2011-06-14 13:30:02Explosion in jellyfish numbers may lead to ecological disaster, warn scientists -- The Observer
John Hartz
John Hartz

Explosion in jellyfish numbers may lead to ecological disaster, warn scientists

A dramatic global increase in jellyfish swarms could damage the marine food chain

Global warming has long been blamed for the huge rise in the world's jellyfish population. But new research suggests that they, in turn, may be worsening the problem by producing more carbon than the oceans can cope with.

Research led by Rob Condon of the Virginia Institute of Marine Science in the US focuses on the effect that the increasing numbers of jellyfish are having on marine bateria, which play an important role by recycling nutrients created by decaying organisms back into the food web. The study, published in the journal Proceedings of the National Academy of Sciences, finds that while bacteria are capable of absorbing the constituent carbon, nitrogen, phosphorus and other chemicals given off by most fish when they die, they cannot do the same with jellyfish. The invertebrates, populating the seas in ever-increasing numbers, break down into biomass with especially high levels of carbon, which the bacteria cannot absorb well. Instead of using it to grow, the bacteria breathe it out as carbon dioxide. This means more of the gas is released into the atmosphere.

2011-06-14 14:34:39
Glenn Tamblyn


I haven't heard anyone suggest that Global warming was a cause of the growth in Jellyfish numbers. I thought it was due to fishing removing predator species that control jellyfish numbers. Increasing jellyfish numbers is certainly a problem. In the Sea of Japan it has even been reported that fouling of nets by the jelly's has lead to fishing boats capsizing.


2011-06-15 00:01:31Glenn
John Hartz
John Hartz

Over the past few years, I have seen articles state that the warming of the oceans leads to more jellyfish. I'll so some research on this topic and report back my findings.

Perhaps the Portugese Man of War will become the iconic sysmbol of AGW?

2011-06-15 17:04:09


a small google search gives you numerous examples of the jellyfish-GW connection :





I also think (don't know if it is studied) that, because jellyfish don't have a skeletton that they are probably less vulnerable towards acidification of the ocean. For several years during the summer, 'jellyfishinvasions' are reported at the western european coastlines and often with more exotic species than usual.

2011-06-15 17:22:04
Glenn Tamblyn


This might be one of those hard to unpick environmental change issues where multiple athropogenic factors may be involved and knowing the relative contribution from differing factors - nutrients and algal blooms, chnaged predation due to fishing and warming - may be difficult to apportion.


We will probably see more effects like this. Synergies between multiple factors we are causing.

2011-06-15 19:06:16
Rob Painting

Like Glenn mentions, a cocktail of anthro factors are probably causing these blooms. Along with overfishing, a prime candidate is low oxygen conditions in the ocean; global warming and eutrophication of coastal waters are responsible for the expansion of these 'dead zones'.

Jellyfish can tolerate low oxygen conditions (hypoxic) better than fish, because their swimming movements are less energy intensive and they can store sufficient oxygen within their tissues to survive even moderate exposure to zero oxygen (anoxic) conditions.

I am planning to cover this stuff (ocean anoxia, toxic diatom blooms etc) in the near future. I can knock up a post on this jellyfish phenomenon if enough think it's worthwhile? It seems to be attracting curiousity amongst forum contributors at least.  

2011-06-15 22:34:16Rob Painting
John Hartz
John Hartz

Now that summer has arrived,  jellyfish invasions of popular beaches along the East Coast of the US get media attention.