Consequences of Catastrophic Amphibian Declines on the Food Web Attributes of a Neotropical Stream

Understanding the effects of species losses on food web structure can help bridge significant knowledge gaps of how declining biodiversity affects ecosystems. Empirical assessments of the influence of species losses on the structure of species-rich food webs have not been performed. We use gut content analyses to empirically assess fourteen food web attributes of a periphyton-insect food web before and five years after a disease-driven amphibian declines in a highland Panamanian stream. The connectance and linkage density from pre- to post-decline food webs in stream pools was reduced from 0.11 to 0.10 and 6.86 to 4.76, respectively. However, other food web attributes such as consumer generalism, omnivory, and average path length did not change despite the loss of 25% of taxa (including tadpoles, insects, and diatoms). Nearly 50% of the trophic linkages present after the decline were not present before, reflecting a reorganization of food web topology, possibly mitigating the effect of species loss and suggesting that food web attributes may be more resistant to species loss than previously predicted.