Effects of Salinity on Physa acuta, the Intermediate Host for the Parasite Posthodiplostomum minimum: Implications for the Translocation of the Protected White Sands Pupfish

Abstract

AbstractWe report the salinity tolerance of snails to evaluate how parasite communities with complex life cycles have been altered by translocations of the White Sands pupfish Cyprinodon tularosa to habitats with altered salinity levels. Native and introduced pupfish populations co‐occur with the gastropods Physa acuta and associated white grub parasite, Posthodiplostomum minimum, at two brackish springs (Malpais and Mound), but physids are absent from the two saline habitats occupied by White Sands pupfish. We conducted a salinity challenge experiment to test the hypothesis that environmental salinity limits the distribution of physid snails. A 22‐d survival experiment with the Malpais Spring physid population indicated that exposure to elevated salinities significantly reduced survival. We also saw sequential declines in survival and reproduction that were proportional to salinity exposure. Salinity of 7‰ was the apparent threshold for these effects. These results have implications for the use of translocation as a conservation tool in the management of fish populations.