Zinc accumulation in fiddler crabs Uca annulipes latreille and Uca triangularis (Milne Edwards)

The effect of exposure time and concentration on the tissue-specific accumulation of Zn in two fiddler crabs, Uca annulipes and Uca triangularis, obtained from polluted (Visakhapatnam Harbor) and unpolluted (Bhimilipatnam) areas was studied. Hepatopancreas registered major accumulation of Zn when the crabs were exposed to sublethal concentrations (6.38 to 15.39 ppm) for 30 days. However, when the crabs were exposed to different concentrations of Zn (LCO, LC25, LC50, LC75) ranging from 12.93 to 99.38 ppm, higher accumulation was recorded in gills than in hepatopancreas. There was a progressive increase in the percentage body burden of Zn in hepatopancreas, but that in gills showed a decreasing trend. The standardized body burdens for both species of crabs were calculated to evaluate their sensitivity to exposure time as well as to concentration. The fractional retention coefficients for exposure time estimated for exposed crabs indicate that U. triangularis from Bhimilipatnam, having the highest value, is sensitive and U. annulipes from Visakhapatnam Harbor, showing the lowest value, is resistant.