The Birds of the Alien Acacia Thickets of the South Western Cape |
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| Authors: | J M Winterbottom |
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| Institution: | Percy FitzPatrick Institute of African Ornithology, University of Cape Town |
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| Abstract: | The plough shell, Bullia rhodostoma (Mollusca: Gastropoda), has been studied on an open sandy beach where it is a common scavenger. Samples taken over a year indicate hatching of young individuals from December to February. They reach a length of about 10 mm after 1 year and 40 mm after 10 years. The von Bertalanffy growth equation is Lt = 47 (1 - e-0,19(t+0,23)) and the annual mortality rate is 0,79. Mean decalcified dry biomass is 209 mg m-2 and production by growth 189 mg m-2 y-1 giving a P/B of 0,9. Most production by adults (>15 mm shell length) goes into reproduction, particularly In the females which grow larger than the males. Production by reproduction is estimated to be about 135 mg m-2 y-1. Average calorific values are 19,04 kJ g-1 dry tissue |
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