Distribution of Astomatia Schewiakoff, 1896 and Hysterocinetidae Diesing, 1866 (Ciliophora, Oligohymenophora) along the digestive tract of Alma emini (Oligochaete, Glossoscolecidae) is correlated with physico-chemical parameters

International audienceThe paper demonstrates the influence of physico-chemical parameters on the distribution of endocommensal ciliates through the gut of the earthworm Alma emini. We measured physico-chemical parameters of the intestinal liquid extracted with the vacuum aspiration technique and concomitantly recorded biological parameter (species abundance). Furthermore, correlation analysis between physico-chemical parameters and biological parameter was performed in different compartments. In the foregut, among the eleven species of Astomatia recorded, correlation was significant between Metaracoelophrya intermedia, Coelophrya roquei and Water Content (WC = 46.94 ± 7.77%). In the midgut, among the nine species of Hysterocinetidae recorded, a significant correlation was observed between Metaptychostomum ebebdae, Ptychostomum macrostomum and Electric Conductivity (EC = 84.55 ± 12.94 μS/ cm). In the same compartment, a significant correlation was also observed between Ptychostomum macrostomum and Total Dissolved Substance (TDS = 16.20 ± 3.46%). In the hindgut, eight species of Astomatia were found, among which significant correlation was obtained between Coelophrya roquei and Hydrogen potential (pH = 7.35 ± 0.16). In the same compartment, taking into account the eleven species of Hysterocinetidae recorded, a significant correlation was also obtained between Ptychostomum macrostomum and pH; Ptychostomum commune and WC (28.84 ± 3.97%). These results suggest that each part of the digestive tract of A. emini can be considered as a set of natural microhabitats in which certain physico-chemical factors generate ecological niches suitable for one or another group of species

Les crustacés aquatiques souterrains d’Afrique et de Madagascar : bilan et enjeux

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Assessment of the impact of the biological larvicide VectoMax G: Combination of Bacillus thuringiensis and Lysinibacillus sphaericus on non-target aquatic organisms in Yaoundé-Cameroon

There has been a renewed interest for larviciding during the recent decade. Although biological larvicides are considered not to be harmful to non-target organisms, there is still not sufficient data on the effect of new long-lasting larvicide formulations such as VectoMax G combining and on the environment especially on non-target organisms. The present study aimed to assess the possible influence of VectoMax G on the diversity and abundance of the aquatic fauna cohabiting with mosquito larvae in breeding habitats during a larviciding trial in the city of Yaoundé. Twelve districts of the city of Yaoundé divided into 6 intervention and 6 control sites were chosen for the study. In each district 4 semi-permanent or permanent aquatic habitats were followed. VectoMax G application was done once every two weeks during 6 months and aquatic organisms were collected 48 h after each treatment. All collected organisms were brought to the laboratory for identification. Physico-chemical parameters were recorded as well. A high diversity of the zooplankton was recorded in the intervention areas with 28 species collected against 14 species in the control areas. Cladocerans were the most represented group in both sites while Ostracods were found only in control sites. A total of 19 macro-invertebrates species were recorded in the control areas vs 16 species in the intervention areas. Gasteropods were the most represented groups of macro-invertebrates. Vertebrates such as larvivorous fishes and amphibians larvae were also found in approximately similar densities in both sites. The study indicated no significant influence of larviciding with VectoMax G on the diversity and abundance of the non-target aquatic fauna in the city of Yaoundé. [Abstract copyright: © 2023 Published by Elsevier Ltd.

First evidence of the presence of the freshwater amphipod genera Gammarus and Pseudoniphargus in Central and Western Africa

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Bioindicateurs des milieux aquatiques lotiques en République Centrafricaine : Macro-invertébrés benthiques et pression anthropique du cours d'eau NGuitto.

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First evidence of the presence of the freshwater amphipod genera Gammarus and Pseudoniphargus in Central and Western Africa

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Gestion durable des ressources en eau, biodiversités de la faune aquatique souterraine et du zooplankton de trois bassins versants d’Afrique (Afrique centrale et de l’ouest) : impacts des perturbations anthropiques, climatiques et de la pollution. Premiers résultats.

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Bioindicateurs des milieux aquatiques lotiques en République centrafricaine : macro-invertébrés benthiques et pression anthropique du cours d’eau Nguitto

