Small Fish "Tracers" Detect Bay Mercury Threats

In collaboration with the San Francisco Estuary Institute, UC Davis researchers have made headway in understanding the sources of toxic mercury in the San Francisco Bay and Delta. The findings, revealed in SFEI's annual report of the Regional Monitoring Program for Water Quality (RMP), indicate that changes in current habitat management techniques could prevent mercury from entering the food web and threatening the health of wildlife and humans. A small fraction of elemental mercury is converted to the organic form methylmercury by bacteria in the sediments of aquatic environments. Metyhylmercury poses a health concern if it enters the aquatic food web and builds up to toxic levels further up the food chain. According to SFEI's annual report, this threat is a reality. Researchers at the U.S. Geological Survey documented a higher risk of hatch failure for the eggs of exposed Bay water birds, and mercury concern is the main incentive for fish consumption advisories in the Bay.

Mercury remains an important focus for the RMP," said SFEI senior project manager Meg Sedlak. "More extensive small fish monitoring is a key component of the RMP Mercury strategy."