Mercury Accumulation in the Water Column, Stream Sediments and Larval Black Fly (Diptera: Simuliidae) Tissue in Coastal Streams of Alabama, USA

Daniel, Chelsea E.; McCreadie, John W.

Mercury Accumulation in the Water Column, Stream Sediments and Larval Black Fly (Diptera: Simuliidae) Tissue in Coastal Streams of Alabama, USA

2014

Daniel, Chelsea E. | McCreadie, John W.

Larval black flies (Diptera: Simuliidae), which inhabit streams and rivers, are both filter-feeders and a dominant part of the macroinvertebrate community. As filter-feeders, these insects are potentially an important entrance point for mercury into lotic food webs. The objectives of our study were to (1) document mercury concentrations in the water column, streambed sediments, and larval black fly tissue in select streams in coastal Alabama, USA, over both spatial (among streams) and temporal (across and within season) gradients and (2) determine if levels of mercury in stream ecosystems can be predicted based on stream predictors. Mercury was found consistently in both the black fly larval tissues and streambed sediments but was not detected in the water column. The range of total mercury found in larval tissue and stream sediments varied between 23.73–142.05 and 0.60–56.98 ppb, respectively. Mean mercury levels in both tissue and sediments show significant variation among summer, fall, and spring collections. In addition, mercury levels in tissue and sediments were significantly associated with dissolved oxygen, conductivity, or temperature within a season.

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