Histopathological effects of calcium, temperature and ammonia on selected organs of the crayfish, Procambarus clarkii

Abstract

The effects of four concentrations of water calcium, means of 16 ppm, 86 ppm, 192 ppm, 300 ppm; three temperatures, 15.6(DEGREES)C, 21.1(DEGREES)C, and 26.7(DEGREES)C; and two concentrations of total ammonia, < 0.5 ppm and 1.00 ppm, at each of the three temperatures on the crayfish Procambarus clarkii were assessed on the basis of histopathologic lesions using light microscopy. A total of 55 crayfish were in the water calcium experiment and 44 crayfish in the ammonia and temperature experiment. The following histopathologic findings were observed in the crayfish in both experiments. Melanization was seen around the periphery of necroticareus, in the shell and the cuticular lining of the foregut, hindgut and gill and in the parenchymal tissue of the hepatopancreas, gill and hindgut. An inflammatory response composed of hemocytes, fibrocytes and collagen-like material surrounded necroticareas in the hepatopancreas. Hemocytosis was seen in the hepatopancreas and foregut wall and in the gill, where it was often accompanied by an elevated number of eosinophilic granular hemocytes. A globular, deeply basophilic, subcuticular material was present in the hindgut. An encapsulated nematode was present in the wall of the foregut and hindgut. Psorospermium haeckeli, a sporozoan protozoon, was seen in the hepatopancreas, muscle of the foregut, abdominal muscle bundles and connective tissue, connective tissue beneath the shell, and in the hindgut wall. This was the first report of P. haeckeli in the western hemisphere and in Procambarus clarkii. Ectoparasites, a stalked peritrichous ciliate and a free living oligochaete were present on the gill, only in the calcium experiment. In the calcium experiment, there was an increase in the incidence of hemocytosis in the gill in the x = 192 ppm CaCO(,3) group. There was an increase in the incidence of parasitism in the foregut in the x = 86 ppm CaCO(,3) group. The incidence of Psorospermium haeckeli in the tissues beneath the shell, eosinophilic granulocytes in the gill, and parasitism of the foregut was increased in the 21.1(DEGREES)C temperature group. The last two conditions were increased in the 21.1(DEGREES)C, < 0.5 ppm ammonia concentration group, in the temperature and total ammonia interaction experiment. . . . (Author's abstract exceeds stipulated maximum length. Discontinued here with permission of author.) UMI