EFFECT OF DIFFERENT SALINITIES AND ZERO-WATER EXCHANGE ON THE PERFORMANCE OF Litopenaeus vannamei POSTLARVAE REARED WITH BIOFLOC

Héctor M. Esparza-Leal1,2*, João A. Amaral Xavier2, Wilson Wasielesky, Jr.2
 
1Departamento de Acuacultura, Instituto Politécnico Nacional-CIIDIR Unidad Sinaloa, Boulevard Juan de Dios Bátiz Paredes # 250, Guasave, Sinaloa 81101, Mexico. hesparza@ipn.mx
2Universidade Federal do Rio Grande (FURG), Instituto de Oceanografia, Laboratório de Carcinocultura. Rua do Hotel, 02, Praia do Cassino, Rio Grande, Estado do Rio Grande do Sul, Brasil, CEP 96210-030

The performance of Litopenaeus vannamei postlarvae in the nursery at different salinities with a biofloc technology (BFT) system needs to be explored further, as the nursery is currently used as a transitional stage between the hatchery and grow-out ponds. Therefore, this study evaluated the effect of seven salinity levels (2, 4, 8, 12, 16, 25, and 35 ‰) on the performance of L. vannamei postlarvae reared with a BFT system and zero-water exchange at 2000 orgs/m3. After 28 days of culture, the findings showed that under biofloc conditions, the salinity affected the performance of some variables of water quality in some cases, but only the combination of a high nitrite-N concentration (> 4 mg/l) and low salinity (2 and 4 ‰) caused up to 100 % shrimp mortality in the first two weeks. In the rest of the treatments (8, 12, 16, 25, and 35 ‰), the shrimp survival was > 72 %. It was also noted that shrimp mortality was affected by salinity, especially when it decreased from 35 ‰-25 ‰-16 ‰ to 12 and 8 ‰. The organisms reared at low salinities presented lower final weights and specific growth rate (SGR) than those reared at higher salinities. An inverse relationship was shown among the ion concentrations and the final weight of shrimp.