Open Journal of Marine Science, 2020, 10, 41-51 https://www.scirp.org/journal/ojms ISSN Online: 2161-7392 ISSN Print: 2161-7384 DOI: 10.4236/ojms.2020.102004 Apr. 2, 2020 41 Open Journal of Marine Science Spatio-Temporal Study of Toxic and Harmful Planktonic Taxa at Two Oceanic Sites Mehdia and Moulay Bousselham, Rabat Sale Kenitra Region, Morocco, between 2017 and 2018 A. Hal Aberrhaman, B. Bouhaddioui, L. A. Lrhorfi, R. Bengueddour Biology Department, Laboratory Biochemistry, Biotechnology, Health and Environment, Faculty of Science, Ibn Tofail University, Kenitra, Morocco Abstract Phytoplankton is all cyanobacteria and microalgae (microscopic plants) present in surface water that may be carried by water currents. The study was conducted at two oceanic sites Mehdia and Moulay Bousselham, Rabat sale Kenitra region, Morocco, between 2017 and 2018. The objective of this study is to compare the spatiotemporal evolution of certain toxic planktonic species between the two sites. The planktonic species identified all have toxic potency but to varying degrees such as Alexandrium, Dinophysis, Gymnodinum, Pseudonitzschia and Proocentrum. The comparison of the abundance of these taxa in the two sites confirms that the Moulay Bousselham site is cha- racterized by the presence of the most toxic planktonic species represented mainly by Pseudonitzschia in contrast the Mehdia site experienced an abun- dance of the Proocentrum kind. This situation requires a more detailed study of the essential causes of the proliferation of these species. Keywords Phytoplankton, Surface Water, Toxic Power, Spatiotemporal Evolution, Mehdia, Moulay Bousselham 1. Introduction Phytoplankton is all the cyanobacteria and microalgae (microscopic plants) present in surface water that can be carried away by water currents [1] [2]. They are defined as unicellular or multicellular organisms, either eukaryotes or pro- karyotes [3]. Microalgae occupy most ecological niches, mainly aquatic envi- How to cite this paper: Aberrhaman, A.H., Bouhaddioui, B., Lrhorfi, L.A. and Bengueddour, R. (2020) Spatio-Temporal Study of Toxic and Harmful Planktonic Taxa at Two Oceanic Sites Mehdia and Moulay Bousselham, Rabat Sale Kenitra Region, Morocco, between 2017 and 2018. Open Journal of Marine Science, 10, 41-51. https://doi.org/10.4236/ojms.2020.102004 Received: December 22, 2019 Accepted: March 29, 2020 Published: April 2, 2020 Copyright © 2020 by author(s) and Scientific Research Publishing Inc. This work is licensed under the Creative Commons Attribution International License (CC BY 4.0). http://creativecommons.org/licenses/by/4.0/ Open Access