| Japanese scallop Patinopecten yessoensis has been cultured in large-scale in China for over 20 years. However, with maricultural scale increasing, serious problem, such as high mortality, low rate of capture and small size etc has caused huge economic loss. In this thesis, effects of temperature fluctuations, starvation stresses and double stess of temperature fluctuations, starvation on the physiological, immunological parameters and behavioral characteristics of scallop Patinopecten yessoensis were studied by indoor simulation method. The response characteristics of different size and veriety scallop(Zhangzidao Island Red, Haida gold scallop, general scallop) to environmental stress were understood. The main research results were as follows: 1.Effects of temperature fluctuation on scallop Patinopecten yessoensisThe influence of temperature fluctuation on physiological parameters and immune activity of 3 different size scallop Patinopecten yessoensis was studied in this paper. Temperature fluctuated in the range of 15-10-15℃, with increasing or decreasing 5℃ per 2h. Temperature was fluctuated 4 times in the experiment totally, which named B1, B2, B3 and B4. Results showed that:(1) The mortality rates of big, middle and small size of scallop P. yessoensis were 4%, 6% and 6%, respectively. The mortality rate of big size scallop was lower relatively, and the mortality only appeared in B1 and B2.(2) Oxygen consumption rates of 3 different size scallops were lower at B1 than initial value B0. With temperature fluctuation, oxygen consumption rates gradually increased and then were higher than B0 in the end. Ammonium excretion rates(AER) decreased with temperature fluctuation, except B1 of small size scallop. For the big size of scallop, the AER in B3 was significantly lower than B0(p<0.05), where for middle size of scallop, AER in B4 was significantly lower than B0(p<0.05).(3) Comparing with physiological parameters, the immune activities were more sensitive to temperature fluctuation. Superoxide dismutase(SOD) and Catalase(CAT) activities decreased significantly as the temperature fluctuated 1 or 2 times(ANOVA, P<0.05). In conclusion, the temperature fluctuation in optimum range had impact on the physiological parameters and immune activities of scallop P. yessoensis to a certain extent. 2.Effects of starvation stress on different size and different varety scallop Patinopecten yessoensisDuration of starvation on different sizes and variety of scallop Patinopecten yessoensis was 60 days and 30 days, respectively. The results showed that: for the different size of scallop,(1) at the end of experiment, the mortality rate of small size scallop was highest(6.33%), mortality rate of big and middle size was 2.67% and 3.33%, respectively.(2) Starvation had significantly influence on oxygen consumption rate and AER(P<0.05). The oxygen consumption rate and AER of different size scallop had same variation trend, increasing firstly and then decreasing. The peak value of oxygen consumption rate appeared in tenth days. The peak value of AER for small size scallop appeared in seventh day, in tenth day for big and middle size scallop. With starvation, the mole ratio of O and N increased signigicantly(p<0.05).(3) The activities of superoxide dismutase(SOD) and catalase(CAT) were slightly increased and then decreased significantly during starvation.(4) With the increase of the starvation time, the maximum contraction force of adductor muscle decreased. For the different viety of scallop,(1) After 30 days’ starvation, the mortality rates of Haida golden scallop, Zhangzidao red scallop, ordinary scallop were 7.2%, 8.8%, 7.2%, respectively.(2) Starvation had significantly influence on oxygen consumption rate and AER(p<0.05). During the starvation, the changes of the oxygen consumption rate and AER were increased firstly and then decreased. But, the peak time is different, which for Zhangzi Island red, Haida Goden scallop and ordinary scallop was in 10 days, 15 days and 7 days respectively. In conclusion, long time starvation could cause oxygen consumption rate, AER, immunity activity and maximal force of clap decreased. Small size scallop was worst to starvation. The tolerance ability to starvation of 3 variety scallops had not significantly different. 3. Effects of double stress of temperature fluctuation and starvation on scallop Patinopecten yessoensisThe mortality rate, oxygen consumption rate and AER of scallop were measured under the stress of high temperature fluctuation(15-22-15℃) and low temperature fluctuation(15-6-15℃) after starvated 60 days. Results showed:(1) under high temperature fluctuation condition, the mortality rate of small size scallop was the lowest, and the mortality rate of big, middle and small size of scallop was 20%,33.33%,13.33%, respectively. Under low temperature fluctuation condition, the mortality rate of big size scallop was the lowest, and the mortality rate of big, middle and small size of scallop was 0%, 13.33%, 13.33%, respectively. High temperature stress could cause higher mortality rate than low temperature stress after starvation, and small size scallop had highest tolerance to high temperature fluctuation stress and big size scallop had highest tolerance to low temperature fluctuation stress.(2) With initial temperature fluctuations, the decline extent of oxygen consumption rate, AER were higher in high temperature fluctuation than that of the low temperature fluctuations, which showed that Patinopecten yessoensis was more sensitive to high temperature fluctuation stress.(3) With fluctuation times increasing, the influence extent of high temperature fluctuations and low temperature fluctuations on oxygen consumption rate and AER of scallop was almost same. For the oxygen consumption rate, after 5 times fluctuation in high temperature, it decreased by 22.3%, 40.6% and 13.8%, respectively for big, middle and small size scallop, after 5 times fluctuation in low temperature, it decreased by 29.2%,40.1% and 14.7%. For AER, after 5 times fluctuation in high temperature, it decreased by 22.2%,31.3%,55.5%, respectively for big, middle and small size scallop, after 5 times fluctuation in low temperature, it decreased by 13.4%,18.1%,60.7%. |
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