BARIUM, STRONTIUM AND CALCIUM LEVELS IN THE EXOSKELETON, HEPATOPANCREAS AND ABDOMINAL MUSCLE OF THE GRASS SHRIMP, PALAEMONETES-PUGIO - RELATION TO MOLTING AND EXPOSURE TO BARITE

1. 1. The Ba, Sr and Ca levels in the exoskeletal and soft tissues of the grass shrimp, Palaemonetes pugio, were determined in relation to ecdysis, postecdysial mineralization of the cuticle and exposure to media containing barite. 2. 2. The exoskeletal tissues discriminated in favor of Ba and against Sr, relative to Ca. The hepatopancreas and abdominal muscle discriminated in favor of both Ba and Sr. 3. 3. The Ba/Ca and Sr/Ca ratios of the exoskeletal and soft tissues varied during the molt cycle. 4. 4. Long term (106 days) exposure of shrimp to either seawater (10% salinity) or seawater containing 500 mg barite/1 led to a decrease in the Ca concentration in the abdominal muscle and an increase in the Ca concentration in the exoskeleton. 5. 5. When exposed to media containing barite the shrimp ingested particulate barite. 6. 6. The shrimp exposed to barite media accumulated higher levels of Ba in their exoskeletal and soft tissues than control shrimp in seawater. The relative concentrations of the minerals in the exuvia of barite-exposed shrimp were Ca > Ba > Sr, while those of control shrimp were: Ca > Sr > Ba. © 1979.