11-19-07 Science Advisory Board (sab) Hypoxia Panel Draft Advisory Report Do Not Cite or Quote

Название11-19-07 Science Advisory Board (sab) Hypoxia Panel Draft Advisory Report Do Not Cite or Quote
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  • investigate freshwater plume dispersal, vertical mixing processes and stratification over the Louisiana-Texas continental shelf and Mississippi Sound, and use three-dimensional hydrodynamic models to study the consequences of past and future flow diversions to NGOM distributaries;

  • advance the understanding of biogeochemical and transport processes affecting the load of biologically available nutrients and organic matter to the Gulf of Mexico, and develop a suite of models that integrate physics and biogeochemistry;

  • elucidate the role of P relative to N in regulating phytoplankton production in various zones and seasons, and investigate the linkages between inshore primary production, offshore production, and the fate of carbon produced in each zone;

  • improve models that characterize the onset, volume, extent, and duration of the hypoxic zone, and develop modeling capability to capture the importance of P, N, and P-N interactions in hypoxia formation;

To advancing the science on sources, fate and transport of nutrients, the SAB Panel recommends research to:

  • develop models to simulate fluvial processes and estimate N and P transfer to stream channels under different management scenarios;

  • improve the understanding of temporal and seasonal nutrient fluxes and develop nutrient, sediment, and organic matter budgets within the MARB;

To enhance the scientific basis for implementation of management options, the SAB Panel finds that research is needed to:

  • examine the efficacy of dual nutrient control practices;

  • determine the extent, pattern, and intensity of agricultural drainage as well as opportunities to reduce nutrient discharge by improving drainage management;

  • integrate monitoring, modeling, experimental results, and ongoing management into an improved conceptual understanding of how the forces at key management scales influence the formation of the hypoxia zone; and

  • develop integrated economic and watershed models to support adaptive management at multiple scales.

Developments in the biofuels industry have created new questions for researchers to address. More research is needed on biofuel life cycles in order to identify system efficiency with respect to environmental effects, economics, and resource availability of biofuel alternatives. That is, research needs to evaluate the environmental effects of different biofuel production processes on soil, water quality and climate under realistic strategies of deploying production facilities and moving the biofuels to the market. Current incentives favor corn-based ethanol production, although research has thus far shown fewer environmental consequences with other feedstocks, e.g., cellulosic feedstocks such as switchgrass. Yet the technology for conversion of cellulosic feedstocks to biofuel is not yet commercially viable. Policies of all kinds (taxes, subsidies, trade) could be used to support research and technological developments for those biofuels that balance high energy yields with the lowest environmental impacts.

Recommendations for Adaptive Management

Adaptive management provides a framework for ongoing management in the face of uncertainty. It requires that conceptual models be developed to guide management and that management actions be treated like well-monitored experiments that answer questions for improving decisions with each successive cycle of learning. The most urgent need is to decrease nutrient discharge. In fact, nutrients should be decreased as soon as possible before the system requires even larger nutrient reductions to reduce the area of hypoxia. Already many taxa are lost during the peak of hypoxia, and there has been a shift in the relative abundance of fish species. Increases in certain pelagic species can disrupt food web structure, and the new system may respond in a quite different way to changes in nutrient level. The SAB Panel thus agrees with the CENR’s emphasis on decreasing nutrient discharge in the context of adaptive management.

These adaptive management actions must be interpreted in view of both field measures and models of their effects. Conceptual models are needed for nutrient management at several spatial resolutions from small catchments, to large watersheds, to the entire MARB in order to guide research and ongoing adaptive management at each of the relevant scales. To the greatest extent possible, feedbacks should be incorporated into the models so that management is accompanied by learning about the full systems of linkages between human activities and hypoxia as well as the full range of co-benefits of N and P reductions.

Management Options

Large N and P reductions, on the order of 45% or more, are needed to reduce the size of the hypoxic zone. To do this, the SAB Panel found the most significant opportunities for N and P reductions occur in five areas:

      • promotion, via research and economic incentives, of environmentally sustainable approaches to biofuel production and associated cropping systems (e.g., perennials).

      • improved management of nutrients by emphasizing infield nutrient management efficiency and effectiveness to reduce losses;

      • construction and restoration of wetlands, as well as criteria for targeting those wetlands that may have a higher priority for reducing nutrient losses;

      • introduction of tighter N and P limits on municipal point sources; and

      • improved targeting of conservation buffers, including riparian buffers, filter strips and grassed waterways, to control surface-borne nutrients.

Importantly, not all approaches will be cost-effective in all locations; the optimal combination and location of these practices will vary across and within watersheds.

