Diatoms

Diatoms are algae that reflect the biotic condition of streams, lakes and estuaries. Diatoms are important indicator organisms because they are sensitive to natural and human impacts, and monitoring their condition provides information about ecosystem health. A large, living Pleurosira laevis cell has many disc shaped chloroplasts. Three cells of Cocconeis are growing attached to the exterior of the frustules of the P. Laevis cell.