Copper-induced microstructural alterations in the chitin-protein matrix and calcium dissolution in the exoskeletal carapace of the mud crab Scylla serrata.

Understanding the exoskeletal microstructural alterations is important for assessing the broader implications of metal pollution on crustacean aquaculture systems. Through this investigation, we seek to contribute valuable insights into the harmful effects of copper pollution on Scylla serrata and inform better management practices in crustacean culture. Current study reveals that copper exposure induces calcium carbonate dissolution from the exoskeleton especially from the endocuticle and the subsequent irreversible microstructural alterations finally lead to the broken mode of the exoskeleton. The field emission scanning electron microscope (FE-SEM) images of copper exposed crab shells show that the reduction of the size of epicuticular spines (3 ± 1.23 μm), decreased surface roughness and the presence of arc or necking pattern of chitin fibers in the endocuticle were observed, indicating the loss of stiffness and structural integrity. The attenuated total reflectance fourier transform infrared spectrophotometer (ATR-FTIR), X-ray diffraction analysis (XRD) and energy dispersive X-ray analysis (EDX) confirmed that these alterations in crab shells are due to the calcium dissolution, copper incorporation and micro precipitation. These findings underscore the adverse effects of copper on the structural integrity of crab shells and provide crucial insights into understanding the need for improved practices to protect aquaculture systems from metal pollution.