THERMAL ECOLOGY AND STRESS 



357 



40 



30 



I- 

 o 



20 





10 



• , Thermal 

 O, Ambient 



1.0 1.2 1.4 1.6 



1.8 2.0 2.2 

 K-FACTOR 



Fig. 17 Seasonal changes at ambient and thermally altered locations 

 in infection percentages among bass with body conditions <1.8 and 

 >1.8. Thermal samples at K-factors of 2.8 and 3.0 were pooled 

 because of small sample sizes. 



probability of a fish's being infected with red-sore disease. Second, 

 body condition and infection probability appear to be dependent 

 variables, except that the relationship is muted among bass in 

 thermally altered locations. It is suggested that the muted effect is 

 produced by the higher mean annual temperature in the heated areas 

 of Par Pond and that the effect may operate via an immediate and 

 direct stress on bass in these locations, which increases susceptibility 

 to infection without necessarily having to induce an initial reduction 

 in body condition. 



Red-Sore Disease and Stress: A Hypothesis 



On the basis of the evidence presented thus far, there seem to be 

 relations among red-sore disease, bass body condition, and water 

 temperature. Since these relationships are consistent from year to 

 year, can a hypothesis be generated to provide an explanation? The 

 answer to this question appears to be yes, and, furthermore, the 

 hypothesis will incorporate the stress concept into our thinking on 

 the epizootiology of red-sore disease. Indeed, since red-sore disease is 

 known to occur in aquatic systems that are not affected by thermal 

 effluent (e.g., Albemarle Sound and Badin Lake, North Carolina), it 

 is conceivable that stress may be of greatest overall significance. 



