The spatio-temporal evolution of the genus Nitzschia Longissima at the level of the lagoon in Nador, Morocco

O Omari,S Bourekkadi,K Slimani,J Abouchabaka,Ouassila Riouchi,Ali Skalli,Eric Abadie,Mourad Baghour,Faid El Madani

doi:10.1051/e3sconf/202123400081

Abstract

This work aims to study the spatio-temporal evolution of the genus Nitzschia longissima, one of the most important genera of marine plankton diatoms, from 3 sampling stations in the Nador lagoon and during 2 seasons (spring and summer 2018), Using Nitzschia longissima, as a study system, one of the most diverse and abundant genera among marine planktonic diatoms. This species counts, in addition to the form Nitzschia longissima forma parva Grunow, three varieties namely Nitzschia longissima var. closterium (W. Smith) Van Heurck, Nitzschia longissima var. longissima (Breb.) Ralfs and Nitzschia longissima var. reversa Grunow. Nitzschia Longissima genus density was high during the warm season (Summer 2018) with a value of 8000 cells/liter, and low during the cold seasons (Spring 2018), which may be caused by water temperature and zooplankton community structure; and underwater light intensity was an important factor influencing the spatial distribution of Nitzschia density.

Highlights

Several scientific studies have been published on coastal lagoons focusing on their hydrology, geochemistry, biology and ecological classification criteria [1,2,3,4,5,6]
The pH of the Nador lagoon recorded at the level of the 3 stations sampled in the two study periods, oscillated between a minimum of 8 at the level of station 2 which corresponds to the treatment plant during the summer period
A maximum of 3.4g/l recorded at station 3 and during the summer period.(Fig.3)The water temperature of the Nador lagoon measured during the study period varies between a minimum value of 17.5°C recorded in the Spring period at station 1 and a maximum value of 24.2°C recorded at station 3 during the Summer period, Our results are similar to those found by [16]. (Fig.4) Dissolved Oxygen measured at the 3 study stations of the Nador lagoon reaches a maximum of 10 mg/l at station 3 at the spring period this value is comparable to that found by [17]

Summary

Introduction

Several scientific studies have been published on coastal lagoons focusing on their hydrology, geochemistry, biology and ecological classification criteria [1 ,2,3,4,5,6]. The Nador lagoon, located on the Moroccan Mediterranean coast between the Cap des Trois Fourches and the Cap de l'Eau, is of great socio-economic interest for the region where different types of activities are carried out, especially those related to artisanal fishing. This lagoon has been the subject of various studies aimed at understanding the functioning of its ecosystem. Its genesis and evolution are governed by the neotectonic evolution of the Rifane chain built in the Mio-Plio-Quaternary [12] This lagoon is highly urbanized at its periphery and subject to significant anthropogenic pollution. This lagoon was first studied by the Spaniards, who,through their prospecting trips, have described its geographical, orographical, hydrological and hydrographic characteristics [13]

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Conclusion