Oyster Die-Off in Pacific May Be Linked to Ocean Acidification

The oyster industry in parts of Washington state in the Pacific Northwest is experiencing its fifth year of a massive die-off of oyster larvae, a condition that may be linked to increasing acidification of ocean waters from high levels of CO2 in the atmosphere. The Seattle Times reports that the larvae have been dying before they have a chance to attach to hard surfaces, such as rocks or other oyster shells, and grow their own shells made from calcium carbonate. Researchers have noticed periodic drops in the pH of the surrounding ocean waters, apparently linked to upwellings of deep, more acidified water. Those waters can easily corrode the calcium carbonate that is vital to oyster shell formation, the newspaper reports. The high larval mortality is causing steep financial losses in the Pacific Northwest’s $110 million oyster industry, although scientists say that other causes, such as outbreaks of an ocean-borne bacteria, Vibrio tubiashii, may also be taking a toll on the oyster larvae. Scientists are concerned that high atmospheric concentrations of carbon dioxide are quickly making the world’s oceans more acidified and are already damaging corals worldwide.