Stress tolerance of two freshwater invaders exposed to Microcystis aeruginosa and microcystin-LR

Invasion of freshwaters by non-native animal species is a major threat to global aquatic systems. Asian clams (Corbicula fluminea) and quagga mussels (Dreissena rostriformis bugensis) are two highly invasive bivalves in North America that share life histories that facilitate invasion; however, they may experience different stress tolerances which can influence local population distribution. We compare the sensitivity of these two bivalves to the environmental stressors Microcystis aeruginosa and its associated toxin, microcystin. In laboratory assays, we exposed both species to M. aeruginosa and measured oxygen consumption and filtration rate. Sensitivity to microcystin was evaluated through two oxidative stress biomarkers, catalase, and lipid peroxidation. Quagga mussels exhibited elevated physiological responses, consuming more oxygen with cyanobacteria exposure, at an approximately doubled rate compared to Asian clams. Both species had increased filtration rates when fed M. aeruginosa with quagga mussels filtering at an overall higher rate. Oxidative stress was variable in both species. These results indicate that quagga mussels may be more sensitive to M. aeruginosa and microcystin than Asian clams, possibly due to physiological differences associated with invasion histories. The findings from these studies can be used to predict range expansion and lead to more effective control of nuisance populations.