Temperature 
Brett (25) refers to temperature as a polymorphic environmental factor that 
may be a lethal agent, a controlling factor regulating metabolism and 
development, a limiting factor restricting activity and distribution, a masking 
factor interacting with other environmental factors, or a directing agent such as 
a thermal gradient. It appears that the major temperature effect on marine fish 
larvae is that of a controlling factor regulating metabolic and developmental 
rates. In turn, those rates can affect survival of larvae through their influence 
on establishment of exogenous feeding and regulation of food requirements 
(e.g. 43, 57, 59, 60). For clupeiform, perciform, and pleuronectiform larvae, a 
6-10°C range has been reported in which culture attempts are most successful 
(8, 10, 43, 57, 59, 61), although some survival can be obtained over wider 
temperature ranges. 
There are few temperature effect-metabolic rate studies on marine fish 
larvae. Laurence (59) examined growth and metabolism of feeding winter 
flounder larvae at 2°, 5° and 8°C. Larvae reared at 5° and 8°C were tested 
until metamorphosis and the specific growth rate at 8°C (10.1 percent/day) 
was significantly higher than that at 5°C (5.8 percent/day). The growth rate at 
2°C (2.6 percent/day) was less than at 5°C but not significantly less. 
Metamorphosis took 49 days and 80 days at 8° and 5°C, respectively. At 2°C 
larvae did not survive more than six weeks after yolk absorption. Power 
functions describing oxygen consumption of winter flounder in relation to 
body weight had exponential coefficients lower than the expected theoretical 
value of 0.80 (0.49 for 8°C, 0.56 for 5°C, 0.54 for 2°C). When separate power 
functions were fitted for larvae and for metamorphosed juveniles, the 
exponential coefficients for larvae closely agreed with the theoretical 0.80 
value for all three temperatures, but the coefficients for metamorphosed 
juveniles were lower. 
Hoss et al (41) examined the effect of a rapid 12°C rise in temperature 
(thermal shock) on growth of pinfish Lagodon rhomboides and spot 
Leiostomus xanthums, and oxygen consumption of pinfish, to determine if 
growth and metabolism could be used to detect sublethal effects of power 
plant thermal pollution. The fish that they used were transformed juveniles, in 
most respects (5.15-7.89 mg dry weight for pinfish, 11.23-23.70 mg for spot). 
No significant difference in growth was observed for thermally shocked and 
control groups. Oxygen consumption rates of experimental and control pinfish 
indicated that a 12°C shock produced a slight increase in consumption rate 
which returned to normal levels within a few hours. Their determinations (41) 
of critical thermal maxima and survival after acute thermal shocks may not 
represent responses that might be obtained for smaller larvae. 
Time-temperature exposure histories are critical for determining thermal 
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