High bioaccumulation factors and ecological risk index of Cd and Hg in Indian white shrimp, hooded oyster, brown algae, and sediment in northern coasts of the Gulf of Oman before and after a monsoon

This study analyzed the concentrations (dry weight basis) and bioaccumulation factors (BAF) of copper (Cu), lead (Pb), cadmium (Cd), and mercury (Hg) in pre- and post-monsoon samples at five stations (Chabahar, Darak, Gowatr, Jask, and Pozm) in the Gulf of Oman. For this purpose, ten samples of hooded oyster Saccostrea cucullata, brown algae Sargassum ilicifolium, and Indian white shrimp Penaeus indicus were collected once a month during fall and spring (a total of 60 samples were obtained from each species per station). Additionally, sediment samples were collected three times a month during these two seasons (ten samples per each season). Our results indicated that metal concentrations were lower than the maximum permitted limit in the sediment across the tested stations (<0.42 ppm). In both seasons, the highest concentrations of metals in the sediment were found in Chabahar, followed by Jask. The concentration of Hg was higher in the Indian white shrimp (0.16 ppm) and hooded oyster (0.20 ppm) than in the standard (0.10 ppm), while for other metals and tissues the concentrations were lower than the standard level. Also, BAF of Hg was higher than the standard permissible level in Jask(spring: 109.71%) and Pozm station (spring: 123.12%, fall: 125.76%). Except for Cd and Cu at the Chabahar station, the monsoon did not have any significant effect on metal concentrations and bioaccumulation. Preventive measures and management strategies are required as these concentrations and BAF of metals can become an actual threat to the environment and human health in this area.