Water quality monitoring and aquatic insect communities as indicators of water quality in Maan River at agricultural highland, Dan Sai District, Loie Province

Abstract

Aquatic insects are generally recognized and widely applied to environmental monitoring as bioindicators of surface water quality. The objectives of this study were to monitor the water quality and investigate the diverse aquatic insects for environmental indicators in the Maan River in agricultural highland areas of Loie province. The water and aquatic insect samples were randomly collected at six sites upstream and downstream of the river during the rainy and winter seasons. The results revealed that the temperature and pH did not exceed the surface water quality standard of Thailand, excluding NO₃^-, pH, Cu, and Mn, which slightly exceeded the standard criteria. Besides, the water quality depended on the land use patterns of the areas and the concentration of pollutants (TS, TDS, Cu, Mn) tended to increase along the river. Additionally, the number of 426 aquatic insects were found from six families and nine species in Maan River. The most abundant family was Hemiptera (98%) followed by the Coleoptera family (4.93%) and Ephemeroptera (1.64%), respectively. This study demonstrated that the Shannon-Wieners diversity index, the Evenness index, and the Richness index were 1.644–1.655, 0.748–0.758, and 1.376–1.552, respectively. The dominant family was the Notoctidae, in which Anisop sp. and Limnogonus mastudai were mostly found. The study showed a difference in the diversity of aquatic insects between the rainy and winter seasons, and it increased the diversity of aquatic insects in the winter. The Biological Monitoring Working Party score (BMWP) reported a score of 7.000–0.733, which classified the water quality of the Maan River as rather good and adequate for aquatic biota.