Population dynamics and energy budget for a population of Donax variabilis (Say) on an exposed South Carolina beach
In: Journal of Experimental Marine Biology and Ecology. Elsevier: New York. ISSN 0022-0981; e-ISSN 1879-1697, more
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| Keyword |
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| Author keywords |
Donax; Energy budget; South Carolina; Sandy beach |
| Abstract |
Donax variabilis is widely distributed over the lower half of the shore at Waites island on the South Carolina coast. Densities peaked at almost 12?000 individuals m-2 at spawning, which also coincided with a concentration of the population in a narrow strip at mid-tide level. Following this, the population almost disappeared from the shore until late in the year, when numbers of small individuals started to appear. Evidence for a second, autumn spawning was equivocal. Mean annual biomass over the lower part of the beach was low (6.45 kj m-2) but P:B very high (6.74) and in addition, gamete output accounted for another 86.6 kj m-2 y-1, equivalent to 64% of total production. The evidence also suggested that the majority of the population was effectively semelparous, but the population reproductive strategy was classified as one of restraint rather than reckless. The productivity makes a significant contribution to neighbouring land and nearshore systems. |
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