shrimp were acclimated to the respective media for one week at 25°C. 

 The animals were fed daily during acclimation but were starved during 

 the test period. Plastic boxes of 7 L capacity were used as test 

 containers. Aeration was continuous but no substrate or filtration 

 was provided. 



For the first series, brown shrimp were acclimated separately to 

 salinities of 5, 10, and 15°/oo. The shrimp acclimated to 15°/ooS 

 were tested in media of 15°/ooS changing the concentration (in per- 

 centage) of one cation at a time. The test solutions were prepared 

 so that different media contained the respective cations in the following 

 concentrations: 85, 95, 120, and 150% Na; 5, 10, 15, 25, and 35-6 Ca; 

 0, 1, 4, and 6% Mg; and 10, 30, 40, 50, and 60% K. Testing was done 

 at 25''C in salinity media of 10°/oo having concentrations of 85% Na; 

 15 and 25% Ca; and 4% Mg; and 40, 50, and 60% K. Animals acclimated 

 to 5°/ooS were tested in media with concentrations of 85% Na; 15% Ca; 

 0% Mg; and 60% K at a salinity of 5°/oo and temperature of 25°C. 



Ten shrimp were tested in each of the above conditions. Tliey 

 were rinsed with 500 ml of distilled water before transfer to the 

 test media. Behavior and survival rates were monitored for 24 

 hours. 



For the second series of tests, shrimp were acclimated sep- 

 arately in media at 5 and 10°/ooS in which the percentage of one 

 cation was changed: 120% Na; 15% Ca; 6% Mg; or 40% K. After 

 acclimation the shrimp were directly tranferred to normally composed 

 artificial seawater of 2.5 and 42.5°/ooS at temperatures of 18° 

 and 32 °C. 



Acclimation of large numbers of brown shrimp to the deviated 

 ionic media was difficult. Mortalities occurred during acclimation 

 from 50% up to almost 100% in some cases. Very few shrimp survived 



39 



