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The variability of Fe, Mn, Zn, Cu, Pb, Cd, and Ni concentrations was studied in soft tissues of the common mytilid mollusk Septifer bilocularis collected in May 2013 at the coral reefs along the entire Vietnamese coast from the Gulf of Siam to Ha Long Bay. The salinity, suspended solids, and nutrients were determined during the sampling; these hydrochemical characteristics of the surrounding waters were controlled by the river runoff and the content of chlorophyll a. The concentration of Mn in the mollusk S. bilocularis was elevated under the river runoff effect. However, concentrations of Cd and Zn in S. bilocularis were the lowest within the areas of river influence and increased in waters of central Vietnam and the Gulf of Siam, where upwellings are an important driving force. A comparison of our data with those obtained for Mytilidae from other regions showed that the mussel S. bilocularis can be recommended for biomonitoring of the concentrations of trace metals in the waters of coral ecosystems along the Vietnam coast. [ABSTRACT FROM AUTHOR]

The contents and geochemical forms of Mn, Zn, Cu, Pb and Cd were studied in the coastal sediments at the Sea of Japan, an area adjacent to the watershed with a developed mining industry (Rudnaya River basin, middle Sikhote-Aline). Solid discharge into the Rudnaya River has abnormally high metal contents that are in leachable forms, including sulfides. Metal levels in the coastal sediments were elevated as a result of this polluted matter dissipation. Sediment pollution by Pb, Cd, Cu and Zn (normalized Clark Concentration measure) exceeds 20-50 within Rudnaya Bight and varies from 5 to 10 within a 25-km plume southward of the bight due to current action. An alteration of the metal forms also occurred, due to mechanic decomposition of the sulfide minerals and dissipation of all river-derived forms. [ABSTRACT FROM AUTHOR]

The relationship between Zn, Cu, Cd, Pb, and Ni concentrations in soft tissues of mussels and oysters and those in ambient sediments was examined. The study area was the coastal habitats of the northwestern Sea of Japan, which has a broad range of contamination due to urban sewage. Significant increases of all metals, except Ni, were observed in mussel Crenomytilus grayanus at concentrations of easily leachable metals in ambient sediments higher than 2, 100, and 800 microg/g for Cd, Cu, and Zn, respectively. Pb was accumulated by the mussels with no distinct threshold in Pb contamination of sediments. After 2 months, C. grayanus transplanted from a pristine to a contaminated locality increased in Pb up to 12%, and Cu up to 68% of concentrations of these metals in the contaminated local mussels, but Zn and Cd concentrations increased only in the excretory tissue, not in the somatic tissue, or in the soft tissue as a whole. Such regulation of metal accumulation puts limitations on the use of C. grayanus for monitoring of slightly and moderately contaminated localities. On the other hand, the oyster Crassostrea gigas showed definite accumulation of all metals, except Ni, at moderate contamination of ambient sediments. As contamination of sediments increased, increases of Pb, Zn and Cu concentrations in C. gigas slowed, possibly due to physiological control at very high metal concentrations in oyster soft tissue. Thus, the mussel C. grayanus should be used mainly for the monitoring of heavy contaminated localities, and the oyster C. gigas is more suitable as an indicator of low and moderate contamination.

Concentrations of cadmium, copper, iron, lead, manganese, nickel and zinc were investigated in two species of mussel from the Kuril Islands in the north-western Pacific Ocean: the short-lived mussel Mytilus trossulus and the much larger and longer-lived Crenomytilus grayanus. The concentrations of most elements were low, and these reported levels are believed to reflect background values for pristine locations. However, both iron and zinc concentrations were elevated in some samples taken from areas of hydrothermal vent activity, and these are believed to reflect the enrichment of the two metals in solution at such sites. Furthermore, the concentrations of cadmium were unusually elevated in both species of mussel, especially in the longer-lived C. grayanus. The high accumulation of cadmium in mussels from the Kuril Islands is believed to reflect regional upwelling, but it is also postulated that filtration rates of the mussels are high due to low levels of suspended matter, and this leads to a high assimilation efficiency for cadmium. The distribution of cadmium amongst the tissues of C. grayanus is also reported, and the need for further ecotoxicological studies in the area is proposed.