Seasonal and spatial assessment of aquatic pollution in the Mediterranean crab Callinectes sapidus

Pollution in the Mediterranean Sea driven by heavy metal contamination, declining water quality, and rising parasite prevalence seriously threatens marine life and ecosystem health. This study examined the spatial and temporal variation of seawater pollution on the Mediterranean crab Callinectes sapidus. Seawater, sediment, and crab samples were seasonally collected from June 2023 to May 2024 at two sites (El Bogus, Site1, and El Matar, Site2) in Port Said, Egypt. Heavy metals analysis showed elevated levels in the sediments compared to those in the water and crab muscles. Fortunately, Cd was undetected. However, Pb showed higher concentrations compared to Cu. Its concentration was the highest at Site 2 in all seasons. The current study proved that Cu concentration was within the safe limits in the crab muscles. Whereas Pb exceeded the WHO limit, but was still within the FAO limit. MDA and comet assays revealed elevated oxidative stress. The recovered parasites collected from C. sapidus belonged to Ciliphora, Rotifera, and Nematodes. The total parasitic infection was higher at Site1 (62.8%) than at Site 2 (38.4%). Male crabs and those that were larger in size and greater in carapace length exhibited the highest infection dominance compared to females. This study highlighted the impact of spatial and temporal variations of seawater pollution on the Mediterranean crab C. sapidus, with respect to external (heavy metals) and internal (parasitic infection) stressors. Hence, regular monitoring and pollution control, especially targeting lead contamination and parasitic infections, are essential to protect the aquatic ecosystem and public health.