Dungeness Crab Shells Aren't Developing Properly Due to Acidic Ocean Water

The last decade was a tough one for Dungeness crabs—and the 2020s don’t appear to be starting any better. In recent years, the fishing season for the crabs has been disrupted multiple times by issues like toxic algae blooms and concerns over increasing whale entanglements—both of which have been tied to climate change. Now, a new study points to another issue: A rise in the acidity of the Pacific Ocean is dissolving the shells of young Dungeness crabs larvae, inhibiting their development.

Ocean waters in the crab’s Pacific Northwest habitat are shifting to lower pH levels—meaning higher acidity—a change that’s not only limiting the strength of developing Dungeness crabs’ shells but also potentially damaging their sensory organs, likely affecting these larvae’s behavior, according to the study which was funded by the National Oceanic and Atmospheric Administration (NOAA). The findings are especially troubling because, though scientists knew the crabs were vulnerable to increases in ocean acidification, they didn’t expect it to affect them this soon. “We found dissolution impacts to the crab larvae that were not expected to occur until much later in this century,” Richard Feely, a senior scientist with NOAA’s Pacific Marine Environmental Laboratory and one of the co-authors of the study, stated.

“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,” lead author Nina Bednarsek, a senior scientist with the Southern California Coastal Water Research Project, hammered home.

As the NOAA pointed out, issues with Dungeness crabs can be significant beyond your seafood dinner. Economically, the crabs support one of America’s most valuable fisheries. And environmentally, scientists were already concerned that Dungeness crabs could see population declines due to a lack of smaller prey; this damage could exacerbate the decline by making crab larvae more vulnerable to predators. Meanwhile, it’s especially troublesome if these developmental problems also carry into adulthood—where, though not proven, researchers speculate it could even affect reproduction. And any change is almost certain to continue to throw off the ecosystem at large.

Regardless, though the NOAA doesn’t specifically mention climate change (beyond tagging the article with “Climate Change,” oddly enough), consider this another warning sign. As the NOAA explains, ocean acidification is “primarily caused by the uptake of carbon dioxide from the atmosphere over long time spans”—which is pretty on the nose. At the very least, as Rich Childers, the ocean acidification policy lead at Washington Department of Fish and Wildlife, stated, “These data and results give state and tribal fishery managers and policy makers information that's vital for harvest and conservation planning.”