Global warming: crabs victims of ocean acidification


Increasing levels of CO2 in the atmosphere lead to acidification of oceans, endangering marine life. On the Pacific Northwest coast, this phenomenon result in the disappearance of Dungeness crabs, a well-known crustacean sought by fishermen.

Dungeness crab


What is ocean acidification ?

Ocean acidification refers to the reduction in the pH of ocean water, primarily caused by the increase level of carbon dioxide in the atmosphere over long time spans. When the CO2 is absorbed by seawater, a series of chemical reactions occur, leading to an increase in the concentration of hydrogen ions. Consequently, it causes the seawater to increase its acidity and causes carbonate ions to be less abundant.

Crab’s armour is not resistant to acidification  

They are not imune. While scientists thought that acidification only concerned and affected only corals, they observed that crustaceans are also affected by this phenomenon. On the Pacific Northwest coast, Dungeness crabs have seen their shells and sensory organs deteriorate as a result of this acidification. This is proven by a study by the National Oceanic and Atmospheric Administration (NOAA).

The scientists are making their observations on samples taken in 2016. “This is the first study that demonstrates that larval crabs are already affected by ocean acidification in the natural environment, and builds on previous understanding of ocean acidification impacts on pteropods,” said lead author Nina Bednarsek, senior scientist in the Southern California Coastal Water Research Project.

Bad news for fishermen

This acidification of the oceans leads to the disappearance of the larvae and thus of the future crabs present in the ocean. Crabs larvae that showed signs of shell dissolution were also smaller than others. This could lead to growth delays, according to American researchers. “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” also said Nina Bednaresk”.


Sources :

A propos de Vincent DUBARLE

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