Fish Contribute to Curbing Greenhouse Gas Emissions

Emissions of methane gas, a greenhouse gas, can be reduced in paddy fields inhabited by fish, according to a study by the Lake Biwa Museum and Tokyo Metropolitan University. It was one of the projects conducted by the museum since it opened in 1996. The researchers started their analysis in 2005, and finished compiling the results on July 25, 2006.

It has long been reported that paddy fields are a major source of methane gas, which is thought to be about 20 times more potent as a greenhouse gas than carbon dioxide. Methane is generated when bacteria oxidize and decompose organic matter, but fish eat this organic matter, thereby reducing the methane emissions from the paddy fields. The researchers estimate that methane emissions are reduced by 90 percent in rice paddies containing fish.

Furthermore, when fish reduce the organic matter that would otherwise be decomposed, oxidization of the rice paddy soil is increased, which allows phosphorus from fertilizers to bond with iron in the soil, thus remaining in the paddy fields. Because overabundance of phosphorus causes eutrophication of waters, paddy fields inhabited by fish are also expected to prevent water pollution by keeping phosphorus from being drained into ponds or lakes.

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Posted: 2006/11/04 12:07:55 PM
Japanese version