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

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 degrees 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.