New research of acidification threat to mussels


Swings in acidity may be worse for mussels than long-term acidification.

The acidity of ocean water can vary due to tides, location, and the time of day or year. But the shallow water along the coast is more susceptible to ups and downs in acidity than the open ocean.

And recently, scientists, including marine biologist Ceri Lewis at the University of Exeter, have been paying more attention to how this variability in acidity may affect marine life now and in the oceans of the future.

In recent experiments, Stephanie Mangan, who was a master’s candidate working with Lewis, examined how blue mussels responded to seawater at current acidity levels (at pH 8.1), and water with an acidity 150 percent higher, around pH 7.7.

This more acidic water is expected by century’s end because of anthropogenic climate change. But unlike most ocean acidification studies, which plop marine life into seawater with steady acidity, Mangan’s experiments also tested how mussels fare when the acidity fluctuates.


The researchers had expected the more acidic water to be more stressful to the mussels than the present-day conditions. But, after evaluating several stress markers, they determined that was generally not the case.

“What our data showed was that actually the variability mattered more than the total change,” Lewis says. Mussels living in seawater where the acidity yo-yoed worked harder and burned more energy to keep running basic metabolic processes, even under present acidity.

But when the acidity level remained steady—whether at present or future conditions—mussels responded similarly.

Lewis acknowledges the pressing need for more data. In particular, she says, scientists need better measurements of the ocean’s actual short-term fluctuations in acidity, which this study lacked.

She’s looking for funding to put in place sensors to remotely and continuously monitor coastal conditions. “I think it’s really important that we get a good sense of how variable coastal environments are,” she says, especially for species like mussels.

Read the full article at Hakai Magazine and the research paper here.

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