Growing evidence indicates that parasites—when considered—can play influential roles in ecosystem structure and function, highlighting the need to integrate disease ecology and ecosystem science. To strengthen links between these traditionally disparate fields, we identified mechanisms through which parasites can affect ecosystems and used empirical literature searches to explore how commonly such mechanisms have been documented, the ecosystem properties affected, and the types of ecosystems in which they occur. Our results indicate that ecosystem-disease research has remained consistently rare, comprising less than 2% of disease ecology publications. Existing studies from terrestrial, freshwater, and marine systems, however, demonstrate that parasites can strongly affect (1) biogeochemical cycles of water, carbon, nutrients, and trace elements, (2) fluxes of biomass and energy, and (3) temporal ecosystem dynamics including disturbance, succession, and stability. Mechanistically, most studies have demonstrated density-mediated indirect effects, rather than trait-mediated effects, or direct effects of parasites, although whether this is representative remains unclear. Looking forward, we highlight the importance of applying traits-based approaches to predict when parasites are most likely to exert ecosystem-level effects. Future research should include efforts to extend host–parasite studies across levels of ecological organization, large-scale manipulations to experimentally quantify ecosystem roles of parasites, and the integration of parasites and disease into models of ecosystem functioning.
Keywordsparasite pathogen infection host ecosystem structure ecosystem function ecosystem dynamics biogeochemistry energy flow stability
We thank S. Collinge, M. Joseph, V. McKenzie, J. Mihaljevic, Y. Springer, and two anonymous reviewers for comments that improved the manuscript. This research was supported by a fellowship from the David and Lucile Packard Foundation and funds from the University of Colorado and the National Science Foundation (DEB-0841758, DEB-1149308, DEB-1311467, and a Graduate Fellowship to DLP).
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