Imposex in Odontocymbiola magellanica (Gmelin, 1791) (Caenogastropoda: Volutidae) in Patagonia.

GREGORIO BIGATTI & PABLO E. PENCHASZADEH

Comunicaciones de la Sociedad Malacológica del Uruguay

Año: 2005 vol. 9 p. 377 - 379

ABSTRACT Odontocymbiola magellanica is a volutid snail from Patagonian shallow waters. Sampling by scuba diving in depths of 6-10 m was performed in Golfo Nuevo, Golfo San José and Golfo San Matias, Patagonia in order to study the imposex occurrence. O. magellanica showed between 85% and 100% imposex near harbors with high marine traffic in Puerto Madryn, Golfo Nuevo, and a Relative Penis Size Index (RPSI) between 0.77 and 3.84; in scuba diving zones with sport boats traffic the imposex percentage decrease between 35% and 59% and the RPSI was between 0 and 0.15; in zones with low marine traffic the percentage of imposex was null. Although the species is under imposex occurrence in the area we could observed females spawning in 2002. A posterior study in 2004 near the harbor zone showed the persistence of imposex in these marine gastropods. In Golfo San José the imposex was null and in San Antonio Este, Golfo San Matias the imposex was 100 % and the RPSI 0.12.Imposex occurrence confirms the presence of TBT in the areas near harbors. KEY WORDS: Imposex, TBT, Volutidae, marine pollution.