Linking Knowledge with Action: Refining Maine’s Mercury Fish Consumption Advisory (Phase I)

Participating Institution:
University of Maine

Team leader:
Aria Amirbahman, Civil & Env. Engineering

Team members:

• Kathleen Bell, Economics
• Linda Bacon, Maine DEP & Graduate Student
• Kevin Simon, Biology & Ecology
• Steve Norton, Earth Sciences
• Ivan Fernandez, Plant, Soil & Env. Sciences

Project partners:
Dave Courtemanch, Barry Mower (ME DEP)

Mercury (Hg) is a global contaminant of major concern because exposure to this neurotoxin poses risk to human and wildlife health. It is number two on the Agency for Toxic Substances and Disease Registry (ATSDR) priority pollutant list. Toxic effects for humans range from impairment of motor
coordination and sensory ability at low exposures, to tremors, inability to walk, convulsions, and death at extremely high exposures. Increased loadings of Hg from non-point sources were documented in the continental U.S. in the early 1990s (Swain et. al., 1992). The increases translated to Hg contamination in fish in freshwater and coastal environments (Boesch et. al., 2001). The threat of this toxin to human
health resulted in the establishment of consumption advisories of marine and freshwater fish in 44 states in the U.S. and all of the eastern Canadian provinces. This widespread non-attainment of the Fish Consumption Designated Use under the Clean Water Act caused states in northeastern U.S. to collaborate in producing the Northeast Regional Mercury Total Maximum Daily Load study in October of 2007.

Maine’s fish consumption advisory for Hg has undergone only minor refinements following its establishment by the Maine Bureau of Health in response to Maine Department of Environmental Protection’s (DEP) assessment of fish tissue contamination in Maine lakes (DiFranco et. al., 1995; Mower
et. al., 1997). This assessment, designed to make a statistically valid evaluation of fish tissue Hg concentrations in lakes managed by the Maine Department of Inland Fisheries and Wildlife, indicated concentrations of Hg above values considered safe for human consumption. Currently, the advisory applies to all inland waters of the state. Recognizing potential limitations of this uniform and indiscriminate advisory, Dave Courtemanch of Maine's DEP is interested in supporting scientific research to support consideration of alternative approaches (see attached letter of support October 2009). The proposed collaborative research project is responding directly to this demand for new scientific knowledge.

In the northeastern U.S., there is a close linkage between lake trophic status (productivity) and Hg body burden in freshwater fish (Adams et al., 2009; Dittman and Driscoll, 2009; Chen and Folt, 2005; Chen et al, 2005). As such, further refinement of fish advisories may be possible by closely evaluating lake trophic status in concert with Hg concentrations (in water, seston, fish tissue, and sediment) and watershed characteristics. Watershed characteristics are hypothesized to control (1) the flux of Hg from the watershed to the lake, and (2) lake productivity, and thereby the accumulation of Hg in the food chain.

The goals of this Phase I research are to use existing data (University, state, and regional resources) to identify relationships among watershed attributes, lake trophic state, and fish Hg burden to build a predictive model. This research will (1) identify data gaps, (2) determine target lakes for additional data acquisition, and (3) initiate a stakeholder engagement process to inform a rigorous assessment of the
current Hg advisory and potential revisions to that advisory. We consider this to be an Intermediate 2 Integration Project with an ecological/K-A research focus with a social component.

During Phase II, results obtained from Phase I will be used as a basis to choose candidate lakes for additional studies. Assessment of new data and stakeholder engagement activities are expected to lead to the development of a quantitative process-oriented model that accounts for a significant portion of variation in fish tissue Hg concentrations in Maine lakes. Results of model testing (Phase II) are likely to
lead to fish consumption advisory refinements that will have significant social and economic impacts.

In addition to the Hg focus, secondary outcomes of this project have broad implications in terms of SSI goals and priorities of landscape change, urbanization, forest ecosystem management, and climate change. Elucidating the complex relationships among the drivers of lake trophic status (i.e., nitrogen, phosphorus, iron, aluminum, pH), Hg concentrations, and watershed characteristics will improve understanding of how human alterations of Maine’s landscape affect lake water quality and lake biota. Increased knowledge of these complex interactions between watershed characteristics and lake water chemistry will promote action in the development of watershed-specific resource management practices. These new approaches will support sustainability of lake ecosystem ‘services’ for future generations in the face of changes of land-use, land-cover, and climate, by indentifying the natural resilience within lake/watershed ecosystems, individually or within geographic regions.