Hectare for hectare (acre for acre) the worldís freshwater ecosystems have a greater diversity of flora and fauna compared to any other biome (Dudgeon et al., 2006; MEA, 2005). The worldís rivers are also the centre of human life: the centre of most major cities and the valleys where agriculture has taken root in support of ever larger populations (Richter et al., 2010; Vorosmarty et al., 2010). Groundwater systems are also of significance for biodiversity and water supply for people but are not considered further in this chapter on rivers. Because it is central to humanity, the freshwater realm is also more threatened than any other part of our environment. In 2005 the Millennium Ecosystem Assessment (MEA, 2005) concluded that freshwaters have more threatened species per unit area. Two ecosystem services were declared over-exploited: consumption of water and of wild-capture fish from freshwater and marine systems. Further, despite promises to establish ecologically representative reserve systems by national governments under the Convention on Biological Diversity and Ramsar Convention on Wetlands, less extensive protected areas have been established for freshwater and marine ecosystems (MEA, 2005; Pittock et al., 2008). The assessment goes on to say: ëThe most important direct drivers of change in ecosystems are habitat change (land use change and physical modification of rivers or water withdrawal from rivers), overexploitation, invasive alien species, pollution, and climate change. These direct drivers are synergisticí (MEA, 2005: 27).
You are not authenticated to view the full text of this chapter or article.
Get access to the full article by using one of the access options below.