The Pacific Ocean Is So Acidic It’s Dissolving Crab Shells

One of the most unexpected effects of climate change would have to be the Pacific Ocean’s increasing acidity. Previously, scientists were aware that the world’s oceans were becoming more acidic, however, the changing nature of the marine environment’s pH is starting to affect the wildlife within it. 

The Dungeness Crab is labeled by Washington’s Department of Fish and Wildlife (WDFW) as one of the most vital commercial “fishes” in the Pacific Northwest. This is especially troubling considering that the decrease in the Pacific’s pH is beginning to dissolve parts of the Dungeness crab’s shell, and damage some of their sensory organs, according to a new study

“Their injuries could impact coastal economies and forebode the obstacles in a changing sea. And while the results aren’t unexpected, 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 really 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.

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So how does the ocean’s pH become more acidic in the first place? Like most of the ailments to the natural world in the 21st century, the answer is climate change. As carbon emissions and greenhouse gases continue to rise in our atmosphere, they do the same in our oceans. An increase in carbon dioxide, specifically, in the Pacific Ocean is what has caused its pH to lower. 

According to the National Oceanic and Atmospheric Administration (NOAA), ocean acidification shifts coastal ecosystems by releasing an excess of nutrients that “can create algae blooms and increase sea temperatures and salinity.” Salinity is how high the salt levels are in a given body of water. 

Crustaceans such as crabs, oysters, clams, coral, and plankton all rely on compounds known as carbonate ions in order to build their shells and coral skeletons. The more acidic a body of water is, the less carbonate ions will be present, as they need a more neutral pH in order to truly grow and thrive. Without carbonate ions present, crustaceans aren’t able to build their shells as strongly; and now the Dungeness crabs are really feeling the effects of that. 

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The deterioration of the Dungeness crab’s shell began with its larvae. Scientists began to notice that the larvae’s young shells were already becoming corroded. They were able to notice because the larvae itself was much smaller than it normally should’ve been. Upon further research, they discovered that their shells were dissolving; which explained the small size of the larvae. This quickly became an issue for the crabs, as their shells are their main defense mechanism from predators.

“We found dissolution impacts to the crab larvae that were not expected to occur until much later in this century. The tiny hair-like structures crabs use to navigate their environments were damaged by the low pH levels, too. Crabs without these mechanoreceptors could move more slowly and have difficulty swimming and searching for food,” said Richard Feely, study co-author.

It’s hard to combat a massive issue such as ocean acidification without some serious systematic change occurring. The NOAA suggests that a reduction in greenhouse gas emissions overall would be the only way to truly return the ocean’s pH to what it was. The Dungeness crab is the first to begin to fall victim to this issue, but as time progresses, and the Pacific’s pH continues to decrease, who’s to say what other crustaceans will be affected.