ABSTRACT
The diversity of oceanic phytoplankton communities depends in part on environmental, physical, chemical and biological factors where they are. The study that we conducted in cape 7 (Aftissat) zone, south of Morocco, located 232 km south of Laayoune city and 62 km south of Boujdour city, aims at the identification of planktonic genera/species and determination of the physicochemical factors favoring the growth of these species. The study was carried out on 427 samples, distributed, therefore, as follows, 57.2% (n = 245) of the samples during the year 2016 and 42.5% (n = 182) in the year 2017. In addition, 32.8% and 27.6% of the samples were taken, respectively, in winter and autumn, 24.4% of the samples in summer and 15.2% of all samples taken in the spring. We have identified 30 phytoplankton species, of which 70% (n = 21) are diatoms, 26.67% are dinoflagellates and one species is silicoflagellates. Moreover, the most abundant species in the diatoms are Navicula sp. (69), Licmophora (47), Nitzschia sp. (35), Pseudo nitzschia spp. (31) and in the class Dinoflagellates, Scrippsiella spp. (24), Protoperidinium spp. (11). The physicochemical parameters show very significant associations with density, so they favor a very high abundance species, especially those belonging to the diatom class. Some toxic species have also been identified, but with very low frequencies, below the norm. The cape d’Afissat has a very important role in the economic life of the region, so we must increase efforts to preserve it and if it is possible to improve the quality of water.