Earth to Ocean Research Group, Department of Biological Sciences, Faculty of Environment, Simon Fraser University, 8888 University Drive, Burnaby, British Columbia, Canada, V5A 1S6.
Proc Biol Sci. 2013 Jan 2;280(1753):20122433. doi: 10.1098/rspb.2012.2433. Print 2013 Feb 22.
A general rule in ecology is that the abundance of species or individuals in communities sharing a common energy source decreases with increasing body size. However, external energy inputs in the form of resource subsidies can modify this size spectrum relationship. Here, we provide the first test of how a marine resource subsidy can affect size spectra of terrestrial communities, based on energy derived from Pacific salmon carcasses affecting a forest soil community beside streams in western Canada. Using both species-based and individual approaches, we found size structuring in this forest soil community, and transient community-wide doubling of standing biomass in response to energy pulses from Pacific salmon carcasses. One group of species were clear outliers in the middle of the size spectrum relationship: larval calliphorid and dryomyzid flies, which specialize on salmon carcasses, and which showed a tenfold increase in biomass in their size class when salmon were available. Thus, salmon subsidize their escape from the size spectrum. These results suggest that using a size-based perspective of resource subsidies can provide new insights into the structure and functioning of food webs.
生态学中的一个普遍规律是，在共享共同能源的群落中，物种或个体的丰度随着体型的增大而减少。然而，以资源补贴形式出现的外部能源输入可以改变这种体型谱关系。在这里，我们首次测试了海洋资源补贴如何影响陆地群落的体型谱，研究对象是加拿大西部溪流旁森林土壤群落中来自太平洋鲑鱼尸体的能量。我们使用基于物种和个体的方法，发现了这个森林土壤群落的体型结构，并且由于太平洋鲑鱼尸体的能量脉冲，群落的生物量在整个范围内出现了短暂的两倍增长。有一组物种在体型谱关系的中间明显是异常值：幼虫花蝇科和干蝇科蝇，它们专门以鲑鱼尸体为食，当鲑鱼可用时，它们在体型类别中的生物量增加了十倍。因此，鲑鱼补贴了它们对体型谱的逃避。这些结果表明，使用基于体型的资源补贴视角可以为食物网的结构和功能提供新的见解。
