Gigantic Nation-Sized Mat of Bacteria Found Off South American Coast

Photo: Teske Lab
'Spaghetti'-like megabacteria
One of the largest collaborations to investigate marine biodiversity has uncovered something on a mind-boggling scale: a giant mat of string-like bacteria - the size of Uruguay or the U.S. state of Alabama - has been discovered deep in the ocean depths off the coasts of Chile and Peru.

Uncovered as part of the Census of Marine Life - a global, decade-long effort to systematically identify and study oceanic organisms - scientists are now speculating whether this huge mat of mega-bacteria may somehow contribute to thriving fisheries found in these waters."Some 50 percent of the world's fish catch comes from fisheries off the west coast of South America, where the biggest of these bacterial mats are found," said Dr Víctor Ariel Gallardo, vice-chair of the Census of Marine Life Scientific Steering Committee.

String-like in appearance and measuring from two to seven centimetres (0.7 to 2.75 inches), the megabacterium Thioploca spp. is actually visible to the naked eye. It was first found in the sixties, but scientists then lacked the funding and molecular and genetic technology to properly study these country-sized colonies.

The mat off the South American coast measures a whopping 130,000 square kilometres, and was only one of the thousands of marine species turned up by the Census, which range from unfamiliar microorganisms to zooplankton, crustaceans, worms, burrowers and larvae.

No oxygen needed
Flourishing under oxygen-deficient conditions, the bacteria feed off toxic hydrogen sulphide, which is produced when organic matter degrades without oxygen. Where there is no oxygen, large whitish mats of Thioploca spp. can be found at 50 to 200 metres deep. Scientists believe that Thioploca spp. is ancient - at least 2.5 billion years old - and most likely covered the oceans' surface back then when there was no oxygen at all.

"There are fossils of bacteria from that time that are very similar to what we find now," said Gallardo.

Scientists hypothesize that these mats may now exist in many of the oceans' deeper, oxygen-poor zones and may extend along vast tracts of ocean floor, covering thousands of kilometers.

Other smaller mats have been found living on sulphide chimneys near Galápagos Archipelago, Ecuador, off the Pacific coasts of Mexico, Panamá, Costa Rica and near Namibia, which is also known for its abundant fisheries. The mats have also been found in "dead zones" created by agricultural run-off and salmon farms.

"Fishermen sometimes can't lift nets from the bottom because they have more bacteria than shrimp," said Gallardo. "We've measured them up to a kilo (2.2 lbs) per square meter."

Nonillion microbes in sea
While the link between the bacterial mats boosting fish populations is not totally clear yet, what is clear is that microbes - which make up 50 to 90 percent of all marine biomass - are crucial in regulating the planet's atmosphere, climate, nutrient recycling and decomposition. According to Census estimates, there may be a "nonillion" individual microbes in the seas - that's 1,000,000,000,000,000,000,000,000,000,000 (with 30 zeroes) and weighing the equivalent of 240 billion African elephants. Who would've thought such small critters could be so hefty?

InterPress Service
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Tags: Oceans

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