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Trophic transfer and bioaccumulation of trace metals have a profound impact on the structure and function of coastal areas; however, the metal accumulation patterns in detritus-based food webs and the influence of climatic variability have not been thoroughly investigated. The Tampamachoco Lagoon (Gulf of Mexico) is a coastal system impacted by emissions from a thermoelectric plant. We evaluated the spatial–temporal distribution patterns of Al, Cd, Hg, Cr, Cu, and Pb in water, sediments, and in organisms categorized by trophic levels (TLs), trophic guilds, and habitat preferences. The sediments had the highest concentrations of metals with no significant differences between seasons. The indices of geo-accumulation and potential ecological risk classified sediments as "moderately contaminated", evidencing a threat to human health through consumption of detritivores and filter-feeders. The lowest TLs (filter-feeders and detritivorous) reached the maximum Metal Pollution Index in the rainy season. According to discriminant analyses of metals and species, omnivorous and zoobentivorous organisms were associated with Hg during the rainy and dry seasons; while Al, Cd, and Cu were related to low TLs, and seston was associated with Pb. Food web magnification factor analysis showed that: (a) Pb, Cu, and Cr were biodiluted as trophic levels increased; (b) Cd and Hg showed temporal biomagnification trends; (c) Al, Pb, Cu, and Cd showed significant biodilution from the lowest TL to intermediate TLs; and (d) Hg was transferred from the lowest to intermediate TLs with clear biomagnification effects. [ABSTRACT FROM AUTHOR]

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Seasonal flooding changes chemical and morphometric characteristics of the tropical floodplain lakes, affecting stratification which can influence mercury dynamics. We investigate the influence of flooding on the mercury dynamics in an Amazon floodplain lake. Three points on the lake, the Solimões River, and the connecting channel to the river were sampled along the annual flood pulse. During high-water, the lake was deep (12.7 m, on average) and the area farthest from the river was stratified with low oxygen and high methylmercury concentrations ([MeHg]) at depths below 7 m (0.37 ng l, on average). The two sites closest to the river were destratified and the [MeHg] was lower (0.077 ng l, on average along all depths). At low-water, the lake was shallower (3 m, on average) and destratified, with higher oxygen concentrations, and no difference in [MeHg] along the water column at all lake sites. Independent of season, the [MeHg] in the connecting channel was higher than those in the river. The [MeHg] in phytoplankton varied in response to changes in biomass, showing a biodilution effect. Variations in lake morphometry controlled the stratification and [MeHg] in the lake during the high-water. Floodplain lakes export hypolimnetic MeHg to their associated rivers during high-water. [ABSTRACT FROM AUTHOR]

Relationships between the concentrations of 13 trace elements and δN were identified to investigate the trophic-level-dependent accumulation of elements in biota from Suruga Bay, Japan. The results showed biomagnification for Hg, As and Se (very weak for As and Se), biodilution for Cd, Cu, Mn, Ni, Pb, Sb and Zn, and nontrophic relationships for Co, Cs and Mo. It is likely that the biomagnification of Hg does not differ significantly with the location, whereas some trace elements, such as As, Se and Zn, show a characteristic trophic transfer in each location, depending on the food web structure and environmental factors. [ABSTRACT FROM AUTHOR]

We report on mercury (Hg) contamination in waters, sediments, and biota of Vermont and New Hampshire (USA) lakes measured during 1998-2000, using a geographically randomized design. Waters and sediments of 92 lakes were sampled for mercury, methylmercury, and ancillary parameters. Yellow perch (Perca flavescens) muscle tissues were analyzed for mercury on 47 of these lakes. Interannual variation in mercury was limited; only epilimnetic Hg was elevated by approximately 1.5 ng/L in 1998 over remaining years because of wet weather. Aqueous total and methylmercury concentrations were elevated in both dystrophic and eutrophic lakes over other types. Yellow perch tissue concentrations were elevated by 0.218 μg/g in dystrophic lakes over other types and were very low in eutrophic lakes. Fish tissue mercury concentrations showed no relationship to hypolimnetic or sediment mercury or methylmercury. A statistical model indicated that yellow perch tissues in 40.2 ± 13% of lakes were likely to exceed the U.S. Environmental Protection Agency (U.S. EPA) methylmercury criterion of 0.3 μg/g, and yellow perch from New Hampshire were twice as likely to exceed the criterion as those from Vermont. Results of this study provide a regional-scale baseline against which the success of future reductions in mercury emissions can be assessed. [ABSTRACT FROM AUTHOR]

We found no relationship between fish growth rate and mercury concentration in a lake trout population and conditional support for an inverse relationship in a smallmouth bass population. A bioenergetics model indicated that mercury concentration was more responsive to dietary mercury intake than to growth rate. When biodilution is evident, it may bias contaminant versus fish size relationships. [ABSTRACT FROM AUTHOR]