Ecological thresholds of the Chinese mystery snail (Cipangopaludina chinensis) in relation to Nova Scotia environments

Abstract

The Chinese mystery snail, Cipangopaludina chinensis, is a non-indigenous, potentially invasive aquatic species found throughout North America. They are highly fecund and viviparous, birthing live young. These features make them a potential threat to biodiversity and ecosystem function. To better understand the potential spread of C. chinensis in Nova Scotia, the ecological thresholds for different environmental parameters need to be established. Here, I focused on salinity, pH, and temperature using field and laboratory approaches. The salinity tolerance [(0, 5, 10, 15, and 20) ppt], and pH tolerance (pH 4, 5, 6, 7) were tested in a 2-week and 4-week laboratory experiment, respectively. The migration patterns of C. chinensis were monitored bi-weekly at three Halifax Regional Municipality lakes with temperature measurements. Migration monitoring was done in spring and summer, conducting surveys of the relative frequency of snails found at various depths to estimate the seasonal migration pattern of the snails. C. chinensis did not survive in salinity concentrations 10 ppt or higher, but did survive in 0 ppt and 5 ppt. This suggests C. chinensis could inhabit freshwater to brackish water. There was some mortality with juvenile C. chinensis in low pH conditions, and further research is recommended to establish the pH threshold for at least one life cycle of the snails. The snail migration surveys show the snails are typically found in shallow water when the surface water temperature is 20⁰C and above, and in deeper water when the surface water temperature is 20⁰C and below. This research suggests the ecological tolerances of C. chinensis may allow for the species to spread into vulnerable ecosystems in Nova Scotia not previously considered as a suitable habitat, including brackish estuaries and acidic dystrophic lakes.