Relative Growth Rates of the Noble Pen ShellPinna nobilisThroughout Ontogeny Around the Balearic Islands (Western Mediterranean, Spain)

Abstract

ABSTRACT In this study, we evaluated the growth of adults and juveniles of the endangered noble pen shell Pinna nobilis, calculated the growth rates of newly recruited juveniles, and described relative directional growth during ontogeny. We described growth using posterior adductor muscle scars (PAMS) and fit of the von Bertalanffy growth curve for adult population data at shallow depths (5–10 m) around the Mallorca and Ibiza islands, and compared the parameters with other Mediterranean populations. Populations around Mallorca could be fitted according to the von Bertalanffy function Lt = 65.31(1 - e-0.11(t + 0.53)), whereas for Ibiza the function was Lt = 154.55(1 - e-0.03(t + 4.31)). We compared first-year growth rates obtained in the laboratory and from field collections with newly settled individuals. We found that experimentally evaluated growth rates of juveniles in the laboratory of 0.18 mm/day are low compared with minimum values obtained in the field, which range, on average, from 0.28–0.32 mm/da...