Evaluation of liposomes for the enrichment of rotifers (Brachionus sp.) with taurine and their subsequent effects on the growth and development of northern rock sole (Lepidopsetta polyxystra) larvae

•We evaluated the use of liposomes for the enrichment of rotifers with the water-soluble nutrient taurine.•We compared liposomes with standard enrichment methods in which taurine was dissolved in the rotifer enrichment water.•A larval growth study was conducted to compare experimental enrichments.•Liposome enriched rotifers had taurine concentrations similar to those previously reported in copepods.•Growth indices and whole body taurine concentrations of rock sole larvae varied with enrichment method.

The naturally occurring taurine concentrations of rotifers (Brachionus sp.) may not be sufficient to meet the nutritional demands of several species of marine fish larvae. In this study, we evaluated the use of liposomes for taurine-enrichment of rotifers and compared them with standard methods in which taurine was dissolved in the rotifer enrichment water i.e., the “dissolved method”. Each enrichment method was further evaluated by determining the growth performance of northern rock sole (Lepidopsetta polyxystra) larvae fed on the taurine-enriched rotifers. Results indicated that rotifers enriched with taurine-containing liposomes obtained approximately 1.2% taurine on a dry weight basis, similar to the upper concentrations reported in wild copepods and approximately 10-fold higher than in control rotifers. Northern rock sole larvae grew significantly larger, were more developed and had higher whole body taurine concentrations when fed rotifers enriched with taurine-containing liposomes, compared to larvae fed either unenriched rotifers or rotifers enriched with equivalent concentrations of taurine using the dissolved method. The dissolved method required 60 × more taurine to achieve rotifer enrichment levels and larval growth performance observed using the liposome-enrichment method. Fluorescent markers indicated that rotifers were able to break down liposomes, liberating water-soluble nutrients into their guts and body cavity. Differences and similarities are discussed between the efficacy of liposomes and previously studied wax spray beads (WSB) for rotifer enrichment and subsequent nutritional effects on fish larvae.