The Environmental Food Crisis

IMPACTS FROM INTENSIFICATION OF CROPLANDS

zones (UNEP, 2001; 2008). In the northwestern Gulf of Mexico, nutrient enrichment mainly from fertilizer use in the Missis- sippi Basin has accounted for the world’s largest hypoxic or dead zone (Turner and Rabalais 1991; Rabalais et al ., 1999; UNEP, 2008). Without significant nitrogen mitigation efforts, marine areas will be subjected to increasing hypoxia and harmful algal blooms that will further degrade marine biomass and biological diversity (Sherman and Hempel, 2008; UNEP, 2008). In some regions, diversion of water for agricultural and other purposes has reduced river flow to coastal areas, with severe impacts on coastal habitats and estuarine-dependent species. For example, damming of the Colorado River has drastically changed what used to be an estuarine system into one of high salinity and reduced critical nursery grounds for many com- mercially important species, including shrimp (Aragón-Norie- ga and Calderon-Aguilera, 2000). There are many well-docu- mented examples where diversion of water for agriculture has degraded and reduced the extent of inland water bodies (e.g., the Aral Sea), affecting fish spawning and migration and caus- ing a collapse of the fishing industry and a loss of species diver- sity in the affected areas (MA, 2005).

Intensive management to increase agricultural production – through irrigation and the application of fertilizers and pesticides – can further reduce the wildlife value of farmed land. From 1961 to 1999, the area of land under irrigation nearly doubled; the use of nitrogenous and phosphate fertilizers increased by 638% and 203%, respectively, and the production of pesticides increased by 854% (Green et al ., 2005). Such intensification has had major di- rect impacts on biodiversity, such as on farmland birds (Figure 28) and aquatic species. Large-scale use of fertilizers and pesticides, coupled with fragmentation and losses of important farmland habitat qualities, also reduces the number of flowers and plant diversity, diminishes insect biodiversity, and subsequently the sur- vival of farmland birds, particularly the young that are dependent upon insects in their first weeks or months of life (see box). Aquatic ecosystems are also being widely affected by food pro- duction in terrestrial areas, through high nutrient inputs (Seitz- inger and Lee, 2008) in run-off from agricultural and livestock production and alteration of freshwater flows. The ensuing reduction in water quality (Mitchell et al ., 2005) is evident in increased eutrophication and subsequent algal blooms and oxy- gen-deficient waters, which when extreme, could result in dead

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