Effects of dry and rainy seasons on the chemical composition of Ulva fasciata, Crassiphycus corneus, and Sargassum vulgare seaweeds in tropical environment

Algae that are found in the coastal regions are an important food source for humans and animals. They are highly susceptible to the influence of environmental parameters on their chemical composition. Thus, the aim of this study was to analyze the influence of seasons (dry and rainy) and species on the biochemical composition of the seaweeds Ulva fasciata, Crassiphycus corneus, and Sargassum vulgare occurring in tropical environment. It was found that crude protein (10.32–22.93%), total lipids (1.74–4.11%), ash (16.51–36.79%), carbohydrates (23.55–42.24%), and neutral detergent fiber (16.50–25.20%) differed significantly among species (p < 0.05). The essential amino acids, histidine, isoleucine, leucine, lysine, methionine + cysteine, phenylalanine + tyrosine, threonine, tryptophan, and valine were identified. Saturated fatty acids, essential fatty acids, and n-6 polyunsaturated fatty acids (PUFAs) were predominant. The lowest protein and PUFA content were found in C. corneus, whereas U. fasciata contained the highest carbohydrate concentrations. Photosynthetic pigments, phenolic, and mineral compounds (such as high concentrations of Sr and As) were found in S. vulgare. However, all seaweed showed significant concentrations of Mn, Zn, K, and Mg indicating that they can be important sources of minerals in animal feed. The three seaweeds showed susceptibility to seasons (rainy and dry), indicated by the synthesis of chemical constituents that consequently affected biomass composition. However, the results demonstrated that because of their biochemical composition, they have biotechnological potential that could be explored in several industrial sectors, including human and animal nutrition.