The wetland environments, stable as they may appear, are often subject to drastic and sometimes rapid changes, sometimes man-made. To understand these changes and exercise control over them for the long term benefit of mankind, it is essential to have as much knowledge as possible about each area, and also a pattern of conservation areas (call them nature reserves, national parks, biosphere reserves) together with the scientific resources available for observation and experiment within them. A distinction should be drawn between the preservation (which means leave it alone) of wetlands and the conservation (conservation through wise use).