Age-dependent accumulation of heavy metals in a pod of killer whales (Orcinus orca) stranded in the northern area of Japan

Levels of Mercury and Organohalogen Compounds in the Muscle and Liver of Kidako Moray Eels (<i>Gymnothorax kidako</i>) Caught off the Southern Region of Japan

“…[2][3][4][5][6][7] In our survey of Hg in fish and marine foods (unpublished data), the average concentration of total mercury (T-Hg) in roasted eels purchased in Kochi Prefecture between 2004 and 2005 was 0.42 µg/wet g (n=9), which is similar to the levels of T-Hg found in spiny dogfish 7) and yellowfin and albacore tuna. 8) As Hg toxicity due to fish consumption is estimated by the amount of ingested methylmercury (M-Hg), 9) further study of Hg in the kidako moray eel, including M-Hg determination, is necessary to estimate Hg toxicity due to their consumption more precisely.…”

“…[10][11][12] As a reflection of their preferential feeding on cephalopods, the hepatic Cd concentration found in the kidako moray eel (1.37± 1.08 µg/wet g, n=26, Table 1) was markedly higher than that in the tiger shark (0.15± 0.24 µg/wet g, n=24), 5) but lower than that in toothed whales, such as the killer whale (7.84± 2.90 µg/wet g, n=6), 4) melon-headed whale (7.24± 2.08 µg/wet g, n=15) 6) and some dolphin species. 24) In contrast, the δ 15 N value in the muscle of moray eels was higher than that in whales and dolphins caught off the central and southern regions of Japan 29) as well as that in tiger sharks (our unpublished data).…”

“…Chemical Analyses The total mercury (T-Hg) concentrations in the muscle and liver samples were determined using a flameless atomic absorption spectrophotometer (Hiranuma Sangyo Co., Ltd., HG-1, Ibaraki, Japan) after digestion by a mixture of HNO 3 , HClO 4 and H 2 SO 4 . 22) Methylmercury (M-Hg) concentrations in the samples were determined using a gas chromatograph (Shimadzu Co., Ltd., GC-14A, Kyoto, Japan) with a 63 Ni electron capture detector (ECD).…”

“…10,11) Higher levels of Cd are reported to be accumulated in some predators which preferentially eat cephalopods. [4][5][6][10][11][12] A high level of Cd was expected to be accumulated in the kidako moray eel because of their preference for cephalopods. As far as we know, however, no data for Hg and Cd concentrations in the muscle of the kidako moray eel is available.…”

Mercury, cadmium, zinc and copper concentrations and stable isotope ratios of carbon and nitrogen in tiger sharks (Galeocerdo cuvier) culled off Ishigaki Island, Japan

“…Squid species represent a significant source of Cd in predatory fish and marine mammals (Honda et al, 1983;Bustamante et al, 1998), and Cd is preferentially accumulated in some predators in a body length (age)-dependent manner. The concentrations of the essential metals, zinc (Zn) and copper (Cu), in the liver and muscle of marine mammals and fish tend to decrease during the growth period (Honda et al, 1983;Storelli and Marcotrigiano, 2000;Zhang and Wang, 2005;Endo et al, 2007), while these concentrations in the liver of marine mammals tend to increase after the growth period with concomitant increases in Cd and Hg burdens (Das et al, 2000;Endo et al, 2007). Increases in the Cd burden induce the synthesis of metallothionein (MT) in the liver and Cd subsequently binds to MT along with Zn and Cu (Das et al, 2000).…”