engleski

Age and growth of Noah's Ark shell, Arca noae L., in the Croatian Adriatic Sea

The Noah's Ark shell (Arca noae) is a widely distributed and common bivalve in the coastal waters of the eastern Adriatic Sea and is one of four commercially exploited bivalves in the region. Little is known about its population structure, and there is no data on its growth and longevity. In this study we estimated age of A. noae collected at three sites in Croatian Adriatic using 1) external surface growth rings, 2) scars on the internal shell surface, and 3) growth lines in acetate peel replicas of the umbo region and 4) prismatic shell layer. Growth of A. noae was investigated by measuring the distance between the umbo and each growth line in the outer prismatic shell layer and fitting data to the von Bertalanffy growth function. All age determination methods undertaken in this study were successfully used to estimate the age of A. noae, however counting of the prismatic growth lines seems to be most precise. Since it is expensive and time- consuming method, for future population structure studies, we recommend a combination of internal growth lines and external growth rings. Our results show that A. noae can attain an age of up to 16 years and a length of 70 mm, and is therefore a slow growing species whose populations will be vulnerable if subjected to over-exploitation.

bivalve; Arca noae; age; growth; Adriatic Sea

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