The Effects of High Temperatures on Survival Rates and Immunity of Saltwater Clam Meretrix meretrix from Different Geographical Populations

Abstract

High temperature has significant effects on the survival and immunity of organisms. In order to conduct a detailed investigation into the response of the saltwater clam Meretrix meretrix from different geographical populations (GuangXi, JiangSu, ShanDong, LiaoNing) to high temperatures, we examined the survival rates and antioxidant enzyme activities of these clams that were exposed to different temperature treatments (25°C, 35°C, 37.5°C, 40°C). Results showed that the survival rate of clams from GuangXi was highest at 40°C, followed by JiangSu. SOD and CAT activities of all the clams increased with the increasing temperatures, and then gradually decreased at 40°C over time. The expression levels of Hsp70 of M. meretrix from four populations were analyzed by qPCR sampled from the hepatopancreas after 72 h under different temperatures. Higher Hsp mRNA expression of GuangXi at 40°C indicated that clams of GuangXi have stronger high temperature resistance than those of the other geographical populations. Our findings provide a basis for the choice of cultured clams with a high temperature tolerance.