Evaluation of the tolerance of “pacamã” Lophiosilurus alexandri Steindachner, 1877 (Pisces:Siluriformes) larvae to different salinities - DOI: 10.4025/actascibiolsci.v30i4.791

Abstract

The aim of this study was to analyze the salinity tolerance of “pacamã” Lophiosilurus alexandri larvae at different ages. The test was conducted in post-hatching-larvae and larvae with 8 and 12 days old post-hatching. Larvae were acclimatized to experimental conditions for 24h, kept in 18 plastic tanks with 1 L at a density of 15 larvae L^-1. After this period, larvae were subjected to the salinities: freshwater, 2, 4, 6, 8 and 10 g salt L^-1, and observed over a period of 96h. Post-hatching larvae exhibited complete mortality in 6, 8 and 10 g salt L^-1. Survival was 100% in freshwater, 2 and 4 g salt L^-1 – although with the decrease in weight and length values to the salinities of 2 and 4 g salt L-1. The CL(I)_50-96h of larvae 8 days old post-hatching was 8.9 g salt L^-1. The weight was diminished with the increase in salinity, but no difference was registered in length between the different treatments. Larvae 12 days old post-hatching did not show differences in length and weight. The survival was lower in 8 and 10 g of salt L^-1. Larvae 8 and 12 days old post-hatching changed their swimming activity behavior to saline water up to 6 g of salt L^-1. “Pacamã” larvae showed higher tolerance to the different salinities with larval development.