Morra Kaycee E, Chikaraishi Yoshito, Gandhi Hasand, James Helen F, Rossman Sam, Wiley Anne E, Raine Andre F, Beck Jessie, Ostrom Peggy H
Department of Integrative Biology, Michigan State University, 203 Natural Science Building, 288 Farm Lane, East Lansing, MI, 48824, USA.
Institute of Low Temperature Science, Hokkaido University, Kita-19, Nishi-8, Kita-ku, Sapporo, 060-0819, Japan.
Oecologia. 2019 Feb;189(2):395-406. doi: 10.1007/s00442-018-04330-8. Epub 2019 Jan 8.
We investigated how foraging habits vary among three ecologically distinct wide-ranging seabirds. Using amino acid δN proxies for nutrient regime (δN) and trophic position (ΔδN), we compared Newell's shearwater (Puffinus newelli) and Laysan albatross (Phoebastria immutabilis) foraging habits over the past 50-100 years, respectively, to published records for the Hawaiian petrel (Pterodroma sandwichensis). Standard ellipses constructed from the isotope proxies show that inter-population and interspecific foraging segregation have persisted for several decades. We found no evidence of a shift in nutrient regime at the base of the food web for the three species. However, our data identify a trophic decline during the past century for Newell's shearwater and Laysan albatross (probability ≥ 0.97), echoing a similar decline observed in the Hawaiian petrel. During this time, Newell's shearwaters and Hawaiian petrels have experienced population declines and Laysan albatross has experienced range extension and apparent population stability. Counting other recent studies, a pattern of trophic decline over the past century has now been identified in eight species of pelagic seabirds that breed in the Hawaiian Islands. Because our study species forage broadly across the North Pacific Ocean and differ in morphological and behavioral traits and feeding methods, the identified trophic declines suggest a pervasive shift in food web architecture within the past century.
我们研究了三种生态特征不同、分布范围广泛的海鸟的觅食习性如何变化。利用氨基酸δN作为营养状况（δN）和营养级（ΔδN）的指标，我们分别比较了纽厄尔氏鹱（Puffinus newelli）和黑背信天翁（Phoebastria immutabilis）在过去50 - 100年的觅食习性，并与夏威夷海燕（Pterodroma sandwichensis）已发表的记录进行对比。根据同位素指标构建的标准椭圆表明，种群间和种间的觅食隔离已经持续了几十年。我们没有发现这三个物种的食物网基础营养状况发生变化的证据。然而，我们的数据表明，在过去的一个世纪里，纽厄尔氏鹱和黑背信天翁的营养级有所下降（概率≥0.97），这与在夏威夷海燕中观察到的类似下降情况相呼应。在此期间，纽厄尔氏鹱和夏威夷海燕的种群数量减少，而黑背信天翁的分布范围扩大且种群数量明显稳定。综合其他近期研究，现已确定在夏威夷群岛繁殖的八种远洋海鸟在过去一个世纪里都出现了营养级下降的模式。由于我们研究的物种在北太平洋广泛觅食，且在形态、行为特征和觅食方式上存在差异，所确定的营养级下降表明在过去的一个世纪里食物网结构发生了普遍变化。
