Impact De L’exploitation Artisanale De La Sabliere De Toutsang Sur La Structure Des Communautes De Macroinvertebres Du Cours D’eau Doulahang A Dschang (Ouest Cameroun)

Abstract

The impact of wastewaters from the Toutsang sandpit (Dschang), both on water parameters and on benthic macro-invertebrate community structure of the Doulahang stream was studied from March 2015 to February 2016 on a monthly basis in three sampling stations named TS1, TS2 and TS3. The physico-chemical analysis were carried out according to standard protocols while the benthic macro-fauna was harvested using a haze net of 30 cm side and 400 μm mesh size. The analysis of physico-chemical parameters revealed that the introduction of wastewater from the sandpit at the TS2 station led to an increase of the temperature, conductivity, total dissolved solids, salinity, suspended matter, turbidity and colour. The wildlife inventory identified 63 taxa divided into 4 phyla, 6 classes, 13 orders and 31 families. The lowest values of the taxonomic richness (18 taxa, against 46 taxa and 47 taxa respectively to stations TS1 and TS3), the Shannon diversity index (2.48 bits / ind.) and the Pielou's evenness (0.62) were observed at station TS2 which received wastewaters from the sandpit. Similarly, the low values of the richness and abundance of the pollutionsensitive groups (Ephemeroptera-Trichoptera-Odonata) were recorded in this station. Significant negative correlations were found between some metrics (total taxonomic richness, taxonomic richness of the Diptera, Richness of Ephemeroptera-Trichoptera-Odonata, Taxonomic richness of insects, Relative abundance of Ephemeroptera-Trichoptera-Odonata, ShannonEuropean Scientific Journal August 2017 edition Vol.13, No.23 ISSN: 1857 -7881 (Print) e -ISSN 1857 255 Weaver diversity index, Pielou's evenness) descriptors of the structure of benthic macro-fauna communities and physico-chemical parameters indicative of physical pollution such as turbidity, suspended matter and colour.Keywords: Toutsang sand pit, Dcshang, water quality, physical pollution, benthic macroinvertebrates RésuméL'influence des eaux usées en provenance de la sablière de Toutsang à Dschang sur la qualité des eaux, la structure et la composition des assemblages des macroinvertébrés benthiques du cours d'eau Doulahang a été étudiée de mars 2015 à février 2016 selon un rythme mensuel dans trois stations d'échantillonnage dénommées TS1, TS2 et TS3. Les analyses physicochimiques ont été effectuées suivant les méthodes standards, tandis que la macrofaune benthique a été récoltéé à l'aide d'un filet troubleau de 30 cm de côté et 400 µm d'ouverture de maille. L'analyse des paramètres physico-chimiques a révélé que l'introduction des eaux usées de la sablière au niveau de la station TS2 entraine une augmentation des valeurs de la température, de la conductivité, du taux de solides dissous, de la salinité, des matières en suspension, de la turbidité et de la couleur. L'inventaire faunique a permis d'identifier 63 taxons repartis entre 4 embranchements, 6 classes, 13 ordres et 31 familles. Les plus faibles valeurs de la richesse taxonomique (18 taxons, contre 46 et 47 taxons respectivement aux stations TS1 et TS3), de l'...

Limnology of the Ndongo stream (South-West Cameroon): wastes management, water physicochemical quality and phytoplankton species richness

“…The aquatic biota is closely linked to water properties and changes in water abiotic variables will affect their population structure. For instance, phytoplankton, that form the basis of aquatic food webs may be used a biomonitors of water abiotic condition [6][7][8][9][10][11]; macrophytes are very useful in nutrient and heavy metals retention and may be exploited in the bioremediation of polluted ecosystems [12,13]; groups such as macroinvertebrates have been reported to be good bioindicators in tropical freshwaters bodies [14][15][16][17][18][19].…”