The influence of size on growth energetics and ecological efficiences in a large decapod
Aldrich, J.C. (1976). The influence of size on growth energetics and ecological efficiences in a large decapod, in: Persoone, G. et al. (Ed.) Proceedings of the 10th European Symposium on Marine Biology, Ostend, Belgium, Sept. 17-23, 1975: 2. Population dynamics of marine organisms in relation with nutrient cycling in shallow waters. pp. 1-16 In: Persoone, G.; Jaspers, E. (Ed.) (1976). Proceedings of the 10th European Symposium on Marine Biology, Ostend, Belgium, Sept. 17-23, 1975: 2. Population dynamics of marine organisms in relation with nutrient cycling in shallow waters. European Marine Biology Symposia, 10(2). IZWO/Universa Press: Wetteren. ISBN 90-6281-002-0. 712 pp., more In: European Marine Biology Symposia., more |
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| Abstract | The problem of sampling dispersed invertebrate populations led to calculations of growth and ecological efficiences based on extrapolations from observed larger sizes. Calculations were based on the relative change in maintenance costs throughout the 2x106-fold range of weight in a large decapod, Libinia emarginata (Leach). The calorific values of maintenance, exuviae, and the whole crab were measured. Observed values for rates of increase per moult, lengths of intermoult periods, and likely lengths of growing period, were used to calculate four growth curves. The daily energy demands of these growth curves (as cal/cal of animal/day) ranged from 56% at the highest rate of growth in zoea I, down to 5-7% in the largest growing size. Calculated growth efficiencies ranged from 23-64% in larvae, to overall averages of 63-65%. Calculated ecological efficiencies ranged from 24-51%, depending on the type of mortality and the rate of growth. It is concluded that the very large final sizes of this crab overshadow the contribution of the smaller sizes to the extent that only the larger sizes need to be considered when calculating growth and ecological efficiencies. At the other extreme, because of the very high relative costs of maintenance in larval sizes, variations in feeding rate will drastically affect their growth rates and growth efficiency. However, with the normally assumed logarithmic mortality of invertebrate planktonic larvae, ecological efficiency would not be affected. |
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