Tolerance of neonates of freshwater snails to starvation and desiccation and its relationship to invasiveness

Abstract

Biological invasions threaten biodiversity and cause severe ecological and socioeconomic impacts. Freshwatersnails are very diverse and many became invasive or have the potential to do so. Studies on the relationship betweenbioecological traits and invasiveness are needed to prevent new invasions. The tolerance to environmental stressorsof the neonate, one of the most vulnerable ontogenetic phases, may be an important component of invasiveness infreshwater snails. We hypothesise that tolerance of neonates to environmental stressors increases the chances ofpopulation establishment and persistence and hence of becoming an invader. We predict that the neonates ofinvasive freshwater snails will show higher survival under starvation and desiccation than those of non-invasiveones and tested this experimentally for three species of each type. We also estimated neonate volume as a proxy oftolerance. We found that the desiccation stress was more severe than the starvation one. The tolerance to starvationof two of the invasive species (Melanoides tuberculata and Pomacea canaliculata) was much higher than that ofremaining species but the pattern was less clear for desiccation, which was more directly related to neonate volume.None of the non-invasive species showed high tolerance to these stressors and the invasive Physella acuta groupswith them in this regard. On the whole our prediction about the relationship between neonate tolerance andinvasiveness stands for five out of the six species tested, indicating that the tolerance of neonates of freshwatersnails merits more research effort on other stressors to gain a sounder comprehension of their invasiveness.