TEMPORAL AND SPATIAL VARIABILITY OF METHYLMERCURY ACCUMULATION IN SMALL STREAM ECOSYSTEMS

Abstract

Maryland has state-wide fish consumption advisories for mercury, and there is a need to explain these trends. I explore two tools for characterizing MeHg conditions in Maryland. The first explores benthic macroinvertebrates as vectors of MeHg from sediments to fish. I examined macroinvertebrate communities over two years from two first-order streams differing in land-use and historical stream water MeHg concentrations. I assessed temporal and spatial variability in invertebrate populations in conjunction with an assessment of the distribution of MeHg in water and sediment. I tested a second tool, an autonomous continuous water sampler that would allow MeHg to be measured without laborious expeditions. I observed differences in concentrations of MeHg across trophic levels between watersheds and identified a candidate organism as a bioindicator of MeHg exposure risk and watershed MeHg condition, as well as a potential sampling mechanism for MeHg in aquatic ecosystems.