Growth and Survival of the Polychaete Hediste diversicolor (of Müller, 1776) under Various Salinity Levels in Captive Conditions

Abstract

The polychaete Hediste diversicolor is a valuable live feed for shrimp broodstock, yet its physiological responses to salinity fluctuations under captive aquaculture conditions remain understudied. This 25-day study investigated the effects of different salinity levels (15, 20, 25, and 30 ppt) on the survival, longitudinal growth, weight accumulation, and sexual maturation of H. diversicolor. The experiment was conducted using a completely randomised design with three replicates per treatment at a stocking density of 500 individuals m-2. Repeated Measures ANOVA showed that chronological time exerted a highly significant effect on both length and weight growth (P < 0.001). However, ambient salinity and the interaction between salinity and time had no statistically significant effect on growth trajectories (P > 0.05). At the end of the trial, final body lengths, weights, daily growth rates, and specific growth rates were statistically uniform across all treatments (P > 0.05). Furthermore, H. diversicolor exhibited exceptional survival rates (ranging from 96.3% to 99.7%) and statistically comparable sexual maturation rates (P > 0.05) across the entire spectrum tested. These findings indicate that the broad salinity range of 15 to 30 ppt constitutes a cohesive physiological comfort zone for both somatic development and reproductive maturation. Consequently, H. diversicolor is a resilient candidate for brackish-water aquaculture, capable of maintaining stable productivity without requiring complex salinity manipulation in hatchery operations.