Influence of light intensity on biofilm formation and the performance of pink shrimp Farfantepenaeus paulensis juveniles reared in cages

Abstract

A reduction in light intensity may increase shrimp activity, although it may also negatively a¡ect the development of photoautotrophic organisms present in bio¢lm, an important natural food source for shrimp. This experiment evaluated the in£uence of light intensity on bio¢lm development and on the growth of cultured Farfantepenaeus paulensis juve-niles. Six cages were deployed in a shrimp culture pond and stocked with 60 juveniles (0.72 Æ 0.03 g). Three cages were randomly chosen and covered with ¢ve layers of polyamide net to reduce light incidence(shaded treatment), while the other three cages were not covered (control treatment). Bio¢lm chloro-phyll a and microorganism abundance, as well as shrimp growth, were monitored during the experi-ment. Chlorophyll a concentration and the abun-dance of bacteria and £agellates were signi¢cantly lower in the shaded treatment (Po0.05). After 75 rearing days, shrimp stocked in control treatment achieved signi¢cantly higher (5.98 g) (Po0.05) mean weight than shrimp reared in shaded treatment cages (5.13 g). Similarly, the biomass produced was also signi¢cantly higher (Po0.05) in the control treatment (322.92 g) than in the shaded treatment (287.31g). The results of this study demonstrate that light intensity has a huge in£uence on shrimp performance mainly due to the increase in natural food availability.