A pond can be described as a small body of still, fresh water between one square metre and two hectares in area which holds water for at least four months of the year.
Some ponds are formed naturally, filled by an underground spring or by rainwater, and others are man made.
There is no such thing as a perfect wildlife pond because different ponds will support different communities of plants and animals, even ponds that are close together. But they can all be fascinating habitats to study.
Ponds can take care of their own waste. The natural waste from living and dead organisms is ‘recycled’ by special tiny organisms called bacteria. They need plenty of oxygen to break down the waste. But pollution from run off from agricultural land can cause problems for this process and for some of the wildlife in the pond.
Rain can wash off excess chemicals from crops into nearby ponds, poisoning wildlife, and wash off artificial fertilisers, put on crops to help them grow. The rich supply of nitrogen that introduces causes water plants, especially algae, to grow very quickly, using up so much oxygen that there is little or none left for the other pond life and preventing sunshine reaching the organisms below.
It is estimated that since 1880 the number of ponds in the country has declined by in excess of 75% (approaching one and a half million ponds). Many ponds have been lost through development for housing and roads. Others have gone as a result of land drainage, lowering of the water table by abstraction, or by in-filling to improve farm efficiency. Piped water has replaced most ponds for watering livestock.