Contribution to the knowledge of the macroinvertebrate fauna of the streams of Kahuzi-Biega National Park, Democratic Republic of Congo

The Albertine Rift is one of Africa’s major biodiversity hotspots. However, the aquatic fauna of its western border in Democratic Republic of Congo (DRC) remains understudied and poorly characterised. Kahuzi-Biega National Park (KBNP) in DRC is a crucial link for biodiversity conservation of this hotspot; however, scientific studies of this rich biodiversity are scarce because of insecurity and harsh field conditions. In the current study, benthic macroinvertebrates communities and some environmental conditions were investigated in 10 rivers in the KBNP. Eighty-four morphospecies, belonging to 47 families and 12 orders, were sampled from 13 sites. The abundance and diversity of taxa within systematic groups varied across the study area. Spatial distribution of systematic groups was also analysed. The high morphospecies richness, characterised by the number of families and Shannon’s and Simpson’s Diversity Indices, recorded at some sites was probably owing to the diversity of substratum and undisturbed environmental conditions observed in these forested rivers. Conversely, some sites presented lower species richness, possibly because of unfavourable natural conditions

Diversité des macroinvertébrés benthiques des rivières du nord-est de l’île d’Idjwi, République Démocratique du Congo

The purpose of this study was to determine the diversity of benthic macroinvertebrates and the quality of rivers in the North East of Idjwi Island, Democratic Republic of the Congo. Macroinvertebrates were collected from June to September 2017 in 4 rivers: Nyamisheke, Tama, Miriri and Nyahonga. Eight sampling trips were conducted and 32 samples taken in 20 sites (5 sites per river) using a dip net. The results obtained revealed 5531 specimens captured in total. These macroinvertebrates are distributed in 3 phyla (arthropods, mollusks and annelids), 5 classes (insects, crustacea, gastropods, oligochaetes and achaetes), 11 orders and 43 families. Their relative abundance varies according to the rivers: Nyamisheke (31%), Tama (28%), Miriri (25%) and Nyahonga (16%). The Shannon index calculated variates between 1.4 and 2.6 and reflects a disproportionate diversity across sites. Overall, the stations located upstream are more diverse than those located downstream. However, the Global Normalized Biological Index (GNBI) values indicate significant pollution in the four rivers, which is a consequence of the multiple anthropogenic activities (overexploitation of sand, fishing, washing up, bathing and presence of agricultural organic waste) in and around these rivers. This excessive pollution negatively impacts the diversity and abundance of macroinvertebrates in these sites. Therefore, measures should be taken by the competent structures to discourage these anthropic activities in order to preserve the health of these river ecosystems and of human populations

Evaluation of Schistosoma mansoni cercaricidal activity of Solamargine a steroid glycoalkaloid from Solanum syzybrilifolium

ABSTRACT- The cercaricidal activity of a mixed solamargine (1) and β-solamarine (2) solution were directly tested against Schistosoma mansoni cercariae and a time-concentration relationship was observed; the concentrations needed to kill all cercariae (LC100) within 10 min of exposure were 0.01 mg/mL. Mixed solamargine (1) and β-solamarine (2) solution have a high level of cercaricidal activity against free swimming cercariae and it seems to be ecologically safe, since it is known to have very low toxicity to fish. The possible use of such sublethal concentrations in schistosomiasis transmission sites as an oriented promising technique to control this parasite and to minimize or prevent water pollution with pesticides

Évaluation comparée de la pollution des rivières Kahuwa et Mpungwe par l'utilisation des macroinvertébrés benthiques

The environmental disturbances due to human activities increase in many countries and draw away various types of water pollutions. These pollutions are important and cause a serious regional and local problem in public health. In Bukavu and the surrounding areas, there are enough aquatic systems which shown signs of pollution resulting from human activities. In order to estimate the impact of human activities on the water quality within rivers, this study was carried out in the Kahuwa river, located in Bukavu, urban area, and Mpungwe river, located in rural area, so far at 20 Km of Bukavu. The physico-chemical and biological parameters from 7 sampling sites of both rivers (4 in the Kahuwa river and 3 in the Mpungwe river) was assessed in-situ and in the laboratory of the Lwiro Research Centre in Natural Sciences, Democratic Republic of Congo. According to the results obtained, Kahuwa river is more polluted than Mpungwe river during the period of this study. The physico-chemical parameters reach from upstream to downstream in both rivers Kahuwa and Mpungwe. The nutrients (phosphorus and nitrogen) increased in the sites which is intensively anthropogenic activities (Kibonge, Cheche and SNCC for the Kahuwa river and Murhesa factory for the Mpungwe river). The organic pollution is intensified by anthropogenic used. In general the physico-chemical water quality parameters show a significant difference (p <0,05). The major sources of the high levels of nutrients are in general the waste dumping, the mechanical erosion of rocks and soil particles due to agriculture blocks, the septic hole, the domestic sewers and industrial effluents in the water bodies, which are not regulated. The taxanomic diversity presents fewer species in Kahuwa river (14) than Mpungwe river (31). The difference is significant between both rivers (p <0,001) as regards species richness. The water quality was found to be the major factor contributing to the species richness of Kahuwa river and the impact of agriculture land use in the catchment on benthic macroinvertebrates distribution is significant. The several diversity (Shannon-Weaver, Hilsenhof, Simpson and Maragelf Indices) and pollution biotic macroinvertebrates indices show variations of the population diversity between the samples sites and rivers. In order to reduce the organic materials loading from Kahuwa micro catchment and Lake Kivu, there is need of erosion prevention and sanitation program (VIP toilet)

