Fuiman and Ottey: Temperature effects on behavior of young Saaenops ocellatus 



33 



._ 1000 



Q 



a 



12 3 4 5 6 7 8 



Time Since Transfer (h) 



Figure 5 



Time-course for pause duration of young red drum Sciaeiwps 

 ocellatus at two acclimation temperatures. Annotated as in 

 Fig. 1. 



be an immediate cost in terms of locomotor efficiency. 

 Perhaps the most hostile type of natural temperature 

 fluctuation is exemplified by inundation of tidal pools. 

 It is both unpredictable and abrupt, and concomitant 

 physical changes (e.g., sound and pressure) probably 

 add to the thermal effects on behavior. Our results 

 show that acute temperature changes of 5°C alone 

 engender behavioral changes that persist for about 

 2h. These changes may act directly on a fish's ability 

 to forage normally, or they may be merely indicators 

 of a generally stressed condition in which a fish could 

 be more susceptible to predators or disease. 



In addition to the thermal impacts, our fish exhib- 

 ited a handling effect which was overcome in 3-5 h. 

 The most similar circumstance experienced by young 



red drum in the field occurs during stocking from 

 hatcheries into natural waters. Young red drum, 

 3-40 mm in length, have been stocked into bays and 

 estuaries routinely since 1975 (Dailey 1991). Stocked 

 fish experience the combined effects of handling and 

 temperature change (often more than 5°C). Simi- 

 larly, fish used in laboratory experiments often in- 

 cur handling and thermal stress. Our results sug- 

 gest that even careful handling affects behavior for 

 at least as long as a 5°C temperature change. Mini- 

 mal handling and an acclimation period of 2-5 h 

 would benefit young red drum during both labora- 

 tory experiments and stocking. 



Acknowledgments 



This research was supported by a grant from the Sid 

 W. Richardson Foundation. We are grateful to Dr. 

 Connie R. Arnold, Janie Munoz, and Dana Allen for 

 providing red drum eggs. Gerald R. Hoff and Dennis 

 M. Higgs assisted in caring for the fish. 



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