Efeito da intensidade luminosa sobre a capacidade de predação de larvas do peixe-rei marinho Odontesthes argentinensis

Abstract

This study evaluated the effect of light intensity on predation capacity of marine pejerrey Odontesthes argentinensis larvae. Fertilized eggs were collected at Cassino Beach (Rio Grande-RS). At two and 14 days after hatching, 15 groups of 10 larvae were transferred for 800mL beakers and maintained without food during under light intensities of 0, 75, 150, 1,500 and 3,000lux (each treatment was replicated three times) during 12h. Immediately after that, Artemia sp. (8 nauplii mL-1) were offered during 15 min and larvae were sampled, anaesthetized and fixed in formol 10% to count the number of nauplii in the digestive tract of each larvae. The number of prey consumed 2 days after hatching did not differ (P>0.05) among larvae kept under 75, 150, 1,500 and 3,000lux, but there is a trend towards a smaller prey consumption as light intensity increases. Larvae kept in the dark consumed significantly less Artemia (P<0.05) than those maintained at 75, 150 and 1,500lux, but similar (P>0.05) to those under 3,000lux, suggesting that high light intensity and darkness are not appropriate for newly hatched larvae. Considering 14 days old larvae, Artemia nauplii consumption increased proportionally to the light intensity until 1,500lux, when it was stabilized. Therefore, it is suggested that O. argentinensis larvae should be maintained under light intensity equal or higher than 75lux for the first feeding, and light intensity should be increased to 1,500lux 14 days after hatching.