Abstract
A study of the age, growth and population structure of Acanthocardia tuberculata from the eastern Adriatic Sea was carried out. The condition index analysis identified one reproductive peak, which occurred between April and May, for a population of A. tuberculata in the Cetina River estuary with uni-modal recruitment. Annual growth rings on the external shell surface consisted of a dark ring deposited during the summer-autumn period and a light ring deposited during winter-spring. This was validated by acetate peels of shell sections and marginal increment analysis. Shell lengths of aged specimens ranged from 19.7 to 62.9 mm (mean = 41.21±8.96 mm). Estimated ages ranged from 5 months to 11 years, with mean values of 2.1, 2.4 and 3.1 years for Rab Island, Pag Bay and the Cetina River estuary respectively. Shell deposition is fastest during the first two years of life and significantly decreases after the 4th year. The growth parameters L∞ and k were estimated using the Gulland-Holt method and by fitting length at age data to a von Bertalanffy growth curve. Values of L∞ ranged from 52.6 mm (Rab Island) to 59.7 mm (Pag Bay). The growth constant k showed greater variations (0.49 to 0.77 year-1), while growth performance index values (o’) ranged from 3.13 to 3.36.
Highlights
The cockle Acanthocardia tuberculata (Linnaeus, 1758) lives on sand, mud or gravel bottoms from the intertidal zone to depths of 100 m
The condition index analysis identified one reproductive peak, which occurred between April and May, for a population of A. tuberculata in the Cetina River estuary with uni-modal recruitment
Annual growth rings on the external shell surface consisted of a dark ring deposited during the summer-autumn period and a light ring deposited during winter-spring
Summary
The cockle Acanthocardia tuberculata (Linnaeus, 1758) lives on sand, mud or gravel bottoms from the intertidal zone to depths of 100 m. It is distributed from the British isles south to Morocco and the Mediterranean (Zavodnik and Šimunović 1997, Poppe and Goto 2000). There have been some previous studies on the biology of this species, notably on the accumulation of biotoxins Other studies have focused on analyzing metal concentrations (Hornung 1989), reproduction (Marano et al 1980), shell structure (Zolotoybko and Quintana 2002), the importance in the diet of the labrid Xyrichtys novacula (Castriota et al 2005), and gene organization of the mitochondrial genome (Dreyer and Steiner 2006). Distribution data have been provided in several publications (e.g. HrsBrenko et al 1998, Jukić et al 1998, Zenetos et al 2005, Šiletić 2006, Rufino et al 2010)
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