Reuters: 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) …