Will Bay fish feel the bite from ocean acidification? ‘Hooked on OA’ series shares latest science

Ocean waters are becoming more acidic — but how does that affect the Chesapeake Bay? And what does it mean for fish and the people fishing for them?

The ‘Hooked on Ocean Acidification’ webinars answered these questions for mid-Atlantic Anglers in March and April. The four webinars walked through recent research about acidification in coastal waters and out in the open ocean. The webinars were hosted by the Mid-Atlantic Coastal Acidification Network, in collaboration with other mid-Atlantic partners.

In the mid-Atlantic, there are many pieces in the puzzle of acidification

Globally, the oceans absorb carbon dioxide from the atmosphere — and since the industrial revolution, human activities are adding carbon dioxide to the atmosphere 10 times faster than the earth has experienced in the last 50 million years. As the ocean absorbs carbon dioxide, the water becomes more acidic. This effect is known as ocean acidification.

But the effects of acidification aren’t uniform across all water, and the mid-Atlantic region gets its ocean water from several sources, explained Grace Saba, an assistant professor at Rutgers University. The mid-Atlantic continental shelf gets currents of cold water, which can be more acidic, and also warmer, less acidic water from the Gulf stream.

Water acidity also changes from day to day and season to season. During the day, plants and algae near the surface of the water use sunlight for photosynthesis, removing carbon dioxide from the water and converting it to the oxygen. Less carbon dioxide in the water means less acidic water. After dark, plants stop photosynthesizing, and the water becomes more acidic.

The Chesapeake Bay also receives freshwater, which is naturally more acidic. Runoff from land carries nutrients into the water, which can cause algal blooms. These blooms photosynthesize and remove carbon dioxide, making the surface water less acidic. But when the blooms die and sink to the bottom of the water, bacteria break down the algae and create carbon dioxide in the process, making the bottom waters more acidic for crabs and other fish that live there.

Sea Grant Virginia, 18 June 2021. Article.

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