FIRST PRODUCTION OF JUVENILE SEA URCHIN Lytechinus variegatus AND EFFECT OF TEMPERATURE ON GROWTH UNDER LABORATORY CONDITIONS.   

Sea urchin larval development, the production of post-larvae and their feasibility in laboratory conditions were described. In addition the study was to investigate the effect of temperature on sea urchin growth response. Wild, mature individuals were collected in the Bay of Rodadero (Santa Marta, Colombia) and transported to the laboratory of Aquaculture, Universidad del Magdalena. Spawning and fertilization occurred spontaneously in 200l tanks. The fertilized eggs were transferred to 250l tanks filled with filtered seawater (1 micron) and treated with UV light. The feeding was based on a commercially available artificial diet Shellfish Diet 1800 (Isochrysis sp, Pavlova sp, Tetraselmis weissflogii, and Thalassiosira pseudonana) at a rate of 20,000 cells / ml in prism stage; 40,000 cells / ml in two and four larvae arms; and 60,000 cells / ml in six arms larvae (Figure 1), eight arms to the competent larva stage. The fertilization membrane and the formation of the gastrula was observed at 5 minutes and 9 hours respectively after fertilization; prism state occurred at 15 h from this time and until the formation of the competent larva took 21 days, at which the larva became juvenile, which was fed with macroalgae of the genus Ulva. Wild juveniles' sea urchin (21.11 ± 6.72g) were adapted to temperatures of 23, 25 and 27 °C in three replicate groups (n = 14 per replicate group) during 45 days and the effect on growth was evaluated. Growth rate, was significantly influenced by temperature. Highest growth rate was seen in the 23 °C group, while lowest growth was observed at 27 °C group. Optimal temperature for growth increased with sea urchin weight. Our results indicate that low temperature (below to 25°C) have significant effect on sea urchin growth.