Biomphalaria snails release immune proteins in aquaculture water that influence egg production and development

Biomphalaria snails, as a highly adaptable and rapidly reproducing freshwater mollusk, serve as an ideal model for studying the physiology, behavioral regulation, and population dynamics of gastropods. It is highly sensitive to aquatic pollutants and environmental stressors, making it an effective indicator for assessing the health status of aquaculture environments. This provides a scientific basis for optimizing water quality management and enhancing the stability of aquatic ecosystems. In our study, we found that Biomphalaria exhibited reproductive suppression, referred to as the Negative Allee Effect, solely due to increased density under conditions of resource abundance and favorable environmental factors (water temperature, oxygen levels, light, and microbial environment). Further research indicates that when the culture water is not changed but kept clear by removing microorganisms, the egg-laying rate of the snails significantly declines, especially under high-density conditions, where it nearly ceases entirely. This phenomenon is attributed to the mucus proteins released by the snails, which inhibit egg-laying and embryo development, resulting in a near-zero hatching rate of the newborn snails. Mass spectrometry analysis revealed that these mucus proteins are largely associated with immune functions, challenging our traditional understanding of their role and uncovering their potential role in population regulation. This finding not only expands our understanding of the physiological regulatory mechanisms in gastropods but also offers new insights for developing sustainable aquaculture strategies to precisely regulate snail populations.