Water for people.pdf - WHO Thailand Digital Repository

1 3 8 / C H A L L E N G E S T O L I F E A N D W E L L - B E I N GProtecting Ecosystems for People and PlanetBox 6.2: Non-native speciesThe ‘National Census of River and Waterside’ in Japan aimsto provide information relevant to ecosystem condition,focusing on aquatic species (e.g. fish, molluscs, benthicorganisms, plants) and human water-related activities.Alien species such as black bass Micropterus salmoides andother North American fish are included. The data show thenumber of reservoirs where the species were recordedknowledge publication on biodiversity and its implications for humanhealth. Such links are highly complex with many confounding factors,but water is a common theme throughout. So far, it is clear that:■ high levels of biodiversity imply a great deal of diversity inpathogens and vectors, which in part explains the burdens ofhigh infectious disease in the tropics; and■ where ecosystem degradation causes loss of biodiversity, moreoften than not this habitat simplification works in favour ofspecies that play a role in the transmission of human disease.In managing ecosystems, both ecosystem integrity and theenvironmental determinants of human health need to be taken intoaccount. Local communities must be involved and their health (and thehealth of their children) will provide a strong incentive for doing so. ThePrimary Health Care approach developed by WHO and the United NationsChildren’s Fund (UNICEF) following the 1978 Alma Ata Conference(Declaration of Alma Ata, 1978) and the Primary Environmental Careapproach championed by the World Conservation Union (IUCN) in theearly 1990s should be integrated to serve as a basis for communityaction aimed at improving ecosystem and human health.Lake Malawi (southern Africa) is an aquatic system that wasoriginally endowed with a great deal of fish and also freshwater snailbiodiversity. However, loss in fish biodiversity has resulted in thefavouring of certain snail species that play a role in the transmissionof schistosomiasis. The increased health risk has greatly affected thetourist industry of Malawi and the whole economy has declined. TheGlobal Environment Facility (GEF) project for Lake Malawi is unique inthat it is the only one combining biodiversity and human health.during two survey periods. This evidence suggests that thedistribution of introduced species is increasing in thecountry (seven additional reservoirs showed introducedspecies during the second survey), and the number of siteswhere they occur provides a useful indicator of ecosystemcondition.1st survey (1991–1995) found not found found not found2nd survey (1996–2000) found found not found not foundNumber of reservoirs 26 7 0 42Source: Water Resources Environment Technology Centre (Japan), 2001.Assessment of Current EcosystemCondition and TrendsGlobal condition of freshwater ecosystemsThere is a wealth of data on the condition of freshwater ecosystemsaround the world ranging from quantitative local and global data toanecdotal or unstructured qualitative information. A recent attempt tosynthesize available information on freshwater ecosystems worldwide(Revenga et al., 2000) reviewed data on the extent of humanmodification, water quantity, water quality, fisheries and biodiversity(some twenty-two measures in all), and suggests that at a globalscale the picture is not encouraging. Among the conclusions:■ 60 percent of the world’s 227 largest rivers are strongly tomoderately fragmented by dams, diversions and canals, and ahigh rate of dam construction in the developing world threatensthe integrity of remaining free-flowing rivers;■ water quality appears to have declined worldwide in almost allregions with intensive agriculture and large urban/industrial areas;■ historical data for well-studied commercial fisheries showdramatic declines throughout the twentieth century, mainly fromhabitat degradation, invasive species and overharvesting.Another study aimed at global assessment (Groombridge and Jenkins,1998) used the terrestrial Wilderness Index (a measure of the spatialextent of roads, settlements and other human infrastructure) toestimate the probable degree of anthropogenic disturbance to majorriver basins. Because degradation of freshwater ecosystems is highly