EFFECTS OF SIMULATED ENTRAINMENT 



819 



TABLE 4 



EFFECTS OF ENTRAINMENT STRESSES 

 ON OXYGEN CONSUMPTION OF 



ADULT Daphnia pulex 



*Significant at the 0.05 level. 



expected to cause mortality in cladocera and other crustaceans 

 (Beck, Poje and Waller, 1975). 



Adult animals that survived the mechanical stress had higher rates 

 of oxygen consumption, and preadults did not survive after 3 days. 

 The exact effect of mechanical stress on oxygen consumption is not 

 known, but it may be related to increased energy expenditure in 

 reorientation behavior and tissue repair. This increase in oxygen 

 consumption may have in part accounted for the poor survival of 

 preadult Daphnia. 



Temperature was the second most important parameter affecting 

 cladoceran biology. A 14°C stress significantly reduced oxygen 

 consumption, and 10 to 14°C stresses reduced filtering rates. In no 

 case did thermal stress significantly affect growth, molting, or 

 reproduction when there was an ad libitum supply of algae. The 

 depressant effect of thermal shock on oxygen consumption may be 

 the result of prolonged undershoot in response. Kinne (1964), citing 

 studies of others, noted that, when Daphnia magna encountered a 

 sharp thermal gradient, it showed a characteristic overshoot or 



