Acidification edification

Some ocean water hasn’t seen the light of day for decades, lying deep beneath the continental shelf where it’s starved for oxygen, enhanced with carbon dioxide, and acidic from the activities of tiny marine microbes. When this low-oxygen water—known as hypoxic water—surges closer to the surface, coastal marine life is exposed to this harmful mixture that can inhibit the growth and even dissolve the shells of oysters, clams, and mussels.

OSU scientists are studying the degree to which the shells of larval oysters, mussels, and clams can withstand hypoxic seawater—relatively new research prompted by recent problems in one of Oregon’s most iconic industries: oyster culture.

Oysters build their shells from the inside by depositing calcium carbonate. Yet, at the same time, corrosive water can dissolve the outer shell.

[caption caption="Oregon State University scientists have charted a course to revolutionize the oyster industry. Beginning in 1996 with just 600 wild oysters collected on the West Coast, the Molluscan Broodstock Program (MPB) has used genetic selection and precise breeding to produce meatier shellfish and boost yields."][/caption]

“The first 24 hours in the oyster larvae’s life is a critical time when they build their initial shells,” said Chris Langdon, an expert in shellfish biology. “Acidified water requires vulnerable larvae to exert more energy when building a shell.”

While researchers aren’t certain why there’s an increase in deep, hypoxic ocean water rushing to the surface (a process known as upwelling), they suspect this change in ocean currents is related to rising levels of carbon dioxide in the atmosphere and climate change.

Recently, an OSU study definitively linked increases in ocean acidification due to upwelling to decreases in oyster larval production at an Oregon hatchery. Scientists found that corrosive, upwelling ocean water kept larvae from developing shells and growing at a pace that would make commercial production cost-effective.

In the meantime, Langdon and his colleagues with OSU’s renowned Molluscan Broodstock Program are aiming to develop oyster larvae that are more resistant to acidified water.