Response of Corbicula fluminea's ingestion rate and branchial ATPase activity to salinity stress.
In order to explore the effects of salinity stress on shellfish, the ingestion rate and branchial Na+/K+-ATPase, Ca2+-ATPase and Mg2+-ATPase activity of C. fluminea exposed to different acute salinity stresses were investigated. The paper is to evaluate the salinity tolerance of Corbicula fluminea and select the potential indicators for evaluating the salinity tolerance of freshwater bivalves. C. fluminea's ingestion rate decreased significantly (P < 0.01) during 7 days of salinity stress exposure. They were 2.11×108 cells.g-1 for treatment of salinity 5, 1.09×108 cells/(g.h) for treatment of salinity 15, 7.68×107 cells/(g.h) for treatment of salinity 25. In the treatment of salinity 5 and 15, the activity of three branchial ATPases reached the maximum on 4 d (P < 0.01), Na+/K+-ATPase and Mg2+-ATPase activity returned to the initial value from 5 d (P > 0.05), while Ca2+-ATPase activity returned to the initial value on 7 d (P > 0.05). The activity of three branchial ATPases of salinity 25 treatment did not increase on 4 d, and no significant difference was found compared to the control (P < 0.05). The survival rate of C. fluminea in salinity 25 treatment was 19%. It was indicated that salinity 5 was the start of salinity stress-point for C. fluminea, the highest tolerance salinity was about 15. Certain correlation between the ingestion rate and the salinity tolerance of C. fluminea indicated that ingestion rate was a potential indicator for evaluating the salinity tolerance of bivalves. Stability of branchial Na+/K+-ATPase activity within 4 d could also be a potential indicator for salinity tolerance.