Évaluation comparée de la pollution des rivières Kahuwa et Mpungwe par l'utilisation des macroinvertébrés benthiques

Les perturbations environnementales dues aux activités anthropogéniques se multiplient dans de nombreuses régions du globe et entraînent diverses pollutions des eaux. Ces pollutions sont importantes et causent un grand problème régional et local de santé publique. Dans la ville de Bukavu et ses environs, il y a suffisamment des systèmes aquatiques qui présentent des signes de pollution résultant des activités humaines. En vue d’estimer l’impact des activités anthropogéniques sur l’environnement des rivières, cette étude a été menée sur les rivières Kahuwa, située en milieu urbain, la ville de Bukavu et Mpungwe, située en milieu rural, à 20 km de la même ville. Des analyses physico-chimiques et biologiques réalisées in situ et au laboratoire du Centre de recherche en sciences naturelles de Lwiro, République Démocratique du Congo dans 7 sites des deux rivières (4 dans la rivière Kahuwa et 3 dans la rivière Mpungwe). Les résultats obtenus ont montré que la rivière Kahuwa est plus polluée que la rivière Mpungwe durant la période d’étude. Les paramètres physico-chimiques étudiés varient de l’amont en aval dans les deux rivières. Les concentrations en nutriments (phosphore et azote) sont en générales très élevées dans les sites où les activités anthropogéniques sont intenses (Kibonge, Cheche et SNCC pour la rivière Kahuwa et Usine Murhesa pour la rivière Mpungwe). Ces concentrations montrent bien que la pollution organique est intensifiée par les apports anthropogéniques. En général, la différence des concentrations des paramètres physico-chimiques dans les deux rivières est significative (p < 0,05). Les sources de ces nutriments sont généralement les effluents domestiques, les fosses septiques, les érosions provenant de l’agriculture, les rejets des industries et rejets des déchets divers qui ne sont pas réglementés. Les sites de la rivière Kahuwa ont moins d’espèces (14) que les sites de la rivière Mpungwe (31). La différence est significative entre les deux rivières (p < 0,001) en ce qui concerne la richesse spécifique. Cette faible richesse spécifique de la rivière Kahuwa serait due à la dégradation de la qualité des eaux comme déjà observée dans les facteurs physico-chimiques. En effet, il a été remarqué que l’utilisation des terres dans le bassin versant avait un impact significatif sur la distribution des macroinvertébrés. L’indice de Shannon et Weaver H’, l’indice biotique de pollution des macroinvertébrés l’indice de Hilsenhof, l’indice de Simpson et l’indice de Margalef montrent des variations entre les sites de prélèvement et les rivières. Des mesures de lutte antiérosive dans le bassin versant de la rivière Kahuwa et de mesures d’éco-sanitation (utilisation des toilettes VIP) sont recommandées pour diminuer la quantité des matières organiques apportées par la rivière Kahuwa dans le Lac Kivu.The environmental disturbances due to human activities increase in many countries and draw away various types of water pollutions. These pollutions are important and cause a serious regional and local problem in public health. In Bukavu and the surrounding areas, there are enough aquatic systems which shown signs of pollution resulting from human activities. In order to estimate the impact of human activities on the water quality within rivers, this study was carried out in the Kahuwa river, located in Bukavu, urban area, and Mpungwe river, located in rural area, so far at 20 Km of Bukavu. The physico-chemical and biological parameters from 7 sampling sites of both rivers (4 in the Kahuwa river and 3 in the Mpungwe river) was assessed in-situ and in the laboratory of the Lwiro Research Centre in Natural Sciences, Democratic Republic of Congo. According to the results obtained, Kahuwa river is more polluted than Mpungwe river during the period of this study. The physico-chemical parameters reach from upstream to downstream in both rivers Kahuwa and Mpungwe. The nutrients (phosphorus and nitrogen) increased in the sites which is intensively anthropogenic activities (Kibonge, Cheche and SNCC for the Kahuwa river and Murhesa factory for the Mpungwe river). The organic pollution is intensified by anthropogenic used. In general the physico-chemical water quality parameters show a significant difference (p <0,05). The major sources of the high levels of nutrients are in general the waste dumping, the mechanical erosion of rocks and soil particles due to agriculture blocks, the septic hole, the domestic sewers and industrial effluents in the water bodies, which are not regulated. The taxanomic diversity presents fewer species in Kahuwa river (14) than Mpungwe river (31). The difference is significant between both rivers (p <0,001) as regards species richness. The water quality was found to be the major factor contributing to the species richness of Kahuwa river and the impact of agriculture land use in the catchment on benthic macroinvertebrates distribution is significant. The several diversity (Shannon-Weaver, Hilsenhof, Simpson and Maragelf Indices) and pollution biotic macroinvertebrates indices show variations of the population diversity between the samples sites and rivers. In order to reduce the organic materials loading from Kahuwa micro catchment and Lake Kivu, there is need of erosion prevention and sanitation program (VIP toilet)