Mentum deformities in Chironomidae communities as indicators of anthropogenic impacts in Swartkops River
Physics and Chemistry of the Earth
Unilever Centre for Environmental Water Quality, Institute for Water Research, Rhodes University, P.O. Box 94, Grahamstown, South Africa
Swartkops River is located in Eastern Cape of South Africa and drains a heavily industrialised catchment and has suffered deterioration in water quality due to pollution. Water quality impairment in the Swartkops River has impacted on its biota. Deformities in the mouth parts of larval Chironomidae, particularly of the mentum, represent sub-lethal effects of exposure to pollutants, and were therefore employed as indictors of pollution in the Swartkops River. Chironomid larvae were collected using the South African Scoring System version 5 (SASS5) protocol. A total of 4838 larvae, representing 26 taxa from four sampling sites during four seasons were screened for mentum deformities. The community incidences of mentum deformity were consistently higher than 8% at Sites 2-4, indicating pollution stress in the river. Analysis of variance (ANOVA) conducted on arcsine transformed data revealed that the mean community incidence of mentum deformity was significantly higher (p<0.05) at Site 3. ANOVA did not reveal statistically significant differences (p>0.05) between seasons across sites. Severe deformities were consistently higher at Site 3. Strong correlations were found between deformity indices and the concentrations of dissolved oxygen (DO), total inorganic nitrogen (TIN), orthophosphate-phosphorus (PO 4-P), electrical conductivity (EC) and turbidity. © 2012 Elsevier Ltd.
Anthropogenic impacts; Chironomid larvae; Chironomidae; Deformities; Electrical conductivity; Inorganic nitrogen; Sampling site; Scoring systems; South Africa; Statistically significant difference; Strong correlation; Water quality impairment; Analysis of variance (ANOVA); Catchments; Deformation; Electric conductivity; Phosphorus; Pollution; Rivers; Turbidity; Water quality; River pollution; anthropogenic effect; bioindicator; community structure; concentration (composition); dissolved oxygen; electrical conductivity; fly; inorganic nitrogen; orthophosphate; pollution exposure; river pollution; sublethal effect; taxonomy; turbidity; variance analysis; water quality; Eastern Cape; South Africa; Swartkops River; Chironomidae