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Jellyfish Rising Up

Thu Jan 29 2009

As regular readers no doubt know, I’m often scouring television for documentaries on topics that may be of interest. Last night, I came across just such a show, this one a National Geographic production shown as a ‘Wild Docs’ feature on CBC, that I thought I’d share. The show in question is called Jellyfish Invasion, a rather sensationalist title, to be sure. Normally I find these things to be a red flag, but in this case the visuals and story kept me sufficiently interested to press on.

The show focuses, predictably, on what are apparently alarmingly high rates of Jellyfish attacks, and more to the point, Jellyfish numbers, worldwide. The show mentions growing numbers of ‘dead zone’ (a situation in which Jellyfish seem to prosper) locations worldwide (North America, South America, Africa, the Mediterranean), but focuses largely on locations in Australia and Japan, where the problem and research both seem to be at the forefront:

To investigate this phenomenon we go to Japan, where the population of a jellyfish hundreds of pounds heavier than the Irukandji is growing so fast, it’s transforming marine environments. Known as Nomuras, these giant jellyfish are now blooming in unimaginable numbers. Since 2002, they have poured into the Sea of Japan by the billions, wreaking havoc on the fishing industry. As similar blooms crop up around the world, scientists are forced to wonder: is man somehow responsible

Interesting stuff, well worth a watch. Some of the visuals and stories are dramatic, and legitimately concerning. I take all these things with a grain of salt, but am always eager to learn more, and learn I certainly did.

An interesting point, brought up by a chap whose job it is to spawn jellyfish for an aquarium display, is that the resurgence of Jellyfish is quite likely tied to incremental changes in stressors and environmental conditions (e.g. Temperature, Nutrient Levels, pH, etc) which are encouraging polyps to produce jellyfish, which then begin to grow and rise, at higher frequencies (as an aside, I suspect this is something of an evolutionary insurance policy for survival). The key point of course is that human activities have greatly increased the zones and frequency where such variations might be significant.