Global climate change is expected to impact ocean ecosystems through increases in temperature, decreases in pH and oxygen, increased stratification, with subsequent declines in primary productivity. These impacts propagate through the food chain leading to amplified effects on secondary producers and higher trophic levels. Similarly, climate change may disproportionately affect different species, with impacts depending on their ecological niche. To investigate how global environmental change will alter fish assemblages and productivity, we used a spatially explicit mechanistic model of the three main fish functional types reflected in fisheries catches (FEISTY) coupled to an Earth system model (GFDL-ESM2M) to make projections out to 2100. We additionally explored the sensitivity of projections to uncertainties in widely used metabolic allometries and their temperature dependence. When integrated globally, the biomass and production of all types of fish decreased under a high emissions scenario (RCP 8.5) compared to mean contemporary conditions. Projections also revealed strong increases in the ratio of pelagic zooplankton production to benthic production, a dominant driver of the abundance of large pelagic fish vs. demersal fish under historical conditions. Increases in this ratio led to a “pelagification” of ecosystems exemplified by shifts from benthic-based food webs toward pelagic-based ones. The resulting pelagic systems, however, were dominated by forage fish, as large pelagic fish suffered from increasing metabolic demands in a warming ocean and from declines in zooplankton productivity that were amplified at higher trophic levels. Patterns of relative change between functional types were robust to uncertainty in metabolic allometries and temperature dependence, though projections of the large pelagic fish had the greatest uncertainty. The same accumulation of trophic impacts that underlies the amplification of productivity trends at higher trophic levels propagates to the projection spread, creating an acutely uncertain future for the ocean’s largest predatory fish.

中文翻译：

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尽管海洋食物网浮出水面，但大型中上层鱼类对气候变化最敏感

预计全球气候变化将通过温度升高、pH 值和氧气降低、分层增加以及随后初级生产力下降来影响海洋生态系统。这些影响通过食物链传播，导致对次级生产者和更高营养水平的影响扩大。同样，气候变化可能会不成比例地影响不同的物种，其影响取决于它们的生态位。为了研究全球环境变化将如何改变鱼类组合和生产力，我们使用了反映在渔业捕捞量中的三种主要鱼类功能类型的空间显性机械模型 (FEISTY) 与地球系统模型 (GFDL-ESM2M) 相结合，以进行预测2100。我们还探讨了预测对广泛使用的代谢异变及其温度依赖性的不确定性的敏感性。当在全球范围内进行整合时，与当代平均条件相比，在高排放情景 (RCP 8.5) 下，所有类型鱼类的生物量和产量均有所下降。预测还显示中上层浮游动物产量与底栖动物产量的比率大幅增加，这是历史条件下大型中上层鱼类与底栖鱼类丰富度的主要驱动因素。这一比率的增加导致生态系统的“远洋化”，例如从基于底栖的食物网转向基于远洋的食物网。然而，由此产生的远洋系统以饲料鱼为主，由于大型中上层鱼类在变暖的海洋中代谢需求增加，浮游动物生产力下降，而浮游动物生产力下降在更高的营养水平上被放大。尽管大型中上层鱼类的预测具有最大的不确定性，但功能类型之间的相对变化模式对于代谢异基因组和温度依赖性的不确定性是稳健的。营养影响的累积是更高营养水平生产力趋势放大的基础，传播到预测范围，为海洋最大的掠食性鱼类创造了一个非常不确定的未来。尽管大型中上层鱼类的预测具有最大的不确定性。营养影响的累积是更高营养水平生产力趋势放大的基础，传播到预测范围，为海洋最大的掠食性鱼类创造了一个非常不确定的未来。尽管大型中上层鱼类的预测具有最大的不确定性。营养影响的累积是更高营养水平生产力趋势放大的基础，传播到预测范围，为海洋最大的掠食性鱼类创造了一个非常不确定的未来。