mid-slope depths (ca. 500 m) north and west of Shetland; Cb) the discovery of a population of sediment surface dwelling enteropneusts associated with a sandy contourite deposit at the base of the West Shetland Slope (ca. 900m); (c) the widespread and abundant occurrence of phytodetritus in the RT but not the FSC; and fd) the discovery of the 'Darwin Mounds' at ca. 1000m in the northern RT, a field of numerous, small seabed mounds that support significant growths of the coral Lophelia pertusa.These mounds also have 'acoustically visible tails' with dense populations of xenophyophores (Syringammina fragilissima), a species found to be common elsewhere in the RT. (C) 2001 Elsevier Science Ltd. All rights reserved.