Fluoride alters feeding in lab-bred pond snails but not in wild snails or their progeny.

Increasing concentrations of fluoride in natural bodies of water due to anthropogenic activities can lead to potentially detrimental effects on residing species. Here we investigated the differences in fluoride exposure on feeding behaviour between freshly collected (i.e., wild) and lab-bred Lymnaea stagnalis and if developmental exposure plays a key role in fluoride tolerance. We show that wild snails that reside in naturally fluoridated waters and their fluoride naïve lab-reared progeny have a fluoride tolerance that does not suppress feeding when introduced to a fluoridated food stimulus. These results were also seen in our lab-bred snails who were exposed to artificially fluoridated pond water (at similar concentrations to natural levels) throughout development. However, lab-bred snails that have never been exposed to fluoride, or only exposed during the egg stage demonstrated suppression of feeding in the fluoridated food stimulus condition compared to an unfluoridated food stimulus. Genetic diversity and phenotypic plasticity are suspected to be two key underlying mechanisms for fluoride ion tolerance. These results are critical in understanding how parental and developmental exposure can influence a phenotypic tolerance to a potential chemical pollutant.