A recent study found that ocean acidification is dissolving the shells of Dungeness crabs across the US Pacific Northwest.
The findings were published this month in the journal Science of the Total Environment and funded by the National Oceanic Atmospheric Administration (NOAA). Researchers found lower pH levels corroded young shells of Dungeness crab larvae, which could impact the crabs’ ability to move, feed, protect itself, and mature into healthy reproductive adults.
As carbon dioxide levels continue to increase, they have a direct impact on the acidity of the ocean. This is because oceans absorb a significant amount of carbon dioxide that is released into the atmosphere. Likely, about a third of all carbon dioxide released from fossil fuel combustion is trapped in the world’s oceans.
Typically, the more carbon dioxide that is added to the ocean the more than carbon dioxide (CO2) dissociates, leaving carbon and oxygen. The carbon can precipitate into calcium carbonate (CaCO3), but the key is what happens to the oxygen. The oxygen, now O2- is now unstable and picks up a free H+. pH is a measure of how many H+ cations there are, hence removing them lowers the pH.
Therefore, the increased concentration of carbon dioxide in the atmosphere directly lowers the pH of the ocean and makes it more acidic. This increased acidity acts to dissolve calcium carbonate, the “bones” of most organisms in the ocean. Organisms with exoskeletons (like crabs) are especially susceptible to more acidic water because their calcium carbonate shell is in direct contact with ocean water.
Their injuries could impact coastal economies and forebode the obstacles in a changing sea. And while the results aren’t unexpected, the study’s authors said the damage to the crabs is premature: The acidity wasn’t predicted to damage the crabs this quickly.
“If the crabs are affected already, we need to make sure we pay much more attention to various components of the food chain before it is too late,” said study lead author Nina Bednarsek, a senior scientist with the Southern California Coastal Water Research Project.
This information will be key in determining how fisheries in the Pacific Northwest deal with the Dungeness crab industry and the fishing industry in general. Unfortunately, the only way to reduce the impact of ocean acidification is to decrease the concentration of CO2 in the atmosphere.
As for the acidifying ocean, NOAA proposes two methods of attack: Reducing our overall carbon footprint to reduce the carbon dioxide absorbed by the sea or teach wildlife and the people who rely on it to adapt to how the sea will change.