Vibrio tubiashii infection has led to several Babylonia areolata pandemics on the southeast coast of China, yet the immune response of the ivory shell against V. tubiashii and the specific pathogen–host interaction remain unclear. This dynamic study aimed to characterize the response of B. areolata to V. tubiashii infection with the use of pathology, transcriptomics, an enzymatic assay, and inflammatory cytokines. Hepatopancreatic cells showed marked vacuolar degeneration with intact cell membrane and extensive cytoplasmic vacuolization after infection. The dynamic transcriptome of the hepatopancreatic tissue was analyzed by RNA-seq after V. tubiashii infection, and a total of 2733 (3 h), 5610 (24 h), 3323 (48 h), and 418 (72 h) differentially expressed genes (DEGs) were identified during infection. The GO and KEGG analyses showed that the DEGs were enriched in metabolic regulation, lysosome, and multiple immune-related pathways such as the MAPK signaling pathway. The immune response of B. areolata was distinct, where the early stage of immune response (3 h) showed binding, focal adhesion, and apoptosis, as well as an activated antioxidant system. Here, expression of TNF-α, IL-1, and IL-8 was significantly increased in the hepatopancreas, whereas expression of IL-6 and IL-17 increased afterward. During the middle stage (24 h and 48 h), a large number of DEGs were suppressed, especially those associated with metabolism and lysosomes, although their expression returned to normal during prolonged infection (72 h). The PPI network showed that ppp2, atp6, and sos1 were the top immune-related DEGs during infection. Key infection-related and time-course-related genes were analyzed by WGCNA. This study illustrates that oxidative stress, inflammation, and apoptosis are strategies of the hepatopancreatic immune response in B. areolata against V. tubiashii infection and enlightens conservation and production by furthering our understanding of gastropod immunity.

In aquaculture, reduced water exchange helps constrain exogenous pathogen invasion, lower pumping costs, and improve management efficiency; nevertheless, its effects on the growth of cultured aquatic animals remain poorly characterized. This study compared two daily water-exchange rates (100% and 0%) to evaluate growth and associated intestinal responses in Babylonia areolata (ivory shell). Growth performance and intestinal enzyme activities were measured, while 16S rRNA gene sequencing and untargeted metabolomics were used to characterize microbial composition and metabolite profiles. The low-water-exchange group exhibited significantly lower weight gain rate (WGR, p < 0.0001), specific growth rate (SGR, p < 0.0001), daily increments in shell length (DISL, p = 0.0060), and shell width (DISW, p = 0.0012). Intestinal total superoxide dismutase (T-SOD, p < 0.0001) and lipase (LIP, p = 0.0011) activities were also significantly lower. The relative abundances of Vibrio, Halodesulfovibrio, and Fusibacter were higher, whereas that of Christensenellaceae_R-7_group was lower. Lipid-related metabolic pathways showed the most pronounced intestinal differences. Intestinal levels of prostaglandins (PGs), leukotrienes (LTs), and sphingosine (Sph) were significantly higher under low-water-exchange conditions. The relative abundance of Halodesulfovibrio correlated positively with PGs and LTs but negatively with lysophospholipids (Lpc) and T-SOD activity. The relative abundance of Christensenellaceae_R-7_group correlated positively with LIP activity and was significantly associated with metabolites involved in primary bile acid biosynthesis. Overall, low-water-exchange conditions were associated with coordinated changes in growth, intestinal enzyme activities, microbial composition, and metabolite profiles, although the underlying mechanisms require functional validation. These findings provide new insights into intestinal microbiota–metabolite responses to low-water-exchange conditions and may guide future validation and intervention studies in RAS-based ivory shell culture.

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.