A foodweb model to explore uncertainties in the South Georgia shelf pelagic ecosystem
A foodweb model to explore uncertainties in the South Georgia shelf pelagic ecosystem
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DOI：
10.1016/j.dsr2.2011.09.001
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发表时间：
2012-01-01
影响因子：
3
通讯作者：
Murphy, Eugene J.
中科院分区：
文献类型：
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作者：
Hill, Simeon L.;Keeble, Kathryn;Murphy, Eugene J.
食物网模型为汇编有关生物量、生产、消费和饲养关系的数据提供了一个有用的框架。它们特别有助于确定数据中的差距和不一致之处，并有助于探索可能发生变化的情景。我们汇编了关于南乔治亚大陆架的远洋食物网的数据，这是南大洋研究最深入的区域之一。数据表明，目前平均的桡足类年产量是南极磷虾的三倍，飞翔的海鸟和鱼类分别占当地磷虾消费量的25%和21%。最引人注目的不一致之处在于，鱼的估计消费量是其估计产量的5倍。我们开发了一个食物网的静态质量平衡模型，代表了数据中不一致的许多可能解决方案之一。该模型包括了足够的鱼类生物量，以平衡最初的消费估计，因此鱼类成为磷虾的主要消费者。尽管如此，当地只有74%的磷虾产量被捕食者吃掉，这表明还有其他死亡来源，我们没有明确建模。我们开发了进一步的模型，以探索纳入气候驱动的磷虾生物量减少的合理情景。在捕食者食物不变的情况下，磷虾生物量减少80%会导致脊椎动物生物量减少73%。然而，当不同食物的捕食者能够转而以浮游动物替代猎物为食时，脊椎动物的总生物量保持在目前的水平。将80%的磷虾生物量替换为桡足类生物量的情景需要增加28%的初级生产量，因为桡足类的估计消耗率高于磷虾。额外的桡足类生物量并没有改变对脊椎动物的影响。这些情景说明了在气候变暖的情况下，从磷虾转变为以桡足类为主的系统可能产生的广泛后果。他们提出，脊椎动物产量的维持和大幅减少都是看似合理的结果，尽管前者需要对捕食者的饮食进行重大改变。(C)2011爱思唯尔有限公司。保留所有权利。
Foodweb models provide a useful framework for compiling data on biomass, production, consumption and feeding relationships. They are particularly useful for identifying gaps and inconsistencies in the data, and for exploring plausible scenarios of change. We compiled data on the pelagic foodweb of the South Georgia shelf, which is one of the most intensively studied areas in the Southern Ocean. The data suggest that current average annual copepod production is three times that of Antarctic krill and that flying seabirds and fish are, respectively, responsible for 25% and 21% of local krill consumption. The most striking inconsistency was that estimated consumption of fish was 5 times their estimated production. We developed a static mass balance model of the foodweb representing one of many possible solutions to the inconsistencies in the data. The model included sufficient fish biomass to balance the original consumption estimate, and consequently fish became the main krill consumers. Nonetheless, only 74% of local krill production was consumed by predators, suggesting that there are additional mortality sources that we did not explicitly model. We developed further models to explore scenarios incorporating plausible climate-driven reductions in krill biomass. In scenarios with unchanged predator diets, an 80% reduction in krill biomass resulted in a 73% reduction in vertebrate biomass. However, when predators with diverse diets were able to switch to feeding on alternative zooplankton prey, total vertebrate biomass was maintained at current levels. Scenarios in which 80% of krill biomass was replaced with copepod biomass required 28% more primary production because the estimated consumption rate of copepods is higher than that of krill. The additional copepod biomass did not alter the consequences for vertebrates. These scenarios illustrate the wide range of potential consequences of a shift from a krill to a copepod dominated system in a warming climate. They suggest that both maintenance and dramatic reduction of vertebrate production are plausible outcomes, although the former requires major changes in predator diets. (C) 2011 Elsevier Ltd. All rights reserved.