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Are jellyfish increasing in response to ocean acidification?

No large scale impact on jellyfish populations in the North Atlantic, report Richardson and Gibbons (Limnology and Oceanography 2008).

While there is a consensus that increasing atmospheric CO2 over the industrial age has decreased ocean pH by 0.1, two studies in 2008 demonstrate that measuring the effect on natural populations may be more complex than anticipated.

In April 2008, ocean acidification’s impact on calcifying organism was re-examined by Iglesias-Rodriguez et al. (Science, 17 April 2008, see highlights) and underlined the need to better understand the mechanisms underlying biogenic calcification. The impact on the food webs proves to be just as difficult to gauge. In 2007, Attrill et al. (2007) offered first results suggesting that lower pH in parts of the North Sea open a niche for non-calcifying plankton, and particularly jellyfish.

Jellyfish are sometimes regarded as trophic dead-ends, with few and sparse predators, and their explosion can be of serious ecological and economic consequence as is the case in the Black Sea.

To further test the findings by Attrill et al., Richardson and Gibbons have gathered Continuous Plankton Recorder and pH (ICES) data from the North Sea and much of the North Atlantic for the period 1946–2003. Their analysis shows that on basin-scale, the available data offers little support for a relationship between ocean acidification and jellyfish populations.

The study does not rule out a relationship between acidification and jellyfish populations on local scales, but concludes if low pH has any effect on natural populations, this may be negated by the much more important effect of warmer water temperatures.

Richardson A. J.,  M. J. Gibbons, 2008. Are jellyfish increasing in response to ocean acidification? Limnol. Oceanogr., 53(5), 2008, 2035–2040.

Attrill, M. J., J.Wright, M. Edwards. 2007. Climate-related increases in jellyfish frequency suggest a more gelatinous future for the North Sea. Limnol. Oceanogr. 52: 480–485



- Effect of Ocean Acidification ‘turned on its head’ – Science 17 Apr 08
- Coastal Ocean More Acidic Than Anticipated – Science 22 May 08
- Ocean Acidification – an EUROCEANS film in French and English with the participation of James Orr and Jean-Pierre Gattuso
- Ocean Acidification Network -
- Ocean Acidification – An information outlet on ocean acidification moderated by Jean-Pierre Gattuso

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