Abstract:
The growing dependence on lotic aquatic ecosystems for agriculture, construction, water obstruction among others is posing degradation of the quality of water in these ecosystems. Traditionally, water quality in water bodies was assessed using only physico-chemical means but recent studies focus on combination of biota and physico-chemical parameters to assess water quality in streams and lakes. Macroinvertebrates are aquatic dwelling animals that lack backbones of sizes >0.5mm that live on rocks, logs, sediments and detritus during whole or part of their lives.
This study investigated both spatial and temporal variation in macro-invertebrate communities and physico-chemical parameters of River Nyakomisaro. Five sampling sites were selected and physico-chemical parameters were determined in situ using a water quality multi-parameter meter model 85 – 15 ft YS1 while macroinvertebrate samples were collected using kick sampling method, preserved and taken to laboratory for identification. Minitab statistical software was used to test for macroinvertebrates abundance variance between the stations and months, where means were significant post hoc analysis was carried out using Tukey test. Pearson correlation in SPSS computer program was used to determine the association of macroinvertebrate abundance to physico-chemical parameters. Principle Component Analysis was used to determine physico-chemical features relationship to macroinvertebrates variation. In the present study, 22 taxa of macroinvertebrates were recorded. Among these, Diptera had the highest diversity distribution and abundance in station 4 and in the month of August while Ephemeroptera and trichoptera had high diversity, distribution and abundance in station 1 and the month of September. Generally, there were significant differences (P<0.05) in diversity, distribution and abundance of macroinvertebrates. The results established that macroinvertebrates communities responded to changes in the physico-chemical features. Authorities responsible for safeguarding the environment should put in place measures and enforce laws of aquatic environment conservation for sustainability of the water resource.
