Algae are a promising feedstock for biofuels, but their growth on a large scale will require vast nutrient and energy inputs. Diazotrophic cyanobacteria, like the genera Nodularia, can fix their own nitrogen and reach very high densities in nitrogen-deplete growth media. Nodularia can also be co-cultured with diatoms, which can provide not only higher biomass yields than monocultures of either species, but also a wider range of lipid species including [omega]-3 polyunsaturated fatty acids (PUFAs) like [alpha] -linolenic acid, [Upsilon]-linolenic acid, arachidonic acid, and EPA. Monocultures of Nodularia sp. WHNOD and co- cultures with diatom strains were characterized under laboratory conditions and also at the UC San Diego Biology Field Station in both 100L photobioreactors and 800L ponds. Field station trials were performed over nearly 2 years, indicating that these strains are robust and can thrive in a wide range of conditions