Interactions of different sodium and potassium concentrations on Macrobrachium rosenbergii (de Man) offspring quality parameters

摘要

The present study evaluated various sodium and potassium concentrations in hatchery water to determine which proportions would be optimal for Macrobrachium rosenbergii larviculture. Using a closed RAS system (60-L), experiments were conducted in two stages. In the first stage, larval quality parameters were compared among triplicate treatments of sodium (2000, 3000, 4000 and 5000mgL(-1)) and potassium (100, 150, 200 and 250mgL(-1)). During the second stage, these same parameters were compared from interactions of the two best concentrations determined in the first stage. Initial larval density was fixed at 100 larvaeL(-1) and larval quality parameters such as larval stage index (LSI), larval condition index (LCI), larvae dry weight, survival (%), LC50-24h for formalin stress and time of the first postlarvae (PL) appearance were measured. Results showed that during the early larval period time LSI, LCI and survival parameters were affected only by potassium and the interaction with sodium was not significant. At a later period of the larval development, interactions between both sodium and potassium were measurable for LSI (P0.05) while the interactions on LCI and survival were not significant. Measurable differences among the combined treatments 4000mg L-1 sodium and 150mgL(-1) potassium resulted in the best performance for M. rosenbergii larviculture. This concentration also provided the highest final survival to PL metamorphosis (40.6 +/- 2.5%) which was at least 10% higher than the other treatments.