The effect of light intensity on first feeding of the spotted sand bass Paralabrax maculatofasciatus (Steindachner) larvae

The effects of light intensity on feeding incidence and prey consumption at first feeding of spotted sand bass larvae (Paralabrax maculatofasciatus Steindachner), using four light intensity treatments (0, 100, 400, and 700 lx) were evaluated. Specimens were fed the rotifer Brachionus plicatilis at a density of 3 rotifers mL^-1. One hour after the addition of prey, 30 ± 3 (mean ± SEM) larvae were sampled from each treatment aquarium. Feeding incidence was evaluated as the percentage of larvae with prey in the digestive tract. Feeding intensity was measured as the number of prey in the digestive tract of the larvae. Histological analysis was carried out to describe the eye structure at the time of first feeding. Larvae fed in darkness (0 lx) had a significantly lower (P< 0.05) feeding incidence (1.2 ± 2.2%) and intensity (0.4 ± 0.7 rotifers larvae^-1) than those larvae fed at 100 (28 ± 11%, 1.8 ± 0.2 rotifers larvae ^-1 400 (48 ± 10%, 2.4 ± 0.3 rotifers larvae^-1 and 700 lx (52 ± 4%, 2.4 ± 0.1 rotifers larvae^-1). Feeding incidence of the spotted sand bass larvae increased with light intensity while the feeding intensity showed no significant difference (P> 0.05) between light treatments. Histological analysis of the eye structure showed that first feeding larvae had well-formed lens along with a retina composed of pure single cones as photoreceptors.