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Tuesday, October 8, 2013

Seajellies, a slippery problem and growing

The ocean is changing all the time however the speed and nature of the recent changes related has links to human activities. (See related articles here, here and here)

Jellies may be change indicator species and reports around the world are telling us about growing numbers of seajelly 'smacks' or' swarms' or 'blooms'. 
A common Australian jelly, Catostylus mosaicus, or blue blubber jelly (Photo courtesy of Tony Isaacson)
The blue blubber (or brown blubber in some parts of Australia) is quite a common sight and last year a Queensland man took a video of a massive swarm off the coast. However this relatively mild cnidarian does not appear to have gone into the kind of plague proportions we are hearing about in Japan, Scotland, Israel or Florida where the size and numbers of jellies have caused serious problems for nuclear power and desalination plants.


Probably the most spectacular example are the devastating blooms of the massive jellies,  'Nomuras', off the coast of Japan. As adults they weigh in  at 220kg and measure 2m in diameter. They have been swarming in the Japan Sea since 2002, clogging fishnets and overturning trawlers owing to their size. (see BBC article here).


Why is this happening? Some scientists remind us that we have been taking too many fish from the sea that eat jellies. Others point out that changes occurring from human activities like; marine pollution from stormwater, ocean acidification and temperature rise to name a few, may just be giving jellies the edge they need to reclaim the ocean where they were once the top predator hundreds of millions of years ago.




www.ausmepa.org.au

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