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	PCE program: PCE Facts and Figures Coastal ecosystems are among the most productive yet highly threatened systems in the world, comprising heavily used coastal lands, areas where freshwater and saltwater mix, and nearshore marine areas. The Coastal Zone contributes to 25% of global primary productivity; accounts for nearly 90% of the world’ marine fish catch; deposits 80% of global organic matter; deposits 80% of global carbonate; contributes to 50% of global denitrification; supports 90% of global sedimentary mineralization and is a sink for 70-90% of global suspended matter. Coastal systems are experiencing growing population and exploitation pressures; nearly 40% of the world population lives in this thin fringe of land. Demographic trends suggest coastal populations are rapidly increasingly, mostly through migration and somewhat due to fertility and tourist visitation to these areas. Communities and industries exploit fisheries, timber, fuelwood, construction materiel; oil, natural gas, sand and strategic mineral, and genetic resources. Additionally, people increasingly use ocean space for shipping, waste disposal, security zones, recreation, aquaculture, and even habitation. Many coastal inhabitants are dependent on coastal resources; human settlements are highly correlated with critical coastal subtypes, and most humans express strong spiritual links to the sea. Coastal communities aggregate near the most productive systems, which are the most ecologically critical and the most highly vulnerable. For instance, 27% of the world population lives within 100 km of estuaries, while 12% live in the same close proximity to coral reefs. Within the coastal population, 71% live near estuaries, 45 % live near mangroves, and 31% live near reefs. Many of these habitats are unprotected or marginally protected (enforcement and surveillance costs being extremely high for marine areas); while 51% of the coastal population lives near a marine protected area (terrestrial coastal protected areas included), many of these are protected in name only. By all known measures of human well being, people living in coastal areas live better than those living in inland areas, but the vulnerability of coastal ecosystems puts these coastal inhabitants at greater relative risk. Spatially referenced figures of gross national product show that the world’s wealthiest populations occur primarily in coastal areas, and life expectancy is thought to be higher while infant mortality is thought to be lower in coastal regions. However, many coastal communities are politically and economically marginalized, and may thus not derive the economic benefits that living in coastal areas might accrue. Wealth disparity has led to denied access to resources for many coastal communities. Access issues have in turn led to increased conflict, as between small scale artisanal fishers and large scale commercial fishing enterprises. Regime shifts and habitat loss have led to irreversible changes in many coastal ecosystems, and thus nonlinear losses in ecosystem services. Finally, the fact that many degraded coastal systems are near thresholds for healthy functioning, and given the simultaneous vulnerability of coastal systems to catastrophic impacts from sea level rise and storm events, coastal populations are at great risk of having their relatively high levels of human well being severely compromised. Human pressures on coastal resources compromise many of the ecosystem services crucial to the well-being of coastal economies and peoples. Coastal fisheries have depleted stocks of finfish, crustaceans, and mollusks in all regions. Serial depletions cause not only resource scarcity but also change viability of coastal and marine food webs. Trade and globalization drives much over-exploitation. Large scale coastal fisheries deprive coastal communities of subsistence and are causing increasing conflicts, especially in Asia and Africa. Demands for aquaculture have been on the rise in response to failing capture fisheries, but aquaculture also drives habitat loss and pollution. The greatest threat to coastal systems is development-related conversion of coastal habitats that leads to large scale losses, but degradation is also a severe problem. Some 35% of mangroves have already been destroyed worldwide and a similar figure is claimed for coral reefs. Wetlands loss in some places reaches 20% annually. Dredging, reclamation and destructive fishing also accounts for widespread, irreversible destruction. Additionally, coastal zones are the downstream recipients of negative impacts of land use. Freshwater diversion from estuaries has meant catastrophic losses of water and sediment (30% decrease worldwide) delivery to critical nursery areas and fishing grounds. Nutrient pollution is the main source of degradation leading to compromised ecosystem services, resulting in eutrophication and hypoxic (dead zones) and polluted groundwater. Eutrophication has been implicated in coral reef regime shifts and other irreversible changes to coastal ecosystems. Nitrogen loading has doubled worldwide, making coastal areas the most highly chemically altered ecosystems in the world. Water-borne diseases and harmful algal blooms that affect both human health and marine organisms are on the rise. Alien species invasions, including release of GMOs, have already altered ecosystems and pose grave threats for marine species, and in some cases, ecosystem functioning. *The health of coastal systems and their ability to provide critical services is very strongly linked to that of marine, freshwater and terrestrial systems, and vice versa.* Land-based sources of pollutants are delivered via rivers, from run-off, and through atmospheric deposition, and these indirect sources account for the large majority of degrading toxins and pollutants. In some, especially dryland areas, pollution in coastal zones lead to groundwater contamination as well. Warming of seawater has been implicated in expanding desertification of Africa, while that same desertification has caused coral reef die off half a world away through the transport and deposition of Saharan dust. Destruction of coastal wetlands has similarly been implicated in crop failures due to severe freezing in inland areas. Uncertainties regarding what constitute sustainable limits to resource use, what ecological linkages exist between habitats within systems and between systems, and the role that coastal ecosystem services play in human well being are all amplified in coastal and marine systems. In part these uncertainties exist because marine ecology is decades behind terrestrial ecology, and in part because of scaling issues, in which the open nature of marine systems makes their study inherently more difficult (and costly). Furthermore, common property regimes in coastal areas and lack of effective monitoring of both ecosystem changes and human use have led to opacity regarding the condition and trends in coastal ecosystems and coastal communities. Coastal systems management to safeguard services has been inadequate, but there are reasons to believe some trends can be slowed or even reversed. Effective coastal area management requires the integration of management across many sectors that have traditionally been separated, though in some places institutional restructuring has occurred. Marine protected area networks that effectively protect critical, linked habitats are beginning to emerge, and comprehensive ocean zoning holds great promise. Recognizing the values that coastal systems hold for mankind will promote greater attempts to protect these ecosystems and the ecosystem services they support. Business as usual, however, will not avert continued degradation, associated loss of services, and declining human well being.

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