shrimp acclimated at 31°C withstood such sudden changes better than 

 those acclimated at 21°C. In growth studies conducted simultaneously, 

 several groups of postlarvae were acclimated separately in 8.5, 17.0, 

 25.5, and 34.0°/ooS in combination with 21°, 26°, and 31°C tempera- 

 tures for three weeks. Later they were raised for six weeks in their 

 acclimated conditions. In each condition the animals received daily 

 feeding rations at 4.5, 6.2, 8.1, and 11% of their biomass. Food 

 consumption was highest at 31°C, but the best conversion ratios were 

 obtained at 26°C. At 21°C the survival, food conversion efficiency 

 and growth rates were lowest of all temperatures. Growth and survival 

 rates were influenced by the interaction of salinity and temperature. 

 By virtue of their euryhalinity, young brown shrimp were found to 

 grow in salinities ranging from 8.5 to 34.0°/oo, but growth rates 

 were best in the near-optimal conditions of 8.5 and 17.0°/ooS and 

 26°C. Also in these concentrations the animals survived temperature 

 changes better than in higher salinities. Similarly, salinity vari- 

 ations were better tolerated in normal temperature conditions (26°C) 

 that in either 21°C or in 31°C. 



In estuaries frequent salinity changes from low to high and vice 

 versa can occur at almost any time but the major temperature changes 

 are seasonal. For this reason, apparently, the compensatory means to 

 tolerate adverse salinity conditions are better developed in brown 

 shrimp than are those for temperature (Venkataramiah et al. 1974, 

 pp. 62-63) . In the absence of an effective mechanism for temperature 

 regulation, the shrimp seem to have a limited capacity to tolerate 

 temperature changes. This was shown by the high incidence of muscle 

 paralysis, convulsions, necrosis, and loss of diurnal rhythmicity in 

 animals exposed suddenly to low temperatures (Venkataramiah et al . 

 1974, pp. 31-36). Recently we observed the occurrence of abdominal 

 cramps in brown shrimp that were confined to 18°C (unpublished results) 



In adjusting to the ill effects of extreme salinity and tempera- 

 ture changes, penaeid shrimp usually show a number of behavioral and 



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