Climate change scenarios affected tiny marine crustaceans called copepods. (Photo: abdn.ac.uk)

Ocean acidification modifies climate change impact on fisheries: study

CANADA
Thursday, February 23, 2012, 15:30 (GMT + 9)

New projections show that climate change will not benefit nations in cooler waters with richer fisheries and greater biodiversity as previously thought. Instead, when taking into account ocean acidification and deoxygenation, some regions may see lower catch potential by 2050, according to research released this week by University of British Columbia (UBC) researchers.

Previous projections suggested that the effects of warmer water temperature would lead to fish moving toward the poles and cooler waters, resulting in an increase of fish catch potential of as much as 30 per cent in the North Atlantic by 2050.

But new projections that add in the impact of de-oxygenation and ocean acidification show that some regions may see a 20-35 per cent cut in maximum catch potential by 2050 (relative to 2005) depending on the individual species’ sensitivity to ocean acidification.

"What we find is that if we just look at warming, the animals will shift their distribution, because for fish and for some of the shellfish, they like to live in a certain temperature of the water, and if water gets warmer, they will very likely move to a higher latitude or move north, so that they can find cooler water to live," said William Cheung, an assistant professor in UBC’s Fisheries Centre, who presented his research at the Annual Meeting of the American Association for the Advancement of Science (AAAS) in Vancouver.

However, when considering acidification and de-oxygenation, the increase in fisheries catch potential turns to a decrease of 15 per cent, the researchers wrote.

“Loser” regions closer to the equator could become poorer due to scanter resources and need better strategies to alleviate potential food security issues.

Climate change and the related physical and chemical changes in the ocean lead to lower levels of oxygen in the water in some regions. In addition, approximately one-third of the carbon dioxide that humans produce by burning fossil fuels is being absorbed by the oceans and gradually causing them to become more acidic.

"There is a study that shows that more acidic water may affect animals that form shells, specifically, for example, the mussels or the oysters, which form shells when they grow," Cheung explained, NEWS1130 reports.

Cheung believes rebuilding global fisheries could boost the capacity of marine species to cope with the destructive impacts of climate change and ocean acidification.

This will require efforts including curbing overfishing and reducing carbon dioxide emissions, added Cheung.

Separately, research conducted by the University of Aberdeen and Marine Scotland Science stresses that conducting an experiment only once can breed unreliable results. Scientists examined how different climate change scenarios affected tiny marine crustaceans called copepods.

While the first study showed that future global warming and ocean acidification scenarios would lead to a major decline in the number of copepod eggs that successfully hatch, the second study run a week later found that the effect of global warming depends on water temperature and when the eggs were collected, explicated Dr Daniel Mayor, an Independent Research Fellow at the University of Aberdeen’s Oceanlab.

Related article:

- Corals and molluscs proved to weaken due to ocean acidification

By Natalia Real
editorial@fis.com
www.fis.com

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