Imposex in coastal marine gastropods from Argentina (South-Western

PABLO E. PENCHASZADEH; ANDRES AVERBUJ; MAXIMILIANO CLEDÓN; VICTORIA ZAVATTIERI

Vienna, Austria

Congreso; World Congress of Malacology; 2001

UNITAS

Imposex is a widespread phenomenon in marine molluscs, having been documented in more than 118 gastropod species. Its occurrence is explained as a result of an anti-fouling paint compound called TBT (tributyltin), whose presence is related to high marine traffic. The grade of TBT presence in the water or sediment causes a directly related response on non-target gastropods, consisting in the masculinization of females of dioecious molluscan species. This mutation can be observed by the appearance of a vas deferens and a penis in females. Concentrations lower than 0.5 ng/l can induce imposex in meso- and neogastropods. The phenomenon of imposex was demonstrated for three endemic species of the south-western Atlantic coast, two in the vicinity of Mar del Plata harbour and one in Puerto Madryn harbour in Patagonia, Argentina. Two shallow water (5 to 15 m depth) species, Buccinanops monilifer and Adelomelon brasiliana were studied in two localities in Mar del Plata and a control area in Mar Chiquita restricted reserve. Imposex in this second locality was null. In Mar del Plata, B. monilifer reaches an imposex percentage of 85.7 and A. brasiliana 50. Buccinanops globulosus, also a Patagonian shallow-water species, was studied in the locality of Puerto Madryn, where 100% of imposex was recorded. All observations for this work were controlled by means of histological studies.