in response to temperature change. In 0% magnesium the oxygen up- 

 take decreased with temperature increase and in 30% potassium it 

 increased. The high oxygen uptake in 0% magnesium at 18°C corre- 

 sponded with the relatively high activity. In 30% potassium there 

 was a good correlation between the increased metabolic rates and 

 the progressively increasing potassium levels with temperature. 



The conclusions derived on the effects of deviated ions on the 

 physiological responses on a 24 hour basis may not be similar to 

 those derived from long-term experiments. The high mortality which 

 occurred in the process of acclimation to 5 and 10°/ooS with 40% 

 potassium and 25% calcium ion concentrations indicated more serious 

 consequences of long-term exposure than the short-term effects. 

 Also, very little is known about the sublethal effects that might 

 occur in shrimp due to ionic deviations. 



The osmotic regulation and metabolic studies provided no evi- 

 dence in favor of sex effects on the functional responses in brown 

 shrimp. However, this conclusion leaves us in the dark regarding 

 the disproportionate distribution of the sexes in natural conditions. 

 Our own field collection during several years had shown that usually 

 females outnumber males in the catches in local bayous and estuaries. 



Euryhaline invertebrates are known to exhibit greater osmo- 

 regulatory capacity in the lower part of their normal temperature 

 range than in the upper (Kinne 1971). The degree of osmotic in- 

 dependence in these animals also tends to increase with decreasing 

 tolerable temperature. The partial accuracy of these conclusions 

 is shown in the high survival rates of brown shrimp at 18°C. The 

 survival was best of all the test temperatures at 18°C as long as 

 the shrimp were held in the control salinity (15°/oo) or in its 

 vicinity. Also the survival was highest at 18°C in salinity media 

 with reduced calcium, potassium, and magnesium levels; but the 



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