Feeding and overwintering of Antarctic krill across its major habitats: The role of sea ice cover, water depth, and phytoplankton abundance
Feeding and overwintering of Antarctic krill across its major habitats: The role of sea ice cover, water depth, and phytoplankton abundance
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DOI：
10.4319/lo.2014.59.1.0017
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发表时间：
2014-01
影响因子：
4.5
通讯作者：
K. Schmidt;A. Atkinson;D. Pond;Louise Ireland
中科院分区：
文献类型：
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作者：
K. Schmidt;A. Atkinson;D. Pond;Louise Ireland
南极磷虾(Euphausia Superba)的样本来自不同的栖息地：季节性冰覆盖的深海(拉扎雷夫海)，北部山脉(南乔治亚州)和南极半岛(布兰斯菲尔德海峡)的无冰搁架，以及斯科舍海的陆架和海洋遗址。在92个站点中，磷虾胃中的食物量由71±29%的藻类、17±21%的原生动物和12±25%的后生动物组成。脂肪酸营养标记表明，桡足类一直是磷虾食物的一部分，而不是替代食物。在开放水域，硅藻和桡足类的消耗量都随着浮游植物的丰度而增加。在海冰下，摄取硅藻的情况变得罕见，而以桡足类为食的情况保持不变。在冬季，幼体含有高比例但不同比例的硅藻标记，而在幼体中，桡足类的作用随着磷虾体长的增加而增加。越冬因栖息地不同而不同。南乔治亚州的磷虾比布兰斯菲尔德海峡或拉扎雷夫海的磷虾储存的脂肪更少。拉扎列夫海磷虾的摄食努力大大减少，而布兰斯菲尔德海峡和南乔治亚州的大多数个体胃里都有浮游植物和海底碎屑。它们保留了基本的身体储备，这表明磷虾在拉扎雷夫海经历了最艰难的冬季，其次是南乔治亚州，然后是布兰斯菲尔德海峡。这反映在拉扎雷夫海从青少年到成年人的延迟发育中。环极长度频率的比较表明，西南大西洋的磷虾生长条件比拉扎雷夫海或南极洲东部更有利，因为浮游植物繁殖期更长，而且获得海底食物的机会更大。
Antarctic krill (Euphausia superba) were sampled in contrasting habitats: a seasonally ice‐covered deep ocean (Lazarev Sea), ice‐free shelves at their northern range (South Georgia) and the Antarctic Peninsula (Bransfield Strait), and shelf and oceanic sites in the Scotia Sea. Across 92 stations, representing a year‐round average, the food volume in krill stomachs comprised 71 ± 29% algae, 17 ± 21% protozoans, and 12 ± 25% metazoans. Fatty acid trophic markers showed that copepods were consistently part of krill diet, not a switch food. In open waters, both diatom and copepod consumption increased with phytoplankton abundance. Under sea ice, ingestion of diatoms became rare, whereas feeding on copepods remained constant. During winter, larvae contained high but variable proportions of diatom markers, whereas in postlarvae the role of copepods increased with krill body length. Overwintering differed according to habitat. Krill from South Georgia had lower lipid stores than those from the Bransfield Strait or Lazarev Sea. Feeding effort was much reduced in Lazarev Sea krill, whereas most individuals from the Bransfield Strait and South Georgia contained phytoplankton and seabed detritus in their stomachs. Their retention of essential body reserves indicates that krill experienced most winter hardship in the Lazarev Sea, followed by South Georgia and then Bransfield Strait. This was reflected in the delayed development from juveniles to adults in the Lazarev Sea. Circumpolar comparisons of length frequencies suggest that krill growth conditions are more favorable in the southwest Atlantic than in the Lazarev Sea or off East Antarctica because of longer phytoplankton bloom periods and rewarding access to benthic food.