Effects of Salinity and Temperature on Survival, Growth, and Food Intake of Ramshorn Snail (Helisoma anceps).

Understanding the salinity tolerance of Helisoma anceps is crucial for its application in aquaculture systems, particularly at the Fish Conservation and Culture Laboratory (FCCL), where the species is used to maintain water quality in Delta and Longfin Smelt culture tanks. This study investigated the effects of salinity and temperature on the survival, growth, and food intake of H. anceps under non-acclimated conditions. Adult snails were exposed to seven salinity levels (0, 2.5, 5, 7.5, 10, 12.5, and 15 ppt) at two temperatures (12°C and 16°C) for 42 days, and survival, growth, and feeding rates were analyzed using Kaplan-Meier survival analysis and linear mixed-effects models. Results showed complete mortality at ≥ 10 ppt within 48 h, identifying a salinity tolerance limit between 7.5 and 10 ppt. Growth and food intake significantly declined with increasing salinity, while temperature modulated these effects, with higher activity and food intake observed at 16°C. Shell volume-specific growth rate (SVSGR) was more sensitive to salinity stress than shell length-specific growth rate (SLSGR), reflecting reduced calcification efficiency under hyperosmotic conditions. The findings classify H. anceps as a stenohaline species with limited osmoregulatory capacity and suggest that its optimal performance occurs within 0-5 ppt salinity at 16°C. These insights provide a physiological basis for managing H. anceps in smelt hatchery systems and highlight the need for careful salinity control to sustain its ecological function in aquaculture operations.