Water Chemistry and Benthic Macroinvertebrate Ecology in Response to Acid Mine Drainage.

摘要

Benthic macroinvertebrates, especially aquatic insects, are documented indicators of environmental quality, and often respond predictably to changes within a freshwater system. Within West Virginia, acid mine drainage (AMD) forms as a result of oxidizing sulfide rich minerals which occur alongside coal. The resulting effluent is acidic and laden with heavy metals. As a result, valued services and ecological functions provided by freshwater resources are lost. Treatment of AMD is expensive and therefore studies documenting their effect on aquatic resources are valuable. Benthic macroinvertebrate and stream water samples are often used as the deciding factors for the condition of a stream or river and its subsequent listing on a state's 303(d) list. However, little is understood about the natural variation in water chemistry and benthic macroinvertebrates over time within an AMD polluted watershed. A long term dataset consisting of water chemistry and benthic macroinvertebrates from 25 study sites was used to address the following goals (1) understand how alkaline treatment of AMD affects water chemistry and benthic macroinvertebrate assemblages along a treatment continuum, and (2) understand how variable water chemistry and benthic macroinvertebrate assemblages are temporally under different settings.;Water chemistry and benthic macroinvertebrate data were gathered at select confluences and along longitudinal continua in the Muddy Creek watershed, a sub-watershed of the Cheat River basin that is severely impaired by AMD. Samples were gathered in riffle habitat annually, over 7 years during spring. Results showed that (1) water chemistry improved greatly post-AMD treatment while benthic macroinvertebrate assemblages generally did not, and (2) groups of reaches classified by water chemistry experienced significantly different temporal variation in chemical parameters and significantly different invertebrate diversities over the seven year study period. These findings support our current understanding of AMD treatment in heavily mined regions of Appalachia. Water chemistry will improve but often the fragmenting of waterways by AMD prevents biological recovery. We also present considerations for future assessments of AMD impaired watersheds. Researchers should attempt to account for temporal variation and understand its potential influence on waterways.