Light Intensity Effects on Embryos, Prolarvae, and First-Feeding Stage Larvae of the Summer Flounder, Paralichthys dentatus

Abstract The effects of light intensity and salinity on eggs and yolk sac larvae of the summer flounder, Paralichthys dentatus, were examined under controlled, laboratory conditions. Fertilized eggs (early gastrula stage), obtained by induced spawning of captive broodstock, were stocked (53 eggs/L) into forty-eight 5-L, cylindrical translucent containers under light intensities of 0 (constant dark), 500, 1,000 and 2,000 lux and at salinities of 26,31 and 36g/L. Temperature was 19°C and photoperiod was 12 L: 12 D. Although hatching success (x = 94%) and larval survival (x = 85%) were not influenced by light intensity or by salinity within the ranges tested, significant (P< 0.05) additive effects on larval growth were observed. At the 97% yolk sac absorbed stage (114-131 hours post-fertilization = hpf), at the first-feeding stage (129.5-135 hpf), and at yolk exhaustion (153.5-159 hpf), notochord lengths were generally maximal at low light intensity (500 lux) and high salinity (36 g/L), and minimal at high i...