THERMAL ECOLOGY AND STRESS 347 



protozoan produces erosion of the mucous-epithelium layer of the 

 scale (Hazen et al., in press; Hazen, Raker, and Esch, 1977). Bacteria 

 (presumably A. hydrophila) were observed adhering to the stalk of 

 Epistylis but not in association with the zooids, or feeding bodies 

 (Fig. 8). Histological sections of the surface lesions suggest a very 

 loose association of the colonial ciliate with the scale surfaces and 

 intensive inflammation in muscles beneath the scales. Within the 



B. 



\ 



Fig. 8 Cross section of Epistylis sp. zooid and stalk viewed by 

 transmission electron microscopy. Note presence of bacteria closely 

 adhering to stalk, but not to the zooid (S = stalk, Z = zooid, B = 

 bacteria). 4600 X. 



