Acidic oceans are dissolving shells of snails
There is now evidence that the seawater off the west coast of the United States has grown so acidic that it’s dissolving shells of snails. These snails, pteropods, termed “sea butterflies,” are between an eighth and half an inch when fully-grown and one of the principal food sources of herring, mackerel, pink salmon, whales and some birds.
A study funded by the National Oceanic and Atmospheric Administration (NOAA) estimated that the amount of pteropods with dissolving shells has doubled over the industrial era and will triple by 2050, by which time coastal waters will be 70 percent more corrosive than prior to the arrival of industry. This is happening faster now than ever before in the previous 20 million years. Fishermen have speculated that several pink salmon runs failed due to decreases in the prevalence of pteropods, however this is unproven.
The effects of a decline in pteropods
The lead author of the paper, Nina Bednarsek, PhD, who works for the NOAA’s Pacific Marine Environmental Laboratory in Seattle, called it the first evidence that a generous fraction of the west coast’s population of pteropods has been affected by ocean acidification and pointed out that effects could be felt by the entire marine ecosystem. A vast number of marine species reside in nearshore waters, including economically significant fish upon which coastal economies depend and which provide food for many people. Another study in 2012 which again involved the NOAA found the same thing to be happening in the Antarctic.
Seawater absorbs almost a third of the CO2 released into the atmosphere by human sources. Much marine life can be expected to be affected, especially animals whose shells are made of calcium carbonate, which includes corals, mussels, oysters and tiny creatures at the bottom of the food chain. Dissolving shells wouldn’t necessarily kill pteropods but would leave them increasingly vulnerable to predation and infection.
The research team, which included scientists from Oregon State University, discovered that the largest percentage of pteropods with dissolving shells was between northern Washington and central California, where 53 percent of snails sampled had greatly-dissolved shells.
Why we should be worried
Gretchen Hofmann, a scientist for the University of California-Santa Barbara, warned that while pteropods are not as charismatic as penguins or polar bears, they were “harbingers of change.” They could be unable to form shells by 2050, and their disappearance would be “catastrophic” to the marine food chain.
William Peterson, PhD, another co-author of the paper, enunciated that this large an effect upon pteropods had not been expected for several decades, but this and similar studies will illustrate what is going on.
About the Author Timothy Chilman
Timothy Chilman used to work in IT. Once, in Sydney, he was turned down for a job because he was “too flamboyant” (“Someone who wears green tartan suspenders to a job interview probably isn’t going to fit in here”). Timothy then became an English teacher. University students in Bangkok complained that he was “too enthusiastic” and company students in Prague complained that he was “too theatrical.”