Bioaccumulation, tissue distribution and joint toxicity of erythromycin and cadmium in Chinese mitten crab (Eriocheir sinensis)

The bioaccumulation of erythromycin (ETM) and cadmium (Cd) in Chinese mitten crab (Eriocheir sinensis) and subsequent toxicity on pathological changes and enzymatic activities were investigated during 21-day exposure to ETM, Cd, and Cd + ETM mixture. The bioaccumulation of Cd and ETM residues in crab tissues decreased as gill > hepatopancreas > muscle > ovary, with higher Cd bioaccumulation than ETM. The highest Cd bioaccumulation in crab reached 1.15 mg/g dry weight in gill and 461.29 μg/g in hepatopancreas, on the 14th day of Cd treatment. Cd exposure promoted the bioaccumulation of ETM in four tissues. ETM exposure caused tubular vacuolization in epithelial and edema and degeneration of hepatic ducts in hepatopancreas, and disconnected gill epithelial layer and indistinctly cellular structure in gill. During Cd exposure, mitochondria acted as a main biomarker to identify the damage, including reduced and swollen mitochondria, and broken mitochondrial structure. Moreover, Chinese mitten crab showed defence capability against ETM and Cd exposure by physiological adjustment of metabolic enzymes glutathione S-transferase activity.