Received: 2 July 2019 | Revised: 3 December 2019 | Accepted: 18 December 2019 DOI: 10.1111/fwb.13476 REVIEW ARTICLE Positive biotic interactions in freshwaters: A review and research directive Samuel Silknetter1,2 | Robert P. Creed2 | Bryan L. Brown3 | Emmanuel A. Frimpong4 | James Skelton5 | Brandon K. Peoples1 1Department of Forestry and Environmental Conservation, Clemson University, Clemson, Abstract SC, USA 1. Positive interspecific interactions such as mutualism, commensalism, and facilita- 2 Department of Biology, Appalachian State tion are globally ubiquitous. Although research on positive interactions in terres- University, Boone, NC, USA 3Department of Biological Sciences, Virginia trial and marine systems has progressed over the past few decades, comparatively Polytechnic Institute and State University, little is known about them in freshwater ecosystems. However, recent advances Blacksburg, VA, USA have brought the study of positive interactions in freshwater systems to a point 4Department of Fish and Wildlife Conservation, Virginia Polytechnic Institute where synthesis is warranted. and State University, Blacksburg, VA, USA 2. In this review, we catalogue the variety of direct positive interactions described 5School of Forest Resources and to date in freshwater ecosystems, discuss factors that could influence prevalence Conservation, University of Florida, Gainesville, FL, USA and impact of these interactions, and provide a framework for future research. 3. In positive interactions, organisms exchange key resources such as nutrients, pro- Correspondence Brandon K. Peoples, Department of Forestry tection, transportation, or habitat to a net benefit for at least one participant. and Environmental Conservation, Clemson A few mutualistic relationships have received research attention to date, namely University, Clemson, SC 29634, USA. Email:
[email protected] seed-dispersing fishes, crayfishes and their ectosymbiotic cleaners, and commu- nal-spawning stream fishes.