Warmer temperatures increase egg laying and egg hatching frequency in the invasive freshwater snail Physa gyrina from Pennsylvania, USA.

Climate change continues to impact populations of organisms and to affect physiological adaptations to their environments. Freshwater snails have been so impacted globally, not only by climate change, but by the concomitant exposure to environmental pollutants like human antidepressants released from wastewater treatment plants. To test the effect of climate change and antidepressants, we exposed the freshwater snail, Physa gyrina to three temperatures (12 °C, 20 °C, and 25 °C) and to a concentration of the antidepressant fluoxetine, known to modulate snail behavior, and measured time to egg laying and egg hatching. Snails exposed to 20 °C and 25 °C laid significantly more egg masses sooner than snails at 12 °C. Embryos hatched from egg masses significantly sooner at the two warmer temperatures than those at 12 °C. Exposure to fluoxetine had only a minor effect on the timing of egg laying and no effect on the timing of egg hatching. Our findings suggest that warmer temperatures may be more important in modulating reproduction in P. gyrina than fluoxdetine fluoxetine. Since this species is invasive in Europe, we discuss our results in terms of the possible consequences of climate change on the potential geographical spread of invasive species.