PHYSICOCHEMICAL PARAMETERS AND MACROINVERTEBRATE FUNCTIONAL FEEDING GROUPS IN RIVER CHANCHAGA, MINNA, NIGER STATE

Abstract

ABSTRACT Functional group classification is useful in examining ecological relevant community-level associations within any lotic ecosystem. To examine the functional structure of aquatic biota in River Chanchaga, Minna, Niger State North Central Nigeria, macroinvertebrate samples along with water samples were collected from four ecologically distinct stations monthly for ten (10) months January-October 2019. Physicochemical parameters of the water were analysed using standard methods while macroinvertebrate taxa recorded were allocated to functional feeding groups using published literature and examination of gut contents. Findings on the physicochemical parameters of the water revealed that temperature, depth and conductivity were highest in station 4 28.43±0.52 ¬0C, 0.48±0.06 m and 10.14±0.35 µ/cm respectively while transparency, dissolved oxygen and biochemical oxygen demand were highest in station 1 17.68±2.28 mg/L, 5.65±0.54 mg/L and 4.80±0.67 mg/L respectively. The flow velocity, pH, sulphate and phosphate values were highest in station 3 0.38±0.14 mg/L, (7.57±0.41 mg/L, 27.04±1.74 mg/L and 1.51±0.18 mg/L. Clearly, the spatial distribution of most species reflected morphological and trophic suitability to particular environmental conditions. Predators and collector gatherers (Odonata and Ephemeroptera) dominated the functional groups at stations 1, 2, and 3. Scrappers particularly the Thiaridae were highest at stations 3 and 4. Shredders were few and restricted to stations 1 and 2 only. The macroinvertebrate assemblage reveal a total of 2707 individuals from 25 families belonging to 11 orders of macroinvertebrates were recorded during the study period in River Chanchaga (Table 4.2). A total of 180 (6.6 %), 165 (6.10 %), 437 (16.14 %) and 1925 (71.11 %) individuals were recorded for Stations 1, 2, 3and 4 respectively. The majority of taxa encountered in station 1 were those that survive only in water which are unperturbed, while it was observed that those that were more tolerant to pollution increases along the river course as the rate of pollution increased, this indicate that the water will pose a health risk if the rate of pollution is not controlled. Attempt to conserve macroinvertebrates biodiversity will help maintain high water quality in the river.