ASSESSMENT OF PHYSICAL-CHEMICAL PARAMETERS AND EPHEMEROPTERA, PLECOPTERA AND TRICHOPTERA (EPT) RICHNESS INDEX ALONG RIVER KIMININI, TRANS-NZOIA COUNTY, KENYA

Abstract

Water plays a major role to human beings and their environs. These various uses range from domestic and industrial use, irrigation, recreational activities, transport, energy production and a habitat. Human activities such as agriculture, deforestation, destruction of riparian zones, poor waste disposal and animal watering have become rampant and adversely impact the river water quality. The study assessed the physical chemical parameters and Ephemeroptera, Plecoptera and Trichoptera (EPT) index richness along River Kiminini. Ten sampling stations were selected to reflect the different human activities that occur along the river. Using a multi parameter meter (YSI hydro lab model 650 MDS), physical and chemical water quality parameters were measured in situ and nutrients determined calorimetrically using standard analytical methods. Macro invertebrates were collected by kicking and dipping method and then sorted and preserved with 70% ethanol in the field for taxonomic resolution and richness counts in the laboratory, then, they were organized to order level using taxonomy key. The community attributes and physico-chemical parameters relationship were determined using Pearson correlation. Canonical correspondence analysis (CCA) described macro invertebrate community assemblage and the physico-chemical parameters relationships. Mean variations in physico-chemical parameters were tested using ANOVA and post hoc Duncan’s Multiple Test compared means among stations and sampling period. The analysis was done in R programming software version 4.4.0. The temperature ranged from 17.20±1.92℃ to 22.27±0.55℃, total solids dissolved, ranged from 90±10.00 mg/L to 100 ± 8.16 mg/L, electric conductivity ranged from 116.67 ± 22.90 µs/cm to 143.33 ± 28.13 µs/cm, pH ranged from 7.65± 0.08 to 8.2 ±0.14, nitrates ranged from 8.29± 2.02 mg/L to 14.40 ±2.04 mg/L and phosphates ranged from 0.69±0.17mg/L to 1.32 ± 0.56 mg/L. A total of 42 macro invertebrate genera were encountered with EPT dominating the upstream stations, Ephemeroptera taxa dominated followed by Diptera which increased downstream. Most physicochemical parameters determined the structure of macro invertebrates in the stream. The results indicated a decrease in EPT richness as nutrients levels increased downstream. The variation of EPT among station was influenced by the water quality in River Kiminini. The study recommends control of riparian land use and buffer zones to improve habitat quality of the stream and also continuous monitoring using EPT to assess the water quality.