PA ImagesAn increase of carbon dioxide levels in the Pacific Ocean has made the water so acidic it’s literally dissolving crabs’ shells.
The shocking findings come from a study published this week in Science of the Total Environment, which is based on a 2016 survey of Oregon, Washington, and British Columbia coastal waters.
Scientists examined larval Dungeness, a species of crab that inhabits eelgrass beds and water bottoms on the west coast of North America, and found the lowered pH of the Pacific Ocean is causing young Dungeness crab shells to corrode.
The infographic above shows the location of larval Dungeness crab sampling in 2016, examples of impacts from ocean acidification, as well as photos of a larval (left) and adult (right) crab. Credit: Nina Bednarsek, SSCWRP
— NOAA Research (@NOAAResearch) January 23, 2020
The oceans absorb a significant amount of the carbon dioxide released into the atmosphere, and carbon dioxide levels have a direct impact on the acidity of the ocean. As carbon dioxide levels continue to increase due to fossil fuel combustion, the pH of the ocean lowers, making it more acidic.
Of course, increased acidity is less than ideal as it poses a risk to marine life. Acid levels dissolve calcium carbonate, which forms the ‘bones’ of most organisms in the ocean. Organisms with exoskeletons like crabs, therefore, are especially susceptible because their calcium carbonate shell is in direct contact with the water.
Previous research has shown that the ocean absorbs as much as 25 percent of human-made carbon dioxide. As the carbon mixes into the ocean, chemical reactions in the water column produce more hydrogen ions and fewer carbonate ions, lowering pH levels and increasing acidity. (8/10)
— The Oregonian (@Oregonian) January 28, 2020
Scientists expected marine life to be impacted by acidity levels at some point later this century, but they did not expect it to happen so soon.
Nina Bednarsek, the lead author of the study, commented:
If the crabs are affected already, we really need to make sure we start to pay attention to various components of the food chain before it is too late.
Researchers found some Dungeness larvae in the wild already have ‘severe carapace dissolution’, meaning their shells are pitted and folded, the Seattle Times reports. These crabs were also typically smaller in size.
Bednarsek added:
We were really surprised to see this level of dissolution happening.
The study also revealed damage to the hairlike structures that act as sensory receptors for the crabs. The researchers believe this could lead to slower movements, impaired swimming and other problems.
Wikimedia CommonsCoastal waters where the crabs have previously thrived have recently been found to have ‘hot spots’ of ocean acidification, due to a combination of periodic strong upwellings of deeper ocean water, which is rich in carbon dioxide, and surface waters that have absorbed gas released by fossil fuel combustion and other human activity.
Though the findings are telling, the authors say more research is needed to understand what they may mean for the future of the Dungeness crab as Pacific coastal waters continue to absorb carbon dioxide.
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Emily Brown first began delivering important news stories aged just 13, when she launched her career with a paper round. She graduated with a BA Hons in English Language in the Media from Lancaster University, and went on to become a freelance writer and blogger. Emily contributed to The Sunday Times Travel Magazine and Student Problems before becoming a journalist at UNILAD, where she works on breaking news as well as longer form features.