Combined methods to detect TBT effects on shell shape and structure in Caenogastropoda.

FEDERICO MARQUEZ; ROLANDO GONZÁLEZ-JOSÉ; GREGORIO BIGATTI

Puerto Madryn

Workshop; Third International Workshop on Neogastropods 2009: Origins, Phylogeny, Biogeography and Evolutionary Mechanisms; 2009

Centro Nacional Patagónico

Odontocymbiola magellanica exposed to tributyltin (TBT) pollution have been compared with animals from a non polluted zone using 3D geometric morphometrics. Also, the microstructure and density of shells from the both areas were analyzed. TBT compounds are widely used as antifouling agents in marine environments, producing imposex in caenogastropod females (i.e. neoformation of a vas deferens or a penis).Near the Storni pier (Golfo Nuevo, Patagonia Argentina) TBT concentration in sediments was 1.70 ng Sn.g(named as polluted area: P) and the imposex incidence 100%. Specimens from Cerro Avanzado (non polluted area: NP) did not show the imposex phenomenon. Prior studies made in O. magellanica in the same zone based on traditional multivariate morphometrics showed a difference in size but was unable to detect differences in shell shape among individuals from P and NP areas. Departing from 3D geometric morphometrics, CT scan and SEM techinques, we have registered the presence of patent differences on shell shape and structure in animals from TBT polluted (P) and non polluted (NP) areas, which could not be detected before by traditional multivariate morphometrics. Most of the shells from the NP area presented higher densities and three calcium carbonate layers, while those collected at the P area presented only two layers and lower densities. Furthermore, a body weight loss of around 30% and a shell weight loss of 20 % were registered in animals from the P area. Our combined results suggest that the coordinated use of 3D geometrics morphometrics, CT scan and SEM could be of great utility in order to detect the effect of environmental fluctuations on Caenogastropoda shell shape.