Effect of mercury and cadmium on early life stages of Java medaka (Oryzias javanicus): A potential tropical test fish

Abstract

Several organisms have been used as indicators, bio-monitoring agents or test organisms in ecotoxicological studies. A close relative of the well established Japanese medaka, the Java medaka (Oryzias javanicus), has the potential to be a test organism. The fish is native to the estuaries of the Malaysian Peninsula, Thailand, Indonesia and Singapore. In this study, newly fertilised eggs were exposed to different concentrations of Cd and Hg. Observations were done on the development of the embryos. Exposure to low levels of Cd and Hg (0.01-0.05 ppm) resulted in several developmental disorders that led to death. Exposure to ≥1.0 ppm Cd resulted in immediate developmental arrest. The embryos of Java medaka showed tolerance to a certain extent when exposed to ≥1.0 ppm Hg compared to Cd. Based on the sensitivity of the embryos, Java medaka is a suitable test organism for ecotoxicology in the tropical region.

PRELIMINARY STUDY OF LARVAL DEVELOPMENT Oryzias javanicus IN INDONESIA

“…Ikan ini tersebar di sebagian besar wilayah Asia. Ikan ini dapat hidup di air tawar, payau maupun air laut (Ismail and Yusof, 2011). Genus Oryzias terdiri lebih dari 14 spesies, diantaranya adalah O. latipes, salah satu spesies yang telah dikenal sebagai biota uji (Khodadoust et al, 2013).…”

“…Genus Oryzias terdiri lebih dari 14 spesies, diantaranya adalah O. latipes, salah satu spesies yang telah dikenal sebagai biota uji (Khodadoust et al, 2013). Spesies yang lainnya yaitu Java medaka (O. javanicus) tersebar di Malaysia, Singapore, Indonesia, Thailand dan Bagian Barat Kalimantan (Ismail and Yusof, 2011). Oryzias dancena (atau dikenal O. melastigma) terdistribusi di Pakistan, India, Burma dan Thailand.…”

Water pH effects on survival, reproductive performances, and ultrastructure of gonads, gills, and skins of the Javanese medaka (Oryzias javanicus)

“…Briefly, the newly spawned fish egg clusters were collected gently from the female's body by hand or from the bottom of the aquarium using plastic pipettes. The clusters of eggs were separated using forceps and then surface sterilized using a mixture of culture medium (NaCl, KCl, CaCl•2H 2 O, MgSO 4 •7H2O) and methylene blue for 5 min (11). The eggs were then placed in a petri dish with new culture medium and incubated at 28 °C.…”

“…This small tropical fish has been widely used as a test organism in toxicology and ecotoxicology studies (2)(3)(4)(5). This species has also been used in several studies to represent marine and freshwater fish due to its ability to occupy fresh, brackish, and saltwater (6).…”

Investigation of hormone receptor expressions in the fins of Oryzias woworae (Actinopterygii: Beloniformes: Adrianichthyidae)

“…Among the various teleosts species, the fishes of the genus Oryzias are notable for their extensive use as vertebrate model organisms for research in many fields, such as endocrinology, developmental biology, and reproductive biology (Chakraborty et al 2011, Ismail and Yusof 2011, Zhang et al 2013. In this genus, the dorsal and anal fins are suggested to be typical secondary sex characteristics.…”