A Response-Surface Analysis of Temperature-Salinity on Growth and Survival of the Caridean Shrimp, Macrobrachium americanum (Bate, 1868)

The effect of different levels of temperature (23, 26, 29, and 32 degrees C) and salinity (0, 5, and 10 parts per thousand) on growth performance and survival of Macrobrachium americanum was studied under controlled laboratory conditions. Sub-adult's prawns (10.29 +/- 0.27 g) were reared in these conditions for 72 days. Each experimental group contained 25 prawns in an approximately 100-L water capacity tank. The experimental design was factorial with three repetitions per treatment. Prawns were fed (commercial shrimp feed with 35% protein, 12% lipid) daily at a ratio of 10% body weight, twice a day (10:00 and 18:00 h). The optimal growth intervals were from 26 to 29 degrees C and from 3 to 11 parts per thousand of salinity, and survival was at 23 to 29 degrees C and 0 to 5 parts per thousand. The greatest effect of the temperature-salinity interaction was on the upper extremes of response. The analysis of response surfaces showed that the final weight and weight gain increased as temperature increased and, in the upper end, salinity had a linear synergistic effect, with a greater effect on growth at high temperatures. M. americanum attains its best growth in freshwater and low salinities (< 11 parts per thousand) in subtropical zones.