Ocean warming has been blamed for a huge rise in the world's jellyfish population.
We've reported on two recent examples of this icky phenomenon … see “Jellyfish Swamp Irish Salmon Farm”, and “Jellyfish Boom Signals Ocean Warming and Overfishing.”
And as The New York Times reported earlier this month, a jellyfish invasion in Florida left tourists hot, frustrated … or covered in stings.
See “Small but Innumerable, Jellyfish Storm a Beach.” ... an event tied to warming in a separate Times report: “The bloom on the state's Atlantic Coast probably had its origins on the Gulf Coast, where mauve stingers have been seen in huge numbers for the past several years. Warmer sea temperatures may have allowed populations to persist over winters and thrive ...”.
Now, alarming new research suggests that the increasing swarms of the amorphous creatures may be worsening the problem by helping make ocean water more acidic.
Rob Condon of the Virginia Institute of Marine Science is researching the effect of the jellyfish boom on marine bacteria, which recycle nutrients created by decaying organisms.
His new study, published in the journal Proceedings of the National Academy of Sciences, finds that while bacteria absorb the carbon given off by fish when they die, they cannot do the same with jellyfish.
Condon's team came to a disturbing conclusion: “These results further suggest fundamental transformations in the bio-geochemical functioning and biological structure of food webs associated with jellyfish blooms.” (Condon RH et al. 2011)
Carbon from dying jellyfish overwhelm bacteria's ability to recycle it
Dead jellyfish release especially high levels of carbon, which the bacteria cannot absorb well, and instead breathe out as carbon dioxide, putting more CO2 into the seas and atmosphere.
Dr Carol Turley, a scientist at the UK's Plymouth University, 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.”
As Turley says, “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.”
The shellfish affected by increasing ocean acidity include krill and other “zooplankton” in the crustacean family, which are critical to the ocean food web … especially salmon and whales.
A Swiss researcher put the problem in stark terms just last month:
“The changes in the ocean's carbonate chemistry induced by the uptake of anthropogenic [man-caused] carbon dioxide (i.e. ocean acidification) will probably affect many organisms and processes … once these changes have occurred, it will take centuries for the ocean to recover.” (Gruber N 2011)
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.
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 for jellyfish populations explode, sparking panics on beaches around the world.
Last year scientists at the University of British Columbia found that global warming was causing 2,000 jellyfish species to appear earlier each year … and expanding their number (Brotz L et al 2011).
The proliferation of jellyfish has caused problems for seaside power and desalination plants worldwide.
The blooms also threaten swimmers, with effects of a jellyfish sting ranging across the many species from painless to annoying to agonizing … and, in rare cases, death.
  • Brotz L et al. Changing jellyfish populations – trends in large marine ecosystems (Abstract ID:7769). Feb. 17, 2011, American Society for Limnology and Oceanography. 2011 ASLO Aquatic Sciences Meeting 13-18 February 2011 San Juan, Puerto Rico, USA
  • Condon RH, Steinberg DK, Del Giorgio PA, Bouvier TC, Bronk DA, Graham WM, Ducklow HW. Jellyfish blooms result in a major microbial respiratory sink of carbon in marine systems. Proc Natl Acad Sci U S A. 2011 Jun 21;108(25):10225-30. Epub 2011 Jun 6.
  • Ducklow HW, Purdie DA, Williams PJ, Davies JM. Bacterioplankton: a sink for carbon in a coastal marine plankton community. Science. 1986 May 16;232(4752):865-7.
  • Gruber N. Warming up, turning sour, losing breath: ocean biogeochemistry under global change. Philos Transact A Math Phys Eng Sci. 2011 May 28;369(1943):1980-96.
  • Teira E, Gasol JM, Aranguren-Gassis M, Fernández A, González J, Lekunberri I, Alvarez-Salgado XA. Linkages between bacterioplankton community composition, heterotrophic carbon cycling and environmental conditions in a highly dynamic coastal ecosystem. Environ Microbiol. 2008 Apr;10(4):906-17. Epub 2008 Jan 22.