Fuiman and Ortey Temperature effects on behavior of young Saaenops ocellatus 



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Time Since Transfer (h) 



Figure 4 



Time-course for the effect of an acute temperature change of 5°C on pause frequency of young red drum Scmenops 

 ocellatus. Annotated as in Fig. 2. 



ity over time followed similar trends at the two tem- 

 peratures within each size-class, showing the same ini- 

 tial response in activity followed by stable behavior 

 after 2-4 h. Once stabilized, the proportion of time 

 spent actively swimming was 21-26% greater at the 

 higher temperature. This is equivalent to a tempera- 

 ture coefficient (Q 10 ) of 1.5-1.6, which is similar to val- 

 ues reported for various other whole-animal measures 

 of fish swimming. Maximum sustainable speed of carp 

 has a Q lft of 1.5-1.6 (Rome et al. 1984). Larval zebra 

 danio and Atlantic herring have temperature coeffi- 

 cients between 1.4 and 1.7 for burst distance and maxi- 

 mum burst speed (Fuiman 1986, 1991). Larger rain- 

 bow trout have values of 1.8 for burst distance (Webb 

 1978). 



Stabilized activity (after 4h) in the control experi- 

 ments, combined with pause frequency, describe a tem- 

 perature effect on the duration of active bouts between 

 pauses. The average duration of active bouts is very 

 nearly the ratio of total activity to pause frequency, 

 since pause frequency is essentially equal to the num- 

 ber of active periods. Higher values for activity at the 

 upper temperature, accompanied by lower or equiva- 

 lent pause frequencies, result in longer periods of ac- 

 tivity in warmer water. This effect holds for all three 

 size-classes, although the magnitude of the effect is 

 greatest for small fish. 



All variables we evaluated relate to foraging activity, 

 and since fish were not fed during the experiments, 

 there should have been ample motivation for fish to 



