Population Dynamics,Growth and Productivity of Abra ovata (Mollusca,Bivalvia) in the Evros Delta (North Aegean Sea) |
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Authors: | Th Kevrekidis A Koukouras |
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Abstract: | Monthly samples of Abra ovata were collected during February 1983-January 1984 in the Evros Delta (N. Aegean Sea). Population density (mean annual value = 2407.5 ind · m−2) was characterized by seasonal variation. An analysis of the length frequency distributions shows that one annual recruitment of juveniles (> 2 mm) occurred in October-January; and also that, throughout the year, two age groups existed in the population. One growth ring was formed on the shells of the oldest age group during July-August. Mean growth in shell length can be described by Bertalanffy function. A positive correlation existed between shell length and decalcified dry weight. Secondary production in A. ovata, calculated by the instantaneous growth method, showed a mean biomass of 29.221 g dry weight m−2yr−1, a productivity of 17.086 g dry weight m−2yr−1 and an annual turnover ratio of 0.59. |
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Keywords: | Abra ovata density seasonal variation productivity Aegean Sea |
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