Analysis of the Growth of Anadara granosa (Bivalvia: Arcidae) in Natural, Artificially Seeded and Experimental Populations

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Abstract
The growth of both natural and artificially seeded populations of A. granosa (L.) was monitored at 2 locations on the west coast of West Malaysia. Growth conforms to the von Bertalanffy model and the best estimates of the growth constant (k) and asymptotic length (L.infin.) are 1.01 yr-1 and 44.4 mm, respectively, for populations under optimum conditions. Initial results from natural populations indicated that density and exposure (height on the shore) are the major factors exerting an influence on growth rate. There was no evidence of any seasonal variation in growth, but other factors such as extreme salinity fluctuations may be important in marginal populations. A series of field experiments confirmed the observations on natural populations that density and exposure do indeed have a marked effect upon growth. Equal changes in exposure did not produce proportional changes in growth rate. The observed pattern may be part of a general negative sigmoidal relationship between growth and exposure. A relation which linked growth (in the form of a variable asymptotic size) to population biomass (dry weight tissue per unit area) was developed as a 1st step toward accounting for the effects of changes in population biomass on predicted growth rates and yields.