Morphology and distribution of some marine diatoms of the genus Rhizosolenia in the lagoon of Nador (North East of Morroco)

Abstract

This work aims to study the distribution and quantification of the genus Rhizosolenia known for its abundance and diversity among planktonic diatoms at 9 sampling stations in the Nador lagoon and during 2 seasons (spring and summer 2018). The diatoms collected in the 9 sampling stations were identified morphologically using an inverted optical microscope. A total of 10 species of the genus Rhizosolenia have been listed including: Rhizosolenia bushsolei, R alata forma alata, R bergonii, R cochlea, R hyalina, R imbricata, R setigera, R bushsolei, Rhizosolenia sp and R styliformis. The quantitative analysis of the species collected shows that the maximum cell density was recorded respectively at stations 9 and 7 located in the center of the Nador lagoon, with values of 21680 Cell/l and 15710 Cell/l. However, the minimum cell density was recorded at station 5 corresponding to Oued Bou Areg located at the edge of the lagoon with a value of 5120 Cell/l.

The influence of the environment on the diversity of Euglena species and their abundance in the lagoon of Nador-Morocco

“…The average summer salinity was around 36.5 ppm. These results are in line with those reported in other studies [27,28,29,30,35], reinforcing the consistency of the measurements made (Figure 3). The data collected in this study provide valuable information on salinity levels in the Nador lagoon, both in spring and summer.…”

“…Continuous temperature monitoring of the Nador lagoon is therefore crucial to understanding and preserving this unique environment (Figure 2). Our results for the period studied are in agreement with previous studies [25][26][27][28][29][30][31][32]. These concordances enabled us to draw the conclusion that this development had no significant impact on the thermal homogeneity of the ecosystem as a whole, as no perceptible thermal zonation was observed.…”

“…During the summer period, the minimum nitrate value measured in Nador lagoon was 0.37 g/l recorded at station 4, and a maximum value of 0.98 mg/l at station 2, with an average value of 0.675mg/l (Figure 5). Our results are similar to those found by [27,28,41]. These results indicate the presence of nitrates in the waters of the Nador lagoon, although concentrations remain relatively low.…”

“…In summer, the minimum pH value measured in the Nador lagoon is 7.89 at station 2, which corresponds to the wastewater treatment plant, and the maximum pH value recorded is 8.3 at station 4, with an average value of 8.09 (Figure 4). Our results are similar to those found by [25,27,28,40]. These pH variations in the Nador lagoon can be influenced by several factors, such as freshwater inputs, biological processes, human activities and environmental conditions.…”