London: Biologists have warned that the
global explosion in jellyfish numbers -- due to global warming
-- could damage the marine food chain and thus lead to a major
ecological disaster.
Global warming has long been blamed for the huge rise
in the world's jellyfish population. Now, a research suggests
that they, in turn, may be worsening the problem by producing
more carbon than the oceans can cope with.
The study, 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 bacteria,
which play an important role by recycling nutrients created by
decaying organisms back into the food web.
The study has found 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 Observer' reported.
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.
Dr Carol Turley, a scientist at Plymouth University's
Marine Laboratory, said the research highlighted the growing
problem of ocean acidification, the so-called "evil twin" of
global warming.
He said: "Oceans have been taking up 25 per cent of
the carbon dioxide that man has produced over last 200 years
so it's been acting as a buffer for climate change. When you
add more carbon dioxide to sea water it becomes more acidic.
"And already that is happening at a rate that hasn't
occurred in 600 million years. The acidification of the oceans
is already predicted to have such a corrosive effect that
unprotected shellfish will dissolve by middle of the century."
The study also found that the spike in jellyfish
numbers is also turning the marine food cycle on its head. The
creatures devour huge quantities of plankton, thus depriving
small fish of the food they need.
"This restricts the transfer of energy up the food
chain because jellyfish are not readily consumed by other
predators," said Condon.
PTI
First Published: Sunday, June 12, 2011, 15:34