Synergistic Effects of Salinity and Temperature on the Survival of Two Nonnative Bivalve Molluscs, Perna viridis (Linnaeus 1758) and Mytella charruana (d’Orbigny 1846)

Abstract

This study examined the combined salinity and temperature tolerance of two marine bivalve molluscs, Perna viridis and Mytella charruana, which have recently invaded the southeastern United States. It is essential to understand the role that these abiotic variables play in invasions and establishment of nonnative species. We simultaneously explored survival at three salinity ranges (5–9, 20–22.5, and 35–40 ppt) in both cold and warm water for juveniles and adults of both species. We determined that Perna viridis can survive at a wide range of temperatures (9–35°C) when the salinity is 35–37 ppt; however, as salinity decreased, the thermal survival range for P. viridis became narrower. With M. charruana, our data suggest that juvenile and adult individuals can survive at a wide range of salinities (5–40 ppt) at 20°C, but the salinity tolerance range narrowed as the temperature decreased or increased. Additionally, we observed that temperature rapidly impacted survival of P. viridis and M. charruana (within hours), while salinity impacts were more gradual (days to weeks). These data can be used to help predict successful introductions and future expansions of P. viridis and M. charruana in introduced habitats.