Graduate Program 

The Role of Periphyton in Mercury Bioaccumulation in Stream Ecosystems

Graduate Student: Amanda Bell (Roehrborn)
Adviser: Earl Spangenberg

Most studies of mercury bioaccumulation have been done in lakes, reservoirs and wetlands. The focus has mostly been on the top predator fish, water column and streambed sediments; while few studies have examined the bioaccumulation of total mercury and methylmercury in river systems and at each trophic level. In 2003, the United States Geological Survey (USGS), National Water Quality Assessment Program (NAWQA) and Toxics Program began a study to examine benthic marcroinvertebrates. Missing from the NAWQA Mercury study was an investigation of the role of periphyton - primary producers in riverine systems - in mercury methylation and mercury from the water column and sediments to the invertebrates and fish by conducting an evaluation of the periphyton (benthic attached algae) at the eight NAWQA Mercury study sites. Periphyton is important in methylating and transferring mercury to the food web within the wetland environment and algal blooms resulted in reduced bioaccumulation in a eutrophic lake, based on previous investigations. Additional research is needed on the role periphyton play in bioaccumulation of methylmercury in river systems because many aquatic invertebrates consume periphyton. Using methods adopted from NAWQA protocols for riverine algal sampling, laboratory contracts and independent analysis, our study will outline the role of periphyton in the bioaccumulation of mercury. This study is in progress and expected to be completed by September 2004. Further developing the link between water, sediment, algae, invertebrates and fish will lead to greater information about the relative importance of each in mercury bioaccumulation and will improve our understanding of bioaccumulation of mercury in riverine systems.

Pictures on this page provided by Amanda Bell (Roehrborn)

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