Efecto de Tetraselmis chuii, Nannochloris oculata y Dunaliella salina sobre el crecimiento poblacional de Apocyclops distans (Copepoda,Cyclopoidae) en diferentes condiciones de temperatura e iluminación Effect of Tetraselmis chuii, Nannochloris oculata and Dunaliella salina on the population growth of Apocyclops distans (Copepoda, Cyclopoidae) at different temperature and ligth conditions

Self-fecundation of Diplectrum radiale a synchronic hermaphrodite species, was induced through a manual process; the fertilization percentage was 86.92 ± 2.75%, producing spherical, floating eggs, with a centric oil drop, a reduced perivitelline space and a smooth envelop. Fertilized eggs had an average diameter of 0.67 ± 0.02 mm and a oil drop with an average diameter of 0.13 ± 0.01 mm at 26.41 ± 0.25°C, pH 8.84 ± 0.17 and 38 ± 1 ppm of salinity. The embryonic development was described, observing the first cleavage at 0 h: 36 min after fecundation at 27.25 ± 0.50°C average temperature. The embryonic development described was similar to other species with pelagic eggs. Hatching started 17 h: 23 min after fertilization at 27°C. At 17 h: 50 min the larval total length was 1.33 ± 0.02 mm, the vitelline sac total length was 0.79 ± 0.03 mm and the oil drop diameter was 0.14 ± 0.01 mm. Growth was constant, decreasing at 43 h when the vitelline sac was almost reabsorbed, restarting growing at 53 h when mouth opened. The last embryonic phases were critical, with a percentage of non viable eggs of 18.89 ± 1.92% at 25.80 ± 0.27°C, pH 6.78 ± 0.08 and 38 ± 1 ppm salinity. At temperatures higher than 28°C embryonic development anomalies were evident with a high percentage of non viable eggs. For this reason it was not possible to compare development between natural and controlled ambient. Embryonic and larval development of D. radiale using the manual induction method permitted to obtain larvae from just one mature individual meaning a reduction in cost and time in producing fish larvae.

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