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Abiotic parameters dictating community composition and the ecological functions of freshwater mussels
Proceedings of the 2019 Mississippi Water Resources Conference
Year: 2019 Authors: Atkinson C., van Ee B.
Animal aggregations can lead to localized hotspots of nutrient and material flux in streams. Yet, the abiotic characteristics driving the spatial structure of these hotspots due to species-specific preferences remain a mystery. Historically, unionid mussels dominated benthic biomass in many river ecosystems, but have undergone extensive declines. We examined reach-scale physical attributes of sites encompassing a gradient of mussel densities, evaluated quadrat-scale abiotic variables, and the role various species play in nutrient (C, N, P) sequestration and regeneration. We sampled mussels and abiotic variables at 1,218 quadrats, measured tissue nutrient composition and excretion and biodeposition rates of 11 species across 12 reaches in the Sipsey River, Alabama. Using geostatistical analyses, species distributions and their associated ecological functions were mapped and models were developed to examine species distributions and species' roles in recycling and storing nutrients. These models were used to examine species-specific roles in reach- and quadrat-scale nutrient recycling and storage. Our results demonstrate that mussels are important to nutrient dynamics through nutrient regeneration and the creation of storage hotspots, but their significance varies with distribution, species composition, and abiotic context.