Diet, provisioning and productivity responses of marine predators to differences in availability of Antarctic krill
Diet, provisioning and productivity responses of marine predators to differences in availability of Antarctic krill
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DOI：
10.3354/meps177115
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发表时间：
1999-01-01
影响因子：
2.5
通讯作者：
Prince, PA
中科院分区：
文献类型：
--
作者：
Croxall, JP;Reid, K;Prince, PA
了解猎物可获得性和捕食者性能之间的关系是将捕食者用作海洋系统状况指标和评估自然捕食者与人类争夺共同资源的潜在后果的关键。南极磷虾丰度的波动被认为对南大洋依赖磷虾的顶级捕食者物种的繁殖性能有很大影响；这种相互作用的数量很少。在南乔治亚州，两年来声学调查揭示了磷虾丰度的主要差异，我们比较了4个主要捕食者物种的食物、后代的供应和繁殖成功(2只企鹅、2只信天翁，以及来自南极毛海豹的辅助数据)，它们对磷虾的依赖度通常在20%到90%之间。磷虾生物量在1986年(约30克m(-2))和1994年(约7克m(-2))之间相差4倍，伴随而来的是：(1)捕食者饲料中的磷虾质量减少了88%至90%(鱼类成分有所增加)，(2)大多数物种的猎物多样性增加，(3)物种间的食物重叠减少，(4)企鹅通心粉从磷虾转变为两足类，但其他物种的饮食没有重大变化。繁殖率在企鹅中下降了90%，在其他3个物种中下降了40%到50%；这是由于企鹅的食量减少(在企鹅中下降了90%，在通心粉中下降了50%)，以及信天翁的觅食旅行时间增加了一倍。灰头信天翁(最不依赖磷虾的物种)的繁殖成功率下降了50%，黑眉信天翁和正统企鹅的繁殖成功率下降了90%(只有3%到4%的卵产下了羽毛成熟的小企鹅)，但通心粉企鹅的繁殖成功率只下降了10%，这可能反映了它转向对其他物种无利可图的小型猎物的能力。然而，所有物种(黑眉信天翁除外)，特别是通心粉企鹅，产生的幼崽明显比平时轻得多，可能会影响它们随后的生存。也可以推断出对成年动物存活的一些影响。我们的结果显示了物种内部和物种之间的相似和差异的一个连贯的、尽管复杂的模式。这些主要反映了对磷虾的依赖程度，采取替代猎物的可行性，以及觅食适应对旅行时间和/或食物大小的限制(特别是与旅行速度和潜水能力有关，因此不能飞行的潜水员和远洋觅食者有明显的不同)。通过与其他研究，特别是设得兰海鸟的比较，探讨了这些原则的普遍性。
Knowledge of relationships between prey availability and predator performance is the key to using predators as indicators of the state of marine systems and to assessing potential consequences of competition between natural predators and man for common resources. Fluctuations in the abundance of Antarctic krill are believed to have a substantial influence on the reproductive performance of krill-dependent top predator species in the Southern Ocean; few quantifications of such interactions exist. At South Georgia, for 2 years in which acoustic surveys revealed a major difference in krill abundance, we compared diet, provisioning of offspring and breeding success in 4 main predator species (2 penguins, 2 albatrosses, with supporting data from Antarctic fur seal) whose dependence on krill typically ranges from 20 to 90%. The 4-fold difference in krill biomass between 1986 (ca 30 g m(-2)) and 1994 (ca 7 g m(-2)) was accompanied by (1) an 88 to 90% reduction in the mass of krill in predator diets (and some increase in the fish component), (2) greater prey diversity for most species, (3) reduced diet overlap between species and (4) a switch from krill to amphipods in macaroni penguin but no major dietary change in other species. Rates of provisioning of offspring decreased by 90% in gentoo penguin and 40 to 50% in the other 3 species; this was due to reduced meal size in penguins (by 90% in gentoo and 50% in macaroni) and to doubling of foraging trip duration in albatrosses. Breeding success was reduced by 50% in grey-headed albatross (the species least dependent on krill), by 90% in black-browed albatross and gentoo penguin (only 3 to 4% of eggs producing fledged chicks) but by only 10% in macaroni penguin, presumably reflecting its ability to switch to small prey unprofitable for the other species. However, all species (except for black-browed albatross), particularly macaroni penguin, produced fledglings significantly lighter than usual, probably affecting their subsequent survival. Some effects on adult survival could also be inferred. Our results show a coherent, though complex, pattern of within and between species similarities and differences. These mainly reflect the degree of dependence on krill, the feasibility of taking alternative prey and constraints on trip duration and/or meal size imposed by foraging adaptations (especially relating to travel speeds and diving abilities, whereby flightless divers and pelagic foragers differ markedly). The generality of these principles are explored through comparison with other studies, particularly of Shetland seabirds.