Fresh Dungeness Crab packed in ice at Pike Place Market in downtown Seattle.
A recent study found that ocean acidification is dissolving the shells of Dungeness crabs across the US Pacific Northwest.
The study, published in Science of The Total Environment, analyzed Dungeness crabs and found that the lowered pH of the Pacific Ocean is causing young Dungeness crab shells to corrode.
As carbon dioxide levels continue to increase they have a direct impact on the acidity of the ocean. This is because oceans absorbs a significant amount of the 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.
The red line shows increasing carbon dioxide in the atmosphere. This corresponds with a lowered pH ... [+]
You can experience the impact of acidity by increasing carbon dioxide in liquid. The same process is used in soda. Have you ever tried a flat Coke and noticed how syrupy sweet it is, quite unlike a normal Coke. That’s because it lost its carbon dioxide (carbonation), which added acidity to the soft drink to balance out the sweetness.
In a very simplistic summary, the more carbon dioxide that is added to the ocean the more that 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.
Thus, 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.
Fishermen offload Dungeness Crab from their fishing vessel in San Francisco, California.
The more acidic Pacific Ocean is impacting the vital functions of Dungeness crabs, something that scientists thought would happen many decades from now.
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.
“If the crabs are affected already, we really need to make sure we start to pay much more attention to various components of the food chain before it is too late,” said lead author Nina Bednarsek, senior scientist with the Southern California Coastal Water Project, in the NOAA release.
