Response of macroinvertebrates functional feeding groups to agricultural activities in a rural river in North-Central Nigeria

Abstract

Freshwater bodies are being contaminated by the growing human population in many developing nations and one of the major contamination source is agricultural activities within the land used catchment. In this study the response of macroinvertebrates functional feeding group in response to agricultural activities in River Wanzum Niger state Nigeria was investigated. Four (4) sites were sampled base on anthropogenic impact in the river for a period of 24months (December 2021- November 2023). From the result of the physicochemical parameters measured, only turbidity and dissolved oxygen showed significant difference (p<0.05) between the sampling sites. All the physicochemical parameters measured in this study differs significantly (p<0.05) among the sampling months. A total of 2, 863 macroinvertebrates belonging to 33 families were identified. The family notonectidae was the most dominant taxa and the least dominant taxa were Teleganonidae and Hirudinidae. The macroinvertebrates were classified into shredders, collector-gatherers, collector-filterer, scraper and predators functional feeding group. There was significant difference (p<0.05) in abundance of the FFG as predators account for 72% abundance followed by scrappers 12%, collector-gatherer 8%, shredders 5% and the least FFG were the collector-filterer with 3% abundance in all the sampled sites. The CCA ordination plot has an eigen value of 0.047and 0.012 with 78.44% and 21.33% variance in dataset. The correlation between the functional feeding group and the physicochemical shows the shredders, collector-gatherer and collector-filterer were associated with site 1 and 4 which are the less perturbed station and were influenced by pH and dissolved oxygen. The scrapers were positively associated with CCA axis 2 which was influenced by temperature, depth, pH and nitrate in site 3 and the predators were negatively associated with CCA axis 2. Overall, this study shows that predators population increased with increased agricultural activities around river Wanzum.