Jellyfish have long been seen as a harbinger of climate change, and so have received quite a negative reputation (at least in my mind). Imagine my surprise, then, at reading an article published July 30 in the journal Nature that says these creatures might actually help mitigate climate change.

Jellies are like the weeds of the ocean. They are fairly resistant to changing environments, so as carbon pollution causes ocean waters to warm up and to become more acidic--a process that kills more sensitive organisms like coral and plankton-- jellyfish have moved in and taken over emptying habitats. In droves.

In recent years, cnidarians have been seen cruising up the Hudson River during triathalons, swarming beaches in Spain, and drifting far north, off the coast of Ireland. But the Nature study suggests there may be another side to these mobs, other than ruining your summer holiday. As the hordes pulse their way through the ocean current, they might also be stirring the sea, in the same way that a boat, when pushing through the water, creates a wake behind it that churns the water.

How, then, is stirring the ocean connected to climate change? NPR reports, “Mixing plays a role in global climate change because carbon dioxide in the air above oceans dissolves in the surface water. Through mixing, it can get pulled into the depths and stored there for long periods.”

Interesting. But don’t get carried away: hordes of jellies stirring the ocean are not the next best thing to carbon sequestration. If jellies are truly creating a turbulence and pulling CO2 deep into the ocean, that action has consequences of its own. When carbon dioxide meets ocean water, carbonic acid is formed. It’s a natural chemical reaction that, when amplified due to carbon pollution, lowers the pH of the ocean. In turn, acidification leads to the death of shelled organisms, because high acidity prevents them from growing shells (or, if waters are corrosive enough, dissolves them all together). For more on ocean acidification, read the Fall issue of OnEarth magazine. But for now, check out the work that marine biologist Tierney Thys is doing on Mola mola, one of jellyfishes’ only known predators. And check out the videos of jellies swimming through dye, provided by the Nature researchers who used the set up to see how moving jellyfish were able to pull water in different direction. 

[Photo credit: Caption: Image of Mastigias jellyfish aggregation in Jellyfish Lake, Palau.
Credit: K.Katija/J.Dabiri]