The effect of size and epibiotic barnacles on imposex in Stramonita haemastoma collected from the northern coast of Tunisia

AbstractImposex was quantified in Stramonita haemastomafrom the Bizerta Channel during a one-year study period and the effect of gastropod size and shell foulingby epibiotic barnacles investigated. Butyltin concentrations ( tributyltin(TBT) and its derivatives di- and mono-butyltin) were also investigated in the soft tissue of the gastropods to depict temporal trends in pollution. Kelibia Beach was chosen as a reference site (not polluted by organotin) to depict whether barnacle foulingcould intervene in imposexdevelopment. Imposexincidence in the Bizerta Channel was greater in females fouledby epibiotic barnacles compared to non- fouledfemales. Considering the size of the gastropods, large females ( fouledand non- fouled) always exhibit higher imposexindices than smaller females. The concentrations of organotin compounds were found to be similar in the studied species, independent of sex or foulingcondition. For Kelibia Beach, no imposexwas recorded in fouledand non- fouledsnails, while butyltin...