JUST off the coast of the world’s driest desert, the lifeless Atacama in northern Chile, lies one of the largest and densest masses of life anywhere on Earth. The vast tangled mat of white “hair”, which has an area of 128,000 square kilometres, roughly the size of Greece, was recently mapped as part of the first comprehensive Census of Marine Life.
The ghostly submarine prairie is made of wispy strings of giant bacteria, says Victor Gallardo, a marine biologist at Chile’s University of Concepción. The bug thrives in water almost devoid of oxygen by extracting energy from hydrogen sulphide in sediments on the seabed, and feeds on nutrients dispersed by fish in the waters of the cold, fertile Humboldt current above.
Gallardo says the wispy bacteria resemble fossilised bacterial mats dating back 2.5 billion years. In total, he and his colleagues estimate that the mat contains hundreds of millions of tonnes of bacteria, and that the whole system regenerates every 10 weeks. Individual bacteria can reach 7 centimetres long.
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“The wispy bacteria resemble fossilised bacterial mats dating back 2.5 billion years”
The decade-long census, whose aim is to catalogue all ocean life, is rapidly changing our ideas about how many species there are on Earth and where they are to be found. The Amazon rainforest has long been thought to contain the greatest biodiversity on the planet. In fact, the winner is more likely to be the “coral triangle”, the region of coral reefs off south-east Asia, according to Ann Bucklin of the University of Connecticut – Avery Point.
Another, entirely unexpected hotspot is the deep ocean below 1000 metres. This huge ocean wilderness may be low in biomass volume, says Bucklin, but it is fabulously diverse.
Bacteria and other microbes may make up as much as 90 per cent of the oceans’ biomass, and there could be up to a billion species on Earth, says John Baross of the University of Washington, Seattle, more than 10 times as many as previously suspected.
