Very difficult with this image and no further info, but look at Nannochloropsis.

A mainly marine microalgae, Nannochloropsis sp. have high lipid content

with high level of polyunsaturated fatty acids - PUFA.

Unicells lacking flagella (no zoospores are produced), spherical to ovoid, 2 – 4 µm diameter. One plastid, no pyrenoid.

Chlorella (Chlorophyceae) also looks similar, but has a positive starch test.

Thank you very much Angelica.

The algae is a bit unclear. But it seems to be algae Trachelomonas or Cyclotella of algae is diatoms. For more information can refer to the following website.

http://biology.missouristate.edu/phycology/houston/lake-houston-algae.htm