Transient dynamics of an altered large marine ecosystem
Transient dynamics of an altered large marine ecosystem
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DOI：
10.1038/nature10285
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发表时间：
2011-09-01
期刊：
影响因子：
64.8
通讯作者：
Leggett, William C.
中科院分区：
文献类型：
--
作者：
Frank, Kenneth T.;Petrie, Brian;Leggett, William C.
在加拿大东海岸的苏格兰大陆架（1,2）和其他地方（3,4），对大型底栖鱼类的过度捕捞及其随后的种群崩溃导致了整个食物网的重组，现在主要是浮游生物、饲料鱼类和大型无脊椎动物。尽管自20世纪90年代初以来实施了严格的管理措施，但苏格兰大陆架生态系统并没有恢复到以前的结构。在这里，我们提供了该生态系统的瞬态性质及其当前回归路径的证据，以底栖鱼类为主导。改变的食物网持续时间的延长，以及它目前的恢复，过去和现在都是由饲料鱼综合体的振荡、失控的消费动态所控制的。这些爆发的饲料物种，其生物量比大型底栖食肉动物崩溃前的那些大900%，现在正在减少，已经超过了它们的浮游动物食物供应。这种抑制以及与之相关的捕食强度的降低，伴随着低营养和高营养水平物种丰度的滞后增长，首先是浮游动物，然后是大型捕食者，所有这些都与向早期生态系统结构的回归相一致。我们得出的结论是，受干扰的生态系统可能出现可逆性，这对其他崩溃的渔业来说是个好兆头。
Overfishing of large-bodied benthic fishes and their subsequent population collapses on the Scotian Shelf of Canada's east coast(1,2) and elsewhere(3,4) resulted in restructuring of entire food webs now dominated by planktivorous, forage fish species and macroinvertebrates. Despite the imposition of strict management measures in force since the early 1990s, the Scotian Shelf ecosystem has not reverted back to its former structure. Here we provide evidence of the transient nature of this ecosystem and its current return path towards benthic fish species domination. The prolonged duration of the altered food web, and its current recovery, was and is being governed by the oscillatory, runaway consumption dynamics of the forage fish complex. These erupting forage species, which reached biomass levels 900% greater than those prevalent during the pre-collapse years of large benthic predators, are now in decline, having outstripped their zooplankton food supply. This dampening, and the associated reduction in the intensity of predation, was accompanied by lagged increases in species abundances at both lower and higher trophic levels, first witnessed in zooplankton and then in large-bodied predators, all consistent with a return towards the earlier ecosystem structure. We conclude that the reversibility of perturbed ecosystems can occur and that this bodes well for other collapsed fisheries.