News Release

Surviving mass extinction by leading a double life

Peer-Reviewed Publication

University of Nottingham

Drifting across the world's oceans are a group of unicellular marine microorganisms that are not only a crucial source of food for other marine life — but their fossils, which are found in abundance, provide scientists with an extraordinary record of climatic change and other major events in the history of the earth.

Now, planktonic foraminifera — single-celled shell building members of the marine microplankton community — have given up a secret of their very own.

A team of experts, including scientists from The University of Nottingham, have presented remarkable evidence that planktonic foraminifera may have survived mass extinction by taking refuge on the sea floor.

Dr Chris Wade from the Institute of Genetics, said: "Using genetic data we have been able to prove that the planktonic species Streptochilus globigerus and the benthic — sediment living — foraminiferan Bolivina variabilis are one and the same biological species. Moreover, geochemical evidence shows that this species actively grows within the open-ocean surface waters, thus occupying both planktonic and benthic domains. Such ecologically-flexible species are eminently suited to the recolonisation of the extinction-susceptible planktonic domain following mass extinctions events, such as the end-Cretaceous event."

It had been thought that all modern planktic foraminifers were descended from the few lucky survivors of the meteor impact that wiped out the dinosaurs and 65 to 70 per cent of life on earth 65 million years ago. However, this might not be the case.

Dr Wade together with PhD student Heidi Seears have shown that live specimens of the planktonic species Streptochilus globigerus, collected 600 miles offshore in the middle of the Arabian Sea, are genetically identical to the benthic species Bolivina variabilis, found off the coast of Kenya.

Their surprising discovery suggests that planktonic foraminifera may have survived the end Cretaceous mass-extinction by abandoning the poisonous oceans for a refuge in the relative safety of the sea-floor. When the oceans returned to normal, the survivors were able to recolonise the ocean surface once more.

The research, carried out in collaboration with the University of Edinburgh, has been published in the Journal Proceedings of the National Academy of Sciences (PNAS).

Dr Kate Darling, from the University of Edinburgh, said: "If some species can switch between free-swimming and bottom-dwelling lifestyles, then it's possible that most planktic foraminifers may have survived the late Cretaceous extinction in the sediment, not in the plankton. It seems likely that the foraminifer species which had the ability to occupy both habitats survived on the sea-floor, avoiding the meteor impact catastrophe in the oceans above.

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Notes to editors: The University of Nottingham is ranked in the UK's Top 10 and the World's Top 100 universities by the Shanghai Jiao Tong (SJTU) and Times Higher (THE) World University Rankings.

More than 90 per cent of research at The University of Nottingham is of international quality, according to RAE 2008, with almost 60 per cent of all research defined as 'world-leading' or 'internationally excellent'. Research Fortnight analysis of RAE 2008 ranks the University 7th in the UK by research power. In 27 subject areas, the University features in the UK Top Ten, with 14 of those in the Top Five.

The University provides innovative and top quality teaching, undertakes world-changing research, and attracts talented staff and students from 150 nations. Described by The Times as Britain's "only truly global university", it has invested continuously in award-winning campuses in the United Kingdom, China and Malaysia. Twice since 2003 its research and teaching academics have won Nobel Prizes. The University has won the Queen's Award for Enterprise in both 2006 (International Trade) and 2007 (Innovation — School of Pharmacy), and was named 'Entrepreneurial University of the Year' at the Times Higher Education Awards 2008.

Nottingham was designated as a Science City in 2005 in recognition of its rich scientific heritage, industrial base and role as a leading research centre. Nottingham has since embarked on a wide range of business, property, knowledge transfer and educational initiatives (www.science-city.co.uk) in order to build on its growing reputation as an international centre of scientific excellence. The University of Nottingham is a partner in Nottingham: the Science City.

Story Credits
More information is available from Dr Chris Wade on +44 (0)115 8230391, chris.wade@nottingham.ac.uk or Lindsay Brooke - Media Relations Manager on +44 (0)115 951 5751, lindsay.brooke@nottingham.ac.uk


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