Could jellyfish take over the world?

Aurelia aurita (Moon Jellyfish) - captive

Image by Arthur Chapman via Flickr

Ok, if you’re a regular here, you know by now I have an interest in these feckers, partly because we get a lot of them in Tramore Bay, I’ve been stung more times than I can remember (first two very minor stings of the year yesterday), AND they are fascinating. On one hand I like them more and more and find them increasingly interesting. On the other hand the various scientific mysteries associated with them can be worrying.

On the interesting side: For years there has been an apparent discrepancy in some figures associated with the sea. It seems when that the cumulative energy figures for winds and tides don’t account for sufficient energy to explain ocean mixing.

Ocean mixing is where the colder deeper water is mixed with warmer upper water. I mentioned recently that cold water carries the nutrients that are the basic of the ocean food chain. The thermohaline system and the tides and storms all mix the water, bringing up the rich cold water. But like the unaccounted-for missing mass and energy in the Universe as a whole, something similar seems to apply to the sea.

Various ideas have been proposed to account for the discrepancy. One theory was that it’s sea swimmers (fish & humans), who add the missing energy. Also considered is that mixing is now aided by krill, the microscopic crustaceans that Basking & Whale Sharks, and Baleen whales eat, because of Krill’s vast numbers. It also seems that large shoals of fish can cause as much turbulence as a storm.

The force that moves an aeroplane, a sail and a propellor, the Bernoulli Principle, causes a low pressure area behind swimming creatures with a high pressure system in front, dragging water behind, leading to mixing of the water, as really well illustrated in the 12-second jellyfish video.

Why is this important though? Well, ocean mixing is an important factor in Climate Change modelling. (Aside: Climate Change is real. Don’t agree? Read the 98% of science that confirms it.). The level of ocean mixing is known, but the contributory factors need to be understood better, since these can change.

Anyhoo. The worrisome side is the global increase of jellies. Some of you may have seen the National Geographic documentary on giant Nomura jellies in the Seas Of China and Korea, and the chaos they are causing to the fishing fleets. So there’s an impact on the human food chain. Of course there’s a theory that jellyfish are increasing BECAUSE of overfishing (since fish eat the young Medusae before maturity), which, given how we completely fail to protect fish stocks worldwide, certainly seems possible. there’s another possibility that the blooms are driven by climate change. So is there a Catch 22?

Overfishing and climate change causes jellyfish blooms, which is turn make fishing more difficult? Partly that could be seen a Gaian correction mechanism, if enough fish are left to consume the jellies, but what if there’s aren’t enough fish left to consume the blooms, as seems to be the case? Current economics dictate as fish get more rare, what actually happens is that prices increase ($396,00 for a single bluefin tuna), and the remaining fleets will work harder to the huge profits (Hardin’s Tragedy of the Commons, when something is owned by everyone, no-one is  responsible).

Jellyfish Shunt - effecting change in the marine food chain

And recently there’s been another disturbing discovery. Most animals in the oceanic food chain produce waste products that are used by other links in the chain. Not so with jellyfish which product a waste slime that is generally inedible. This is called shunting, where jellyfish remove resources from the food chain.

That’s extremely worrying because it obviously means less food available for the oceanic food web. That’s bad for all of us.

This is ongoing science. As many, or more, questions therefore as answers right now. But this is important stuff, more important than the few stings we pick up.

The jellies are important, very important.

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One thought on “Could jellyfish take over the world?

  1. Pingback: Research « Hubble Bubble

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