LAUSR

Abstract This study evaluates tributyltin (TBT) pollution on a spatial-temporal scale using imposex occurrence in Stramonita brasiliensis in a coastal region of the southeast Brazil, between 2007 and 2018, and tests the viability of this species as a tool to evaluate the environmental quality through the Ecological Quality Ratio (EQR). Imposex indexes varied during the monitoring period, with I% varying from 0% to 100%, Vas Deference Sequence Index (VDSI) from 0 to 4.11 and Index of Relative Penis Length (RPLI) from 0 to 51. The EQR indexes indicated high levels of contamination by TBT in the first years of the study (2007 to 2011), followed by an improvement in the ecological status in the last two years (2017 and 2018). This study confirmed the viability of the use of EQR to evaluate the environmental status in a tropical region by means of an endemic species. Our results indicate that the Espirito Santo coastline is still contaminated with TBT, especially in areas close to ports and fishing activity.