Treated and untreated acid mine drainage effects on stream periphyton biomass, leaf decomposition, and macro invertebrate diversity

We studied the effects of acid mine drainage (AMD) on three key stream properties and functions. Four streams from each of three categories (AMD, treated AMD, and reference) were selected randomly from within the Tygart Valley River watershed in West Virginia. Analysis of stream water verified that the three stream types had very distinct chemical characteristics. Periphyton biomass was significantly reduced in AMD streams; however, treated AMD streams were no different from reference streams. Leaf decomposition was significantly slower in treated streams than in reference streams. Compared to reference streams AMD streams exhibited significantly lower macroinvertebrate density and diversity, whereas treated AMD streams had lower diversity. Thus, although treated AMD is much less toxic than raw AMD, it still has substantial impacts on macroinvertebrate diversity and leaf decomposition which could lead to ecosystem-wide impacts.