What factors drive the variations of phytoplankton, ciliate and mesozooplankton communities in the polluted southern coast of Sfax, Tunisia?

We studied the spatial distribution of phytoplankton, ciliate and mesozooplankton communities coupled with environmental factors in the southern coast of Sfax (central eastern coastline of Tunisia). Phytoplankton assemblages were dominated by Dinophyceae (69.99%) and Bacillariophyceae (15.88%). The ciliate community consisted of Spirotrichea with a dominance of Tintinnopsis beroidea (57.69%). The mesozooplankton community was dominated by copepods representing 66.12% of the total zooplankton. Oithona nana showed a high frequency mainly in stations 9 and 10 with 66.86 and 64.65%, respectively. Some toxic phytoplankton species were recorded in the present study site. For this reason, the pollution generated in this area presents a slight degradation of the water quality and can be responsible for the bloom generated by the high proliferation of these toxic microalgae. The pollution generated by industrial activities has an effect on the spatial distribution of phytoplankton, ciliate and copepod communities with a reduction of their diversity indexes.