The effects of effluent from a closed mine and treated sewage on epilithic diatom communities in a Korean stream
Kim, Yeoun; Suk Choi, Jae; Sin Kim, Jin; Hee Kim, Sook; Chan Park, Jung; Won Kim, Han; Soon,
The effect of the effluent from a closed mine and the influx of treated sewage on the epilithic diatom community in a small stream in Korea was studied from February to December 2005. In the vicinity of the closed mine, the water was highly acidic (pH 3.4-4.2) and contaminated by high concentrations of heavy metals, and the epilithic diatom communities were characterized by low diversity and a very low number of taxa (< 10). the acidobiontic diatoms, Eunotia exigua, Pinnularia acidophila and P. subcapitata dominated at sites with high heavy metal concentrations and high acidity (pH 3.4-4.2) due to the effluent from the closed mine. High levels of teratologic forms of E. exigua were observed at the same sites. Achnanthes minutissima dominated when the concentration of heavy metals was lower and the water slightly acidic to alkaline (pH 5.0-7.3). In contrast, at sites not polluted by the effluent from the closed mine, there was a higher number of saproxenous taxa and a variety of dominant species, including Achnanthes lanceolata, Cocconeis placentula var. lineata, Gomphonema clevei, and Nitzschia fonticola. At sites affected by the influx of treated sewage, there was an increase in the species richness and relative percentage of saprophilous taxa. Achnanthes minutissima, Eunotia exigua, Pinnularia acidophila, P. subcapitata and P. sp. were found to be highly tolerant to the heavy metals (Cu, Fe, Mn and Zn). Among them, P. acidophila, Pleurosira laevis and Hydrosera whampoensis were recorded for the first time in Korea. Our results suggest that E. exigua, P. acidophila and P. subcapitata are good indicator species for acidification and P. laevis and H. whampoensis may be indicator species for eutrophic water.