<b>Survival of acclimated Litopenaeus vannamei postlarvae associated with acclimation method, time and water sources</b> - DOI: 10.4025/actascibiolsci.v31i1.307

Abstract

The effects of different acclimation methods to freshwater and oligohalin water on L. vannamei postlarvae (PL₁₀) survival and gills histologic and histochemical studies were analysed. Three methods of acclimation were used: direct shock, gradual diluition and dripping. Three General Linear Models and Stepwise process (p<0.05) were used to analyse the effects of methods and time of acclimation and of differents waters for diluition on survival. The survival rates were higher than 90% in directs shocks in salinities equal or above 10‰. In gradual diluition the oligohalin water had the best survival rate. In dripping only the time of acclimation had a significant effect on survival rate.Gills histologic studies of the PL10 showed short primary filaments and rare secundary filaments. The PL16 had primary elongated filaments and secundary filaments reaching over the prolongament of the primary filament. The APS method showed a negative result and the Alcian Blue method showed positive reaction to acidglicoproteins and acidglicosaminoglicans in all postlarvae gills. The acclimation did not change the morphology of branchiae. Recommended time to acclimation of L. vannamei to freshwater was 48h by dripping and can be started at the PL10 stage.