Klein Emily S, Hill Simeon L, Hinke Jefferson T, Phillips Tony, Watters George M
Antarctic Ecosystem Research Division, Southwest Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, La Jolla, California, United States of America.
Farallon Institute, Petaluma, California, United States of America.
PLoS One. 2018 Jan 31;13(1):e0191011. doi: 10.1371/journal.pone.0191011. eCollection 2018.
Climate change is a threat to marine ecosystems and the services they provide, and reducing fishing pressure is one option for mitigating the overall consequences for marine biota. We used a minimally realistic ecosystem model to examine how projected effects of ocean warming on the growth of Antarctic krill, Euphausia superba, might affect populations of krill and dependent predators (whales, penguins, seals, and fish) in the Scotia Sea. We also investigated the potential to mitigate depletion risk for predators by curtailing krill fishing at different points in the 21st century. The projected effects of ocean warming on krill biomass were strongest in the northern Scotia Sea, with a ≥40% decline in the mass of individual krill. Projections also suggest a 25% chance that krill biomass will fall below an established depletion threshold (75% of its unimpacted level), with consequent risks for some predator populations, especially penguins. Average penguin abundance declined by up to 30% of its unimpacted level, with up to a 50% chance of falling below the depletion threshold. Simulated krill fishing at currently permitted harvest rates further increased risks for depletion, and stopping fishing offset the increased risks associated with ocean warming in our model to some extent. These results varied by location and species group. Risk reductions at smaller spatial scales also differed from those at the regional level, which suggests that some predator populations may be more vulnerable than others to future changes in krill biomass. However, impacts on predators did not always map directly to those for krill. Our findings indicate the importance of identifying vulnerable marine populations and targeting protection measures at appropriate spatial scales, and the potential for spatially-structured management to avoid aggravating risks associated with rising ocean temperatures. This may help balance tradeoffs among marine ecosystem services in an uncertain future.
气候变化对海洋生态系统及其提供的服务构成威胁，降低捕捞压力是减轻对海洋生物群总体影响的一种选择。我们使用了一个极简的现实生态系统模型，来研究海洋变暖对南极磷虾（Euphausia superba）生长的预测影响，可能如何影响斯科舍海中的磷虾种群以及依赖磷虾的捕食者（鲸鱼、企鹅、海豹和鱼类）。我们还调查了在21世纪不同时间点减少磷虾捕捞，以减轻捕食者枯竭风险的潜力。海洋变暖对磷虾生物量的预测影响在斯科舍海北部最为强烈，个体磷虾质量下降≥40%。预测还表明，磷虾生物量有25%的可能性降至既定的枯竭阈值以下（其未受影响水平的75%），这将给一些捕食者种群带来风险，尤其是企鹅。企鹅的平均丰度下降幅度高达其未受影响水平的30%，有高达50%的可能性降至枯竭阈值以下。以目前允许的捕捞率模拟磷虾捕捞，进一步增加了枯竭风险，而停止捕捞在一定程度上抵消了我们模型中与海洋变暖相关的风险增加。这些结果因地点和物种组而异。较小空间尺度上的风险降低也与区域层面不同，这表明一些捕食者种群可能比其他种群更容易受到未来磷虾生物量变化的影响。然而，对捕食者的影响并不总是直接对应于对磷虾的影响。我们的研究结果表明，识别脆弱海洋种群并在适当空间尺度上针对性地采取保护措施很重要，以及空间结构化管理有潜力避免加剧与海洋温度上升相关联的风险。这可能有助于在不确定的未来平衡海洋生态系统服务之间的权衡。
