Home > Uncategorized > Oceans’ rising acidity a threat to shellfish — and humans – latimes.com

Oceans’ rising acidity a threat to shellfish — and humans – latimes.com

The cold, nutrient-laden waters from the deep sea are naturally more acidic than surface waters. Human contributions of CO2 only add to that acidity.

A few years ago, the shellfish industry became alarmed that 80% of oyster larvae at hatcheries were not surviving. Initially, they blamed an aggressive strain of bacteria.

But after Feely found evidence of corrosive waters reaching the West Coast, industry officials asked him and other scientists if there might be a connection to the die-offs. Sure enough, scientists found a link by studying the Whiskey Creek hatchery at Netarts Bay, Ore., whose larvae were bathed in acidic waters drawn in by intake pipes.

Oyster larvae are particularly sensitive in their first few days of life. As acidity rises in the ocean, the abundance of calcium carbonate — a mineral they need to build their shells — is gradually reduced. At extremely high levels of acidity, laboratory experiments show, seawater no longer provides this material and indeed can cause existing shells of corals, snails and other animals to dissolve.

Now, the Whiskey Creek hatchery tries to balance the acidity of its waters by adding soda ash. Costs have increased and production has never fully recovered. “We’re limping along and manipulating the water to stay in business,” Barton said.

Ocean acidification, once an obscure area of scientific inquiry, has quickly become of much wider interest. Because colder water can hold more CO2, scientists expect to see the first major changes in northern waters, where increasing acidity could melt away the bottom rungs of the food chain, such as pteropods, the button-sized marine snails that nourish salmon and other fish.

The chemical changes are then projected to spread to temperate waters.

Scientists have been doing experiments to determine if certain animals are more adaptable. Gretchen Hofmann, a UC Santa Barbara ecologist, has found that purple sea urchins, for instance, are far better at tolerating higher acidity than are commercially grown Pacific oysters. Seafood should remain abundant, she said, if people are willing to eat urchin gonads, sold in sushi bars as uni.

Algae, bacteria and other primitive life forms tend to either be unaffected or to thrive in acidic waters, scientists report — which can create additional problems.

Dave Hutchins, a USC oceanographer, has found that harmful algae, common off the California coast, “like high C02 conditions.” Experiments in his lab reveal that acidified waters trigger these microscopic plants to produce more toxins that contaminate clams and mussels. These shellfish, in turn, can sicken or kill humans who eat them.

Later this century, the rising acidity is projected to reach tropical waters. That will put coral reefs, already in peril, under even more pressure.

via Oceans’ rising acidity a threat to shellfish — and humans – latimes.com.

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