The role of two acidophilic algae as ecological indicators of acid mine drainage sites

Resumen

Acidic effl uents, emerging from four abandoned mines (Valdarcas, Carris, Adoria and Cerquido) in Northern Portugal were analyzed regarding physical-chemical, mineralogical and ecological characteristics. Such effl uents present distinct properties since they were mobilized from wastes of different primary ores and mining procedures. Results show that acidophilic algal colonization is dominated by Euglena mutabilis and Klebsormidium sp.. Abundance and distribution of both algae are related to different intensity of acid mine drainage (AMD) at each mining site. Mineral-alga interactions infl uence metal deposition at Valdarcas and probably contribute to iron mineral precipitation. Euglena mutabilis displayed a preference for schwertmannite-rich AMD precipitates, which may suggest a mineralogical control on algal colonization. Spatial distribution of E. mutabilis can be used to qualitatively assess water quality improvements along the effluent channel.