The light behind Ulva growth: a key to successful tank-based (closed) cultivation

Ulva, a green, palatable seaweed belonging to Chlorophyta, holds immense potential primarily for human consumption because of its rich biochemical profile, which includes proteins, carbohydrates, lipids, antioxidants, vitamins, minerals, polyunsaturated fatty acids (PUFAs), and dietary fibers; followed by animal feed, nutraceutical, and pharmacutical applications. To produce elite biomass of Ulva, tank-based (closed) cultivation is preferable to avoid bio-magnification because it allows precise control of environmental parameters. Among these factors, the optimal wavelength and intensity of light are critical elements in the cultivation process. This review highlights the fundamental effects of the light spectrum, light intensity, photoperiod, seasonality and ultraviolet radiation on the growth rate, nutritional profile, photophysiology, circannual and diurnal rhythms, germination, sporulation and molecular biology of Ulva during tank-based cultivation on the basis of the reported literature. Furthermore, this review focuses on the application of modeling approaches that can be important for the optimization of Ulva cultivation. These models can predict biomass yield and optimize growth conditions through the simulation of multiple environmental factors, including light, temperature, water flow, and nutrients.