Dungeness Crabs Are Starting To Lose Their Shells Due To Ocean Acidity

Ryan Ford 28 Jan 2020

In an alarming report, scientists have determined that the acidification of the Pacific Ocean is affecting marine life earlier than expected, with Dungeness crabs in particular suffering.

For the first time, researchers are seeing the effects of lower ocean pH on marine life as Dungeness crabs in the Pacific Northwest are losing their shells to the acidity.

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In a new National Oceanic and Atmospheric Administration-funded study, researchers observed how the lower pH levels affected the valuable crabs, which are vital to the area's commercial fisheries.

The ocean acidity has damaged Dungeness crabs' shells and also their sensory organs, according to the report.

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The world's oceans are becoming increasingly acidic due to carbon dioxide.


As the oceans absorb carbon dioxide from the atmosphere, the water's pH level drops, making it more acidic.

In the acidic water, carbonate ions are less abundant, and much marine life, including crabs, oysters, clams, and coral rely on carbonate ions as they build up their shells. Building and maintaining shells becomes difficult, especially for marine life that's still developing.

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Prior to this research, Dungeness crabs were not thought to be vulnerable to current levels of acidity.

NOAA | Nina Bednarsek, SSCWRP

However, crab larvae have shown signs of dissolved shells, as well as other developmental delays, and the loss of tiny hair-like structures that help them navigate and orient themselves in the water, an effect scientists hadn't seen before.

Without those structures, they will have more trouble with buoyancy, maintaining verticality, and avoiding predators.

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The researchers said that they expected to start seeing some changes to marine life, but just not yet.

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"We found dissolution impacts to the crab larvae that were not expected to occur until much later in this century," said the NOAA's Richard Feely, one of the study's co-authors.

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Although researchers are taking the findings seriously, it's less clear what can be done about it at this stage.

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The NOAA suggests two major avenues to address the situation: reducing our overall carbon footprint so the ocean absorbs less carbon, or teaching wildlife and those who rely on it to adapt to changes in the oceans.

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More research is needed, however.

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But time is not on the scientists' side. "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 the study's lead author, Nina Bednarsek of the Southern California Coastal Water Research Project.

The study was published in Science of the Total Environment.

h/t: CNN, NOAA

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