SS3.17 Global Mercury Cycling: From Natural to Anthropogenic Sources
Date: Tuesday, June 11, 2002
Time: 4:00:00 PM
Location: Carson C
SveinsdottirAY, University of Maryland, Chesapeake Biological Laboratories, Solomons Island, USA,
Mason, R, P, University of Maryland, Chesapeake Biological Laboratories, Solomons Island, USA,
The Relationship between Concentrations of Methylmercury in Largemouth Bass and prey and Physical and Chemical Characteristics of Maryland Reservoirs.
Mercury contamination in freshwater fish stocks has been recognized as a problem in Europe and North America for over three decades. Although most of the mercury in freshwater environments consists of inorganic mercury, nearly all of the mercury found in piscivorous fish is methylmercury. The relationship between methylmercury levels in fish and inorganic mercury inputs is complex and in-lake processes and/or watershed factors play a significant role in influencing the fish concentration within a particular waterbody. The intention of the study was primarily to investigate methylmercury levels in largemouth bass in 17 Maryland, USA reservoirs, the primary location where recreational fishing occurs. In addition, the most important factors controlling the concentration of methylmercury in largemouth bass (Micropterus salmoides) in eight of the 17 impoundments were investigated. Atmospheric deposition is the main source of mercury to these systems and the regional signal shows little variability. Thus, differences in fish concentration between reservoirs are likely related to in situ processes or watershed/lake characteristics. Methylmercury concentrations were determined in axial muscle tissues of 196 largemouth bass (M. salmoides) and itís main prey, mainly crayfish (Procambarus sp.). Methylmercury concentrations in M. salmoides ranged from 20 to 2076 ng/g wet weight, with the highest concentrations observed in the largest fish. Selected physical and chemical data were collected for all of the eight study sites. Pearson correlation analysis indicated that methylmercury concentrations in largemouth bass were positively correlated with methylmercury concentrations in the prey and in the dissolved fraction of the water as well as with the chloride concentrations in the water.