Influence of Anthropogenic Pollution on the Abundance Dynamics of Some Freshwater Invertebrates in the Coastal Area of Cameroon

E Koji,F M Onana,T Sime-Ngando,O V Noah Ewoti,G Bricheux,S Tchakonté,M Nola,C Lontsi Djimeli,A Tamsa Arfao

doi:10.4236/jep.2017.87051

Abstract

The abundance dynamic of some freshwater invertebrates in relation with the abiotic factors of the medium was studied from March 2013 to March 2014 on the main streams of the Wouri and Sanaga basins. Individuals of Copepoda, Atyidae, Chironomidae and Physidae were collected, identified and counted. Samplings were carried out monthly; meanwhile measurements of the environmental variables were taken. Results of the physico-chemical analyses revealed that water of the Sanaga basin is globally well oxygenated (77%-92%) and faintly mineralized (14-107 µS/cm), excepted in the stations receiving household pollutants. Inversely, in the Wouri basin, waters are hypoxic with high content of organic matters (27.79 ± 9.43 mg/L). During rainy season (June-September), there is a dilution-dispersion of the organic matter due to stormwaters. Concerning biological analyses, the families of Physidae and Chironomidae were more abundant in urban stations than in stations situated in suburban area, especially during low water level period, showing that they are well adapted to anthropogenic and organic pollutions. The hypoxic conditions of urban waterways do not favor the proliferation of sensitive taxa such as Atyidae and Copepoda. These taxa preferred well oxygenated waters with rapid flow, and are more abundant during rainy season in stations located in suburban area or which are less subjected to anthropogenic disturbances.

Highlights

The preservation and the rehabilitation of the ecological quality of surface waters in sub-Saharan Africa is one of the major stakes for the environmental, touristic and socio-economic sustainability
These taxa preferred well oxygenated waters with rapid flow, and are more abundant during rainy season in stations located in suburban area or which are less subjected to anthropogenic disturbances
This study aims to determine the influence of anthropogenic activities through the abiotic factors of the medium on the abundance dynamic of some freshwater invertebrates in the coastal region of Cameroon

Summary

Introduction

The preservation and the rehabilitation of the ecological quality of surface waters in sub-Saharan Africa is one of the major stakes for the environmental, touristic and socio-economic sustainability. The use of biological indicators associated with the physicochemical analyses constitutes one of the most informative and complete method for the water quality assessment. As an important functional group in stream ecosystems, macroinvertebrates show predictable responses since they are sensitive indicators of long-term environmental changes in water and habitat quality [4] [5] [6]. They are used in surface water assessment and monitoring [7] [8]

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