Chironomid Mouthpart Deformity as an Early Signal to Assess the Impact of Dyeing Process Waste in an Aquatic Environment.

Weaving and dyeing, as both a household industry and in small factories, are very popular in Chonnabot District, Khon Kaen Province, Thailand. The dyes used are inorganic and organic substances that can cause high electrical conductivity (EC) and increase biochemical oxygen demand (BOD), affecting the aquatic food chain as well as human health. The mouthpart deformities of chironomid larvae, a member of benthic macroinvertebrates, occur when the developmental homeostasis is insufficient to compensate for environmental stress and has been proposed as a bioindicator of stress in aquatic environment. Studies on the effects of waste from the dyeing processes contaminating freshwater environments were conducted in August 2018. Water quality variables were measured, and benthic macroinvertebrates were investigated in five sampling sites in Kong Kaew Pond. The chironomid larvae were analyzed. The results demonstrate that sites which received dyeing process waste (K02, K03 and K05 sites) directly had higher EC and BOD, lower diversity index, lower evenness index, higher relative abundance of tolerate taxa (Chironomidae and air-breathing freshwater snails) and a higher percentage of chironomid mouthpart deformity than those of less polluted sites (K01 and K04 sites). Dissolved oxygen (DO) concentations were high in all sampling sites. A complete wastewater treatment system is recommended to treat dyeing process wastes before they are discharged and contaminate natural freshwater and to avoid hazards to human health. The combination of benthic macroinvertebrate diversity measurement and the incidence of mouthpart deformity in chironomid larvae may be useful as an early warning to indicate the ecological state of freshwater habitats. [ABSTRACT FROM AUTHOR]