Microbes galore in seas; "spaghetti" mats Pacific

OSLO (Reuters) - The ocean depths are home to myriad species of microbes, mostly hard to see but including spaghetti-like bacteria that form whitish mats the size of Greece on the floor of the Pacific, scientists said on Sunday.

The survey, part of a 10-year Census of Marine Life, turned up hosts of unknown microbes, tiny zooplankton, crustaceans, worms, burrowers and larvae, some of them looking like extras in a science fiction movie and underpinning all life in the seas.

"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 of the Marine Biological Laboratory in Woods Hole, Massachusetts, head of the marine microbe census.

The census estimated there were a mind-boggling "nonillion" -- or 1,000,000,000,000,000,000,000,000,000,000 (30 zeroes) -- individual microbial cells in the oceans, weighing as much as 240 billion African elephants, the biggest land animal.

Getting a better idea of microbes, the "hidden majority" making up 50 to 90 percent of biomass in the seas, will give a benchmark for understanding future shifts in the oceans, perhaps linked to climate change or pollution.

Among the biggest masses of life on the planet are carpets on the seabed formed by giant multi-cellular bacteria that look like thin strands of spaghetti. They feed on hydrogen sulphide in oxygen-starved waters in a band off Peru and Chile.

"Fishermen sometimes can't lift nets from the bottom because they have more bacteria than shrimp," Victor Gallardo, vice chair of the Census Scientific Steering Committee, told Reuters. "We've measured them up to a kilo (2.2 lbs) per square meter."

GHOSTLY MATS

The census said they carpeted an area the size of Greece -- about 130,000 sq km (50,000 sq miles) or the size of the U.S. state of Alabama. Toxic to humans, the bacteria are food for shrimp or worms and so underpin rich Pacific fish stocks.

The bacteria had also been found in oxygen-poor waters off Panama, Ecuador, Namibia and Mexico as well as in "dead zones" under some salmon farms. They were similar to ecosystems on earth that thrived from 2.5 billion to 650 million years ago.

Overall in the oceans, up to a billion microbe species may await identification under the Census, an international 10-year project due for completion in October 2010.

Tiny life was found everywhere, including at thermal vents with temperatures at 150 Celsius (300F) or in rocks 1,626 meters (5,335 ft) below the sea floor. Many creatures lack names or are hard to pronounce like loriciferans, polychaetes or copepods.

One major finding was that rare microbes are often found in samples where they can be outnumbered 10,000 to one by more common species. Isolated microbes may be lying in wait for a change in conditions that could bring a population boom.

Ann Bucklin, head of the Census of Marine Zooplankton that include tiny transparent crustaceans or jellyfish, said the seas were barely studied even by the census.

"Seventy percent of the oceans are deeper than 1,000 meters," Bucklin, of the University of Connecticut, told Reuters. "The deep layer is the source of the hidden diversity."

Paul Snelgrove, of Memorial University in Canada, said one sample in the South Atlantic in an area the size of a small bathroom -- 5.4 square meters -- turned up 700 species of copepod, a type of crustacean, 99 percent of them unfamiliar.

Just finding Latin names for each find will be hard. Scientists had rejected the idea of raising funds by letting people pay to have a marine "bug" named after them.

(Editing by Charles Dick)