| Summary: | Runoff of bauxite residues had caused severe turbidity in two rivers water near Kuantan. Such river turbidity is a global threat to aquatic fauna like fish embryo. To investigate the turbidity effects of suspended bauxite on climbing perch (Anabas testudineus) embryo, the organism was exposed to bauxite after post-fertilisation. The 24-h median lethal concentration (24-h LC50), the lowest effect concentration (LOEC), and no-observed effect concentration (NOEC) were 4.212 g L−1, 2.190 g L−1, and 0.125 g L−1, respectively. Sublethal effects observed were hatching rate and unhatched rate, and mean hatching hours. The lethal effects clearly shown in bauxite levels of 6.00–24.00 g L−1. Fatal effects were observed in these treatment groups which resulted in a mortality above 80%. Among the deadly effects recorded were malformations, shrinking of yolk, bauxite coating, and ruptured chorion. Overall, our finding suggest that the level of bauxite residues in the water should not exceed 0.125 g L−1 to ensure good development and survival of A. testudineus embryos.
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