microalgae have been isolated from four different locations of the Arabian Sea coast at Kozhikode (Calicut), Kerala, India. A Magnus MLXi plus light microscope has been used to isolate and morphologically identify ten different microalgal species. XRD and FTIR have been used to describe four pure isolates (Ag1 to Ag4) of two Chlorophyceae and two Cynobacteria species (Halochlorococcum marinum, Oocystis borgei, Chroococcopsis chroococcoides, and Desmodesmus abundans). Proteins, carbohydrates, and lipids with a variety of functional groups have been identified in the FTIR spectrum. Traces of quartz/siliceous material at 29–30°, which are commonly identified as calcite when present as biomineral or as precipitated carbonate from the growth media, are represented by the XRD peak at 26.6°. To determine the optimal growth for future use, the culture conditions for the selected microalgae have been optimized using a variety of culture media, including Walne's medium and Bold's Basal Medium (BBM), by varying salinity concentration. The Ag1 (Halochlorococcum marinum) and Ag2 (Oocystis borgei) strains grow in BBM at 35 ppt salinity having 8.54 × 10−6 cells/ml and 10.2 × 10−6 cells/ml. Ag3 (Chroococcopsis chroococcoides) and Ag4 (Desmodesmus abundans) grew 0.83 × 10−6 cells/ml and 0.86 × 10−6 cells/ml in Walne medium, despite the salinity of 30 ppt. This suggests that the strains are extremely halotolerant, means they can thrive in conditions with higher salinity. The results reveal that these microalgal strains are a viable choice for large-scale production in salinity conditions ranging from brackish to marine. Ag4 may be a more robust and biotechnologically advantageous strain for applications requiring steady pigment production since it is enriched in both accessory pigments (Chl b) and protective carotenoids, but Ag3 is superior in primary photosynthetic pigment (Chl a) accumulation. Due to their ability to survive in a variety of climatic conditions, the microalgal strains that have been separated during the succession stage may be mass-produced outdoors for industrial uses.