Ill: RESULTS 



Effect of Salinity and Temperature on Behavior and Survival 



When an organism encounters an unfavorable environment it may 

 resort to one or more behavioral or physiological means or to both 

 simultaneously in order to avoid the harmful effects. In nature 

 behavioral regulation takes many forms in relation to time courses, 

 such as diurnal movements and seasonal migrations. Spontaneous 

 escape responses are another form of behavioral adjustment to a 

 harmful situation. 



During the first phase of the studies on salinity-temperature 

 relations of brown shrimp, the spontaneous behavior was studied 

 closely CVenkataramiah et al. 1974, pp. 29-36). The animals were 

 exposed to a spectrum of salinities ranging from 0.34°/oo to 

 59.5°/ooS, which was wider than in the present experiments. Effects 

 of temperature changes were observed at 21°, 26°, and 51 °C. The 

 responses were classified, on the basis of their activity level, as 

 normal activity, hyperactivity, inactivity (or resting) and "de- 

 pression" (stillness to the point of nonreaction) . 



The activity noticed among the control shrimp (17.0°/oo and 

 26°C) was designated as normal. In other salinities, which were 

 classified as critical or lethal depending on the survival, the 

 animals were initially hyperactive. Ther, they became inactive or 

 rested. At this point they either resumed normal activity or en- 

 tered into a state of depression. Hyperactivity included vigorous 

 escape responses such as swimming, walking, digging or jumping out 

 of the tanks. Animals normally recovered from the inactive phase 

 but rarely from depression. The effect of hyperactivity is re- 

 flected distinctly in physiological responses , as will be shown 

 later. Perhaps it was during the resting or inactive phase of 



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