Sea urchins tolerate acid water

Sea urchins are likely to be able to adapt to increasingly acidic oceans resulting from climate change, according to new research.

When the animals, known as echinoderms, were exposed to water high in carbon dioxide early in their lives, there were no adverse effects.

Echinoderms are a diverse group that includes sea cucumbers and starfish.

Their natural resilience could represent a competitive advantage under some climate change scenarios.

The experiments, carried out by Nadia Suarez-Bosche, exposed larvae of the shallow-dwelling sea urchin Psammechinus miliaris to deep-sea water naturally rich in CO2.

After five days of incubation in the water samples, the scientists measured the physiological responses of the larvae and found that they were still growing and developing well even under the highest CO2 concentrations of up to 600 parts per million (ppm).

The current atmospheric CO2 concentration is around 390 ppm.

When CO2 dissolves in water, carbonic acid is formed. Previously, it was thought that the increasing acidity of seawater – caused by the oceans absorbing more CO2 from the atmosphere – would be damaging for these organisms.

It was thought the corrosive effect of the acid would harm their calcium carbonate skeletons.

The key to their ability to tolerate a wide range in water pH (the scale that determines how acid or alkali something is) comes from the variability of their natural habitat, even under present environmental conditions.

“Echinoderms are found all over the world’s oceans, but particularly in coastal environments, where they are naturally exposed to huge fluctuations in pH,” explained Dr Debora Iglesias-Rodriguez, leader of the research team and a co-author of the study.

Rosalind Pidcock, BBC, 25 October 2010. Full article.


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