LAUSR

Abstract Imposex responses were comparatively assessed in Thaisella chocolata and Xanthochorus buxeus, in sites previously studied regarding TBT contamination and under the influence of various levels of ship/boat activities in a coastal zone of Peru. In August 2015, at least 60 adult specimens of both T. chocolata and X. buxeus were simultaneously sampled by SCUBA diving in three subtidal sites. A total of 545 adult specimens of T. chocolata and X. buxeus were analyzed in the present study. Imposex incidence (I%) was detected in the two muricid species in the sampled site closest of Callao harbor — P1 (T. chocolata and X. buxeus = 100%) and also in the P2 (T. chocolata = 100% and X. buxeus = 81%). On the other hand, as expected, no sign of imposex was observed in organisms obtained from P3. Thaisella chocolata is likely to be the most sensitive species to imposex development, followed by X. buxeus. Thus, T. chocolata is the most suitable species to be used as a sentinel of TBT contamination due to its high sensitivity and better discrimination of levels among different sites.