Mercury Science Program

Strategy

The desired result is fish that humans can safely eat without concern and a healthy, well-balanced population of fish and wildlife that sustains the ecological integrity of the Everglades. By understanding the biogeochemical processes that make methylmercury available to the base of the food web, it may be possible to develop strategies that limit its bioaccumulation in top predators.

The South Florida Mercury Science Program includes monitoring, research, risk assessment and risk management investigations. The solution to a problem of this scientific complexity requires extensive data collection and development and testing of quantitative, computer models. The Program is to be carried out in phases, with the first phase emphasizing scoping studies to define the nature of the problem, the important sources and processes, and the characteristics of the system that affect study and model design. The second phase will focus monitoring, research, and modeling efforts on the most significant sources, processes, and risks. The third phase will refine quantitative understanding and evaluate solution strategies. The results will be used to support interagency decisions about restoration in the context of a sustainable South Florida.

The greatest scientific challenge is to gain an understanding of the basic chemical mechanisms and rates of transformation from inorganic mercury sources to methylmercury in base-level food web organisms. It is also important to be able to estimate the potential for control of those transformation factors. Constantly changing conditions, caused by natural and man-induced variability of the milieu in which mercury transformations occur, make this an extremely challenging scientific problem.

Risk Assessment Framework

Risk assessment is an established scientific discipline for rigorous, quantitative estimation of health and ecological risks. Here, its application is intended to provide the information necessary to define maximum, allowable levels of mercury in Everglades food webs. Safe mercury levels will be based upon risk to humans from fish consumption or chronic effects upon sensitive wildlife such as wading birds or the panther. A safe level of mercury in fish for human consumption has been established. Mercury criteria for wildlife can be established through feeding studies or, in the case of endangered species, studies on closely related animals. Given detailed, quantitative knowledge of the food web, it is possible to derive maximum concentrations in the base of the food web that will protect the most sensitive top predators. Concentrations at the base of the food web will be converted into corresponding water and sediment concentrations and used to devise standards and control strategies.

Risk Management & Control

The rate of entry of mercury into the food web may be managed through source control, manipulation of the fundamental biogeochemical processes or some combination of these.

Water management affects transport, chemical transformation and bioaccumulation. The way water is managed is potentially subject to some control with respect to depth, periods of inundation and flow velocity. Dissolved and suspended constituents in the water also affect the chemical transformations and bioaccumulation of mercury. There is some potential for controlling the chemical composition of water supplied for fish and wildlife purposes from farm runoff and as supplementary water from other sources.

Bioaccumulation of methylmercury in predators could be increased or decreased by management measures intended to restore other functions of the Everglades ecosystem, such as nutrient removal or water depth and flow restoration. If this happens, optimal management of the system may require weighing the risks of mercury contamination with other environmental issues. Cognizant of this possibility, the Ecosystem Restoration Task Force has mandated extensive trend monitoring to provide a baseline and ensure that any unintended deleterious effects of restoration management are detected early. This will allow adaptive management of restoration activities to correct undesirable effects.

Multi-Agency Planning

Each agency in this Science Program is independent with respect to management and budget, but all are linked by a common framework. Cooperative planning uses each agency's knowledge to ensure that the study objectives and design are sufficient and necessary, to avoid duplication and to divide the labor of meeting those objectives so as to make best use of available talent and resources.

The Mercury Science Program management functions consist of the following:

• Define technical-scientific, mercury study objectives from pollution control and restoration policy goals;
• Create the study plan and define its objectives as work products;
• Allocate study responsibilities;
• Set priorities and schedules;
• Coordinate funding requests;
• Assess progress toward objectives;
• Based on results, modify the study plan by filling gaps or changing course;
• Obtain peer review of scientific results;
• Disseminate results;
• Define mercury control strategies and management options;
• Report conclusions to resource managers & policy makers.

These functions are the responsibility of the Interagency Mercury Science Program Management Committee. This Committee operates under a flexible, "adaptive science" strategy where particular attention is given to eliminating work discovered to be no longer relevant and to initiating new work as the need becomes apparent. The interagency Mercury Science Program Technical Assessment Committee is responsible for ensuring that the study design meets management objectives, that the scientific products are sound, and for disseminating study results.

Integration with Restoration Efforts

Collaborative studies on South Florida mercury effects began in 1992 to deal with high mercury levels in top predators in the ecosystem. This work was later expanded to investigate the possible effects on mercury bioaccumulation of using man-made marshes to remove nutrients from farm runoff. More recently, the scope of mercury research has been broadened to include effects of restoration through changes in water management in the South Florida ecosystem.

The technical aspects of restoration are coordinated by the South Florida Ecosystem Restoration Task Force. The Task Force has no independent mercury research effort; rather, the agencies already collaborating the Mercury Science Program became members of the Task Force. In its report Scientific Information Needs, the Task Force's Science SubGroup includes a chapter called "Mercury in the Ecosystem." This Mercury Science Program is designed to produce the needed information identified in that report.

Expenditures on mercury studies in South Florida by all participating agencies were about $20 million through 1996. Mercury studies will be fully incorporated into the Task Force's Integrated Science Plan and its Integrated Financial Plan. As the Integrated Financial Plan is revised annually, any changes in projected costs for mercury studies will be incorporated.

The public policy aspects of restoration are a major responsibility of the Governor's Commission for a Sustainable South Florida. The Commission is being kept informed of the status of mercury problems, plans for investigations and study results.

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