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Mussels, freshwater snails and other underwater creatures emit a potent greenhouse gas as they feed, according to a study that adds a small aquatic dimension to the impact of wildlife on global warming.

The animals, also including worms and insect larvae, emitted nitrous oxide -- commonly known as laughing gas -- as a by-product of their digestion when nitrate was present in water. Nitrate is often used in fertilisers, whose use is rising.

"Aquatic animals have never (before) been shown to emit this greenhouse gas," the German and Danish experts wrote in the U.S. journal Proceedings of the National Academy of Sciences, released on Monday.

They said that past studies have shown that earthworms and plants on land are sources of the gas, which is 310 times more powerful at trapping heat in the atmosphere than carbon dioxide, the main greenhouse gas from human activities.

The scientists estimated that nitrous oxide releases by animals were small compared to other natural emissions from underwater soils. They did not not estimate how much reached the atmosphere, where it could be a tiny natural factor affecting the climate.

"It's not something that we should overlook but we should not make a drama of it," Peter Stief, the lead author of the study at Denmark's University of Aarhus and the Max Planck Institute for Marine Microbiology in Germany.

"Carbon dioxide is still the main problem," he told Reuters of the study of seven freshwater and marine sites in Denmark.

Carbon dioxide is released by burning fossil fuels in cars, factories and power plants. The U.N. Climate Panel says that a buildup of greenhouse gases will bring more heatwaves, more powerful storms, droughts, floods and rising sea levels.

Fertilisers

Amounts of nitrous oxide from underwater creatures were likely to rise because of widening use of fertilisers in tropical nations, according to the study. Nitrate fertilisers can be washed off farmland by rains into rivers and the sea.

"Growth rates...are much higher in the tropics than in temperate zones where already some measures are being taken to reduce nitrate use," Stief said.

He said that more study was needed of underwater nitrous oxide emissions. "It will needs more testing -- it's not known whether fish, for instance, release it too," Stief said.

On land, livestock such as sheep, cows and goats emit methane, another type of greenhouse gas, as part of their digestive system. Livestock account for about 3 percent of all greenhouse gas emissions from human activities.

Trees and other plants are a major store of carbon. Deforestation from the Amazon to the Congo accounts for about 20 percent of greenhouse emissions from human activities.

More than 190 nations aim to agree a new treaty to fight climate change at a meeting in Copenhagen in December. Many countries want measures to slow deforestation to be part of the agreement.

Reuters

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From www.worldbulletin.net:
Gardeners were reminded that earthworms, through digestion of undecayed vegable matter, hasten the release of nutrients needed by actively.
Earthworm composting is mainly conducted through earthworms digestion of organic matters. After earthworms have eaten and digested.
This page contains lots of information and pictures relating to all aspects of the earthworm including reproduction,digestion.
Like you, earthworms have a digestive system for processing food. Mouth Oesophagus Pharynx Crop Gizzard Intestine The digestion of food can be broken.
Digestion In earthworms digestion is extracellular. The digestive fluid poured in the pharynx contained mucin and some proteolytic.
Although exposed earthworms were examined using direct dissection, agar, and digestion techniques, no As. suum larva was recovered from the earthworms.
The earthworms then transform into mineral matter by digestion. The earthworms also ensure that the surface layer remains.
Tinguish it from that triggered by earthworm digestion. Materials and methods. The soil used was taken from the upper 10 cm of an ultisol.

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