John Wiley & Sons, Ltd.

Arabian killifish (Aphanius dispar) embryos: A model organism for the risk assessment of the Arabian Gulf coastal waters

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Fish embryos are excellent models for studies aimed at the understanding of toxic mechanisms and the indication of possible acute and chronic effects. For the past 3 years, an Arabian killifish fish embryo test (FET) has been developed in our laboratory as a routine ecotoxicological test that can be used to support risk assessment of potential contaminants in Arabian Gulf coastal waters. Tests were conducted with three reference toxicants (DCA, SDS and Zn) and chlorine a disinfectant used widely in industrial cooling systems around the Arabian Gulf region. The EC50 for DCA was found to be 0.47 and 1.89 mg/L for embryos exposed before 6 hpf and after 168 hpf, respectively. Sub‐lethal effects were mainly observed at concentrations above 2.5 mg/L, the effects included severe pericardial edema and tail shortage. SDS ionic surfactant caused mortality at both early and late stages of embryo development; it caused coagulation, severe deformity and hemolysis. Both the EC50 and LC50 for SDS was found to be 9.37 mg/L Salinity influenced the toxicity of Zn to killifish embryos, at 40 psu Zn was found not to be toxic while at 20 psu toxicity had increased significantly (P < 0.05). EC50 and LC50 were found to be 2.5 mg/L and 4 mg/L respectively. Concentrations above 15 mg/L embryos were often accompanied with upper abdominal edema and inhibition of growth especially evident in the tail shortage. Chlorine caused mortality at a lower concentration for example at 0.05 mg/L 33% of embryos were found dead at the end of experiment. LC50 for chlorine was determined to be 0.08 mg/L Examination of the existing literature showed similar results to the findings reported in this study. The results suggest a more comparable sensitivity of killifish embryos to that of other FET recommended fish species. The findings in this study support the ability of Killifish to be an indicator organism for environmental risk assessments of Arabian Gulf waters. Benefits include; sensitivity to wide range of substances and conditions, animal alternative, ease of fish breeding and clarity of the embryos. This article is protected by copyright. All rights reserved

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