International audienceThis study of benthic macroinvertebrates in Central African Republic (CAR) aimed at determining the structure of their assemblages in relation to the physico-chemical quality of the Nguitto River. The data were collected monthly from May 2015 to April 2016, in five selected sampling points on the Nguitto River. The physico-chemical parameters were measured using standard methods while the benthic macrofauna was collected using a handnet sampler of 150 µm mesh size on a total area of about 6 m2 per station. The physico-chemical analysis revealed a satisfactory water quality in the forest belt and an eutrophication in the urban area. A number of 2052 individuals of benthic macroinvertebrates belonging to 71 taxa were identified and counted. Arthropods was the most diversified (53 taxa) and the most abundant (80.75 %) taxonomic group, followed by molluscs (17 taxa; 23.94 %) and annelids (1 taxon; 0.24 %). The sampling points in the forest belt, which exhibit the lowest anthropogenic activity, were composed mostly of arthropods and dominated by insects. In the urban zone, the strong abundance of molluscs and the presence of annelids indicated an anthropogenic pressure and the usefulness of invertebrates as bioindicators of waste waters in this area.Cette étude sur les macro-invertébrés benthiques en République Centrafricaine (RCA) visait à déterminer la structure de leurs peuplements en relation avec la qualité physico-chimique de l’eau dans le ruisseau Nguitto. Les données ont été collectées de mai 2015 à avril 2016 avec une fréquence mensuelle dans cinq stations d’échantillonnage de l’amont vers l’aval du cours d’eau. Les analyses physico-chimiques ont été effectuées par des méthodes standards tandis que la macrofaune benthique a été récoltée à l’aide d’un filet troubleau avec un vide de maille de 150 µm sur une superficie totale d’environ 6 m2 par station. Les analyses physico-chimiques ont révélé une qualité de l’eau satisfaisante à bonne dans la zone forestière et une eutrophisation en zone urbaine. Au total, 2052 macro-invertébrés benthiques, répartis en 71 taxa, ont été identifiés et dénombrés. Les arthropodes sont les plus diversifiés avec 53 taxa et les plus abondants (80,75 % de l’effectif total), suivis des mollusques (17 taxa ; 23,94 %) et des annélides (1 taxon ; 0,24 %). Les stations en zone forestière sont composées en majorité d’arthropodes dominés par les insectes confirmant un faible niveau de perturbation par les activités anthropiques. En zone urbaine, la forte abondance des mollusques et la présence des annélides indiquent une pression anthropique plus forte, illustrant l’intérêt de ces organismes comme bioindicateurs des petits cours d’eau dans ce pays

Bioindicateurs des milieux aquatiques lotiques en république centrafricaine : macro-invertébrés benthiques et pression anthropique du cours d’eau Nguitto

Bioindicators of running freshwaters in Central African Republic : benthic macroinvertebrates and anthropogenic stress in the Nguitto Stream. This study of benthic macroinvertebrates in Central African Republic (CAR) aimed at determining the structure of their assemblages in relation to the physico-chemical quality of the Nguitto River. The data were collected monthly from May 2015 to April 2016, in five selected sampling points on the Nguitto River. The physico-chemical parameters were measured using standard methods while the benthic macrofauna was collected using a handnet sampler of 150 μm mesh size on a total area of about 6 m² per station. The physico-chemical analysis revealed a satisfactory water quality in the forest belt and an eutrophication in the urban area. A number of 2052 individuals of benthic macroinvertebrates belonging to 71 taxa were identified and counted. Arthropods was the most diversified (53 taxa) and the most abundant (80.75 %) taxonomic group, followed by molluscs (17 taxa ; 23.94 %) and annelids (1 taxon ; 0.24 %). The sampling points in the forest belt, which exhibit the lowest anthropogenic activity, were composed mostly of arthropods and dominated by insects. In the urban zone, the strong abundance of molluscs and the presence of annelids indicated an anthropogenic pressure and the usefulness of invertebrates as bioindicators of waste waters in this area.Cette étude sur les macro-invertébrés benthiques en République Centrafricaine (RCA) visait à déterminer la structure de leurs peuplements en relation avec la qualité physico-chimique de l’eau dans le ruisseau Nguitto. Les données ont été collectées de mai 2015 à avril 2016 avec une fréquence mensuelle dans cinq stations d’échantillonnage de l’amont vers l’aval du cours d’eau. Les analyses physico-chimiques ont été effectuées par des méthodes standards tandis que la macrofaune benthique a été récoltée à l’aide d’un filet troubleau avec un vide de maille de 150 μm sur une superficie totale d’environ 6 m² par station. Les analyses physico-chimiques ont révélé une qualité de l’eau satisfaisante à bonne dans la zone forestière et une eutrophisation en zone urbaine. Au total, 2052 macro-invertébrés benthiques, répartis en 71 taxa, ont été identifiés et dénombrés. Les arthropodes sont les plus diversifiés avec 53 taxa et les plus abondants (80,75 % de l’effectif total), suivis des mollusques (17 taxa ; 23,94 %) et des annélides (1 taxon ; 0,24 %). Les stations en zone forestière sont composées en majorité d’arthropodes dominés par les insectes confirmant un faible niveau de perturbation par les activités anthropiques. En zone urbaine, la forte abondance des mollusques et la présence des annélides indiquent une pression anthropique plus forte, illustrant l’intérêt de ces organismes comme bioindicateurs des petits cours d’eau dans ce pays.Ngoay-Kossy Jean Clair, Zébazé Togouet Serge Hubert, Wango Solange Patricia, Bolevane Ouantinam Serge Florent, Tchakonté Siméon, Piscart Christophe. Bioindicateurs des milieux aquatiques lotiques en république centrafricaine : macro-invertébrés benthiques et pression anthropique du cours d’eau Nguitto. In: Revue d'Écologie (La Terre et La Vie), tome 73, n°4, 2018. pp. 603-616