Theses and Dissertations

Title: Effects of infections with the strigeid trematode, Posthodiplostomum minimum (MacCallum), upon the bluegill, Lepomis macrochirus Rafinesque

Name: Smitherman, Renford Oneal

Degree: PhD

Chair: Dr. Eddie W. Shell


University: Auburn

Location: Auburn, Alabama

Date: 1964

Pages: 66

Keywords: Infections,Trematode,Posthodiplostomum minimum,Bluegill.


Experiments were conducted to evaluate the effects of experimental infections with P. minimum upon the funcintional state of the bluegill, a natural host. Three infection levels of 103.1, and 546.8 parasites per fish were produced by exposing fingerling bluegills to cercariae from physid snails reared and infected in the laboratory with miracidia of P. minimum. The two higher infection levels produced a significant reduction in growth rate of experimental fish over a 32-week period. An average of 353.1 parasites per fish produced a significant increase in mortality rate of bluegills over a 40-week period. Bluegill kidneys infected with an average of 99.8 metecercarise apparently excreted phenol red dye at a greater rate than did the kidneys of control fish. Liver tissue from parasitized fish consumed oxygen at a greater rate than liver tissue fromcontrol fish when temperature was elevated. Parasitism at each infection level produced a depressing effect upon hematocrit values of bluegills. A cyclic effect, apparently independent of temperature, was indicated in the hematocrit of bluegills. Plasms samples taken 9 months after infection indicated that a highly significant increase in total globulin was produced by parasitism of bluegills with P. minimum. A concomitant increase in plasma albumin was observed in parasitized fish. Tissue sections from hearts, livers, spleens, and gonads of parasits was slight, resulting in thin connective tissue cysts. In one case, encysted parasites were implicated in the production of a liver infarct.

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