Effects of metacercariae (Digenea : Microphallidae) on the hepatopancreas of Chasmagnathus granulata (Decapoda : Grapsidae)

We analysed the effects of infection by Microphallus szidati metacercariae on carbohydrate (glucose and glycogen) levels and histopathology of the hepatopancreas of the estuarine crab Chasmagnathus granulata. No significant differences in infection were found between the left and right sides of the hepatopancreas, and infection intensity ranged from 2 to 802. The mean intensity of metacercariae cysts was 54.79 plus or minus 12.64 ( plus or minus 1 SE) with a prevalence of 90.1%. Hepatopancreatic glycogen was higher in infected crabs (28.2 plus or minus 2.2 mg g super(-1) tissue) than in non-infected ones (21.7 plus or minus 1.9 mg g super(-1) tissue). Further, high intensities of infection (>6 parasites per tissue section) promoted necrosis of the hepatopancreatic tubules and hemocytic infiltration around the cysts. Thus, the presence of M. szidati metacercariae in the hepatopancreas of C. granulata can cause structural damage to the tissue, altering its glycogen levels, and can be considered as a potential physiological stress factor.