IMPACT OF LAND USE CHANGE IN WATER QUALITIES, HABITAT QUALITIES AND BENTHIC MACROINVERTEBRATES ASSEMBLEGES IN KIPSINENDE RIVER, LAKE VICTORIA BASIN, KENYA

Abstract

Kipsinende River is being impacted by anthropogenic activities from upstream to downstream. The main pollution sources are agricultural activities, washing, bathing, logging, deforestation and grazing. The main objective of this study was to assess the impact of water and habitat qualities on the abundance and distribution of benthic macroinvertebrates in the Kipsinende River, Lake Victoria Basin. This study was conducted from November 2019 to March 2020 in the wet season at six sampling stations. Six water quality parameters were tested in situ, namely temperature, power of hydrogen, dissolved oxygen, total dissolved solid, conductivity and salinity. Other parameters namely: (ammonia, total suspended sold, nitrate, nitrite and soluble reactive phosphorus) were tested in the laboratory. The weighted arithmetic index method was used to assess the water quality index of the river. The benthic macroinvertebrates were sampled by using a kick net against water current and habitat quality was also evaluated by using rapid bioassessment protocols. Water quality data were analyzed by using descriptive statistics, Pearson’s correlation, One-way analysis of variance (ANOVA) and followed by Post hoc Turkey’s honest significance differences tests to know the significance differences between sites. Benthic macroinvertebrate assemblages were determined by, number of taxa, and the total number of individuals, by computing various indices. Canonical correspondence analysis was also applied to evaluate the relationship between benthic macroinvertebrate community and physicochemical water parameters. The current water quality parameters of the river were within acceptable standards, except for ammonia and soluble reactive phosphorus. Based on the weighted arithmetic index method the water quality status was unsuitable for drinking and fish culture. In this study 20,040 macroinvertebrate individuals were counted and identified, belonging to 13 orders, 48 families, and 68 genera. The relative abundance of Dipteran was 51% followed by Ephemeroptera 27%. The relative abundance of dipteran and taxon group of percent Ephemeroptera, Plecoptera and Trichoptera (% EPT) had inverse relation across study sites. The highest relative proportion (81.18%) for predators feeding group occurred in agricultural land use and the lowest (11.02) in the forested area. Whereas, gatherer (57.53%), shredders (4.16%), and scraper (11.9%) were highest in the forested site. All sites were strongly heterotrophic, non-performing, and presence of plentiful loading of fine particulate organic matter. Physico-chemical parameters affected the macroinvertebrates communities in the river. Further studies should be carried out along the river, covering different seasons, in order to establish the status of water quality of the entire river.