Effects of various sodium adsorption ratio ( SAR) mediums on larval performance of the freshwater prawn Macrobrachium rosenbergii (de Man).

The sodium adsorption ratio ( SAR) is used to describe the ratio of sodium to calcium and magnesium in water that is very important in both aquaculture and agriculture. SAR treatments including of 20, 30, 40, 50 and 60 were adjusted in 10-L containers. Initial larval density was fixed at 100 larvae L−1 and during the culture period, various larval quality parameters were evaluated. Our findings illustrated that at initial stages of larval development, different SAR treatments affected the larval condition index ( LCI), but no influences on larval stage index ( LSI) were apparent. Importantly, this process at the final larval stages became reversed. In addition, survival at SAR 30 was 12.4% greater than among any other treatments. The highest larval resistance to stress (191 ± 5 ppm), as measured by the 24-h LC50 formalin test also was observed for SAR 30, at the 11th larval stage. Analysis indicated that calcium absorption during larval developmental stages is affected by SAR levels in the environment and also showed that the optimal SAR treatment was 30 for Macrobrachium rosenbergii larviculture in inland hatchery brackish water. According to our findings and desired SAR for the environment and agricultural soil (<15), effluent of M. rosenbergii inland hatcheries must be treated at least two times by dilution and adding calcium and magnesium salts. [ABSTRACT FROM AUTHOR]