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The unusual suspects: jellyfish are climate winners

Planet Ocean (photo: NASA)

We live on a planet with a rapidly changing climate and oceans that are getting more acidic. This will allow jellyfish to thrive with climate change.

Ocean acidification is a pretty difficult thing to get your head around. Oceans cover 70 per cent of the earth’s surface, and Jim Bolger the Executive Director of the Pacific Ocean Shelf Tracking project at the Vancouver Aquarium, has even suggested a more accurate name for planet earth would be ‘Planet Ocean’.

We humans live on a small portion of the surface of the planet while most of the action is going on under the surface of the water. Oceans are the biggest carbon sink around, and take up 338 Gigatonnes of CO2 each year (we currently emit 30 Gt a year). The problem is, as humans pour more CO2 into the atmosphere by burning fossil fuels, the ocean is sucking more in.

And by doing us this favour it’s becoming more acidic, with a decrease of 0.11pH below the normal level of 8.2pH which is a 30 per cent increase in acidity. This is due to everybody’s old favourite chemical reaction from chemistry class – acid/base reactions. When you mix ocean and CO2, you get calcium carbonate which reacts with the shells of ocean residents, making their shells thinner.

Why is this good news for the jellyfish? Jellyfish have a few points up on the rest of the ocean in this scenario. Firstly, over-fishing is a huge issue world wide, but we don’t eat jellyfish. Point to the jellyfish.

Jellyfish – not fish, but definitely pretty (photo: the tahoe guy, flickr)

Secondly, ocean acidification isn’t going to be as much of an issue for jellyfish because they don’t have shells. Jellyfish are gelatinous zooplankton (so technically not ‘fish’) and without a shell to worry about that’s another point to the jellyfish. Jellyfish 2, climate change 0.

While jellyfish don’t have a nervous system, respiratory system or a circulatory system, they do still need oxygen (which they just absorb through their gelatinous body), so if climate change gets bad enough to result in Canfield Oceans, it’s unlikely the jellyfish will survive. Score one back for climate change.

Canfield Oceans are both really interesting and really terrifying. The term was named after geologist Donald Canfield who studied ocean chemistry in the late Proterozoic era (2.5 billion years ago) and discovered that when oxygen can no longer circulate through oceans they become sulphuric and eventually contain no oxygen at all, slowly suffocating the inhabitants.

So with a little bit of climate change (2-4oC warming), it looks like good news for the jellyfish – less fish in the ocean means more nutrients hanging around for them to absorb through their jelly and a warmer more acidic ocean won’t bother them too much.

With a lot of climate change (4-6oC warming or more), it’s going to be bad news for the jellyfish, but then again it’s going to be bad news for pretty much all the inhabitants on the planet by that point. But in the meantime, the jellyfish are sitting pretty. 

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