Author(s) :

Clément Kilingwa Munganga, Willy Swana Lusasi, Santos Mutanda Kavumbu, John Makiadi Tembeni, José Mayi Munene Mbimbi, Victor Kiamfu Pwema.

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Abstract :

This study aims to examine the spatiotemporal structure of benthic macroinvertebrate populations in the Bibwa River in the city of Kinshasa, Democratic Republic of Congo, in order to evaluate the distribution of macrofauna taxa in this river in relation to abiotic variables. The research was conducted from June 2023 to January 2024, during which four sampling campaigns were carried out at five stations along this river (three replicates per station, sampled area of 0.09 m², mesh size 1 mm). To collect macroinvertebrates, a kick net was used. Physicochemical parameters were measured in situ using a multiparameter probe, followed by laboratory analysis for other parameters. Statistical analyses included non-parametric tests (Kruskal-Wallis), Spearman correlations, principal component analysis, and canonical correspondence analysis. The results obtained show a total of 317 benthic macroinvertebrate specimens inventoried, of which 204 were during the rainy season and 113 during the dry season, distributed into 3 classes (Insects, Mollusks, and Clitellates), 6 orders (Coleoptera, Hemiptera, Diptera, Odonata, Gastropoda, and Haplotaxida), and 10 families (Hydrophilidae, Dytiscidae, Nepidae, Naucoridae, Chironomidae, Coenagrionidae, Libellulidae, Lymnaeidae, Lumbricidae and Tubificidae). No taxa from the orders Ephemeroptera, Plecoptera, or Trichoptera (EPT) were identified, which constitutes an indicator of ecological disturbance.Z Regarding the variation of the physicochemical parameters of the water, it is observed that the water of the Bibwa River is warm and has a temperature ranging from 24.7±0.24°C to 26.1±0.28°C. The concentration of ions in solution is low; conductivity ranges from 2.66±0.44 to 48.66±7.55 μS/cm, while turbidity ranges from 1.33±1.33 to 24.33±3.77 NTU. Low concentrations of nitrate (ranging from 2.88±0.17 to 4.18±0.46 mg/L) and phosphate (ranging from 0.25±0.01 to 0.4±0.01 mg/L) are noted. Statistical analyses reveal significant seasonal differentiation of communities (p = 0.008) and a major influence of conductivity (ρ = 0.89 with turbidity) and turbidity on taxon distribution. The Shannon diversity indices (1.5 to 2.0) and Piélou's Equitability (0.82 to 0.95) indicate moderate diversity and a favorable ecological condition, allowing macroinvertebrates, particularly pollution-sensitive families, to thrive in this ecosystem. The presence of Chironomidae and Tubificidae suggests moderate anthropogenic disturbance, requiring management measures.

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