Age estimation of the oyster Ostrea puelchana determined from the hinge internal growth pattern

Abstract

A multiproxy approach was used to analyse the internal growth pattern of Ostrea puelchana shells. Field investigations using fluorochrome stains were performed to estimate the deposition time of the lines of irregular growth. Cathodoluminescence (CL) microscopy of the hinge area and isotopic composition analyses of shells were performed. The oxygen isotopic composition of the shells showed seasonal fluctuations across the hinge. The results of CL microscopy and stable isotopes provided the first age estimations for wild specimens of O. puelchana. The maximal age of analysed oysters was 4.5 years. Shell deposition occurred at temperatures above 11 °C approximately, suggesting growth slowdown and/or cessation in winter. Lines of irregular growth showed no consistent temporal pattern; these growth structures cannot be used as sclerochronological proxies of growth season or shell age. O. puelchana is sensitive to seasonal environmental changes, which cause changes in its carbonate structure, although the pattern is not consistent, as in other species. In this study, the age of O. puelchana specimens from San Matías Gulf, Patagonia, Argentina, was estimated, providing a basis for future studies on this species.