Less Antarctic sea ice may not mean fewer krill@en

A dominant Antarctic ecological paradigm suggests that winter sea ice is the feeding ground for krill larvae. However, several recent observations conflict with this hypothesis. Our study presents the first direct evidence that winter sea ice is actually a food-poor environment when compared to neighbouring open water regions. We found that complex under ice habitats are vital for larval krill, providing shelter from currents. During the day the larvae feed on the sparse ice-associated food but after sunset, they migrate into the water below the ice. This behaviour allows access to more food and promotes the dispersal of larvae to spring feeding grounds. Current larval krill overwintering and nursery habitats in the SW Atlantic are predicted to become ice-free in the future. This will lead to an enhanced food supply and faster larval development and growth but might increase the dispersal of larvae out of the SW Atlantic ecosystem.南极主流生态学范式认为，冬季海冰是磷虾幼体的摄食场。然而，近期多项观测结果与该假说相悖。本研究首次提供直接证据表明，相较于邻近的开阔水域区域，冬季海冰环境实则食物匮乏。研究发现，复杂的冰下生境对磷虾幼体至关重要，可为其提供躲避海流的庇护场所。日间，幼体以附着于海冰的稀缺食物为食；日落之后，它们会迁移至冰下水域。该行为不仅能帮助幼体获取更多食物，还可促进其向春季摄食场扩散。目前西南大西洋（SW Atlantic）区域内的磷虾幼体越冬与育苗生境，预计未来将无海冰覆盖。这将带来食物供给的提升以及幼体发育与生长速率的加快，但也可能增加磷虾幼体脱离西南大西洋生态系统的扩散风险。