Moreno Rocío, Stowasser Gabriele, McGill Rona A R, Bearhop Stuart, Phillips Richard A
British Antarctic Survey, Natural Environment Research Council, High Cross, Madingley Road, Cambridge, CB3 0ET, UK.
Scottish Universities Environmental Research Centre (SUERC), Rankine Avenue, Scottish Enterprise Technology Park, East Kilbride, G75 0QF, UK.
J Anim Ecol. 2016 Jan;85(1):199-212. doi: 10.1111/1365-2656.12434. Epub 2015 Oct 6.
Understanding interspecific interactions, and the influences of anthropogenic disturbance and environmental change on communities, are key challenges in ecology. Despite the pressing need to understand these fundamental drivers of community structure and dynamics, only 17% of ecological studies conducted over the past three decades have been at the community level. Here, we assess the trophic structure of the procellariiform community breeding at South Georgia, to identify the factors that determine foraging niches and possible temporal changes. We collected conventional diet data from 13 sympatric species between 1974 and 2002, and quantified intra- and inter-guild, and annual variation in diet between and within foraging habits. In addition, we tested the reliability of stable isotope analysis (SIA) of seabird feathers collected over a 13-year period, in relation to those of their potential prey, as a tool to assess community structure when diets are diverse and there is high spatial heterogeneity in environmental baselines. Our results using conventional diet data identified a four-guild community structure, distinguishing species that mainly feed on crustaceans; large fish and squid; a mixture of crustaceans, small fish and squid; or carrion. In total, Antarctic krill Euphausia superba represented 32%, and 14 other species a further 46% of the combined diet of all 13 predators, underlining the reliance of this community on relatively few types of prey. Annual variation in trophic segregation depended on relative prey availability; however, our data did not provide evidence of changes in guild structure associated with a suggested decline in Antarctic krill abundance over the past 40 years. Reflecting the differences in δ(15) N of potential prey (crustaceans vs. squid vs. fish and carrion), analysis of δ(15) N in chick feathers identified a three-guild community structure that was constant over a 13-year period, but lacked the trophic cluster representing giant petrels which was identified using conventional diet data. Our study is the first in recent decades to examine dietary changes in seabird communities over time. Conventional dietary analysis provided better resolution of community structure than SIA. However, δ(15) N in chick feathers, which reflected trophic (level) specialization, was nevertheless an effective and less time-consuming means of monitoring temporal changes.
理解种间相互作用以及人为干扰和环境变化对群落的影响，是生态学中的关键挑战。尽管迫切需要了解群落结构和动态的这些基本驱动因素，但在过去三十年进行的生态学研究中，只有17%是在群落层面开展的。在此，我们评估了在南乔治亚岛繁殖的鹱形目群落的营养结构，以确定决定觅食生态位的因素以及可能的时间变化。我们收集了1974年至2002年间13个同域物种的传统饮食数据，并对觅食习性之间和内部的 guild内和guild间以及饮食的年度变化进行了量化。此外，我们测试了在13年期间收集的海鸟羽毛的稳定同位素分析（SIA）相对于其潜在猎物的可靠性，作为在饮食多样且环境基线存在高度空间异质性时评估群落结构的一种工具。我们使用传统饮食数据的结果确定了一个四guild群落结构，区分了主要以甲壳类动物为食的物种；大型鱼类和鱿鱼；甲壳类动物、小型鱼类和鱿鱼的混合物；或腐肉。总体而言，南极磷虾在所有13种捕食者的混合饮食中占32%，其他14个物种占另外46%，突出了这个群落对相对较少种类猎物的依赖。营养隔离的年度变化取决于相对猎物的可获得性；然而，我们的数据没有提供与过去40年南极磷虾丰度下降相关的guild结构变化的证据。反映潜在猎物（甲壳类动物与鱿鱼与鱼类和腐肉）的δ(15)N差异，对雏鸟羽毛中δ(15)N的分析确定了一个在13年期间恒定的三guild群落结构，但缺少使用传统饮食数据确定的代表巨鹱的营养簇。我们的研究是近几十年来首次研究海鸟群落饮食随时间的变化。传统饮食分析比SIA能更好地解析群落结构。然而，雏鸟羽毛中的δ(15)N反映了营养（水平）专业化，仍然是监测时间变化的一种有效且耗时较少的方法。
