Effects of Salinity and pH on the Filtration Rate and Ingestion Rate of Meretrix meretrix

Abstract:

Meretrix meretrix is of high commercial value and widely distributed in the coastal area of China. Deterioration of pond environment has caused huge economic loss in pond aquaculture of M. meretrix in recent years. To better understand this process, here we explored the physiological metabolisms of M. meretrix under different salinities and pH. Effects of different salinities (16, 18, 20, 22, and 24) and pH (6.7, 7.7, 8.7, 9.7, and 10.7) on the filtration rate and ingestion rate of M. meretrix were tested under static conditions. Both the filtration rate and the ingestion rate rose as the salinity increased from 16 to 20, and they dropped in the range of 20 to 24. The control group with salinity 20 had the highest filtration rate (1.51 L/g·h) and ingestion rate (6.65 mgPOM/g·h), which were significantly higher than the groups with salinity 16, 18, 22, and 24 (P<0.05). Therefore, salinity 20 was most likely the optimum for the growth of M. meretrix. The filtration rate and ingestion rate increased along with the pH rising from 6.7 to 8.7, but then decreased in the range of 8.7–10.7. Both the filtration rate and the ingestion rate reached the maximum at pH 8.7, which were 1.04 L/g·h and 11.91 mgPOM/g·h respectively, and these values were significantly higher than those in the groups with pH 6.7, 9.7, and 10.7 (P<0.05). Noticeably, there was no difference in the two groups between pH 7.7 and pH 8.7 (P>0.05). So we deduced that the optimum range of pH was 7.7 to 8.7. Our study may provide important information that can help improve the pond aquaculture of M. meretrix.