ASPECTS OF THE PATHOPHYSIOLOGY OF BLUE CRABS, CALLINECTES SAPIDUS, INFECTED WITH THE PARASITIC DINOFLAGELLATE HEMATODINIUM PEREZI

摘要

Blue crabs, Callinectes sapidus, infected with Hematodinium perezi frequently show signs of weakness and lethargy and die when stressed by handling or capture. Radical changes to the hemolymph of heavily infected crabs are obvious by reduced clotting ability, discoloration, and a 50% to 70% decline in total hemocyte density. Few other signs of infection are associated with infections and the resulting mortalities of blue crabs. To assay physiological changes in infected crabs, we measured serum proteins, hemocyanin, serum acid phosphatase, various hemolymph enzymes, hemagglutination activity, and tissue glycogen levels in relation to intensity of infection with H. perezi. Serum proteins and hemocyanin levels were lower in infected versus uninfected males, but not in infected versus uninfected females. Acid phosphatase activity was directly related to infection by the parasite. Acid phosphatase activity in the hemolymph was below the detection limit in uninfected crabs, but was detectably high in lightly, moderately and heavily infected crabs. Hemagglutination, possible indicator of innate humoral defense activity, was not affected by infection. Glycogen levels in the hepatopancreas of infected crabs decreased by 50% in females and 70% in males compared to controls. Infection by H. perezi caused significant alterations to the hemolymph chemistry and metabolism of the crab. Changes in serum proteins, hemocyanin, and glycogen levels in heavy infections indicate that crabs probably die from metabolic exhaustion.