Evaluation and Comparison Germplasm Resource of Two Species of Macrobrachium in China (M. hainanense and M. nipponense)

Abstract

The Macrobrachium genus thrives in freshwater and brackish environments. M. hainanense, a nocturnal freshwater prawn, is economically significant in China due to its delicious meat and rich nutrition. Its distribution is limited to regions like Zhejiang, Guangdong, Guangxi, Fujian, and Hainan due to breeding habits near estuaries and low-temperature tolerance. Despite its economic importance, there are limited studies on M. hainanense, particularly regarding its germplasm resources. This study investigates the growth traits, nutritional composition, enzyme activity, and genetic diversity and structure of seven M. nipponense populations and three M. hainanense populations to inform sustainable aquaculture and conservation efforts, comparing them with the new hybrid varieties of M. nipponense, which successfully cultivated, Because of its fast growth, high adaptability, and strong reproductive capacity was chosen as a control sample due to its well-established quality, economic value, reputation, ensuring competitive comparison. The amino acids, fatty acids, and physiological and biochemical indicators among M. hainanense populations and M. nipponense populations showed significant differentiation. M. hainanense populations showed minor differences in nutritional components except for total sugar and astaxanthin content that were significantly different, whereas M. nipponense populations showed almost no differences. Essential amino acids in M. hainanense comprised 34.42%–37.53% of the total amino acid content. Differences in glycine, isoleucine, and cystine were notable in M. hainanense, while glycine and proline differed in M. nipponense. Fatty acid components varied among the populations studied. Genetic diversity analysis revealed that the polymorphism information content (PIC) values for M. hainanense were higher than those for M. nipponense. The Changhua River (CH) and Nandu River (ND) populations of M. hainanense had the lowest nucleotide diversity, while the Oujiang River (OU) population had the highest. The OU population also exhibited the greatest genetic diversity, with the lowest inbreeding coefficient, while the CH population had the highest. There was slight genetic differentiation among M. hainanense populations, with geographical isolation and artificial selection contributing to genetic structure differences. This study is the first to examine population-wide genetic variability in M. hainanense, highlighting the need for comprehensive conservation and breeding strategies to maintain and enhance genetic variability in this species. The study concludes that both M. hainanense and M. nipponense have rich protein content and low-fat content, with varied genetic relationships and differentiation among populations.