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Ocean Acidification Elicits No Cellular Damage in Shark Juveniles

Paper Reviewed
Lopes, A.R., Sampaio, E., Santos, C., Couto, A., Pegado, M.R., Diniz, M., Munday, P.L., Rummer, J.L. and Rosa, R. 2018. Absence of cellular damage in tropical newly hatched sharks (Chiloscyllium plagiosum) under ocean acidification conditions. Cell Stress and Chaperones 23: 837-846.

Sharks are resilient creatures. Over the past 400 million years they have coped with and survived changes in pCO2 seawater chemistry ranging from 3000 µatm during the Devonian period to below 200 µatm during the last glacial period. Hence, it is quite likely that these marine vertebrates will maintain their key role in the oceanic food web as seawater pCO2 rises in the future. Nevertheless, concerns have been expressed that these top predators of the ocean might be negatively impacted by the rapidity of the projected pCO2 rise that is expected over the next century.

Seeking to evaluate the validity of such concerns, Lopes et al. (2018) subjected newly-hatched whitespotted bamboo sharks (Chiloscyllium plagiosum) to ambient (~390 µatm) and elevated (~890 µatm, i.e., ocean acidification) pCO2 conditions for 50 days in a controlled laboratory setting. At the end of this period they euthanized the animals and measured protein, DNA damage and antioxidant defenses (both enzymes and non-enzymatic molecules) of various shark tissues. And what did those measurements reveal?

In the words of the nine researchers, the newly hatched shark juveniles were able to cope with ocean acidification-related stress "through a range of tissue-specific biochemical strategies, specifically through the action of antioxidant enzymatic compounds." Consequently, there was no significant oxidative damage observed in sharks in the elevated CO2 treatment. And this suggests that sharks will continue to maintain their important role in the oceanic food web in the years and decades to come.

Posted 22 October 2018