Ruminants like cows aren’t the only animals to produce copious amounts of greenhouse gases. Researchers have found that ocean clams and worms do too.
Most of us probably know that cows and cattle produce significant amounts of methane--120 kilograms a year, a thousand times more than even the most flatulent of people--because of their gut bacteria. However, it turns out that cows are not alone in their, well, lethal flatulence. Researchers from Cardiff University and Stockholm University have found that ocean clams and worms are also emitting some pretty harmful gases in amounts comparable to those that cows emit.
Clams and worms aren’t producing just any kind of greenhouse gas. They’re producing methane and nitrous oxide, which are the strongest of these gases. Methane has 28 times more warming potential than carbon dioxide, while nitrous oxide has 265 times more. It’s possible that about 10% of methane emissions in the Baltic Sea come from clams and worms.
But 10% isn’t that bad, is it? Well, it depends on what your definition of “bad” is. That 10% of emissions is equivalent to the amount of emissions produced by 20,000 cattle. That’s about 1% of the UK’s total cow population.
Researchers studied isotopes, molecules, and trace gas from clams and worms by analyzing Baltic Sea sediments. According to a new study, a clam called Limecola balthica and a multi-legged worm called Marenzelleria arctia emit quite a significant amount of methane and nitrous oxide. Though methane and nitrous oxide are rarer than carbon dioxide, we now know that two other very common animals are emitting them.
It’s entirely possible that in seas and oceans around the world, clams and worms are producing just as much or even more emissions than the clams and worms in the Baltic Sea. According to Dr. Ernest Chi Fru, one of the researchers, "What is puzzling is that the Baltic Sea makes up only about 0.1% of Earth's oceans, implying that globally, apparently harmless bivalve animals at the bottom of the world's oceans may in fact be contributing ridiculous amounts of greenhouse gases to the atmosphere that is unaccounted for."
Is coastal enrichment to blame for methane-producing clams?
However, researcher Stefano Bonaglia said that these clams and worms have been producing these gases for a long time, way before the concept of global warming as we know it ever even existed. If that’s so, then why are emissions from clams and worms a problem now?
Bonaglia thinks that agricultural fertilizers may be to blame. The runoff from these fertilizers eventually makes it way to the sea, where it can enrich coastal waters and thus affect clams and worms. This may be why the more recent emissions from the clams and worms have become an issue.
For now, researchers aren’t sure yet if this problem is present in other seas and oceans. Thus, they can only guess at how broad the scope of the issue is. Also, the study has mostly just focused on the greenhouse gases emitted by clams and worms. It’s still possible that these animals have some sort of benefit that can offset their emissions.
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