Integrating spatial patterns and processes in food web and environmental studies: from 'who eats whom' and 'who eats where' to 'who eats whom and where'

摘要

Recently, habitat-specific carbon sources and fluxes have emerged as keystone processes for lake ecosystems (SCHINDLER & SCHEURELL 2002, VADEBONCOEUR et al. 2002, BERTOLO et al. 2005, KARLSSON & BYSTROM 2005, VANDER ZANDEN et al. 2006). Within-lake habitat boundaries allow spatially distinct (i.e. lit-toral-benthic vs. pelagic) and often asynchronous primary producer-consumer population dynamics to occur. These constitute distinct carbon fluxes that can merge via cross-habitat foraging by mobile secondary or tertiary consumers such as fish. Cross-habitat foraging thereby 'decouples consumer success from local constraints of productivity and prey dynamics (Pons et al. 1997, SCHINDLER & SCHEUERELL 2002), affecting trophic interactions, direction of energy flows (trophic cascades) and stability of food webs (SCHINDLER et al. 1996, Post et al. 2000, VADEBONCOEUR et al. 2005). Ecosystem structure and consumer life-history strategies influence the spatial process that is the coupling of habitat-specific carbon sources by consumers (Pons et al. 1997, SCHINDLER & SCHEUERELL 2002). We suggest that consumer ontogeny in fact determines the extent to which ecosystem characteristics may regulate trophic and spatial energy fluxes in food webs. In consequence, we propose a functional classification for consumer species that facilitates the measurement and identification of species-environment relationships, and the characterization of "who eats whom and where" in spatially-explicit aquatic ecosystems.