Isolated strains were identified using their morphological features. The characteristics of the isolates are documented in Table 1. Most isolates (i.e. 83% of the total) were diatom species belonging to the genera of Skeletonema, Thalassiosira, Chaetoceros and Cyclotella sp. Green microalgae, i.e. Nannochloropsis sp. plus some unidentified strains were less abundant than the diatoms, but many isolates from this group exhibited the highest lipid content i.e. >40% as biomass dry weight. Images of representative isolated strains are shown in Fig. 4.