The article describes the effects of channelization on selected water quality parameters and benthic macroinvertebrate assemblages in four Big Black River (Mississippi, USA) tributaries crossing the Natchez Trace Parkway [U.S. National Park Service (NPS)]. Two of the streams were unchannelized (Little Bywy Creek and McCurtain Creek), and two were channelized (Big Bywy Creek and Middle Bywy Creek). Lignite mining occurs in the headwaters of Little Bywy Creek and Middle Bywy Creek. During this 3-year study, benthic macroinvertebrates were collected monthly from all four streams using Hester-Dendy Multiple plate samplers, and enumerated taxonomically and functionally. Hypotheses were tested using analyses of variance. Relationships were determined using multivariate analyses. Relative abundances of mayflies (Ephemeroptera), stoneflies (Plecoptera), caddisflies (Trichoptera) and aquatic beetles (Coleoptera) were associated with moderate to high conductivity, alkalinity, pH, and dissolved oxygen. Hellgrammites (Megaloptera), midges, blackflies, and mosquitoes (Diptera), crayfish (Crustacea: Decapoda) and leeches (Annelida: Hirudinea) were associated with lower values for these parameters. These patterns reflected seasonal rather than spatial variation (i.e., among the streams). Invertebrate assemblage composition was similar among the four streams with respect to functional groups. Invertebrate relative abundances in the two channelized streams were approximately half those of the unchannelized streams. Macroinvertebrate species richness was greater in unchannelized streams. Environmental indices categorized all four streams as having fair to good condition.

Freshwater aquaculture is a prominent activity in Rawang sub-basin of the Selangor River. Despite the importance good water quality in daily life, there is limited study on the impact of aquaculture activities on water quality. This paper discusses water quality parameter status (pH, dissolved oxygen (DO), ammoniacal nitrogen, turbidity, total suspended solids (TSS), chemical oxygen demand (COD) and biochemical oxygen demand (BOD)) based on Water Quality Index (WQI) in the aquaculture-impacted Rawang sub-basin of Selangor River and develops the Inverse Distance Weighted (IDW) maps showing water quality status by using GIS (ArcGIS 10.2.1 software) in order to identify the potential aquaculture impacted sites. Seven river sampling sites were selected including Guntong (SR1), Guntong’s tributaries (SR2/control), Kuang (SR3 and SR7), Gong (SR4), Buaya (SR5), and Serendah (SR6) using random sampling techniques based on accessibility and proximity to aquaculture farms. Seven water quality parameters were recorded and analysed on a bi-monthly basis. Results revealed that Guntong, Kuang, Buaya and Serendah rivers had moderate water quality, whereas Gong River was significantly polluted. The control river recorded clean water quality status. One-way analysis of variance (ANOVA) showed that there were significant differences in all measured water quality parameters among sampling sites (P<0.05).