SPRING STUDY OF PHYTOPLANKTON BIODIVERSITY IN IMESSOUANE BAY (MOROCCAN ATLANTIC COAST)

In order to evaluate the taxonomic composition of phytoplankton, monthly monitoring of the composition and distribution of phytoplankton communities was conducted during the spring period of 2018, at three stations in Imessouane Bay. The systematic study of the samples revealed the presence of 74 phytoplankton species with a dominance of diatoms (69%) over dinoflagellates (31%). The specific diversity was estimated by calculating the specific richness, Shannon-Weaver Diversity Index (H’), Pielou's evenness index (J), Margalef (Mg) and Simpson (Ds). The use of these indices concomitantly has clearly identified the overall state of the living phytoplankton community in Imessouane Bay. The presence of potentially harmful species was detected during the study period but still in small quantities, these mainly belong to the genera ( Pseudo-nitzschia , Dinophysis , Prorocentrum , and Alexandrium ).