Assessment of the embryotoxic potential of contaminated sediments using fish embryotoxicity tests for the river Buriganga, Dhaka, Bangladesh

Sediment samples from six different locations of Buriganga River following exposure to Zebrafish (Danio rerio) eggs and larvae displayed prominent effects on both whole sediments and sediment organic extracts. The acute and sublethal effects during 96 h exposure period included (i) a significant (P 0.05) increase in morality and abnormalities in zebrafish eggs and embryos; (ii) a significant (P 0.05) reduction in hatching success and heart rate; (iii) increased frequency of helical tail and lordosis after 96 h exposure to sediment extracts; (iv) developmental delay and yolk sac edema after exposed to whole sediments at 96h exposure period. Chemical analysis showed the increased concentrations of heavy metals (Zn, Cr, Cu, Pb, and Cd) in downstream (S1, S2, and S3) compared to upstream (S4, S5, and S6), where some ions such as Cd and Cr exceeded the Environmental Protection Agency’s Threshold Effect Level (EPA TEL). The current study delineates the contamination of extremely toxic compounds in the sediment of Buriganga River, which may initiate toxic effects on the early life stages of fish. Therefore, integrating zebrafish embryo toxicity tests may be crucial for evaluating the sediment quality of polluted rivers.