A new study of oyster growth at a major hatchery on Oregon's Pacific coast confirms what scientists have long believed: ocean acidification hampers the development of young shellfish in a big way.
The biological processes underlying the harm wreaked by ocean acidification, itself the result of man's pollution of the atmosphere with carbon dioxide, are not yet fully understood. But it's increasingly clear that it will put more and more pressure on shellfish populations in the coming decades. That spells trouble for the seafood industry -- and everyone who enjoys eating oysters.
The study's authors, led by Alan Barton of the Pacific Coast Shellfish Grower's Association and Burke Hales of Oregon State University, examined oyster larvae at Whiskey Creek Shellfish Hatchery over the course of one summer. Whiskey Creek hatches the larvae in a controlled environment, using water piped in from the local estuary, before shipping them to oyster farms throughout the country to be raised to maturity. The researchers analyzed water samples several times a day to monitor for acidity and dissolved ions, to see how much of an effect those variables had on the growth of the larvae.
"Most of the variability we saw was the result of natural processes of upwelling and photosynthesis and respiration," Hale told the Huffington Post. "We let the ocean drive the signal instead of us taking the larvae into the lab and forcing changes on them."
Larvae that got doused with higher acidity water around the time of hatching didn't, at first, seem to have been affected. But these same larvae had developmental problems they on. When they hit their "midstage growth period," between 120 and 150 micrometers, grew more slowly and died in higher numbers than peers who had been hatched when the water was less acidic.
These larvae were being raised in what should be ideal conditions for growth. Wild oysters, facing higher levels of stress, are even more vulnerable to higher acidity.
The high-acidity water that occasionally washed over the oyster larvae in the study didn't even reflect the current state of the atmosphere. It surged up from deep in the ocean, and hadn't been exposed to the atmosphere since the 1960's. Water acidified by the higher carbon dioxide levels of today, and the still-higher concentrations to come, will hurt oysters even more.
That means that the ocean is only going to get less hospitable to oysters. So savor them while you can; unless we drastically reduce greenhouse gas emissions, soon, they're going to get a lot more scarce in the coming decades.