Achievement

Metal uptake in the marine food chain is an important public health issue. Trainee Jessica Dutton in Dr. Fisher’s group studied the effect of salinity on the uptake of cadmium and inorganic mercury from water into killifish. Salinities ranged from fresh to brackish water. Experiment showed that cadmium concentration in killifish had decreased with increasing salinity, whereas inorganic mercury concentration increased. This contrast is due to the metal binding with chloride ions in seawater. Cadmium passes less readily through biological membranes as cadmium chloride, reducing its bioavailability; whereas inorganic mercury passes more readily as mercuric chloride. Dissections showed that the distribution of inorganic mercury did not change with salinity, but cadmium became increasingly associated with the intestine as salinity increased. Marine fish actively drink seawater whereas freshwater fish do not. Drinking could be an uptake pathway for certain metals in marine fish.