Light intensity effects on early life stages of black sea bass, Centropristis striata (Linnaeus 1758)

Abstract

The effects of four light intensities on growth and survival of first-feeding stage black sea bass larvae Centropristis striata were investigated in a controlled-environment laboratory. Fertilized eggs, obtained from LHRHa-induced spawning of captive broodstock, were stocked (72 eggs L−1) into twenty 15 L black tanks under light intensities of 100, 500, 1000 and 1500 lx, with five replicate tanks per treatment. The photoperiod was 12L:12D, the temperature was 20°C and the salinity was 35 g L−1. Larvae were fed rotifers Brachionus rotundiformis from day 2 post-hatching (d 2ph) at 5–10 rotifers mL−1. Microalgae Nannochloropis oculata and Isochrysis sp. were added (1:1) daily to maintain a density of 300 000 cells mL−1. Hatching success and larval growth and survival from d 2ph through d 15ph were monitored. Hatching success was 28–38% under all light intensities, and notochord length at hatching ranged from 2.8 to 3.0 mm, with no significant differences among treatments. By d 15ph, growth (mg wet weight) was significantly higher in the 1000 lx (0.914) and 1500 lx treatments (0.892) than in 100 lx (0.483), and a highly significant trend (P<0.01) towards increased survival with increasing light intensities was observed, from 1.3% at 100 lx to 13.9% at 1500 lx. Higher light intensities within the range of 100–1500 lx improved growth and survival of early larval black sea bass, suggesting that even higher light intensities may improve culture performance. This is consistent with conditions in shallow, near-shore locations where eggs and larvae are distributed in nature.