Department of Natural Resource Sciences, McGill University, Ste. Anne de Bellevue, Montreal, Quebec H9X3 V9, Canada.
Ecology. 2011 May;92(5):1115-25. doi: 10.1890/10-1185.1.
Fluxes of organic matter across habitat boundaries are common in food webs. These fluxes may strongly influence community dynamics, depending on the extent to which they are used by consumers. Yet understanding of basal resource use by consumers is limited, because describing trophic pathways in complex food webs is difficult. We quantified resource use for zooplankton, zoobenthos, and fishes in four low-productivity lakes, using a Bayesian mixing model and measurements of hydrogen, carbon, and nitrogen stable isotope ratios. Multiple sources of uncertainty were explicitly incorporated into the model. As a result, posterior estimates of resource use were often broad distributions; nevertheless, clear patterns were evident. Zooplankton relied on terrestrial and pelagic primary production, while zoobenthos and fishes relied on terrestrial and benthic primary production. Across all consumer groups terrestrial reliance tended to be higher, and benthic reliance lower, in lakes where light penetration was low due to inputs of terrestrial dissolved organic carbon. These results support and refine an emerging consensus that terrestrial and benthic support of lake food webs can be substantial, and they imply that changes in the relative availability of basal resources drive the strength of cross-habitat trophic connections.
生境边界的有机物质通量在食物网中很常见。这些通量可能会强烈影响群落动态，具体取决于它们被消费者利用的程度。然而，由于描述复杂食物网中的营养途径很困难，因此消费者对基础资源的利用理解有限。我们使用贝叶斯混合模型和氢、碳和氮稳定同位素比的测量值，量化了四个低生产力湖泊中浮游动物、底栖动物和鱼类的资源利用情况。该模型明确纳入了多种不确定性来源。因此，资源利用的后验估计通常是广泛的分布；尽管如此，明显的模式还是显而易见的。浮游动物依赖陆地和浮游初级生产力，而底栖动物和鱼类依赖陆地和底栖初级生产力。在所有消费者群体中，由于陆地溶解有机碳的输入导致透光率较低的湖泊中，陆地依赖度往往更高，而底栖依赖度更低。这些结果支持并完善了一个新兴共识，即陆地和底栖对湖泊食物网的支持可能是巨大的，并且它们意味着基础资源相对可用性的变化驱动了跨生境营养联系的强度。
