Structural and functional changes of aquatic heterotrophic bacteria to thermal, heavy, and fly ash effluents

Heterotrophic bacterial populations were sampled at 9 sites around a fossil fuel power plant to assess the ecological impact of the resulting effluents on naturally occurring heterotrophic microbes. The total colony forming units (CFU) remained relatively high at all stations, ranging from 13,804 CFU ml⁻¹ in the heavy ash basin to 2630 CFU ml⁻¹ in an uninfluenced station, Adair Run—upstream. The percent of the total colony counts which were chromagenic was correlated with physico/chemical stresses and varied from a high of 59.0% at the reference New River station to 13.2% in the heavy ash basin. A Sequential Comparison procedure (SCI) produced diversity indices which ranged from 8.21 in upstream New River to 6.23 in the ash-influenced Adair Run station. Assimilation of [³H]glucose was used to assess the functional status of the organisms and was reduced 86.0% in the heavy ash basin and 65.5% in the fly ash basin. The structure and function of bacterial communities in the ash basins were significantly different from the same parameters of populations inhabiting reference environments; however, the basin effluents had a lesser effect on New River bacteria.