The three major drivers of ecosystem degradation are overexploitation, nutrient and toxic pollution, and climate change. The challenges of bringing these threats under control are enormously complex and will require fundamental changes in fisheries, agricultural practices, and the ways we obtain energy for everything we do. We have to begin somewhere, however, and the following very significant actions could begin right away without further scientific research or technological innovation.
The tools for effective management of wild fisheries are well established (Beddington et al., 2007; Hilborn, 2007), and there are encouraging examples of success (Safina et al., 2005). Nevertheless, the required actions have rarely been implemented (Rosenberg et al., 2006). In contrast, subsistence overfishing in developing nations is commonly a matter of survival, so that alternative sources of protein and livelihood are required to bring the situation under control (McClanahan et al., 2006; Hilborn, 2007). More fundamentally, however, wild fisheries cannot possibly sustain increasing global demand regardless of how well they are managed. Industrial scale aquaculture of species low on the food chain is the only viable alternative. But this in turn will require strong new regulation to prevent harmful ecosystem consequences such as the destruction of mangroves for shrimp farms and the impacts on wild salmon populations caused by the explosion of parasitic copepods that infect salmon farms in British Columbia (Goldberg and Naylor, 2005; Krkosek et al., 2007). Despite all of these concerns, however, the only thing standing in the way of sustainable fisheries and aquaculture is the lack of political will and the greed of special interests. Simply enforcing the standards of the Magnuson-Stevens Act and the U.S. National Marine Fisheries Service would result in major improvements in United States waters within a decade (Safina et al., 2005; Rosenberg et al., 2006).
Heavily subsidized overuse of chemical fertilizers and pesticides, poor soil management practices, and unregulated animal production systems are the major sources of excess nitrogen and other nutrients in the environment that fuel coastal eutrophication (Jackson et al., 2001; Rabalais et al., 2007; Turner et al., 2008) and severely degrade terrestrial ecosystems (Tilman et al, 2002; Clay, 2004; Galloway et al, 2004; Dale and Polasky, 2007). Manufacture of chemical fertilizers also consumes huge amounts of energy from natural gas (Howarth, 2004). Removal of subsidies and taxation of fertilizers would significantly reduce nutrient loading, eutro-phication, and emissions of greenhouse gases with only modest decreases in food production and increased costs.
The rise in greenhouse gases and the resulting global economic, social, and environmental consequences comprise the greatest challenge to humanity today. Moderation of consumption of fossil fuels in a time of rising global aspirations and finding alternative sources of energy will
26 / Jeremy B.C. Jackson require all of the ingenuity humanity can muster and will preoccupy us for the remainder of the century. The problems appear so overwhelming that many are ready to write off coral reefs and all of the other marine life that will be drastically affected. But such defeatism belies the growing realization that local protection from overexploitation and pollution confers some as yet poorly understood level of resistance and resilience to the effects of climate change on coral reefs (Dulvy et al., 2002; Hughes et al., 2007; Knowlton and Jackson, 2008), and the same is very likely true for other marine ecosystems. This is an important area for new scientific research to better understand the synergies among different drivers of ecosystem change and their likely consequences. Most importantly, local conservation measures may help to buy time for marine ecosystems until we bring the rise of greenhouse gases under more effective control.
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