Tuanyu Guo

The ivory shell, Babylonia areolata, is an economically important gastropod along the southeastern coast of China and throughout Southeast Asia. In recent years, overfishing and habitat degradation have driven a continuous decline in wild stocks, while large-scale hatchery propagation and cross-regional translocation pose potential threats to the genetic integrity of germplasm resources. To assess the current genetic diversity and population structure of different geographical populations, 14 microsatellite markers were used to analyse four wild populations collected from Hainan (HH), Zhanjiang in Guangdong (ZJ), Zhao’an in Fujian (ZA), and Changle in Fujian (CL), together with one selectively bred population introduced from Thailand (TT). All five populations maintained high genetic diversity, and the selectively bred TT showed the lowest allelic richness. Pairwise F_st ranged from 0.003 to 0.076: the selectively bred TT population was moderately differentiated from the three mainland populations (F_st = 0.073–0.076) but only weakly differentiated from HH (0.038). AMOVA showed that most genetic variation resided within individuals, with only 4.31% among populations. PCoA, STRUCTURE and UPGMA analyses consistently resolved two major lineages: CL, ZA and ZJ formed one clade, whereas HH and TT clustered together in a second clade. Overall, wild B. areolata populations still retain high genetic diversity with generally weak differentiation among populations, whereas the introduced selectively bred population already shows reduced allelic richness. These findings provide a scientific basis for wild germplasm conservation, translocation management, and genetic breeding of B. areolata.

Dietary lipid sources influence growth, tissue nutrient composition, and physiological responses in aquatic animals, but their effects on female broodstock abalone remain insufficiently understood. This study evaluated the effects of five dietary lipid sources, including fish oil, perilla seed oil, safflower oil, olive oil, and lard, on growth performance, foot muscle nutritional quality, digestive-gland antioxidant status, and survival following Vibrio harveyi AP37 challenge in female broodstock Haliotis discus hannai. A total of 500 female abalone were randomly assigned to five dietary treatments, with four replicates per treatment, and fed isonitrogenous and isolipidic diets for 90 days. Results showed that the dietary lipid source significantly affected growth, foot muscle crude protein and lipid contents, amino acid and fatty acid compositions, and digestive-gland antioxidant status. The fish oil group showed the highest measured total amino acid and taurine contents and docosahexaenoic acid (DHA) proportion in foot muscle, together with the highest observed final survival after V. harveyi challenge. Perilla seed oil and olive oil warrant further evaluation as alternative supplemental lipid sources under the present experimental conditions. These findings provide useful information for lipid source selection in formulated diets for female broodstock abalone.

Global warming and summer heatwaves increasingly threaten the survival of cultured Babylonia areolata, but the heat tolerance of different geographical populations and the potential for genetic improvement by hybridization remain poorly understood. In this study, four geographical populations (Thailand, TL; Wanning, WN; Zhao’an, ZA; Changle, CL) and four hybrid combinations (TH, HT, TF, and FT) were compared for mortality rate, median lethal temperature (LT₅₀), and critical thermal maximum (CTMax) under controlled thermal stress. The results showed that the low-latitude TL population exhibited significantly higher LT₅₀ (36.49 ± 0.05 °C) and CTMax (35.77 ± 0.52 °C) than the high-latitude CL and ZA populations (LT₅₀: 35.90 ± 0.05–36.02 ± 0.04 °C; CTMax: 35.12 ± 0.77–35.26 ± 0.53 °C). All four hybrids had improved heat tolerance compared with their low parents, with TH and HT showing the strongest mid-parent heterosis (e.g., 73.68–78.94% for survival at 36.5 °C). However, none significantly exceeded the high-parent performance (TL), indicating only mid-parent heterosis. These findings reveal significant genetic variation in heat tolerance among geographical populations of B. areolata and confirm that cross-breeding can effectively enhance heat tolerance, though it does not produce transgressive superiority. This study provides key genetic resources and a theoretical basis for breeding heat-tolerant strains of B. areolata.