Marine ecosystems have been affected by contamination from heavy metals and antifouling organotin paints, where the latter generate the imposex phenomenon in marine gastropods. The presence of heavy metals and imposex in the marine snail Thaisella chocolata was evaluated at the "El Faro" artisanal fishing landing stage and at approximately 2 km from said pier, located in Matarani (Arequipa, Peru), during the winter and spring of 2021. In addition, heavy metals in the water and in the marine sediment were evaluated. Heavy metals in the water, sediment and muscle tissue samples of T. chocolata were compared with national and international standards for environmental quality. Boron in the water exceeded the norm in both areas in the spring. No heavy metal exceeded the regulations in the sediment. The values of As, Cd and Cu and Se in the tissues of T. chocolata exceeded some of the eight in...