(7c surviving experimental/"/^ surviving controls X 

 100). The values were then plotted as a function of 

 mortality. Figure 1, a three-dimensional graph rep- 

 resenting total temperature [acclimation + excess 

 temperature (AT)] and excess temperature (AT), 



TABLE 1. — Survival/mortality counts for winter flounder larvae 

 found in compartments of hatching box for AT-f levels (°C-min) 

 from A22-4 to A30-64. Criteria for viability were transparency 

 and heart beat. 



AT-r 



Control 1 

 Control 2 



22-4 



8 



16 

 32 

 64 



24-4 

 8 



16 

 32 

 64 



26-4 

 8 



16 

 32 

 64 



28-4 

 8 

 16 

 32 

 64 



30-4 

 8 



16 

 32 

 64 



Right compartment 



Alive 



Dead 



21 



43 

 41 

 31 

 40 

 22 



42 

 39 

 39 

 29 



1 



63 



10 

















 





 

 





 

 

 

 





 

 2 

 3 



1 1 



9 

 15 



9 

 20 

 56 



6 

 46 

 36 

 52 

 47 



52 

 42 

 48 

 48 

 43 



22 



38 

 64 

 50 

 50 



FIGURE 1. — Three-dimensional graph for 5-d-old winter flounder 

 larvae representing total temperature |acclimation temperature + 

 excess temperature (AT)| and excess temperature (AT), and ex- 

 posure period (time) versus corrected mortality. 



and exposure period (time) versus corrected mortali- 

 ty, shows relatively little or no mortality of 5-d-old 

 winter flounder larvae exposed to a thermal shock of 

 22° C for exposures up to 32 min. Significant mor- 

 tality occurred at A22 and at exposures between 32 

 and 64 min. These conclusions are substantiated by 

 the Chi-square test (Table 2). 



Mortality at lower excess temperatures, AT's of 

 22°, 24°, and 26°C, appears to be a function of time. 

 This is shown in Figure 1 by sharp increases in mor- 

 tality between A22-32 (AT-0 and A22-64. Sharper 

 increases in mortality are found at A24 between 

 exposures of 16 and 64 min, and A26 between 4 and 8 

 min. These increases in mortality are also repre- 

 sented in Table 2 by increases of Chi-square values 

 of an order of magnitude. Total mortality was found 

 in all samples when ATs exceeded 26°C and 

 exposure times exceeded 8 min. 



TABLE 2. — Chi-square probability values of counts of viable 

 winter flounder larvae compared with dead larvae in treatments 

 versus controls. 



'P<005 



Discussion 



Flounder larvae appear to be resistant to acute ther- 

 mal shock. This is substantiated by Barker et aL 

 (1981), Valenti(1974), Carpenter (unpubl. data), and 

 Hoss et al. (1974). Barker et al. (1981) acclimated 

 smooth flounder, Liopsetta putnami, to 4^C and 

 exposed them to ATs of 21.4°, 23.6°, 25.8°, 28.0°, 

 and 30.2°C for periods of 5, 30, and 60 min. Signifi- 

 cant differences in mortality were encountered at a 

 AT of 23.6° C and at exposures between 30 and 60 

 min. Valenti (1974) simulated entrainment at the 

 proposed Shoreham (New York) Nuclear Power Sta- 

 tion, using winter flounder larvae similar in age to 

 those used in the present study. Acclimation tem- 

 peratures of 0°, 3°, 6°, 9°, and 12°C were used with 

 ATs of 8°, 10°, 12°, and 14°C and exposures of 0, 5, 

 and 13 min. Significant differences in mortality were 

 detected only in those larvae acclimated to 3 U C and 

 exposed to a AT of 14°C for 13 min. Carpenter 

 (unpubl. data), using older winter flounder larvae 

 (18-22-d-old) in simulating entrainment at Millstone 

 (Connecticut) Nuclear Generating Station, used an 



Permission was granted from the author to use the data. 



915 



