Drivers of Benthic Macroinvertebrate Assemblages in Equatorial Alpine Rivers of the Rwenzoris (Uganda)

Abstract

The Sub-Saharan alpine freshwater biodiversity is currently impacted by human settlements, climate change, agriculture, and mining activities. Because of the limited biodiversity studies in the region, a better understanding is needed of the important environmental variables affecting macroinvertebrate assemblages. In this paper, macroinvertebrate diversity responses to 18 environmental variables were studied at 30 sites along unique Rwenzori rivers at the equator in Uganda. We hypothesized that anthropogenic disturbance and local environmental variables affect macroinvertebrate diversity, irrespective of altitudinal gradients. Based on altitude and climate, the sites were subdivided into three altitude groups consisting of 10 sites each: upstream (US) 1400–1600 m.a.s.l.; midstream (MS) 1091–1399 m.a.s.l., and downstream (DS) 900–1090 m.a.s.l. A total of 44 macroinvertebrate families and 1623 individuals were identified. The macroinvertebrate diversity patterns were influenced by temperature, altitude, and latitude. Regression analysis revealed that temperature and nickel, were negative predictors of taxa richness. Nickel, which is released by mining activity, is detrimental to aquatic communities in Sub-Saharan alpine ecosystems. Significant longitudinal variation in macroinvertebrate diversity was observed between the sites, which were also affected by mineral and temperature gradients. Our study highlights the need for long-term monitoring in this region to detect and reduce the threats to river biodiversity from anthropogenic activity.

Rwenzori Score (RS): A Benthic Macroinvertebrate Index for Biomonitoring Rivers and Streams in the Rwenzori Region, Uganda

“…Large areas have been designated as protected areas for national parks. The main anthropogenic stresses on the water bodies originate from agriculture, mining, and the effluent from industrial and urban areas [67]. Severe natural disturbances occur during the rainy season, especially from flash flooding.…”

“…All reference sites, except for eight sites, were of excellent water quality with the remnant sites of good quality. In contrast, the none-reference sites were assessed as poor and fair sites, and were characterised by high levels of disturbance due to the animal watering points and direct disposal of human and industrial wastes into the river [67]. Therefore, affirming that several of the protected area sites are negatively influenced by anthropic activities such as rapid urbanization and unplanned human settlements, in particular via nutrient enrichment.…”

Beta diversity of aquatic macroinvertebrate assemblages associated with leaf patches in neotropical montane streams

“…Therefore, the aim of this study was to assess the variation in taxonomic composition (measured as stream-level beta diversity) among CR stream sites. Given that the turnover component made up most of the beta diversity in other Cerrado studies (e.g., Castro et al, 2020;Ligeiro et al, 2010;Pompeu et al, 2019) and that altitude and elevation range were the main drivers for structuring benthic macroinvertebrate assemblages (Gueuning et al, 2017;Musonge et al, 2020), we proposed two hypotheses. (a) Taxa replacement (i.e., turnover) should be the main reason for differences in benthic macroinvertebrate assemblages among stream sites; we predicted that turnover would be higher than nestedness in all streams.…”

Benthic Macro Invertabrate Diversity of Tropical River Kolar, from Nagpur, (M.S.), India

“…Diversity pattern of macrozoobenthic fauna ensures a wide range of sensitivities to change in both water quality and habitats (Hellawell, 1986 andAbel, 1989). Both geographical and physicochemical variables influence the overall macroinvertebrate diversity in tropical rivers (Musonge et al, 2020).…”