Evaluación de la bioerosión producida por Lithophaga patagonica (d'Orbigny) sobre Ostrea puelchana d'Orbigny en el golfo San Matías, Argentina

Extant oyster bed at “Las Grutas” – golfo San Matías, Argentina – was studied in order to identify bioerosional patterns produced by Lithophaga patagonica on Ostrea puelchana. Thus, the morphology of L. patagonica and its borings were described, as well as their frequency and distribution (both within the bed and on the individual oyster valves). In order to identify a pattern of perforation distribution on the shells valves, the latter were divided into sectors, following morphological traits on the shell that could potentially influence the establishment/survival of boring organisms and places where the oyster could afect by the borings. The oysters (157), the borings (283) and the specimens of Lithophaga (212) were all counted and measured for statistical characterization and bivariate analysis of the variables considered. As a result, it became clear that Lithophaga patagonica shows a preferential location on certain sectors of the oyster shell (p<0.01), in the left or concave shell were preferred the anterior margin, the platform and the apice, while in the right or flat shell it were the anterior margin and the apice. Probability of boring was significantly higher on the left valve (89%) (p<0.05), which carries an average of 3 borings while the right (43%) valve only has 1.7 (p<0.05). Borings are similar in shape to the shells of Lithophaga, but are 15% wider and 27% thicker. Oysters bearing borings are significantly larger than those lacking them (p<0.05).