Comparative analysis of growth and nutritional components of Scylla paramamosain cultured in saline-alkali water and marine water

To explore the differences of growth and nutrient composition for Scylla paramamosain under different water conditions, Aleken classification method was used to classify the aquaculture water of the Yellow River Delta group (DY), saline-alkali group (ZD) and Sanmen group based on the ion composition; The t-test method was used to compare the growth of S. paramamosain in 3 groups by measuring the morphological indicators and calculating the condition factor. The amino and fatty acid content of hepatopancreas and muscle were measured, and principal component analysis and cluster analysis were used to analyze the amino acid and fatty acid composition of each group of S. paramamosain. The results showed that the fatness of the 90-day-old crabs in 3 groups was between 0.54 and 0.89, ZD and DY groups were significantly higher than the SM group, while the 140-day-old crabs had no significant difference in the fatness between 3 groups. 20 kinds of amino acids and 26 kinds of fatty acids were detected. The total amino acid contents (TAA) of the hepatopancreas and muscle of 3 groups of crabs were 3.94-6.87 and 9.73-12.42 g/100 g, respectively, and the SM group was the highest. The ratio of total unsaturated fatty acid content of hepatopancreas and muscle of S. paramamosain to total fatty acid content (TUFA/TFA) was 59.68%-68.80% and 70.08%-73.79%, respectively. Among others, the content of C20:5n-3 (EPA) in hepatopancreas of the ZD group was the highest in each group; the results of principal component analysis and cluster analysis respectively showed that the ZD group is distinct from other groups in amino and fatty acids content, but not significantly, while the cluster analysis results of the amino and fatty acid contents were similar in each group. This study showed that compared with normal seawater, the growth rate, plumpness, amino and fatty acids contents of S. paramamosain in saline-alkali aquaculture were not much different, and some indicators were dominant. To ensure the growth rate and aquaculture production, appropriate supplementation of Mg²⁺ and K⁺ in the breeding process can be used in saline-alkali water aquaculture of S. paramamosain. This study provides a reference for the breeding and the cultivation of S. paramamosain in saline-alkali water aquaculture.