稳定同位素模型在水生生态系统食物网中的研究进展

水生生态系统食物网具有错综复杂的营养关系。稳定同位素技术的发展对了解生物间的摄食关系和食物网结构发挥着极为重要的作用。其中,稳定同位素混合模型(stable isotope mixing models, SIMMs)近年来的迅猛发展为进一步解决水生食物网的复杂性问题提供了有力的手段,尤其是在确定食物来源贡献和构建营养生态位方面。在本研究中,作者综述了稳定同位素模型的发展历程、主要模型的特点以及运行这类模型的条件;同时,对稳定同位素混合模型在水生生态系统食物网领域中的应用前景与局限性进行了总结与展望,以期为相关研究者提供参考     

Using stable isotope data to quantify niche overlap and diets of muskellunge,northern pike and walleye in a deep Minnesota lake

Muskellunge (Esox masquinongy Mitchill), northern pike (Esox lucius L.) and walleye (Sander vitreus Mitchill) often coexist in lake communities, yet uncertainty exists about the potential for interspecific competition among these top predators. Stable isotope data were used to assess niche overlap and diets of these predators in Elk Lake (Minnesota, U.S.A). δ¹³C indicated primary production sources (e.g. pelagic v. littoral) and δ¹⁵N indicated trophic position; the bivariate distribution of these isotopes defined the species’ isotopic niche. Niche overlap probabilities were calculated and stable isotope mixing models were used to quantify diet proportions. Muskellunge and northern pike niches overlapped little (<10%), while walleye overlapped muskellunge (15%–60%) and northern pike (33%–53%) more extensively. Muskellunge diets focused (50%) on cisco (Coregonus artedi Lesueur), walleye primarily assimilated non-cisco prey fish (80%), and northern pike diets were dominated by non-cisco prey fish (45%) and invertebrates (40%). The presence of a cisco population and the flexibility of northern pike to use invertebrate resources may decrease potential competition among these predators. However, cisco are threatened by climate change and eutrophication, and our results suggest that extirpation of cisco may cause major changes in potential competitive interactions among these top predators. Moreover, cisco were unique among prey species in their ability to exploit pelagic energy, such that loss of cisco will likely alter energy flow in lake food webs where they currently exist.