Census offers glimpse of oceans' smallest lifeforms

An unprecedented number of tiny, ocean dwelling organisms have been catalogued by researchers involved in a global survey of the world's oceans.One of the highlights was the discovery of a vast "microbial mat", covering an area equivalent to the size of Greece.Microbes are estimated to constitute up to 90% of all marine biomass.The findings form part of the Census of Marine Life (CoML), a decade-long project that will present its full results in October."In no other realm of ocean life has the magnitude of Census discovery been as extensive as in the world of microbes," said Mitch Sogin, leader of the International Census of Marine Microbes (ICoMM)."Scientists are discovering and describing an astonishing new world of marine microbial diversity and abundance."The ICoMM was one of four of the Census's projects that focused on "hard to see" marine organisms.The team, involving researchers from the Netherlands and the US, collected samples from more that 1,200 locations, which resulted in the compilation of a dataset containing in excess of 18 million DNA sequences.CoML researchers suggested that the total number of marine microbes, based on molecular characterisation, could be in the region of one billion species.They added that the micro-organisms were vital for sustaining life on Earth, as they are responsible for about 95% of respiration in the oceans."They play a really critical role in keeping the oceans working," said Paul Snelgrove, leader of CoML's Synthesis Group."Certainly, life in the oceans - and then life on Earth - would collapse very quickly without the microbes."In the 1950s, scientists estimated that about 100,000 microbial cells inhabited in one litre of seawater. However, with the aid of modern technological advances, researchers now suggest that the figure is closer to one billion micro-organisms.They have also calculated that the estimated total mass of marine microbes is equivalent to 240 billion African elephants. By Mark Kinver Science and environment reporter, BBC News