ABSTRACT
Abstract . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 168 13.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 168 13.2 AA concentrations of microorganism diets used
in aquaculture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 169 13.2.1 Live microalgae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 169 13.2.2 Microalgal pastes and powders . . . . . . . . . . . . . . . . . . . . . . 172 13.2.3 Other microorganisms used in aquaculture . . . . . . . . . . . . 173 13.2.4 Significance of AA concentrations in
microorganisms to animals feeding on them . . . . . . . . . . . 174 13.3 Transfer of AA to zooplankton . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 175
13.3.1 Manipulation of AA content in live zooplanktonic organisms . . . . . . . . . . . . . . . . . . . . . . . . 175
13.3.2 Retention of AA in zooplankton . . . . . . . . . . . . . . . . . . . . . . 178 13.4 AA transfer from zooplankton and requirements by larvae . . . . . . 178 13.5 Interaction with other nutrients . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 181
13.6 Ecological significance of AA and its transfer between trophic levels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 182
13.7 Summary and conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 183 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 184
Abstract While the ascorbic acid (AA) requirements of adult and juvenile marine fish and shellfish are well known, less is understood about the AA requirements of larvae. Most of the information available on larval requirements is based on feeding trials conducted using live diets, such as microalgae or zooplankton (rotifers and Artemia sp.)
Nonenriched Artemia nauplii (0.5 to 0.7 mg AA g1 dry weight) and rotifers reared on yeast (0.1 to 0.6 mg AA g1 dry weight) contain sufficient AA for the normal growth and survival of most fish and crustacean larvae. Nevertheless, zooplankton can be enriched with AA (e.g., 1.5 to 2.5 mg AA g1) by feeding them on microalgae or commercial products. This may improve the physiological condition of larvae subsequently feeding on the zooplankton by enhancing their AA tissue concentrations. While the commercial enrichments may be more cost-effective, microalgae may have additional benefits such as increasing the concentrations of other trace nutrients (e.g., other vitamins) in zooplankton, which may further improve growth and/or survival of larvae.
