Biomass, growth and nutritional composition of the seaweed Gracilaria domingensis (Kützing) Sonder ex Dickie (Rhodophyta) under different nitrogen and phosphorus availability

Abstract

Abstract Seaweeds have been used by several industrial sectors, such as the food, feed, pharmaceutical and biofuel industries. Thereby, techniques to increase seaweed production are needed due to the rising global demand for biomass. Thus, we investigated the effects of different weekly nutrient pulses [N and P at ratios of 10:1 (T1), 20:2 (T2), and 50:5 (T3)] on the biomass, relative growth rate (RGR) and biochemical composition of Gracilaria domingensis. A control without nutrient pulses was also established. The highest biomass values were recorded in T1. The RGR was more constant in T1 and T2 than in T3 throughout the cultivation. Significant decreases in RGR were observed in the control compared to the other treatments, and null RGR was recorded in T3. Regarding the seaweed biochemical composition, the lowest carbohydrate and lipid content and the highest ash content were recorded in T1. In our study, G. domingensis showed nutritional values similar or even superior to those reported for other seaweeds used as food. We concluded that T1 is the most suitable treatment to increase G. domingensis production. In addition to being the least expensive treatment, in T1, G. domingensis exhibited the highest biomass values, constant RGR, and nutritional composition suitable for human consumption.

Keywords

• Biochemical composition
• edible seaweed
• macroalgae
• nutrients
• seaweed cultivation.