Hypervitaminosis A during Vertebral Morphogenesis in Larval Japanese Flounder

Abstract

Two experiments were conducted in order to examine the effect of a high amount of vitamin A (VA) given through Artemia on the vertebral development of larval Japanese flounder Paralichthys olivaceus. Ten-day-old flounder larvae were cultured for 30 days. In Experiment I, larvae were fed on Artemia enriched in a 10-liter medium containing 100 mg VA palmitate (1 μg VA palmitate = 1 IU VA), starting from different larval stages until metamorphosis, or at a different rearing period. In Experiment II, critical larval periods (three days) of feeding Artemia enriched in a 10-liter culture medium containing 100 mg VA palmitate on vertebral development were examined. Enrichment of Artemia with 100 mg VA palmitate in a 10-liter culture medium resulted in 1069 and 918 IU VA per g Artemia (dry basis) in Experiments I and II, respectively. Feeding on Artemia containing these high VA concentrations caused the compression of vertebrae in flounder. This vertebral deformity was found to occur when larvae were exposed to these high dosages of VA during the G stage (during day 25-27, about 11 mm of total length) in which notochord segmentation took place. The effect of high dosage of VA was even more distinct in fish receiving VA for a longer period, a high incidence of deformity being accompanied by retardation of growth.