Epistylis

Abstract: Epizootic outbreaks of red-sore disease in several reservoirs in the southeastern United States have been reported to cause heavy mortality among several species of fish having sport and commercial value. The etiologic agent is said to be the peritrich ciliate Epistylis sp.; secondary infection by the gram-negative bacterium Aeromonas hydrophila produces hemorrhagic septicemia which results in death. However, in recent studies on the largemouth bass Micropterus salmoides, Epistylis sp. could be isolated from only 35% of 114 lesions from 114 fish, while A. hydrophila was found in 96% of the same lesions. Transmission and scanning electron microscopy of lesions associated with red-sore disease indicate that neither the stalk nor the attachment structure of Epistylis sp. have organelles capable of producing lytic enzymes. Since other investigators have shown that A. hydrophila produces strong lytic toxins, and in absence of evidence to the contrary, it is concluded that Epistylis sp. is a benign ectocommensal and that A. hydrophila is the primary etiologic agent of red-sore disease.

Abstract: Epistylis sp. (Caliophora: Peritricha) is a facultative ectosymbiont of fresh-water fishes in streams and lakes throughout the southeastern U.S. In combination with the gram-negative bacteria Aeromonas hydrophila, epizootic outbreaks of Epistylis have been implicated in the death of many thousands of game fish, primarily striped bass and several species of Centrarchidae (sunfish), in several reservoirs in North Carolina. While these epizootics have been correlated with high levels of organic loading, recent studies suggest that thermal loading from a nuclear production facility may influence the level of infection by A. hydrophila and Epistylis sp. (A-E complex) on centrarchid sunfish in Par Pond, Savannah River Plant, Aiken, S.C. Utilizing electro-fishing techniques, in excess of 11,500 sunfish, representing six different species, were collected and examined for external lesions associated with the A-E complex. Largemouth bass (Micropterus salmoides) were most heavily infected, followed in incidence of infection by bluegill (Lepomis macrochirus), warmouth (Lepomis gulosus) and redbreast sunfish (Lepomis auritus); lesions were not observed on the surface of black crappie (Pomoxis nigromaculatus). The body conditions (or K-factor) of more than 2,000 largemouth bass were calculated; direct correlations were found between thermal loading, body condition, and incidence of infection. These data are discussed in terms ofmore » thermal effluent and the epizootiology of Epistylis sp. and Aeromonas hydrophila.« less

Abstract: The transmission of Epistylis daphniae infection among Boeckella triarticulata and the effect of peritrich epizoites on the copepod hosts were examined at 15 °C in the laboratory. After being paired with carrier copepodites, 97.5% of non-carrier adults became hosts to E. daphniae. When food was present there was no difference between carriers and non-carriers in growth of copepodites, and in survival and reproduction of adults. When food was absent, copepods infected with E. daphniae survived for shorter periods than non-carriers (p < 0.002). Therefore, colonial peritrichs may contribute to the decline of copepod populations when they are in a food-limited environment.