June 3, 2009

Warm water boosts sea star species growth

Canadian zoologists have determined elevated water temperatures and high carbon dioxide concentrations can boost the growth of a species of sea star.

The University of British Columbia scientists said their study is one of the first to look at the impact of ocean acidification on marine invertebrates that don't have a large calcified skeleton or external shell. The researchers said their findings challenge current assumptions about the potential impact of climate change on marine species.

The scientists discovered a temperature increase of just three degrees and a doubling of CO2 concentrations enabled the Purple Ochre Sea Stars (Pisaster ochraceus) to grow nearly twice as fast as they normally would.

That, said Gooding, means the sea stars could potentially reach adulthood in about half the time it would typically take.

This complicates current assumptions, said Gooding. It looks like increased CO2 may not have negative effects on all marine invertebrates, suggesting that predicting the impact of climate change should consider how different organisms respond to changing climatic variables.

The study, co-led by Assistant Professor Christopher Harley, appears in the early online edition of the Proceedings of the National Academy of Sciences.