San Franciscans fawn over Dungeness crab. Cracking their carapaces and dunking the retrieved meat into melted butter, consuming these crustaceans is a local right of passage. But if our oceans continue to acidify, that bit of ceremony could go the way of Friday nights once spent at Blockbusters.
In a recent peer-reviewed, National Oceanic and Atmospheric Administration (NOAA)-funded study, populations of the beloved crustacean in Oregon, Washington, and British Columbia were found to have shell damaged linked to an increasingly acidic Pacific. Though solely observed in the above-mentioned areas, it's no feat of imagination to believe the same couldn’t happen (or is already happening) off our own ocean fronts.
The survey, first conducted in 2016, examined larval Dungeness crabs along the West Coast and found their exoskeletons had begun to disintegrate … the moment they hatched. Similar findings were observed as far back as 2010, albeit in a different, more obscure family of fauna – phytoplankton and zooplankton, two animals responsible for fundamentally supporting the entire food web in our oceans.
“If [the crabs and other ocean life is] 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,” said lead author for the study Nina Bednarsek, a senior scientist with the Southern California Coastal Water Research Project, to NOAA. She was among thirteen other notable researchers involved in the study.
As defined by the government agency: Ocean acidification refers to a reduction in the pH of ocean water, primarily caused by the uptake of carbon dioxide from the atmosphere over long time spans. When CO2 is absorbed by seawater – a phenomena occurring in nauseam now, due to increasing amounts of fossil fuels being burned annually – a domino's fall of chemical reactions happen, which results in an increased concentration of hydrogen ions, responsible for that pH reduction.
The observed Dungeness crabs showed signs of carapace (read: shell) breakdown, again particularly among larva. This discovery worries researchers for a multitude of reasons, impart because weakened shells could affect everything from their ability to move and feed, to being able to protect themselves against both the elements and predators. Alas, their odds of maturing into healthy (still alive) reproductive critters is, hypothetically, now hindered.
“If these larval crabs need to divert energy to repair their exoskeletons, and are smaller, as a result, the percentage that makes it to adulthood will be at best variable, and likely go down in the long-term,” added Bednarsek to NOAA. “[...] 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.”
Authors of the study express the need for more research to understand the exact effects increasing ocean acidification will have on Dungeness crabs in these Pacific coastal waters. However, The Seattle Times also referenced a 2017 study that, based on expected declines in some Dungeness crab food sources and ocean-acidity levels rising, could mean West Coast crab stocks may fall some 30 percent by 2063.
Reference
Bednaršek et al. (2020) Exoskeleton dissolution with mechanoreceptor damage in larval Dungeness crab related to severity of present-day ocean acidification vertical gradients. Science of the Total Environment. DOI: https://doi.org/10.1016/j.scitotenv.2020.136610
This article has been republished from the following materials. Note: material may have been edited for length and content. For further information, please contact the cited source.
2020-01-28 12:21:02Z
https://www.technologynetworks.com/tn/news/dungeness-crab-shells-dissolved-by-acidified-ocean-329941
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