Effects Of Different Factors On The Feeding Rate, Oxygen Consumption Rate And Ammonia Excretion Rate Of Rock Scallop

As a new species of scallop, rock scallop(Crassadoma gigantea) was introduced into China in 2012. With the efforts of recent years, the artificial breeding technology has made a breakthrough. At present, there are no relevant research reports on the feeding physiology of scallop in China. In this study, the effects of different ecological conditions on the feeding rate, oxygen consumption rate and ammonia excretion rate were studied, which provide the basis for the study of the physiological ecology of the scallop and the guidance for the production practice of artificial breeding, adult culture and so on.This paper was divided into two parts. First, feeding rate and circadian rhythm of feeding rate of the juvenile rock scallop were studied during conditions of different temperature, weight, feed concentration and feed species when it was cultured under an open system. Second, oxygen consumption rate and ammonia excretion rate, and the circadian rhythm of oxygen consumption rate and ammonia excretion rate of juvenile rock scallop were investigated in conditions of different temperature, weight, salinity and p H when it was cultured under closed stagnant water system. The main results were as follows:1. Feeding physiology of juvenile rock scallop:(1) Feeding rate of juvenile rock scallop was significantly affected by temperature(P<0.01). The feeding rate per unit body weight increased with the rise of temperature at 6 ~ 22°C;(2) Feeding rate of juvenile rock scallop was significantly affected by body weight(P <0.01). The feeding rate per ?unit of body weight increased with the increase of body weight;(3) Feeding rates of juvenile rock scallop for four species of unicellular algae were significantly different(P<0.01), which were Nitzschia closterium>Isochrysis zhanjiangensis >Platymonus sp. >Chlorella sp.. There were significant differences in feeding rate rates of scallop for Isochrysis zhanjiangensis and Platymonus sp.(P<0.05);(4) Feeding rate of juvenile rock scallop was significantly affected by feed concentration(P<0.01). The feeding rate was maximum when N. closterium was at 30 * 104 cells/m L, and it declined when N. closterium less than or greater than this concentration.There were no differences in feeding rates between 60 × 104 cells / m L and 75×104 cells / m L(P>0.05).(5) Feeding rate of juvenile rock scallop varied significantly between day and night(P<0.05).The highest peak of feeding rate occurred at 21:00 and two low peaks at 13:00 and 5:00. There were no differences in feeding rates among 9:00, 17:00 and 1: 00(P> 0.05).2. Metabolic physiology of juvenile rock scallop.(1) Oxygen consumption rate and ammonia excretion rate in juvenile rock scallop were significantly affected by temperature(P<0.01). The oxygen consumption rate and ammonia excretion rate per unit body weight increased with the rise of temperature at 6 ~ 22°C;(2) Oxygen consumption rate and ammonia excretion rate in juvenile rock scallop were significantly affected by body weight(P<0.01). Through regression analysis, body weight(x) and oxygen consumption rate or ammonia excretion rate(y) showed a negative exponential relationship: Y=a X-b. The oxygen consumption rate and ammonia excretion rate per unit body weight decreased with the increase of body weight.(3) Oxygen consumption rate and ammonia excretion rate in juvenile rock scallop were significantly affected by salinity(P<0.01),which increased with the increase of salinity(from 24 to 30), reached the maximum at salinity 30, and then decreased with the increase of salinity(from 30 to 36);(4) Oxygen consumption rate and ammonia excretion rate in juvenile rock scallop were significantly affected by p H(P<0.01), which increased with the increase of p H(from 7.0 to 8.0), reached the maximum at salinity 8.0, and then decreased with the increase of salinity(from 8.0 to 9.0);(5) The highest peak of oxygen consumption rate and ammonia excretion rate of scallop larvae occurred at 13:00, the lowest oxygen consumption rate at 21:00 and the lowest ammonia excretion rate at 1:00. The multiple analysis showed that there were no differences in oxygen consumption rates among 9:00, 17:00, 1: 00 and 5:00(P>0.05). The differences were significant in the other groups(P<0.05). The ammonia excretion rate among 9:00, 17:00 and 5:00 was not significant(P>0.05), and the differences in the other groups were significant(P<0.05).