Rotifers enriched with taurine by microparticulate and dissolved enrichment methods influence the growth and metamorphic development of northern rock sole (Lepidopsetta polyxystra) larvae

Naturally-occurring taurine concentrations in rotifers may not meet the nutritional requirements for species of cultured marine fish during the larval stages. Traditional methods for the enrichment of rotifers by immersion in a nutrient solution may be inefficient and may promote the growth of pathogenic bacteria. Microparticles, specifically wax spray beads (WSBs), have the potential to efficiently enrich live prey with water-soluble substances while maintaining optimal water quality for larviculture. The objectives of this study were to 1) compare the efficiency of enriching rotifers using wax spray beads (WSBs) versus methods whereby rotifers were immersed in solutions of taurine dissolved in the enrichment water (hereon referred to as the 'dissolved method') and 2) determine if northern rock sole (Lepidopsetta polyxystra) larvae show increased growth and development as a result of elevated concentrations of taurine in enriched rotifers. Leaching trials and rotifer enrichment trials were conducted to address Objective 1, and a seven-week larval growth trial was conducted to address Objective 2. Results indicated that taurine-WSB enrichment was highly efficient, in that rotifers had higher taurine concentrations (by dry weight) and less taurine was used to enrich rotifers compared to the dissolved method. At the end of the seven-week feeding trial, larvae fed taurine-WSB enriched rotifers (Taurine-WSB) as well as those fed rotifers enriched in 4000 mg taurine l− 1 (Dissolved 4000 mg l− 1) were larger than larvae fed rotifers that had not been enriched with taurine (Control). However, larvae fed rotifers enriched in 50 mg taurine l− 1 (Dissolved 50 mg l− 1) were not significantly larger than larvae in the Control treatment. We conclude that northern rock sole larvae benefit from taurine-enriched rotifers and that enrichment via WSBs is an effective and efficient method for delivering water-soluble nutrients to cold-water fish larvae.