Jellyfish Swarms Invade Ecosystem
The world’s oceans have been experiencing enormous blooms of jellyfish, apparently caused by overfishing, declining water quality, and rising sea temperatures. Now, scientists are trying to determine if these outbreaks could represent a “new normal” in which jellyfish increasingly supplant fish.
Invasion of Jellyfish
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 bacteria, which play an important role by recycling nutrients created by decaying organisms back into the food web. The study, published , 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.
Dr. Carol Turley, a scientist, said the research highlighted the growing problem of ocean acidification, the so-called "evil twin" of global warming. "Oceans have been taking up 25% of the carbon dioxide that man has produced over the 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 the middle of the century."
Condon's research 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. "Jellyfish can bloom in really high numbers. It's not particularly common, (EDF Energy) have been a bit unlucky. If you get a bit of calm and warm weather they can turn up inshore in high numbers," said David Conway, a marine biologist at the Marine Biological Association.
The increase in the jellyfish population has been attributed to factors including climate change, over-fishing and the runoff of agricultural fertilizers. The rise in sea temperature and the elimination of predators such as sharks and tuna has made conditions ideal, and "blooms" – when populations explode in great swarms, sparking regular panics on beaches around the world– are being reported in ever-increasing size and frequency. Last year scientists at the University of British Columbia found that global warming was causing 2,000 different jellyfish species to appear earlier each year and expanding
their number.
The proliferation of jellyfish has caused problems for seaside power and desalination in Japan, the Middle East and Africa. The blooms are also perilous to swimmers; the effects of a jellyfish sting range across the species from painless to tingling to agony and death.
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 bacteria, which play an important role by recycling nutrients created by decaying organisms back into the food web. The study, published , 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.
Dr. Carol Turley, a scientist, said the research highlighted the growing problem of ocean acidification, the so-called "evil twin" of global warming. "Oceans have been taking up 25% of the carbon dioxide that man has produced over the 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 the middle of the century."
Condon's research 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. "Jellyfish can bloom in really high numbers. It's not particularly common, (EDF Energy) have been a bit unlucky. If you get a bit of calm and warm weather they can turn up inshore in high numbers," said David Conway, a marine biologist at the Marine Biological Association.
The increase in the jellyfish population has been attributed to factors including climate change, over-fishing and the runoff of agricultural fertilizers. The rise in sea temperature and the elimination of predators such as sharks and tuna has made conditions ideal, and "blooms" – when populations explode in great swarms, sparking regular panics on beaches around the world– are being reported in ever-increasing size and frequency. Last year scientists at the University of British Columbia found that global warming was causing 2,000 different jellyfish species to appear earlier each year and expanding
their number.
The proliferation of jellyfish has caused problems for seaside power and desalination in Japan, the Middle East and Africa. The blooms are also perilous to swimmers; the effects of a jellyfish sting range across the species from painless to tingling to agony and death.
How Jellyfish are Invading the World
- The supersize sea creatures—normally found off the coasts of China and North and South Korea—occasionally drift east into the Sea of Japan to feed on tiny organisms called plankton. But now one hundred times the usual number of jellyfish are invading Japanese waters. And local fishermen are feeling as if they are under siege.
- The fishermen's nets are getting weighted down, or even broken, by hundreds of jellyfish. The jellies crush, slime, and poison valuable fish in the nets, such as the tuna and salmon that the fishermen rely on to make a living.
- Japan was invaded on a similar scale in the summer of 2005, when the jellyfish damaged nets, rendered fish inedible with their toxic stings and even caused injuries to fishermen. In 2007, there were 15,500 reports of damage to fishing equipment caused by the creatures.