Water quality assessment and application of the biological diatom index in the Kebir-East wadi, Algeria

Abstract

A total of 118 benthic diatom taxa were recorded during a survey in 2007 of the Kebir-East wadi, north-eastern Algeria. Fourteen samples were collected at seven sampling stations in winter and summer. The majority of diatom taxa comprised cosmopolitan species widely distributed along the hydrosystem. Canonical correspondence analysis, used to examine spatial patterns of diatom communities in relation to environmental gradients, was statistically highly significant (p < 0.001). The first axis accounted for 45% and the second for 22% of the total variance. Seasonal and physicochemical gradients were clearly defined and indicated the water quality. A cluster analysis was then carried out to represent the different groups of the sampled stations sharing the same flora. Agglomerative cluster analysis grouped the sampled sites into seven clusters according to the community data. For clusters gathering more than one single sample, typical diatom taxa were determined with an indicator species analysis. The reliability of the biological diatom index BDI 2007 was tested under our environmental conditions and it was concluded that, considering the very particular geochemical context of this wadi, a specific diatom index should be developed.