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The purpose of this review and analysis is to provide a basic understanding of the issues related to worldwide hypoxic zones and the range of economic questions sorely in need of answers. We begin by describing the causes and extent of hypoxic zones worldwide, followed by a review of the evidence concerning ecological effects of the condition and impacts on ecosystem services. We describe what is known about abatement options and cost effective policy design before turning to an analysis of the large, seasonally recurring hypoxic zone in the Gulf of Mexico. We advance the understanding of this major ecological issue by estimating the relationship between pollutants (nutrients) and the areal extent of the hypoxic zone. This "production function" relationship suggests that both instantaneous and legacy contributions of nutrients contribute to annual predictions of the size of the zone, highlighting concerns that ecologists have raised about lags in the recovery of the system and affirms the importance of multiple nutrients as target pollutants. We conclude with a discussion of critical research needs to provide input to policy formation. The Economics of Dead Zones: Linking Externalities from the Land to their Consequences in the SeaOctober 17, 2012 S. S. Rabotyagov, C.L. Kling, P.W. Gassman, N.N. Rabalais, and R.E. TurnerAbstract: The purpose of this review and analysis is to provide a basic understanding of the issues related to worldwide hypoxic zones and the range of economic questions sorely in need of answers. We begin by describing the causes and extent of hypoxic zones worldwide, followed by a review of the evidence concerning ecological effects of the condition and impacts on ecosystem services. We describe what is known about abatement options and cost effective policy design before turning to an analysis of the large, seasonally recurring hypoxic zone in the Gulf of Mexico. We advance the understanding of this major ecological issue by estimating the relationship between pollutants (nutrients) and the areal extent of the hypoxic zone. This "production function" relationship suggests that both instantaneous and legacy contributions of nutrients contribute to annual predictions of the size of the zone, highlighting concerns that ecologists have raised about lags in the recovery of the system and affirms the importance of multiple nutrients as target pollutants. We conclude with a discussion of critical research needs to provide input to policy formation.

A seasonally occurring summer hypoxic (low oxygen) zone in the northern Gulf of Mexico is the second largest in the world. Reductions in nutrients from agricultural cropland in its watershed are needed to reduce the hypoxic zone size to the national policy goal of 5,000 km 2 (as a 5-y running average) set by the national Gulf of Mexico Task Force's Action Plan. We develop an integrated assessment model linking the water quality effects of cropland conservation investment decisions on the more than 550 agricultural subwatersheds that deliver nutrients into the Gulf with a hypoxic zone model. We use this integrated assessment model to identify the most cost-effective subwatersheds to target for cropland conservation investments. We consider targeting of the location (which subwatersheds to treat) and the extent of conservation investment to undertake (how much cropland within a subwatershed to treat). We use process models to simulate the dynamics of the effects of cropland conservation investments on nutrient delivery to the Gulf and use an evolutionary algorithm to solve the optimization problem. Model results suggest that by targeting cropland conservation investments to the most cost-effective location and extent of coverage, the Action Plan goal of 5,000 km 2 can be achieved at a cost of $2.7 billion annually. A large set of costhypoxia tradeoffs is developed, ranging from the baseline to the nontargeted adoption of the most aggressive cropland conservation investments in all subwatersheds (estimated to reduce the hypoxic zone to less than 3,000 km 2 at a cost of $5.6 billion annually).waters are proliferating worldwide, impacting more than 400 coastal marine systems (1, 2). A major cause of their formation and persistence is nutrient pollution (from agricultural, urban, and other sources) delivered from their watersheds. Excess nutrients threaten not only coastal waters (3), but also pose problems within the watersheds (4), diminishing the quantity and quality of the ecosystem services they provide (5-7). For example, 55 percent of US streams are in "poor" condition (4), drinking water supplies are compromised by high nitrate concentrations, harmful algal blooms risk human health, and commercial fisheries are threatened. The second-largest hypoxic zone in the global ocean is in the northern Gulf of Mexico and covers an area averaging more than 14,500 km 2 in the summers of 2004 through 2013 (8). The documentation of this pervasive phenomenon led to the 2008 Action Plan for Reducing, Mitigating, and Controlling Hypoxia in the northern Gulf of Mexico (9). The Action Plan, a joint federal-state effort, set the goal of reducing the size of Gulf hypoxia to less than 5,000 km 2 over a 5-y period.Current analysis of the sources of nutrient loads from the Mississippi-Atchafalaya River Basin (hereafter referred to as the Mississippi Basin) into the Gulf indicate that agricultural sources in the watershed contribute 80% of the delivered nitrogen (N) and more than 60% of the delivered phosphorus (P) (10).A number of cr...

In 2008, the hypoxic zone in the Gulf of Mexico, measuring 20 720 km2, was one of the two largest reported since measurement of the zone began in 1985. The extent of the hypoxic zone is related to nitrogen and phosphorous loadings originating on agricultural fields in the upper Midwest. This study combines the tools of evolutionary computation with a water quality model and cost data to develop a trade‐off frontier for the Upper Mississippi River Basin specifying the least cost of achieving nutrient reductions and the location of the agricultural conservation practices needed. The frontier allows policymakers and stakeholders to explicitly see the trade‐offs between cost and nutrient reductions. For example, the cost of reducing annual nitrate‐N loadings by 30% is estimated to be US$1.4 billion/year, with a concomitant 36% reduction in P and the cost of reducing annual P loadings by 30% is estimated to be US$370 million/year, with a concomitant 9% reduction in nitrate‐N.

Controversial wildlife conservation and management, such as that involving gray wolves (Canis lupus), can be symbolic of broader social conflicts. We conducted an online survey (N = 420) to determine factors shaping public attitudes toward wolf management among residents of Washington state, United States. We used 12 Likert-type statements to form a single latent construct that represented attitudes toward wolf management in a multi-use landscape and fit a simple structural equation model to identify demographic predictor variables. The strongest predictors were that voters self-identifying as Democrats were more likely to hold positive attitudes toward wolves and management to conserve them than those identifying with other political parties (standardized latent variable coefficient = 0.585) and women were more likely than men to hold negative attitudes (−0.459). Older respondents were also more likely to hold negative attitudes (−0.015) and respondents who tried to stay informed about wolf issues were more likely to hold positive attitudes (0.172). Perceived links between wildlife management issues and political ideology may exacerbate community disagreements, hindering coexistence between rural livelihoods and wolves. We recommend appropriate framing and messengers to account for this linkage and improve communication of policy and promote science-based decision-making.