企鹅的主要食物是小鱼和磷虾。中国科学技术大学教授孙立广等人通过分析过去8000年企鹅食谱变化发现，由于近几百年人类对海豹和鲸的猎杀，磷虾在企鹅食谱中的比重显著增加，南极生态系统正承受人类活动和全球变暖带来的双重压力。这一研究成果9月30日发表在国际权威学术期刊《自然》子刊《科学报告》上。
南极磷虾是南大洋食物链中的关键物种，对气候海冰变化极为敏感，气候温暖时期数量偏低，偏凉时则增加，间接影响企鹅食谱的变化。
中科大孙立广、黄涛研究小组通过分析古今企鹅的骨骼、羽毛、粪土沉积物等发现，现代企鹅的氮同位素比值显著亏损，表明磷虾数量丰富。虽然近百年来全球气候变暖，但人类对南极海豹和鲸的猎杀使磷虾天敌减少，磷虾种群密度不降反增。这是人类活动影响海洋生态系统的典型案例。
南大洋磷虾生物量达10亿吨以上，是人类蛋白质资源的重要宝库。该项研究表明，自然气候变化和人类活动都曾对南极磷虾及海洋食物链变化产生过深刻影响，这对评估未来南极气候变化下磷虾的种群动态及南大洋生物资源保护具有重要科学价值（生物谷Bioo.com）。
生物谷推荐的英文摘要
Scientific Reports doi:10.1038/srep02807
Penguin tissue as a proxy for relative krill abundance in East Antarctica during the Holocene
Tao Huang，Liguang Sun，Nanye Long，Yuhong Wang & Wen Huang
Antarctic krill (Euphausia superba) is a key component of the Southern Ocean food web. It supports a large number of upper trophic-level predators， and is also a major fishery resource. Understanding changes in krill abundance has long been a priority for research and conservation in the Southern Ocean. In this study， we performed stable isotope analyses on ancient Adélie penguin tissues and inferred relative krill abundance during the Holocene epoch from paleodiets of Adélie penguin (Pygoscelis adeliae)， using inverse of δ15N (ratio of 15N/14N) value as a proxy. We find that variations in krill abundance during the Holocene are in accord with episodes of regional climate changes， showing greater krill abundance in cold periods. Moreover， the low δ15N values found in modern Adélie penguins indicate relatively high krill availability， which supports the hypothesis of krill surplus in modern ages due to recent hunt for krill-eating seals and whales by humans.
