Determinant factors of diatom assemblage's distribution along the Coastal Central Constantine (Northeastern Algeria)

The present study is based on the identification of benthic diatoms sampled along the Coastal Central Constantine in northeastern of Algeria. Our work aims to address relationships between environmental variables and characterize the spatial and temporal distribution of the diatom flora. Diatoms and samples for physicochemical analysis were collected from 26 sampling sites between May 2017 and August 2018. The number of species accounted for was 109 species in the Safsaf watershed, 117 taxa in the Kebir and 129 species in the watershed of Guebli which was the most diversified catchment. The great majority of diatom taxa were cosmopolitan species. Naviculaceae were the most abundant (47.87%). Our results demonstrated the main environmental variables controlling the diatom distribution in all the watersheds, including conductivity, and pollution gradients highlighted in Canonical Correspondence Analyses (CCA). The results of the Shannon diversity index (H') showed that the species diversity observed in the sampled sites during summer is higher than that observed in spring and winter. During this season, mean Shannon diversity values were around H' = 4.49, 3.98, and 4.17, respectively, while species richness varied between 13 and 34 across the three watersheds.