engleski

Glycymeris bimaculata (Poli, 1795) - a new sclerochronological archive for the Mediterranean?

Glycymeris bimaculata is one of the largest (up to ~110mm) bivalves in the Mediterranean Sea yet there is a paucity of information about the growth of the species. The principal objectives of this study were: i) to assess the periodicity and timing of growth line formation in G. bimaculata collected from Pag Bay in the Adriatic Sea using stable isotope analysis and a statistical cross-match between the growth increment series (GIS) of individuals live-collected in 2008 and 2012, ii) to construct a statistically robust sclerochronology from G. bimaculata growth increment series, iii) to investigate changes in shell growth in response to environmental factors, and iv) to estimate growth parameters and the maximum longevity of the species. The age of 55 shells (ranging in length between 49.1 and 109.5 mm), determined from acetate peel replicas of polished and etched shell sections, ranged in age between 6 and 57 years. The reconstructed seawater temperature records derived from oxygen isotope analysis of the growth increments and lines demonstrate that the lines visible in shell cross section are deposited annually in late autumn. Further confirmation of an annual periodicity of growth line formation was obtained when GIS from shells collected in 2008 and 2012 cross-matched statistically with a positive correlation at a 4 year offset. A master chronology containing growth increment data for the period 1991 to 2007 derived from nine individuals, ranging in age from 17 to 34 years, was constructed with a mean Expressed Population Signal (EPS) of >0.85. The GIS of the analyzed specimens had pronounced inter-annual variability with the period from 1997 to 1999 characterized by slower growth and the period from 2000 to 2005 by moderate growth, while growth increments deposited in the years 2006 and 2007 were widest. Differences in growth between periods were related to temperature and salinity data. The growth of G. bimaculata is described by the von Bertalanffy growth equation relating length Lt at time t: L t= 90.85(1-e-0.10 (t+3.13)).

Adriatic; Pag bay; chronology; bivalve; growth

nije evidentirano