Salinity tolerance assessment of different families of the razor clam Sinonovacula constricta using physiological traits

Abstract

Salinity tolerance is a complex multigenic trait influenced by genetic factors, environmental factors, and their interactions. However, there are few reports of salinity tolerance assessments using multiple indexes in aquaculture animals. Membership function (MF) analysis is a comprehensive, reliable and valid approach to evaluating resistance by considering multiple indexes. This study primarily aimed to evaluate the salt tolerance of the razor clam Sinonovacula constricta based on physiological traits. In this study, six families of S. constricta (1–1, 1–2, 19–1, 19–2, 17–1, and 14–2) were subjected to high salt stress (30 and 35 ppt). Eight physiological traits (enzyme activity) were employed to assess the high salt tolerance using MF analysis. The razor clams in family 19–2 were all dead at the end of the experiment. The mortality rate (MR) of family 17–1 was significantly lower than that of the other families (P < 0.05). The eight physiological traits showed a remarkable positive or negative correlation among them and did not exhibit specificity with salinity. The MF analysis indicated that family 17–1 displayed the highest resistance and family 19–2 showed weak resistance. The high-resistance families showed lower MR and higher enzyme activity compared with the low-resistance families. The degree of dispersion of enzyme activity at different time points was also a good indicator of the resistance based on the boxplots. Grey relational analysis (GRA) showed that most physiological traits reflected salinity tolerance, with a significant correlation observed with malondialdehyde content. Different families of razor clam showed different sensitivities to high salt levels, which is an important prerequisite for family selection. Additionally, we demonstrated the feasibility of using MF and GRA for evaluating high salt tolerance based on physiological traits. Thus, this study serves as a foundation for stress resistance assessment using physiological traits in aquaculture species.