Sea grass underwater

Ocean acidification study offers warnings for marine life habitats

Image courtesy of dreamstime_17348767_Vilainecrevette

 

Acidification of the world's oceans could drive a cascading loss of biodiversity in some marine habitats, according to research published this week in Nature Climate Change with contributions from PML.

The work by biodiversity researchers from the University of British Columbia (UBC) and colleagues in the U.S., Europe, Australia, Japan and China as well as PML, combines dozens of existing studies to paint a more nuanced picture of the impact of ocean acidification.

While most research in the field focuses on the impact of ocean acidification on individual species, the new work predicts how acidification will affect the living habitats, such as corals, seagrasses, and kelp forests, that form the homes of other ocean species.

“Not too surprisingly, species diversity in calcium carbonate-based habitats like coral reefs and mussel beds were projected to decline with increased ocean acidification,” said UBC zoologist and biodiversity researcher Jennifer Sunday, who led the study. Species that use calcium carbonate to build their shells and skeletons, like mussels and corals, are expected to be particularly vulnerable to acidification.

“The more complex responses are those of seagrass beds that are vital to many fisheries species. These showed the potential to increase the number of species they can support, but the real-world evidence so far shows that they’re not reaching this potential. This highlights a need to focus not only on individual species, but on how the supportive habitat that sets nature’s stage responds and interacts to climate change.”

The researchers combined data and observations from 10 field studies that measured the impact of underwater volcanic vents, which release carbon dioxide and mimic the conditions of future ocean acidification, on the density of habitat-forming species. They combined that data with 15 studies looking at how changes in habitat typically impact local species to make their predictions.

“We’ve known for a while that there will be big losers and some winners with climate change,” said UBC marine ecologist Christopher Harley, senior author on the paper.

“We don’t have time to measure the impact of climate change on each individual species, but using this approach allows us to make reasonable predictions. Now we have a much clearer picture of how some losers can drag biodiversity down with them, and how some other species might be able to help their habitat mediate a response to acidification.

“For example, in the Pacific Northwest, the number of medium to large-sized edible saltwater mussels is likely to decrease as the chemistry of our oceans changes, and this is bad news for the hundreds of species that use them for habitat,” added Harley.

PML Head of Science Professor Steve Widdicombe, a contributing author on the paper, commented:

“This analysis has enabled us to step back and take a critical look at our current understanding of OA and evaluate how we progress from species-specific responses to impacts on habitats, especially those habitats that are created from the living organisms themselves. It has helped us to identify some of the potential changes likely to occur in these key biogenic habitats in a future world with higher CO2 levels and how those changes may affect the benefits these habitats provide to other marine life, as well as human beings.”

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