Physiological tolerance of the early life history stages of fresh water prawn (Macrobrachium rosenbergii De Man, 1879) to environmental stress

382-389The present study examines the effect of temperature and salinity on the larval development and survival of Macrobrachium rosenbergii. The larvae showed 100 % mortality at higher temperature (33.5 ± 0.5 °C) in all the salinity conditions (12, 15, and 20 PPT). The survival rate varied between 76-96 % on exposure to lesser temperature conditions. Likewise, the post-embryonic yolk lasted for 4 days at ambient temperature (29 °C); whereas, at 33.5 ± 0.5 °C, it lasted only for 2-3 days. There was an increase in total length of larvae, when exposed to higher temperature and salinity. For the cardiac performance, larval heart beat (fH) significantly increased for higher temperature and salinity conditions (20 PPT; 33.5 °C) and lowered at ambient condition 12 PPT; 29 °C. Larval stroke volume Vs, Cardiac output (Qt) were higher in ambient conditions and lowest in higher temperature and salinity conditions. The larval activity decreased significantly at higher temperature and salinity conditions, compared to ambient conditions