Impact of thermal loading and other water quality parameters on the epizootiology of red-sore disease in centrarchids. Progress report, December 1, 1977--November 30, 1978
Description: The implications from these studies are varied, sometimes clear and sometimes less so, for many of the results have raised new and even more critical questions. Thus, our data clearly show that Aeromonas hydrophila is the etiological agent for red-sore disease. Furthermore, they suggest that the effects of temperature are twofold, first in increasing the density of the pathogen in the water column and then in affecting the physiology of the host organism to such an extent as to increase the probability of acquiring the pathogen. On the other hand, organic loading, suggested by other investigators as being important in red-sore disease, was not identified as being significant in the present study. However, if organic loading, or any of its consequences, can be shown to induce stress, then it may be as important in other systems as temperature is in Par Pond. Thus it is quite conceivable that it (organic loading), or some other water quality parameter, may create conditions conducive to increasing densities of A. hydrophila while simultaneously producing water quality characteristics which would lead to stress in fish, and then to increasing the probability of fish acquiring red-sore disease. An enigmatic observation (see Hazen, 1978, for details) is that A. hydrophila has been recovered from a variety of habitats throughout the U.S., yet red-sore disease is known to occur only in the southeast. This peculiar distribution pattern raises several important questions regarding the epizootiology of red-sore, not the least of which is the possibility of there existing differentially virulent strains of A. hydrophila and/or more or less susceptible populations of potential hosts in various parts of the country. Other significant questions are related to the variability in amplitude of red-sore disease from one year to the next among bass in Par Pond, the mode of entry of the ...
Date: July 1, 1978
Creator: Esch, G.W. & Hazen, T.C.
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