Ecological drivers of change at South Georgia: the krill surplus, or climate variability
Ecological drivers of change at South Georgia: the krill surplus, or climate variability
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南乔治亚岛变化的生态驱动因素：磷虾过剩或气候变化
DOI：
10.1111/j.1600-0587.2012.07330.x
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发表时间：
2012
期刊：
影响因子：
5.9
通讯作者：
Elizabeth A. Masden
中科院分区：
文献类型：
--
作者：
P. Trathan;N. Ratcliffe;Elizabeth A. Masden
通心粉企鹅被认为是南大洋最重要的中层捕食者之一，对猎物的可获得性和丰度的影响比任何其他海鸟物种都大。长期以来，它们的种群中心一直被认为是南乔治亚州，那里的种群被认为由数百万只动物组成。在此，我们报告了最近使用航空调查方法对南乔治亚州通心粉人口进行的普查结果。我们报告说，与20世纪70年代末观察到的数量(∼540万对)相比，数量(∼100万对繁殖)大幅下降，但表明这些减少主要发生在以前数量非常多的地点。在繁殖季节，这些地点鸟类的主要觅食地与南极毛海豹Arctocephalus gazella的觅食地重叠，Arctocephalus gazella是它们的主要猎物-南极磷虾Euphausia Superba的主要竞争对手。我们认为，南乔治亚州通心粉企鹅种群的重新分布反映了最近毛海豹种群的恢复，从而反映了南乔治亚州人类干预的持续后果，这一过程始于两百多年前。隐含的资源竞争和观察到的种群变化也可能因为最近南极磷虾丰度的减少而加剧，这与南极最近迅速的区域变暖后季节性海冰的减少有关；然而，毛海豹种群的恢复和以磷虾为食的鲸鱼种群的持续恢复认为，营养-动力相互作用可能足以解释观察到的变化。
Macaroni penguins Eudyptes chrysolophus are thought to be one of the most important mesopredators in the Southern Ocean having a greater impact on prey availability and abundance than any other seabird species. Their population centre has long been held to be South Georgia where populations were thought to comprise many million animals. Here we report the results of a recent census of the macaroni population at South Georgia undertaken using aerial survey methods. We report dramatic declines in numbers (∼1.0 million breeding pairs) compared to numbers observed in the late 1970s (∼5.4 million pairs), but show that these reductions have occurred principally at sites where numbers had previously been very large. During the breeding season, the main foraging grounds of birds from these sites overlap with the foraging grounds of Antarctic fur seals Arctocephalus gazella, a major competitor for their principal prey, Antarctic krill Euphausia superba. We suggest that the redistribution of the macaroni penguin population at South Georgia reflects the recent recovery of fur seal populations and thus the ongoing consequences of human intervention at South Georgia, a process which started more than 2 centuries previously. The implied resource competition and the observed population changes may also be exacerbated by recent reductions in Antarctic krill abundance which have been linked with reductions in seasonal sea ice following recent, rapid, regional warming in the Antarctic; however, the recovery of fur seal populations, and the ongoing recovery of krill-eating whale populations argues that tropho-dynamic interactions may be sufficient to explain the observed changes