Toxic evaluations of sediments in Tokyo Bay, Japan, using Japanese medaka embryos

Abstract

Toxic risks of sediments collected from seven sites in Tokyo Bay were evaluated using Japanese medaka embryos. Those sediments with slight pore water were placed in grass petri dishes without overlying water. The most remarkable effect in the field sediment was to cause hatching delay in embryos, and the longest time until hatching took was 12.5 ± 1.6 days post-fertilization (dpf), although that in control group was 10.1 ± 0.7 dpf. A significant delay in hatching was observed at four sites. Because total carbon concentrations were relatively high in sediments at three of these four sites, several chemicals were expected to be residues in these sites and could cause their delay. Although extreme mortality was not observed at all sites, sediments collected from the site close to Kawasaki city induced 10 % mortality. Polycyclic aromatic hydrocarbon (PAH) concentrations were remarkably high at this site compared with other sites, and thus PAH toxicities could be causing the mortality. Concentration of heavy metals such as cadmium, copper, lead, and zinc in sediments were also determined, but no clear relationship was found between toxicities to embryos and the distribution of their concentrations.

Sediment Toxicity Testing with the Amphipod <i>Grandidierella Japonica</i> and Effects of Sediment Particle Size Distribution

“…The sediment samples from stations 4 and 6 [43], which were close to S1 and S3 in our study, did not induce significant 6-day mortality but caused growth inhibition. Uno et al [44] applied sediment toxicity tests with Japanese medaka embryos to the risk assessments of sediment collected from Tokyo Bay. In their study, sediment collected from stations 3 and 5, which were close to S5 and S2 in this study, significantly delayed embryo hatchings, though they did not induce significant mortality.…”

Recent advances in toxicity assessment across taxa

“…Kokushi et al (2016) used principle component analysis to determine metabolic effects in Oryzias latipes larvae exposed to 2,4-dichlorophenol. Kawano et al (2016) and Uno et al (2016) also focused on responses of Oryzias latipes to toxicants. In both cases, toxicity endpoints were survival, time to hatching, and developmental abnormalities.…”

“…Kawano et al (2016) exposed the embryos to four oxy-PAHs. Uno et al (2016) similarly exposed embryos to sediments collected from seven sites in Tokyo Bay, measured PAHs and metal concentrations in the sediments, and hypothesized that PAHs might be associated with observed delays in hatching times associated with contaminated sediments.…”