Responses of Stream Biofilm Phospholipid Fatty Acid Profiles to Acid Mine Drainage Impairment and Remediation

Acid mine drainage (AMD) impairs many streams throughout the historical and current coal mining regions. Abandoned mines often have sulfur-rich coal that produces sulfuric acid after exposure to water and oxygen. These streams are characterized by lowered pH, increased metal load, and decreased biotic assemblage complexity in comparison to unimpaired streams. Remediation efforts using alkaline addition have been successful in reducing the impacts of AMD by improving the chemical environment and reestablishing biotic assemblages that more closely resemble unimpacted streams. We used phospholipid fatty acids (PLFA) to detect changes in biofilm fatty acid profiles, differences in specific fatty acid biomarkers, and nutritional quality among AMD-unimpaired, AMD-impaired, and AMDremediated stream sites in southeastern Ohio (USA). In general, the physical, chemical, and biological measurements of the remediated sites were intermediate between the unimpaired and impaired streams. PLFA content was five times greater in AMD-unimpaired sites when compared to AMD-impaired and double that of AMD-remediated sites. PLFA profiles separated sites of the three categories into two statistically distinct groups: AMD-unimpaired/AMD-remediated and AMD-impaired. The results of this study showed that PLFA profiles have great promise as an additional metric to evaluate AMD impact for stream biomonitoring programs.