Ocean acidification raises economic concerns for shellfish hatcheries (audio & text)

Oceans are the most acidic they’ve been in 26,000 years, according to the World Meteorological Organization. That can impact the development of shellfish, like the ones fishermen depend on for income. Joe Raedle/Getty Images

At Whiskey Creek Shellfish Hatchery on the Oregon coast, baby oysters are hatched, raised, then sold to oyster farms throughout the Pacific Northwest. 

“Our pumps pump in about 200 gallons a minute of seawater into the hatchery,” said production manager Alan Barton.

The seawater comes in, gets treated and goes into tanks where the oysters are hatched. Barton grows vats of green and brown algae to feed them. Back in 2007, after nearly 30 years of doing this without incident, something started to go wrong.   

“Just month after month after every group of larvae dying one after another,” Barton said. Entire crops of baby oysters — normally swimming around — just died.

“We thought the causes were things like bacteria, disease,” he said. So they treated the water for bacteria.  

“[In] 2008, with all these sophisticated treatment systems in place, we essentially lost all the larvae in the entire hatchery — $100,000 worth of product — and all just went to the bottom, all within 48 hours or so,” he said. 

More acidic water, more problems

The cause, it turned out, was the water itself. More acidic water from deeper in the ocean was upwelling into their water source, driven by seasonal winds. 

The lower pH water, meaning it was more acidic, was driving changes in the mineral composition of the water and killing the oyster babies. Deeper water is naturally more acidic than surface water, and upwelling is a natural event. But human-caused emissions are increasing the background level of acidity and appear to have tipped those natural conditions just past what the oyster larvae could bear.  

Marketplace, 5 July 2022. Article.

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