Influence of dietary arachidonic acid combined with light intensity and tank colour on pigmentation of common sole ( Solea solea L.) larvae

Abstract

Supplementation of dietary arachidonic acid (ARA) is known to cause hypopigmentation in common sole larvae ( Solea solea L.). This study examined a possible link between dietary ARA supplementation — light intensity and tank colour on pigment defects in common sole larvae. Larval tissue ARA and prostaglandin PGE 2 content increased significantly when fed Artemia enriched by a fish oil emulsion supplemented with 24% dietary ARA during premetamorphosis (until 11 days post hatch, dph) as compared to larvae fed on Artemia enriched by a fish oil based emulsion. More than 90% of all larvae in groups treated with the ARA supplemented emulsion during premetamorphosis showed partly or complete dorsal hypopigmentation. There were no significant effects of light intensity or tank background colour in combination with ARA on malpigmentation. Larval hypopigmentation was below 10% in the groups not treated with ARA supplemented diets. In these groups, however, the proportion of hypopigmented larvae increased significantly by a combination of a high visual light intensity (4000 lx) and transparent tanks. A high light intensity of 4000 lx increased growth as compared to low intensity of 100 lx, suggested to be related to a higher feed intake. Early pigment cell (chromatophor) development until 11 dph (i.e. start of metamorphosis) was not significantly related to dietary treatment, but during metamorphosis (from 16 dph) total chromatophore concentration (cells larvae − 1 ) was significantly lower for larvae treated with ARA and a possible lack of pigment cell differentiation or degeneration/cytolysis continued for this group during post metamorphosis.