The Affon River is one of the important rivers of the Ouémé River whose benthic diversity remained unknown. The present study aims to make the relationship between macroinvertebrates and physico-chemical par...The Affon River is one of the important rivers of the Ouémé River whose benthic diversity remained unknown. The present study aims to make the relationship between macroinvertebrates and physico-chemical parameters to access water quality of the Affon River. The measurement of physico-chemical parameters (temperature, pH, conductivity, transparency, depth and TDS, dissolved oxygen, ammonium, nitrite and phosphate) and the sampling of macroinvertebrates using a Surber net were carried out during floods in eight stations. A principal component analysis (PCA) and canonical correspondence analysis (CCA) were used. The indices of Shannon, Piélou, Simpson, Hilsenhoff, EPT and EPT/Chironomidae were used to assess the level of water pollution. The study identified 9755 macroinvertebrates divided into 4 classes, 14 orders and 49 families. Pollution-sensitive families (14 families) that are organic pollution indicators, as well as pollution-tolerant families (Chironomidae, Limnaeidae, Bithynidae, Physidae) were captured. Chironomidae were the most predominant and abundant family (FO = 100%). The predominance of Chironomidae coupled with the rarity of the Ephemeroptera, Trichoptera and Plecoptera would reflect the poor quality of the Affon River waters. The principal components analysis yielded groups of associations: The first group of stations Taneka 2 and 3 characterized by high values of ammonium and phosphate;and low values of conductivity and TDS;the second group of Tanéka 1 and Kolokondé 1 stations with low values of pH, transparency, ammonium and phosphates;and the third group of stations Kolokondé 2, Kpébouko1, Kpébouko 2 and Affon marked by high values of conductivity, TDS, transparency, depth and temperature. The canonical correspondence analysis revealed a strong positive correlation between Nemouridae and ammonium as well as between Perlidae, Taeniopterygidae, Ephemeridae, Heptageniidae, Isonychiidae, Elmidae and phosphate. This study is a crucial step for any management and monitoring of this river.展开更多
The present study was conducted in the commune of Kérou in North Benin to measure the bioavailability of agricultural pesticides heavily used in the production of cotton on snails. The test was conducted in peasa...The present study was conducted in the commune of Kérou in North Benin to measure the bioavailability of agricultural pesticides heavily used in the production of cotton on snails. The test was conducted in peasant environment in two villages of the commune. In each site, there are three cages containing 6 snails each. The snails are exposed to soil and plants without special protection and are therefore exposed to environmental conditions. Firstly it’s to evaluate the presence or absence of agricultural pesticides in the viscera of snails after exposure. Secondly it consists to compare the different doses found in the viscera of snails in the different sites. And finally it’s to evaluate the effect of the toxicity of the pesticides on the reproduction of snails. The tests consisted of placing steel cages in the two experimental sites. In each site, there are three cages containing 6 snails each. Snails are exposed to soil and plants without special protection and are therefore exposed to environmental conditions. The observations were made in order to establish a study of transfer kinetics. After the analysis of the data, it appears generally that the accumulation of mineral elements highlighted is not proportional to the mineralogical composition of the soil in which the snail is exposed. Total nitrogen and nitrate were significantly accumulated in the flesh of site 2 snails compared to site 1 snails. These different measures show the bioavailability of soil minerals for living organisms. Accumulations are not necessarily accompanied by toxic effects in terms of survival for snails after 28 days of exposure. However, the absence of immediate toxic effect on snails does not imply a lack of effect in food chains due to the trophic availability of contaminants. The use of snails as bio-indicator of soil quality has therefore proved relevant in the context of soils polluted by minerals.展开更多
文摘The Affon River is one of the important rivers of the Ouémé River whose benthic diversity remained unknown. The present study aims to make the relationship between macroinvertebrates and physico-chemical parameters to access water quality of the Affon River. The measurement of physico-chemical parameters (temperature, pH, conductivity, transparency, depth and TDS, dissolved oxygen, ammonium, nitrite and phosphate) and the sampling of macroinvertebrates using a Surber net were carried out during floods in eight stations. A principal component analysis (PCA) and canonical correspondence analysis (CCA) were used. The indices of Shannon, Piélou, Simpson, Hilsenhoff, EPT and EPT/Chironomidae were used to assess the level of water pollution. The study identified 9755 macroinvertebrates divided into 4 classes, 14 orders and 49 families. Pollution-sensitive families (14 families) that are organic pollution indicators, as well as pollution-tolerant families (Chironomidae, Limnaeidae, Bithynidae, Physidae) were captured. Chironomidae were the most predominant and abundant family (FO = 100%). The predominance of Chironomidae coupled with the rarity of the Ephemeroptera, Trichoptera and Plecoptera would reflect the poor quality of the Affon River waters. The principal components analysis yielded groups of associations: The first group of stations Taneka 2 and 3 characterized by high values of ammonium and phosphate;and low values of conductivity and TDS;the second group of Tanéka 1 and Kolokondé 1 stations with low values of pH, transparency, ammonium and phosphates;and the third group of stations Kolokondé 2, Kpébouko1, Kpébouko 2 and Affon marked by high values of conductivity, TDS, transparency, depth and temperature. The canonical correspondence analysis revealed a strong positive correlation between Nemouridae and ammonium as well as between Perlidae, Taeniopterygidae, Ephemeridae, Heptageniidae, Isonychiidae, Elmidae and phosphate. This study is a crucial step for any management and monitoring of this river.
文摘The present study was conducted in the commune of Kérou in North Benin to measure the bioavailability of agricultural pesticides heavily used in the production of cotton on snails. The test was conducted in peasant environment in two villages of the commune. In each site, there are three cages containing 6 snails each. The snails are exposed to soil and plants without special protection and are therefore exposed to environmental conditions. Firstly it’s to evaluate the presence or absence of agricultural pesticides in the viscera of snails after exposure. Secondly it consists to compare the different doses found in the viscera of snails in the different sites. And finally it’s to evaluate the effect of the toxicity of the pesticides on the reproduction of snails. The tests consisted of placing steel cages in the two experimental sites. In each site, there are three cages containing 6 snails each. Snails are exposed to soil and plants without special protection and are therefore exposed to environmental conditions. The observations were made in order to establish a study of transfer kinetics. After the analysis of the data, it appears generally that the accumulation of mineral elements highlighted is not proportional to the mineralogical composition of the soil in which the snail is exposed. Total nitrogen and nitrate were significantly accumulated in the flesh of site 2 snails compared to site 1 snails. These different measures show the bioavailability of soil minerals for living organisms. Accumulations are not necessarily accompanied by toxic effects in terms of survival for snails after 28 days of exposure. However, the absence of immediate toxic effect on snails does not imply a lack of effect in food chains due to the trophic availability of contaminants. The use of snails as bio-indicator of soil quality has therefore proved relevant in the context of soils polluted by minerals.