A light-acquisition problem exists for aquatic algae since submergence can reduce light intensity and dampen photosynthesis. For land plants, full-spectrum of sunlight, from blue to red light, is available for chlorophyll absorption. However, red light is absorbed in the few meters of water closest to the surface of an aquatic environment and the light environment beneath these few meters is mainly blue-green in quality. Algal cells are likely to be transported to such depth of water, and many have evolved a mechanism to better absorb blue-green light.[3] A Nannochloropsis species isoloated from Singapore's costal water was investigated under different light wavelengths (red, green, blue, and white) and intensities to determine the optimal condition for biomass productivity and lipid production. The maximum fatty acid yield was achieved for both phototrophic (sunlight is the only energy source) and mixotrophic (utilize both sunlight and energy from carbon source) cultures at 55.15 and 111.96 mg/L, respectively, under cell exposure to blue light (470 nm). The biomass productivity of the algae also peaked under blue light for both cultures.[6]
In another study, UV-A (320 - 400 nm) was added to the photosynthetically active light spectrum (400 - 700 nm) to culture Nannochloropsis in order to study the effect of UV-A on growth and lipid accumulation. The results showed that modulated UV-A usage can lead to an increase in growth rate.[7]