This is an archive for data and products from the NSF-funded project DEB 1457542, "Collaborative Research: Shifting hotspots - How do consumer aggregations interact to influence resource heterogeneity and fluxes in streams". PIs on this project are Caryn Vaughn from the University of Oklahoma and Keith Gido from Kansas State Univeristy. The project was conducted from March 2015 - March 2019. **Project lay summary:** In terrestrial and aquatic ecosystems, animals frequently occur in dense aggregations. Examples include herds of deer, schools of fish, flocks of birds, and beds of mussels. Research into the effects of such aggregations on ecosystems has typically focused on a single species or animal group. In stream ecosystems, fish and mussels have the strongest animal-mediated biogeochemical and ecosystem effects. Fish schools or mussel beds can increase nutrient concentrations, alter their ratios, increase algal growth, and affect the growth of aquatic insects. These effects have been investigated separately for each group, however, in most streams, dense aggregations of fish and mussels periodically overlap. Our research explored the ecosystem and biogeochemical responses when fish and mussel aggregations overlapped. We investigated these responses with a field survey, field experiment, and several artificial stream experiments with the help of undergraduate students, graduate students, and post-doctoral researchers. In the field, we surveyed the abundances of fish and mussel species along the Kiamichi, Little, and Glover Rivers in Oklahoma and then scaled up their abundances to estimate their impacts on nutrient concentration and stoichiometry. We found that the abundance of fish on mussel beds was driven by hydrology, and that fish mass on mussel beds was highest when the river flows were low. During these periods we found that the overlap had the greatest impact on the modeled ratios of nutrients on those beds. Further field experimentation manipulating the density of mussels revealed that fish were attracted to the structure of mussel shells. Because mussel beds typically occupy areas of rivers where water is always available (even during drought), mussels may provide an important underwater landmark for fish seeking refugia that won’t dry out during drought. In an experimental stream experiment simulating seasonal low flows, we showed that fish survived longer in mesocosms with mussels than those without and at extreme levels of low flow – when streams and mussel beds dry out – we found that mussel bed die-offs can have both short- and long-term influences on the ecosystem services of rivers. Along with this work, we manipulated fish presence on mussel beds. This work extended our understanding of the food web effects of overlapping fish schools and mussel beds. Importantly our work highlights interconnections between animal and microbial ecosystems. Our research provided fundamental insight into how animals influence the organic energy available to microbial community function. Such insight will be important for modeling and anticipating the microbial ecosystem and biogeochemical responses to ongoing losses in animal biomass and biodiversity. Through this project, we provided teacher training that increased the capacity of local school systems to educate students about aquatic ecosystems. We also provided training for graduate students who will continue advancing knowledge in environmental biology. Finally, we provided opportunities for underrepresented groups in STEM that have helped them further their careers.