| Studies were carried on characteristics of physio-ecology in the sea cucumber, Apostichopus japonicus (Selenka), which were widely cultured in North China Sea and on its bioremediation in raft culture system of shallow sea. The main results are listed as follows: 1. The aestivation mechanism of the sea cucumber A. japonicus, bioenergetics of Echinoderms and bioremediation of sediment-feeding holothurians in raft culture system of shallow sea were reviewed in detail according to lots of references. 2. Energy distributions in growth, feces, respiration and excretion were qualified for the sea cucumber A. japonicus with initial wet weight of 32.50±1.03g (mean ± SE) when fed with five different diets in water temperature 13.2-19.8oC and salinity 30-32. The five diets were: diet A- dried feces of bivalves; diet B-75% dried feces mixed with 25% powdered algae; diet C-50% dried feces mixed with 50% powdered algae; diet D-75% dried feces mixed with 25% powdered algae; diet E-powdered algae. Results showed that the diets significantly affected food ingestion rate, feces production rate, food conversion efficiency and apparent digestive ratio, hence the growth and energy budget. Sea cucumbers fed with dried feces of bivalves showed poorer energy absorption, assimilation and growth than individuals fed with other four diets; animals fed with powdered algae could not obtain the best growth. Dried feces, therefore, were not suitable for diet of sea cucumbers in intensive cultivation, nor sole powdered algae. The mixed diets of feces and powered algae showed promising results for cultivation of sea cucumbers. Considering its low-cost and environment-friendly nature, a formula of 75% feces and 25% powdered algae is the best mixture diet for intensive culture of sea cucumbers. Such information would be helpful in further development of artificial diets for the culture of sea cucumbers. 3. To investigate effects of body size and water temperature on feeding and growth in the sea cucumber A. japonicus, the maximum rate of food consumption (Cmaxe; J d-1) and the specific growth rate (SGRe; % d-1) in animals of three body sizes (mean ± SE) - large (134.0±3.5g), medium (73.6±2.2g), and small (36.5±1.2g) - were determined at water temperatures of 10, 15, 20, 25 and 30 °C. Cmaxe increased and SGRe decreased with increasing body weight at 10, 15, and 20 °C. This trend, however, was not apparent at 25 and 30 °C, which could be influenced by aestivation. High water temperatures (above 20 °C) were disadvantageous to feeding and growth of this animal; SGRe of A. japonicus during aestivation was negative. The optimum temperatures for food consumption and for growth were similar and were between 14 and 15 °C, and body size seemed to have slight effect on the optimal temperature for food consumption or growth. Since aestivation of A. japonicus was temperature-dependent, the present paper also documented the threshold temperatures to aestivation as indicated by feeding cessation. Deduced from daily food consumption of individuals, the threshold temperature to aestivation for large and medium animals (73.3-139.3g) was 24.5-25.5 °C, while that for small animals (28.9-40.7g) was between 25.5 and 30.5 °C. These values are higher than previous reports; differences in sign of aestivation, experimental condition and dwelling district of test animals could be the reasons. 4. Energy allocations into growth, feces, respiration and excretion were qualified in the sea cucumber A. japonicus with three body sizes (mean ± SE)-large (134.0±3.5g), medium (73.6±2.2g), and small (36.5±1.2g)-at water temperatures of 10, 15, 20, 25 and 30 °C. Results showed that water temperature, body size and their interaction had significantly effects on energy intake. Significant influence of body size on energyallocation was not found; water temperature was the main effect influencing energy allocation of A. japonicus. To compare differences of energy distributions between non-aestivation period, aestivation-threshold period and full-aestivation perio...
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