Effect of photoperiod on survival and growth of larvae and juveniles of sole Paralichthys orbignyanus

Author: Luiz Roberto Louzada Junior (Currículo Lattes)
Supervisor: Dr Luís André Nassr de Sampaio

Abstract

This work was carried out with the objective of evaluating the effect of the photoperiod on the cultivation of larvae and juveniles of the sole Paralichthys orbignyanus. Three experiments were carried out (EXP1, EXP2 and EXP3), the first two comprised the larval phase and the third the juvenile phase of the organisms. In EXP1 three photoperiods were tested: 0, 12 and 24 hours of light (hL) with two repetitions each and lasting 5 days. EXP2 evaluated two photoperiods: 18 and 24 hL with three replicates each and lasting 30 days. In EXP3, four photoperiods were evaluated: 0, 12, 18 and 24 hL with four repetitions each and duration of 35 days. In EXP1 and EXP2, cylindrical tanks with a flat bottom and a useful volume of 10 liters, 50 larvae per liter (1 aids), green water system, were used.first feeding with rotifers (10-25 ind / mL) followed by artemia nauplii and daily renewal of 50% of the medium. For the EXP3, cylindrical tanks with flat bottom, useful volume of 50 liters, continuous flow, 2 juveniles per liter (35 aids) were used, fed with artemia metanáplios. The EXP1 results show direct proportionality of survival (0, 1.6 and 4.5%, respectively for 0, 12 and 24 hL) and growth (3.44 ± 0.4, 3.75 ± 0.26 mm, respectively for 12 and 24 hL) with the photoperiod. In EXP2, survival was proportional to the photoperiod with 4 and 13%, respectively for 18 and 24 hL. The growth was higher by 24 hL until the start of metamorphosis, after which an inversion occurred, where the photoperiod of 18 hL was significantly (p <0.05) higher than that of 24 hL. The final growth data were 12.7 ± 1.9 and 11.6 ± 1.4 mm,respectively for 18 and 24 hL. The final survival on EXP3 was 38.2 ± 14; 69.2 ± 11; 69.3 ± 5.5 and 81 ± 9% respectively for 0, 12, 18 and 24 hL. The final weight for treatments of 0, 12, 18 and 24 hL in EXP3 were, respectively, 21.8 ± 4.5, 114 ± 3.7, 132.7 ± 3.8 and 105 ± 3.5 mg. Corroborating with the results of EXP2, in EXP3 the photoperiod of 18 hL was significantly superior to the others. Sole larvae, P. orbignyanus, can be grown in the 24 hL photoperiod until 15-20 dae. After this age, the use of the 18 hL photoperiod increases the performance of larvae and juveniles.

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