RECENT PROGRESS IN THE USE OF LIPOSOMES FOR THE DELIVERY OF LOW MOLECULAR WEIGHT WATER-SOLUBLE (LMWS) NUTRIENTS TO AQUATIC ORGANISMS

Many key nutrients needed to support the growth and survival of aquatic organisms are classified as low molecular weight, water-soluble (LMWS) substances, including amino acids, vitamins and minerals. These substances are difficult to deliver to aquatic organisms because they are rapidly lost from current, commercially-available microparticulate diets and enrichment products when suspended in seawater. Liposomes are phospholipid-based microparticles that can be produced in a size range appropriate for marine suspension feeds such as rotifers, Artemia and bivalve molluscs. Liposomes show high retention of LMWS nutrients when suspended in seawater and can be used to deliver these substances to aquatic organisms with high efficiency.

We have shown that liposomes can be used to enrich rotifers and Artemia with several LMWS nutrients, including taurine, iodine, selenium and vitamin C and that these compounds are available and may be beneficial to marine fish larvae. For example, the concentrations of taurine, selenium and iodine can be elevated in rotifers to levels equal or above those typically reported in copepods. Moreover, we have found that rotifers and Artemia enriched with these compounds may improve larval performance in a number of species including Northern rock sole (Lepidopsetta polyxystra), California yellowtail (Seriola dorsalis), white seabass (Atractoscion nobilis) and may improve the survival of juvenile seahorses (Hippocampus reidi) during periods of elevated stress. Liposomes may have broad application in aquaculture and have the potential to deliver a larvae variety of LMWS substances, including nutrients and pharmaceuticals, to marine fish larvae that should improve the quality and quantity of larvae produced by commercial hatcheries, ornamental fish hobbyists and researchers.