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FACTS ABOUT WATER AND BIODIVERSITY What is Biodiversity? Biological diversity - or biodiversity - is the term given to the variety of life on Earth and the natural patterns it forms. The biodiversity we see today is the fruit of billions of years of evolution, shaped by natural processes and, increasingly, by human influence. It forms the web of life of which we are an integral part and upon which we so fully depend. This diversity is often understood in terms of the wide variety of plants, animals and micro-organisms. So far, about 1.75 million species have been identified, mostly small animals such as insects. Scientists reckon that there are actually about 13 million species, though estimates range from 3 to 100 million. Biodiversity also includes genetic differences within each species. Yet another aspect of biodiversity is the variety of ecosystems such as those that occur in deserts, forests, wetlands, mountains, lakes, rivers and agricultural landscapes. In each ecosystem, living creatures, including humans, form a community, interacting with one another and with the air, water, and soil around them. Changes in biodiversity may occur in response to an enormous range of environmental factors, including water quality, quantity and periodicity, the individual significance of which may be unclear. While not substituting for water quality information, which is essential for health-related management goals, biodiversity measures do have the potential to provide an integrated measure of overall ecosystem condition. The four groups with the highest proportion of extinct or at risk species—freshwater mussels, crayfish, amphibians and freshwater fish—are all inhabitants of, or dependent on, inland water habitats. Only about 10% of the world’s fish have been assessed, the great majority of these being from inland waters, but 30% of those are listed as threatened. While 34% of the 64 freshwater fish species found in Croatia are threatened species, in Madagascar and Portugal the proportion is 32%. The highest number of threatened freshwater fish species is found in the United States, with 120 species out of 822 (15%). For example, Lake Malawi (southern Africa) is an aquatic system that was originally endowed with a great deal of fish and also freshwater snail biodiversity. However, loss in fish biodiversity has resulted in the favouring of certain snail species that play a role in the transmission of schistosomiasis. The increased health risk has greatly affected Malawi’s tourist industry, and as a result, the whole economy has declined.
Information from: Source: UN World Water Assessment Programme (WWAP), May 2005
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