Research press release


Nature Geoscience

Oxygen oases for tiny animals


M Gingrasらは、ベネズエラ海岸の塩分が高く酸素の低い礁湖に見られる微生物の塊を分析した。その塊は礁湖の海底を斑状に覆っている。彼らは、塊の中の酸素濃度は、塊のない地域よりもはるかに高いが、夜間には劇的に減少することを発見した。礁湖の大部分では海底に動物はいないが、例外的に塊の中には小さな穴を掘るイソガニと昆虫の幼生が棲息している。


Mats of microbes containing photosynthetic bacteria create an oasis of oxygen-rich sediments in otherwise low-oxygen lagoons that is exploited by small animals, suggests a paper published online in Nature Geoscience. These conditions may be comparable to those found 555 million years ago when mobile animals first appeared in the fossil record.

Murray Gingras and colleagues analysed microbial mats found in high-salinity, low-oxygen lagoons off the coast of Venezuela. The mats cover patches of the sea floor in the lagoons. They found that oxygen levels were much higher in the mats than in the mat-free areas, although they declined dramatically at nightfall. The lagoon was largely devoid of seafloor animals, with the exception of small burrowing shore crabs and insect larvae that lived only in the mats.

The authors suggest that early mobile animals that lived in seafloor sediments may also have exploited the oxygen-rich conditions associated with microbial mats.

doi: 10.1038/ngeo1142


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