Could quagga mussels impact offshore benthic community and surface sediment-bound nutrients in the Laurentian Great Lakes?

Dreissenids have greatly altered ecosystem function within the Great Lakes, but their effects on offshore surface sediments and infaunal communities are not well understood. This study explores the correlation among quagga mussel biomass, density of offshore benthos, and nutrients in surface sediments to understand the potential dreissenid facilitation of interactions between benthos and nutrient dynamics in lakes Michigan, Huron, and Ontario. The strongest relationships seen in this study were the positive associations between oligochaete density and quagga mussel biomass in all lakes. Weaker relationships were noted between quagga mussel biomass and surface sediment organic carbon, total phosphorus, and total nitrogen. In areas with higher mussel biomass, there were lower concentrations of organic carbon and total phosphorus in sediments, even though mussels are thought to increase the delivery of organic material into the benthos. Surface sediment total nitrogen concentrations were lower in high mussel biomass areas in Lake Ontario but not in lakes Michigan and Huron. These results support recent findings that non-native mussels can greatly alter nutrient cycles, as well as demonstrate the need for improved understanding of the effects mussel beds have on the surrounding benthic communities, and the cascading effects these changes may have for nutrient and carbon cycles.