In the UK, about 90% of the total number of standing bodies of fresh water have areas of one hectare or less, and there may be 750,000 of these in England and Wales alone. It is estimated that they are decreasing in number by several thousand per year, largely as a result of new drainage schemes and urbanisation.
4.2.4 Model
Loss of and damage to freshwater ecosystems threatens biodiversity worldwide, but quantitative data at the global scale are lacking. The fundamental requirement is for a dynamic, descriptive model of the quantity, quality and diversity of freshwater ecosystems worldwide. At the core of this model is a world map, possibly sub-divided into biogeographic regions, and, at a range of finer scales, superimposed layers of quantitative information for:
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