The impacts of smoked cigarette butt leachate on a common freshwater gastropod, Lymnaea stagnalis

Cigarette butts (CBs) are one of the most littered items worldwide. As litter they present physical (plastic fibres and burnt tobacco) and chemical (compounds retained on the filter and in the tobacco) contamination with detrimental effects on the receiving ecosystem. There is however a dearth of research on their effects and on the ability of organisms to recover from exposure. Here, the effects of CBs on mortality, growth, feeding, egg production and hatching success of the great pond snail (Lymnaea stagnalis), were investigated, but also their recovery post-exposure. Individuals were exposed to CB leachate at either 0 (control), 0.25, 0.5 or 1 CB L^-1 for four weeks and subsequently they were allowed to recover for a further three weeks without contamination. The presence of CB leachate increased mortality and decreased egg production, egg viability, and growth of snails. Feeding rate was not affected by the presence of CB during exposure phase. All variables showed evidence of recovery once not exposed to the contaminant. Mortality decreased, growth in shell length and biomass increased whilst egg production and viability increased to the same level as controls. This study found that even environmentally realistic concentrations of CB leachate (0.25 CB L^-1) can cause mortality and decreased reproductive success of aquatic snails. The improvement of these responses after removal of the leachate indicates that preventing or removing CBs could restore affected ecosystems.