Seamount megabenthic assemblages fail to recover from trawling impacts.
Seamount megabenthic assemblages fail to recover from trawling impacts.
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海山巨型底栖生物群无法从拖网捕捞的影响中恢复。
DOI：
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发表时间：
2010
期刊：
影响因子：
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通讯作者：
Rudy J. Kloser
中科院分区：
文献类型：
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作者：
A. Williams;T. Schlacher;A. Rowden;F. Althaus;Malcolm R. Clark;David A. Bowden;Robert Stewart;N. Bax;M. Consalvey;Rudy J. Kloser
由于海山在停止拖网捕捞后生物变化的性质、速度和轨迹尚不清楚，因此尚不清楚关闭拖网捕捞是否会导致动物群的恢复，如果是的话，恢复的时间尺度是什么。本文报告了2001年和2006年（间隔5年）在新西兰三个海山（间隔10年）和1997年和2006年在澳大利亚三个海山（间隔10年）进行的重复拖曳相机调查的“恢复测试”。在每个区域，将停止拖网捕捞的海山与附近仍在进行拖网捕捞的海山和从未进行过拖网捕捞的海山进行比较。如果存在恢复信号，则探测到信号的可能性很高，因为海山相对较小，地形简单，并且采用了定量调查方法。多变量模式显示，在停止拖网捕捞的海山上，巨型动物群落在5-10年的时间框架内没有变化，这与恢复一致。基于物种数量和多样性的结果是模棱两可的，在停止拖网捕捞的海底山有增加和减少的情况。在后来的调查中，个别分类群的丰度明显高于拖网捕捞。我们认为这可能是由于它们对拖网捕捞的直接影响（两种黄珊瑚和孤独的硬核珊瑚）的抵抗力，或者是由于拖网捕捞无法进入的自然避难所（未跟踪的海百合、两种黄珊瑚、柳珊瑚和海胆）的保护。或者，这些分类群可能代表了海底山重新定殖的最早阶段。它们有可能在很长一段时间内占据主导地位，因为拖网捕捞前海底山底栖生物组合的组成包括生长缓慢的分类群，或者与几千年来形成生物栖息地的单一楔石珊瑚（螺杆石珊瑚）的“灌木丛”有关联。与大多数其他受海底拖网捕捞干扰的海洋系统相比，以珊瑚为主的海山生态系统的恢复力较低，因为没有具有相同价值的替代栖息地来支持相关物种，而且拖网捕捞通常会从单个海山的大片区域移走珊瑚栖息地。保护海底山生态系统的管理需要考虑到不断变化的海洋学条件（海洋酸化），以及人类活动（如海底拖网捕捞）的直接影响。空间封闭网络包括在一定深度范围内的完整栖息地，特别是<1500 m，以及集群和孤立的海底山，可以有效地维持海底山底栖生物群落的恢复力。
Because the nature, tempo and trajectories of biological changes that follow the cessation of trawling are unknown for seamounts, it is unclear whether closing them to trawling will lead to a recovery of the fauna and, if so, over what time scales. This paper reports on a ‘test of recovery’ from repeated towed camera surveys on three seamounts off New Zealand in 2001 and 2006 (5 years apart) and three off Australia in 1997 and 2006 (10 years apart). In each region, seamounts where trawling had ceased were compared to adjacent seamounts where trawling was still active, and to seamounts that had never been trawled. If recovery signals existed, the likelihood of detecting them was high because the seamounts were relatively small and topographically simple, and because quantitative survey methods were employed. Multivariate patterns showed no change in the megafaunal assemblage consistent with recovery over a 5–10 year timeframe on seamounts where trawling had ceased. Results based on the number of species and diversity were equivocal, with some cases of increase and decrease on seamounts where trawling had ceased. A few individual taxa were found at significantly higher abundance in the later surveys where trawling had occurred. We suggest this may have resulted from their resistance to the direct impacts of trawling (two chrysogorgid corals and solitary scleractinians), or from protection in natural refuges inaccessible to trawls (unstalked crinoids, two chrysogorgid corals, gorgonians, and urchins). Alternatively, these taxa may represent the earliest stages of seamount recolonisation. They have potential to be dominant for long periods because the pre-trawling composition of benthic assemblages on seamounts includes taxa that grow slowly and ⁄ or have an association with ‘thickets’ of a single keystone stony coral (Solenosmilia variabilis) that has generated biogenic habitat over millennia. Resilience of seamount ecosystems dominated by corals is low compared to most other marine systems subject to disturbance by bottom trawling because there are no alternative habitats of the same value for supporting associated species, and because trawling typically removes coral habitat from large areas of individual seamounts. Management to conserve seamount ecosystems needs to account for changing oceanographic conditions (ocean acidification), as well as the direct impacts of human activities such as bottom trawling. Networks of spatial closures that include intact habitats over a range of depths, especially <1500 m, and on clusters and isolated seamounts, may be effective by maintaining the resilience of seamount benthic communities.