Imposex in Odontocymbiola magellanica (Caenogastropoda: Volutidae) in Patagonia.

GREGORIO BIGATTI; PABLO E. PENCHASZADEH

Comunicaciones de la Sociedad Malacológica del Uruguay

Año: 2005 vol. 9 p. 371 - 375

Odontocymbiola  magellanica (Gmelin, 1791) 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 Matías, 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 decreased 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 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 Matías the imposex was 100 % and the RPSI  0.12. Imposex occurrence suggests the presence of TBT in the areas near harbors.