Temperature, Salinity, and Aerial Exposure Tolerance of the Invasive Mussel, Perna viridis, in Estuarine Habitats: Implications for Spread and Competition with Native Oysters, Crassostrea virginica

Abstract

Temperature, salinity, and aerial exposure tolerances of the invasive green mussel, Perna viridis, were investigated under environmentally realistic conditions to address potential competition with native oysters, Crassostrea virginica. This study demonstrated that green mussels exhibit a temperature tolerance range similar to that of its native range (13–30 °C), thereby limiting northern spread of south Florida populations. Salinity tolerances as low as 6 were observed during gradual decreases; however, acute changes resulted in low survival at salinities of 15 and below. At low salinities, even when survival was high, reductions in normal behavior (byssal production and valve closure) were observed. Green mussel survival was significantly inhibited during aerial exposure across all temperatures, and mortality synergistically increased (60–80 %) with increasing temperatures and exposure time. In contrast, oysters demonstrated ≥97 % survival over the exposure period at similar internal temperatures observed in green mussels. Internal temperatures for both species frequently exceeded 33 °C, reaching temperatures as high as 41 °C, while air temperatures averaged only 26.4 ± 1.6 °C. Our results suggest that while Florida green mussel populations exhibit relatively broad temperature and salinity ranges, their spread is limited by the available subtidal habitat, potentially sparing intertidal oyster reefs from habitat and nutrient competition.