| Shellfish aquaculture occupies a larger proportion in China’s water farming, and plays an important role in water farming economic development in our country. With the swift development of economic, the self-pollution and environmental factors changed suddenly caused by natural factors bring serious impact to shellfish aquaculture. Environment factors not only can affect the breathing and excretion, physiological activities of ingestion, but also affect the activity of enzymes and gene expression of shellfish. Thus the normal growth was limited. This experiment used the indoor simulation test method, to study the effects of different pH and salinity on breathing and excretion(oxygen consumption rate, ammonina-N excretion rate, phosphate excretion rate and O:N), physiological activities of ingestion(filtration rate; ingestion rate) and the rule of HSP70 gene expression of Meretrix meretrix, and hope to obtain the rules and characteristics of physiological and behavioral under different salinity and pH of M. meretrix. This study provide important theoretical basis for health cultured of M. meretrix. At the same time, it can accumulated certain base date for shellfish aquaculture capacity, ecophysiology and energetics. The results are as follow:(1). The effects on oxygen consumption rate, ammonina-N excretion rate, phosphate excretion rate and O:N of salinity 20 group were significantly higher than the group of 16, 18, 22 and 24, which under the condition of the pH of 8.7(P<0.05). When salinity changed from 16 to 24, all the oxygen consumption rate, ammonina-N excretion rate, phosphate excretion rate and O:N of M. meretrix increased from 16 to 20, then decreased from 20 to 24. When the salinity reached 20, all of them got the maximum, respectively as 5.66 mg·(g·h)-1, 0.20 mg·(g·h)-1, 0.30 mg·(g·h)-1 and 27.40.(2).The effects on oxygen consumption rate, ammonina-N excretion rate and phosphate excretion rate of pH 8.7 group were significantly higher than the group of 6.7, 7.7, 9.7 and 10.7, which under the condition of the salinity of 20(P<0.05). The effects of O:N in pH 7.7 and 8.7 were significantly higher than 6.7, 9.7 and 10.7(P<0.05). When pH changed from 6.7 to 10.7, all the oxygen consumption rate, ammonina-N excretion rate, phosphate excretion rate and O:N of M. meretrix increased from pH 6.7 to 8.7. When pH reached 8.7, Oxygen consumption rate, ammonina-N excretion rate, phosphate excretion rate and O:N were the highest, respectively as 5.46 mg·(g·h)-1, 0.17 mg·(g·h)-1, 0.19 mg·(g·h)-1 and 27.17. Then they decreased from 8.7 to 10.7.(3). When the salinity range from 16 to 24, both the filtration rate and ingestion rate rised as the increase of salinity in the range of 16~20, and dropped in the range of 20~24. The salinity group of 20 got the maximum in both filtration rate and ingestion rate, respectively were 1.51 L·(g·h)-1 and 6.65 mgPOM·(g·h)-1.Which were significantly higher than the group of 16,18,22 and 24(P<0.05).(4).The filtration rate and ingestion rate of M. meretrix increased with the pH rising in the range of 6.7~8.7, then decreased in the range of 8.7~10.7. Both of them reached the maximum at 8.7, respectively were 1.04 L·(g·h)-1 and 11.91 mgPOM·(g·h)-1. Which were significantly higher than the group of 6.7, 9.7 and10.7(P<0.05). But the group of pH 7.7 and 8.7 on filtration rate and ingestion rate weren’t significant(P>0.05).(5).The expression of HSP70 gene in salinity group of 16,18,22,24 were significantly higher than the group of 20 in muscle of M. meretrix(P<0.05).Except the expression of HSP70 gene in the salinity group of 18 in gill and the group of 24 in mantle have no significant difference with the group of 20(P>0.05),the rest salinity group of 16,18,22 and 24 in gill and mantle of M. meretrix were significantly higher than the group of 20(P<0.05).(6).However, the expression of HSP70 gene in the pH group of 6.7,7.7.9.7 and 10.7 in muscle, gill and mantle have a significant difference with the group of 8.7(P<0.05).The experimental results shown that when the water’s salinity and pH were too high and too low, both can significantly induce the high expression of HSP70 gene in muscle, gill and mantle of M. meretrix. |
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