A study of the assimilation of fluorescent pigments of microalgae Isochrysis galbana by the early larval stages of turbot and herring

Citation

Tytler P, Ireland J & Murray L (1997) A study of the assimilation of fluorescent pigments of microalgae Isochrysis galbana by the early larval stages of turbot and herring. Journal of Fish Biology, 50 (5), pp. 999-1009. https://doi.org/10.1111/j.1095-8649.1997.tb01625.x

Abstract
The appearance of large supranuclear vacuoles in the enterocytes of 1- and 4-days post-hatch larvae of turbot and herring, respectively, revealed by the pinocytotic uptake of a fluorescent marker (FITCdextran), indicates a potential for the absorption of dissolved nutrients by the endotrophic stages of marine fish larvae. Ingestion of algal cells by turbot larvae was observed soon after hatching, but low level pinocytotic absorption of algal material was first seen during the second day. More extensive lysis of algal cells and pinocytotic absorption occurred 24 h later. Although lysis of I. galbana was shown to occur at low external osmolarities, it is unlikely that sufficiently low osmolarities present in the hind gut of turbot larvae explained the observed rupture of algae. Other mechanisms for digestion are discussed. In newly hatched herring larvae, algal cells were unable to pass beyond the constriction in the mid-gut caused by the yolk sac. When algal cells were eventually seen to pass into the hind gut, there was no evidence of algal digestion or absorption throughout the remaining endotrophic and early exotrophic stages of herring larvae, although pinocytosis was observed to occur mid-way through the endotrophic stage.

Keywords
algae; absorption; larvae; herring; turbot; fluorescence microscopy

Journal
Journal of Fish Biology: Volume 50, Issue 5