In terms of cropping systems, research comparing nutrient discharge between alternative cropping systems (including row crops and non-row crops such as perennials) and a corn-soybean rotation shows that significant nutrient loss reductions could be achieved by converting current corn-soybean rotations to alternative crops or alternative rotations. Moreover, since corn crops require more nitrogen input, cellulosic sources (e.g., perennial grasses, fast-growing woody species, etc.) could, by comparison, provide alternative energy while protecting water quality. However, the technology for converting cellulosic sources to biofuel is not yet commercially viable. Significant reductions in nutrient runoff could also be achieved if nutrients are managed more efficiently on farms, for example by moving to spring fertilization rather than fall. More wetlands are needed, especially in those areas that promise the greatest N and P reductions. Since the greatest N and P runoff is coming from upper Mississippi and Ohio-Tennessee River subbasins, where the highest proportion of tile drainage occurs, measures to improve drainage water management are urgently needed. In fact, improved targeting of almost all agricultural conservation practices in the region [e.g., conservation buffers, wetlands, land set aside in the Conservation Reserve Program (CRP), drainage water management, etc.] could achieve greater local water quality benefits and simultaneously contribute to hypoxia reduction. Nearly all of these opportunities were recognized in the Integrated Assessment.

The CENR did not emphasize tighter limits on municipal point sources; however new calculations from the SAB Panel indicate that 22% of annual average total N flux and 34% of annual average total P flux to the Gulf comes from permitted point-source dischargers. The SAB Panel’s calculations further demonstrate that tighter limits on N and P in effluent (3 mg N/L and 0.3 mg P/L) from sewage treatment plants could realize an estimated 11% reduction in annual average total N flux and a 21% reduction in total annual average P flux to the Gulf. Although the exact N and P limit could be debated, clearly there are regulatory opportunities to significantly reduce N and P fluxes to the Gulf. The cost associated with such regulations could be reduced if trading programs for point and non-point sources are properly developed and implemented concurrently with regulations.

Protecting and Enhancing Social Welfare in the Basin

Implementing the management options needed to reduce nutrients will clearly affect the social welfare of many who live in the basin. On the positive side, N and P reductions will improve environmental quality within the basin and, as the Integrated Assessment documented, these co-benefits can be highly valuable. Second, if the costs of implementing these management options are borne largely by residents in the region, then preserving/enhancing social welfare will require implementing policies that target the most cost-effective sources and locations for nutrient reductions.

Subsidies, not regulation, have been the government’s primary tool for managing agricultural production and income support in the U.S., as well as conservation in agriculture. Hence re-structuring subsidies and conservation programs represents an important tool for reducing nutrient runoff from agricultural production. The Integrated Assessment recognized numerous agricultural management practices that improve water quality but did not discuss the efficiency of the tools for their implementation. A large body of economics literature exists regarding the relative merits and cost-effectiveness of taxes, regulations, voluntary approaches, permit trading, subsidies, and other instruments that could apply to reducing nutrient losses. This research indicates that if significant behavioral changes are to be realized, incentives are needed across a wide range of sectors. Such incentives can be positive (e.g., subsidies) or negative (e.g., taxes or direction regulation with enforcement actions), but they must be strong enough to change behavior. A thorough and quantitative comparison of all possible incentives for all sectors was beyond the SAB Panel’s scope; however, research indicates that the following approaches are cost-effective.

First, the establishment (and continuation where appropriate) of targeting and competitive bidding mechanisms results in lands enrolled in conservation programs (e.g., the Conservation Reserve Program, the Environmental Quality Incentives Program, and the Conservation Security Program) that achieve maximum environmental benefits. Moreover, conservation compliance requirements extended to nutrient management, if adequately monitored and enforced, could be cost-effective. Targeting conservation practices to the locations within a watershed where they produce the most N and P reductions (and co-benefits) and targeting entire watersheds that have relatively high N and/or high P contributions are both cost-effective targeting approaches.

Second, economic incentives are needed for the full range of conservation options. Incentives for development of technologies to convert cellulosic perennials to biofuels would be needed to greatly reduce N and P losses from agricultural systems. Re-structuring eligibility requirements for existing subsidies to reward conservation in all its forms (in-field nutrient management, cover crops, conservation buffers, wetlands, alternative drainage, manure management) could help mitigate the unintended consequences of agricultural production.


In sum, environmental decisions and improvements require a balance between research, monitoring and action. In the Gulf of Mexico, the action component lags behind the growing body of science. Moreover, certain aspects of current agricultural and energy policies conflict with measures needed for hypoxia reduction. Although uncertainty remains, there is an abundance of information on how to reduce hypoxia in the Gulf of Mexico and to improve water quality in the MARB, much of it highlighted in the Integrated Assessment. To utilize that information, it may be necessary to confront the conflicts between certain aspects of current agricultural and energy policies on the one hand and the goals of hypoxia reduction and improving water quality on the other. This dilemma is particularly relevant with respect to those policies that create economic incentives. The SAB Panel's recommendation to address the structure of economic incentives stems from sound science.

Basing management decisions on sound science means taking action at several different scales, addressing conflicts between policies, and acting in the face of uncertainties. Lessons learned from current actions can inform and improve future decisions. While actions must come first, they must also be coupled with monitoring and modeling of management activities within a conceptual framework to improve understanding of the system. Done well, this process of adaptive management means that, over time, society will benefit from cost-effective environmental decisions that reduce hypoxia in the Gulf and improve water quality in the MARB.

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