Tracking biological invasions: an assessment of mussel species in the St. Johns River, Jacksonville, FL.
Perna viridis (Asian Green Mussel) and Mytella charruana (Charru Mussel) have been found within the estuaries of Florida, including the St. Johns River, for the past 30 y. This study verified the continuing presence of these 2 invasive mussels as well as the native Ischadium recurvum (Hooked Mussel) within the St. Johns River estuary. We found Hooked Mussels and Charru Mussels at all sampling locations, whereas we documented the Green Mussel at 2 sites. The overall densities and sizes of the Hooked Mussels and Charru Mussels varied by location. We observed higher densities of Charru Mussels at sites with lower salinities; none were observed at sites with salinity greater than 30 per mil. We noted the greatest Hooked Mussel density at moderate salinities, and those mussels had greater mean shell length compared to other mussel species at sites upriver. Our study highlighted the coexistence of native and non-native mussels within the estuary, and stressed the importance of continued monitoring of introduced mussel species in the southeastern US.