Using sclerochronology to estimate the growth rate in Pinna nobilis: a case study of Les Alfaques Bay population (Ebro Delta, Spain).

Fraissinet, Silvia (2017) Using sclerochronology to estimate the growth rate in Pinna nobilis: a case study of Les Alfaques Bay population (Ebro Delta, Spain). [Laurea magistrale], Università di Bologna, Corso di Studio in Biologia marina [LM-DM270] - Ravenna
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Abstract

Pinna nobilis is the biggest Mediterranean bivalve, endemic and semi-infaunal. Provide hard substrates to colonize, increasing the spatial heterogeneity of the softbottom communities. P. nobilis suffer a drastic decline due to the anthropogenic pressures. It’s included in the Habitats Directive, in the Barcelona Convention, and in the red lists of many Mediterranean countries. Estimates the growth rate allows to understand the population dynamics of species and yield knowledge to improve protection efforts. In this study a new methodology based on sclerochronology was used to estimate the age and the growth rate of a P. nobilis population located in Les Alfaques bay. The shells of 35 specimens were cataloged. A subsample of 20 individuals was selected, and one valve of each specimens was cut into radial sections along PAMS (Posterior Adductor Muscle Scar) to study the inner register. Thus, the positions of PAMS obscured by nacre were identified, and the number of missing records was estimated by the width of the calcitic layer in the anterior part of the shell. The first growth curve for the Les Alfaques bay population was calculated from the length/age data. To simulate the growth rate of this population, the growth model based on the modified Von Bertalanffy equation was used. Shallow water usually hosts small sized populations of P. nobilis, while in deeper waters specimens reaches larger size. In Les Alfaques bay the population is composed by large size individuals though it’s located in shallows waters. This unusual size pattern is probably due to a sand bar that offers protection from hydrodynamic stress, allowing individuals to elongate more. This study contributes to the knowledge on P. nobilis biology and, with the aim to monitor this species, the growth curve could be used as baseline for future studies on habitat characteristics that may affect the population structure and dynamics in Les Alfaques Bay.

Abstract
Tipologia del documento
Tesi di laurea (Laurea magistrale)
Autore della tesi
Fraissinet, Silvia
Relatore della tesi
Correlatore della tesi
Scuola
Corso di studio
Ordinamento Cds
DM270
Parole chiave
Sclerochronology, Inner register, Pinna nobilis, Age estimation, Growth rate, Monitoring, Baseline
Data di discussione della Tesi
14 Dicembre 2017
URI

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