Physiological–Biochemical Signatures and Genetic Diversity of Portunus pelagicus Cohorts in Guangdong Coastal Aquaculture

This study comprehensively evaluates the phenotypic traits, nutritional profiles, and genetic diversity of three cultured populations of Portunus pelagicus from Guangdong Province, China, namely from Shenzhen (PpSZ), Zhuhai (PpZH), and Chaozhou (PpCZ). We analyzed key nutritional components, including moisture, ash, crude fat, crude protein, total sugar, amino acids, and fatty acids. Notably, significant differences in total sugar content (p < 0.05) were observed among populations, whereas no substantial variation was detected in the other nutritional parameters. PpSZ exhibited significantly higher levels of specific amino acids, especially essential amino acids (p < 0.05). Fatty acid composition revealed a more favorable nutritional profile in PpZH. Analysis of physiological markers such as total antioxidant capacity (T-AOC), superoxide dismutase (SOD), and catalase (CAT) activities demonstrated comparable levels across populations, with no significant differences. Genetic diversity assessment revealed SNP densities of 6.583, 6.16, and 6.08 SNPs/Kb for PpSZ, PpZH, and PpCZ, respectively. The low polymorphism (PIC < 0.25) indicates limited genetic variation within the species. This study provides valuable insights into the biochemical, nutritional, and genetic characteristics of these populations, offering critical implications for the optimization of aquaculture practices and the conservation of genetic resources for this economically significant species.