Forum on Science to Support Management of Methylmercury in Restored Tidal Marshes

The RMP sponsored a forum to review information and information needs relating to managing methylmercury in restored tidal marshes in San Francisco Bay. There is currently a lack of consensus on the best approach for monitoring methylmercury and using monitoring data in decision-making. This workshop addressed the state of knowledge regarding the role wetland restoration and management play in methylmercury impairment locally and regionally, and helped inform decision-making by the San Francisco Bay Regional Water Quality Control Board and other agencies.

The Mercury TMDL Implementation Plan includes monitoring of wetland restoration projects, in order to address concerns that as restoration projects develop into fully functioning tidal marshes they may increase the exposure of fish and wildlife to methylmercury. To address the TMDL Implementation Plan’s call for monitoring, a number of Board-issued 401 Certifications/Waste Discharge Requirements have included mercury monitoring. The general requirement is that restoration projects should not make conditions in the Bay worse, with respect to water quality and methylmercury, than they are at present. There is a need for a consistent regional approach to monitor these wetland restoration projects.

In addition, the RMP’s mercury synthesis report (Davis et al. 2012) recommended a focus on the design and maintenance of restored marshes and managed ponds as a means of potentially reducing methylmercury impairment in Bay wildlife.

This discussion was structured around management questions and hypotheses of interest to the Regional Water Board.

Meeting Materials

1. The Agenda

2. Marsh Methylmercury Management Questions and Hypotheses

3. Mercury Synthesis Report

Meeting Summary

1. Methylmercury Forum Complete Meeting Summary

2. Methylmercury Forum Condensed Meeting Summary

Referenced Publications

1. Uptake of Mercury by Fish in an Experimental Boreal Reservoir

2. Toxicity of Dietary Methylmercury to Fish: Derivation of Ecologically Meaningful Threshold Concentrations

3. The Rise and Fall of Mercury Methylation in an Experimental Reservoir

Meeting Powerpoints

1. RMP Mercury Strategy and Synthesis

2. Management Information Needs

3. Short-term vs Long-term Effects

4. Local vs Regional Impacts

5. Study Design

6. Restoration Design and Management Actions -Restored Marshes