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

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.1997 The Fisheries Society of the British Isles

Drinking rate, uptake of bacteria and microalgae in turbot larvae

“…has been reported for yolk-sac larvae of Atlantic halibut (1-5% of the ingested carbon, Reitan et al, 1994a). Tytler et al (1997) reported lysis of ingested I. galbana by 2-day-old turbot larvae, and from day 3 after hatching vacuoles containing chlorophyll were observed in the enterocytes of all larvae examined. However, earlier observations on turbot larvae have suggested only limited digestion of ingested I. galbana (Howell, 1979).…”

“…In the early feeding period the larvae have the opportunity to ingest both microalgae and bacteria, which are present together with the prey. Both, the ingestion of microalgae by the larvae (Reitan et al, 1994a;Tytler et al, 1997) and the microbial colonization of the young larvae (Bergh, 1995;Skjermo, 1996) are believed to be fundamental for the viability of the larvae. However, so far little is known about the process determining the colonization of the intestine.…”

Early life cycle description and effects of microalgal diets on larval and post‐larval development of the mangrove cockleAnadara tuberculosa(Sowerby, 1833)

“…The morphology and size of the screened microalgae do not appear to play a significant role in the ingestion preferences of the mangrove cockle larvae, based on epifluorescent microscopy. The usefulness of epifluorescent microscopy for the selection of microalgae species at different stages of the larval was already being proved to be effective in similar studies with gastropod mollusks (Aranda et al, 1991), echinoderms (Duy et al, 2015), fish (Tytler et al, 1997) and crustaceans (García et al, 2011).…”

The Black Sea kalkan and the turbot, its closest relative

“…Ещё в ранних экспериментах было обнаружено повышение скорости роста и выживаемости личинок тюрбо при питания коловратками с добавлением примнезиофитовых микроводорослей Isochrysis galbana . Позднее (Tytler et al, 1997) обнаружил, что личинки вскоре после выклева, еще во время эндогенного питания, потребляют клетки I. galbana и выявил даже низкую абсорбцию (путем пиноцитоза) клеточного материала микроводорослей (пигментов) в заднем кишечнике.…”