Consumer movement through differentially subsidized habitats creates a spatial food web with unexpected results

Energy and nutrient flow between habitats, or allochthonous input, can have a significant impact on food web dynamics. Previous theory demonstrated that resource abundance decreases in habitats where consumers are subsidized. Here we examine the effect of subsidies that are available in localized parts of a habitat (such as near the shore in a marine-subsidized terrestrial ecosystem) with a two-patch model in which consumers move between patches, resources are stationary, and consumers receive the subsidy in only one of the two patches. In contrast to previous theory, our results show that subsidized consumers can increase resource abundance, though only in the subsidized patch. Furthermore, the total resource population responds positively to increasing consumer movement. These results demonstrate the importance of spatial heterogeneity in food web dynamics and the need for further examination of the role of space in multispecies trophic webs.