Native Diatom Diversity of Nador Lagoon (Morocco): A Promising Biological Resource for Sustainable Biofuel Production and Algal Biorefineries

The transition toward sustainable energy systems requires the identification of renewable biomass resources capable of replacing fossil fuels while minimizing environmental impacts. Among microalgae, diatoms are an attractive feedstock for advanced biofuel production due to their rapid growth, high photosynthetic efficiency, and remarkable lipid accumulation capacity. This study investigated the diversity, spatial distribution, and bioenergy potential of diatom communities in the Nador Lagoon (Marchica), Morocco, one of the largest Mediterranean coastal lagoons. Samples were collected at 13 sampling stations during three sampling campaigns in March, April, and June 2024, using both qualitative and quantitative approaches. Diatom identification was performed by microscopic observation, while abundance was estimated using the Utermöhl sedimentation method. Species richness, frequency of occurrence, presence–absence patterns, hierarchical cluster analysis, and principal component analysis (PCA) were used to characterize the diatom community. A total of 22 diatom taxa belonging to 11 taxonomic orders were identified. The total recorded diatom abundance was 23,360 cells mL−1, with Bacillariales contributing the highest relative abundance (38.87%), followed by Rhizosoleniales (15.92%), Chaetocerotales (13.36%), and Naviculales (11.64%). Rhizosoleniales and Fragilariales were the most represented orders in terms of species richness, with four taxa each. Eight taxa with biofuel-related potential reported in the scientific literature were identified, among which Chaetoceros decipiens and Pseudo-nitzschia sp. occurred at six sampling stations, while Nitzschia sigma occurred at five stations. Hierarchical clustering and PCA revealed consistent patterns of spatial co-occurrence among these taxa. These findings highlight Nador Lagoon as a valuable reservoir of indigenous diatom diversity and provide a basis for prioritizing native taxa for future isolation, cultivation, biochemical characterization, and biofuel-related evaluation.