Antarctic Ecosystem Research Division, Southwest Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, La Jolla, CA 92037, USA.
Proc Natl Acad Sci U S A. 2011 May 3;108(18):7625-8. doi: 10.1073/pnas.1016560108. Epub 2011 Apr 11.
The West Antarctic Peninsula (WAP) and adjacent Scotia Sea support abundant wildlife populations, many of which were nearly extirpated by humans. This region is also among the fastest-warming areas on the planet, with 5-6 °C increases in mean winter air temperatures and associated decreases in winter sea-ice cover. These biological and physical perturbations have affected the ecosystem profoundly. One hypothesis guiding ecological interpretations of changes in top predator populations in this region, the "sea-ice hypothesis," proposes that reductions in winter sea ice have led directly to declines in "ice-loving" species by decreasing their winter habitat, while populations of "ice-avoiding" species have increased. However, 30 y of field studies and recent surveys of penguins throughout the WAP and Scotia Sea demonstrate this mechanism is not controlling penguin populations; populations of both ice-loving Adélie and ice-avoiding chinstrap penguins have declined significantly. We argue in favor of an alternative, more robust hypothesis that attributes both increases and decreases in penguin populations to changes in the abundance of their main prey, Antarctic krill. Unlike many other predators in this region, Adélie and chinstrap penguins were never directly harvested by man; thus, their population trajectories track the impacts of biological and environmental changes in this ecosystem. Linking trends in penguin abundance with trends in krill biomass explains why populations of Adélie and chinstrap penguins increased after competitors (fur seals, baleen whales, and some fishes) were nearly extirpated in the 19th to mid-20th centuries and currently are decreasing in response to climate change.
西南极半岛（WAP）和毗邻的斯科舍海拥有丰富的野生动物种群，其中许多物种因人类活动而几乎灭绝。该地区也是地球上变暖最快的地区之一，冬季平均气温上升了 5-6°C，冬季海冰覆盖面积相应减少。这些生物和物理干扰深刻地影响了生态系统。一个指导该地区顶级捕食者种群变化的生态解释的假设，即“海冰假说”，提出冬季海冰减少直接导致“喜冰”物种数量减少，因为它们的冬季栖息地减少，而“避冰”物种的数量增加。然而，30 年来在该地区进行的实地研究和最近对企鹅的调查表明，这种机制并没有控制企鹅的数量；喜爱冰的阿德利企鹅和避冰的帽带企鹅的数量都显著减少。我们赞成一个替代的、更有力的假设，即企鹅数量的增加和减少归因于它们主要猎物南极磷虾丰度的变化。与该地区的许多其他捕食者不同，阿德利企鹅和帽带企鹅从未被人类直接捕捞；因此，它们的种群轨迹反映了该生态系统中生物和环境变化的影响。将企鹅数量的趋势与磷虾生物量的趋势联系起来，可以解释为什么在 19 世纪到 20 世纪中叶，当竞争对手（海豹、须鲸和一些鱼类）几乎灭绝后，阿德利企鹅和帽带企鹅的数量增加，而目前由于气候变化，它们的数量正在减少。
