Title: Influence of Riverine Wetlands on Benthic Macroinvertebrates in Ugandan Rivers
Author: Antoney Ndyasiima
Supervising Institution: BOKU University
Year: 2024
Abstract:
Benthic invertebrates are used as bioindicators of ecological health in developed countries. Its popularity has increased in developing countries including Uganda. This justifies the need to understand the local ecology of benthic macroinvertebrates for effective biomonitoring in these countries. Because many Ugandan rivers are associated with wetlands, this study investigates the influence of wetlands on benthic macroinvertebrates. Macroinvertebrate samples and physico-chemical parameters were taken from 17 sites (12 below wetlands and 5 without wetlands). Three hypotheses were set; (1) the concentration of dissolved oxygen, electrical conductivity, total dissolved solids, total suspended solids, turbidity, pH, nitrate, ammonium, and phosphate is lower in sites located downstream of wetlands (WP) and higher in those without wetlands (WA). At the same time, temperature is higher in WP than in WA. (2) WP have higher abundance of low oxygen tolerant taxa, shredders, collector gatherers, collector filterers, and predators. (3) Afrotropical indices (SASS5, TARISS, RS and ETHbios) would classify WP with lower ecological status than WA. Hypothesis 1 was rejected because despite trends observed in some parameters there were no significant differences between WP and WA. Hypothesis 2 was also rejected despite some trends in low and high saprobic taxa, Functional feeding groups (FFGs), and taxa abundance showed no significant differences. Hypothesis 3 was rejected because biotic scores showed no difference between WP and WA. However, given the observed trends in physio-chemical variables, wetlands are shown as both a sink and a source of material which could influence biotic communities. The study recommends a more robust and systematic approach to investigate the influence of riverine wetlands on macroinvertebrates considering a gradient of distance from the wetland, size of wetlands, slope, and seasons of sampling.
Keywords: Benthic macroinvertebrates, riverine wetlands, river types, biomonitoring