What is ocean acidification?


Ocean water can become more acidic when it absorbs carbon dioxide from the air and converts it to carbolic acid, lowering the pH level of the water by an average of 0.002 per year, Richard Feely of NOAA’s Pacific Marine Environmental Research Laboratory in Seattle explained.

Pure water is very close to 7 on the pH scale from 1-14, and seawater is more alkaline; Lower numbers are more acidic, higher numbers are more alkaline, or basic. Too far in either direction can be bad for sea life.

That can manifest in direct and indirect ways. More acid “can dissolve the shells and skeletons of marine organisms that we, as humans, like to eat, such as scallops, oysters, clams lobsters and so forth,” Feely said.

Small sea snails called pteropods are also affected by more acidic ocean water, which can have ripple effects up the food chain.

“Pteropods in the California current ecosystem are an important food source for a lot of fish, birds, whales, so they are a really important component of the ecosystem in here,” explained Nina Bednarsek, a pteropod researcher and biological oceanographer who will be conducting experiments onboard the Fairweather.

Up to 60 percent of a juvenile pink salmon’s diet can consist of the snails, she added, and they’re also a favorite of herring and mackeral.

“There are going to be effects up the tropic chain because pteropods are missing out of the ecosystem, and that’s definitely worth investigating,” Bednarsek said.

And certain algae species that produce toxins actually thrive in more acidic water. One particular species, Pseudo-nitzchia, will be studied during the research project. It produces toxins that can contaminate shellfish and cause amnesic shellfish poisoning in humans, with symptoms ranging from dizziness and nausea to seizures and coma. The toxin can be fatal to marine mammals.

“Sea lions have been found wandering up on beaches, disoriented, sea otters are impacted, and sea birds as well. It’s even thought that Alfred Hitchcock’s film “The Birds” was modeled after … an amnesic shellfish poisoning event,” said Vera Trainer, harmful algal bloom program manager at NOAA’s Northwest Fisheries Science Center.

The algae can also lead to diarrhetic shellfish poisoning, which some research has suggested promotes tumors, she added.

— Brionna Friederich