THERMAL TOLERANCE OF MOSOUITOFISH 789 



In the CTM type test, either 5 or 10 Gambusia were scheduled to 

 be tested for each dose and time, but injury to fish during testing or 

 loss during time after irradiation resulted in less than 10 fish at each 

 dose for the 30-day test. 



Results of the mean survival times after exposures to lethal 

 temperatures for irradiated Gambusia are given in Table 2. Ten fish 

 were tested at each dose and time period, except for the 30-day time 

 period, when 6 fish were tested. Thirty fish were irradiated at doses 

 of 3000 and 5000 rads, but none survived for the 15- and 30-day 

 tests. Many significant differences were observed which can be 

 explained by dose response and recovery patterns. 



TABLE 2 



MEi^N SURVIVAL TIME (MIN) OF IRRADIATED 



Gambusia affinis AFTER EXPOSURE TO LETHAL 



TEMPERATURE (39.5°C) 



„ Days after irradiation* 



Dose, ^ 



*Values in parentheses are standard errors. Means with 

 different superscripts (a to e) differ significantly (P < 0.05). 



Doses up to 5000 rads tested at either 3 or 5 days after 

 irradiation did not significantly change the lethal-temperature values 

 of Gambusia (Table 1). However, a dose effect on the mean survival 

 time was observed at day 5 for doses of 1500 rads and above 

 (Table 2). The survival times for the 1500- and 3000-rad fish at day 5 

 were significantly different from the controls, but they were not 

 significantly different from each other. When the dose was increased 

 to 5000 rads, however, the survival time was significantly reduced. 

 The mean survival time for a dose of 1500 rads was significantly 

 different from the controls at days 5 and 15 but not at day 30. 

 Apparently after 30 days the fish had recovered sufficiently from 

 radiation injury so that the mean survival times of the irradiated fish 

 and controls were not significantly different. 



The mean survival time of the control fish at day 15 was 

 significantly different from that of the control fish at days 5 and 30. 

 This difference can be attributed to an acclimation temperature of 



