Does sex really matter? Explaining intraspecies variation in ocean acidification responses

Climate change scientists should think more about sex


Climate change can have a different impact on male and female fish, shellfish and other marine animals, with widespread implications for the future of marine life and the production of seafood.

But a paper published today in the Royal Society journal Biology Letters has found that very little research into how males and females respond differently to climate change has been carried out. This is despite recent research on ocean acidification published by lead author Dr Robert Ellis showing that male and female shellfish respond differently to stress.

Dr Ellis says the impact on different sexes should be properly assessed in all aquatic animals to accurately predict how populations will respond to climate change. Any effect on spawning, settlement or survival could have a major impact on sustainable supplies of fish and shellfish.

The latest collaborative research by University of Exeter, Plymouth Marine Laboratory and colleagues reveals that less than 4% of climate-change studies have tested the impact of ocean acidification on males and females separately.

Over the past decade, research into the impacts of rising CO2 on fish and shellfish species has increased dramatically, helping scientists accurately predict the threat climate change poses ecosystems worldwide. Worrying changes in behaviour, survival, growth, reproduction and health have been found in many species.

Co-author of the study Dr Ana Queirós, a climate change and seabed ecologist at Plymouth Marine Laboratory, said ignoring potential differences in how males and females respond has implications for managing the future ocean:

“At present, out best informed guess of how climate change and ocean acidification will impact species in the wild, marine diversity, and our uses of them for instance through fisheries and aquaculture, depends on numerical model forecasts. These models are only as good as the data we use to build them. We now have sufficient evidence to believe that in some species, males and females will respond very differently to climate change and associated stressors because of natural physiological processes. We do not know if all species will show these differences. It is therefore time we started taking this question more seriously into consideration in the design of our experiments and of our models. Without this, we may severely underestimate the impact of climate change on wildlife and vital sectors of the ocean based economy." 

CO2 levels are projected to be 2.5 times higher in the oceans by the end of this century, which is causing the ocean to acidify at a rate unprecedented for 300 million years.

“Understanding climate change impacts is vital to help protect marine ecosystem services that humans rely on so heavily such as fisheries, aquaculture and tourism” said Dr. Rob Ellis, an ecological physiologist based at Exeter University. “Our understanding of these threats has improved significantly over the past decade, but this is still a very new and rapidly evolving field. Many important questions still remain, and sex-based differences will be a key issue with the potential to influence our strategies to mitigate against climate change”.

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