Effects of seawater temperature increase on economically relevant native and introduced clam species

- Both species presented different biochemical responses at 21 and 25 °C.
- At 21 °C, ETS and SOD activity and the Hsp70 expression were induced in R. decussatus.
- At 21 °C, SOD activity, LPO levels and Hsp70 gene were induced in R. philippinarum.
- At 25 °C, R. decussatus Hsp70 gene was inhibited.
- At 25 °C, R. philippinarum induced ETS activity, and the BAX and Hsp70 genes.

As a consequence of climate change, global warming is expected to increase during the 21st century. Taking this into account, the impact of rising temperatures on the native Ruditapes decussatus and introduced R. philippinarum bivalve species was assessed, through biochemical and mRNA transcription analyses. Our findings showed that at 21 °C the electron transport system and antioxidant enzyme activity, as well as the expression of Hsp70 gene were induced in R. decussatus when compared with 17 °C. On the other hand, at 25 °C results suggested that R. decussatus closed their valves during short periods, as a behavioral strategy, down-regulating the expression of genes associated with mitochondrial metabolism (Cox-1 and 16S) and chaperone function (Hsp70) compared with organisms at 17 °C. In addition, the introduced species (R. philippinarum) increased the electron transport system and antioxidant activities, as well as gene expression of antioxidant enzymes and molecular chaperone (Hsp70) at 21 °C. However, antioxidant mechanisms were not enough to prevent lipid membrane damages at 21 °C. At 25 °C R. philippinarum presented increased electron transport system and antioxidant activity, as well as the expression of genes associated with apoptosis regulation and molecular chaperone. Overall, the present findings indicate that in a global warming scenario both species are able to induce different mechanisms to mitigate the impacts of temperature increase.