Spatial patterns of mercury in macroinvertebrates and fishes from streams of two contrasting forested landscapes in the eastern United States

摘要: Controls on mercury bioaccumulation in lotic ecosystems are not well understood. During 2007–2009, we studied and stable isotope spatial patterns of macroinvertebrates fishes from two medium-sized (<80 km2) forested basins contrasting settings. Samples were collected seasonally multiple sites across the Fishing Brook basin (FBNY), New York’s Adirondack Mountains, McTier Creek (MCSC), South Carolina’s Coastal Plain. Mean methylmercury (MeHg) concentrations within macroinvertebrate feeding groups, mean total (THg) most fish groups similar between regions. However, THg game forage fish, overall, much lower FBNY (1300 590 ng/g dw, respectively) than MCSC (2300 780 respectively), due to trophic positions these (means 3.3 2.7, 3.7 3.3, respectively). Much larger variation topography water chemistry contributed greater biotic Hg positive correlations with dissolved MeHg organic carbon streamwater. Hydrologic transport distance (HTD) was negatively correlated FBNY, a better predictor wetland density. The small range landscape conditions resulted no consistent patterns, discernable correspondence local-scale environmental factors. This study demonstrates importance factors topographically heterogeneous landscapes, provides evidence that food-chain length can be an important broad-scale differences among streams.