THESIS
2015
iv leaves, v-xiii, 111 pages : illustrations (some color), maps (1 color) ; 30 cm
Abstract
Two estuaries of Southern China, Pearl River Estuary (PRE) and Jiulong Estuary, suffered from heavily multi-metal pollution, leading to the occurance of ‘colored oysters’. The biological impacts of trace metal pollution in these two estuaries remain unknown. This study measured a suite of biomarkers of native Crassostrea hongkongensis in the PRE and also investigated the temporal changes of biomarker responses in Crassostrea hongkongensis and Crassostrea angulata transplanted in Jiulong Estuary during two-month exposure. In PRE oysters, we found that (1) there were large spatial variations of tissue metal concentrations, especially for Cu, Zn, Cd, Cr and Ni; (2) lipid peroxidation, catalase or glutathione peroxidase were significantly correlated with Cu and Zn accumulations in gills;...[
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Two estuaries of Southern China, Pearl River Estuary (PRE) and Jiulong Estuary, suffered from heavily multi-metal pollution, leading to the occurance of ‘colored oysters’. The biological impacts of trace metal pollution in these two estuaries remain unknown. This study measured a suite of biomarkers of native Crassostrea hongkongensis in the PRE and also investigated the temporal changes of biomarker responses in Crassostrea hongkongensis and Crassostrea angulata transplanted in Jiulong Estuary during two-month exposure. In PRE oysters, we found that (1) there were large spatial variations of tissue metal concentrations, especially for Cu, Zn, Cd, Cr and Ni; (2) lipid peroxidation, catalase or glutathione peroxidase were significantly correlated with Cu and Zn accumulations in gills; (3) glutathione or glutathione transferase were significantly correlated with Cd or Cu accumulation in the gills; (4) alkaline phosphatase or glycogen reserve were significantly correlated with Cu, Zn or Ni accumulation in the digestive glands; and (5) metallothionein concentrations were positively correlated with Cd but negatively correlated with Cu, Ni or Zn concentration in the gills. In both two oysters transplanted in Jiulong Estuary, we found that (1) there was rapid bioaccumulations of metals during exposure period, especially for Cu and Zn which reached up to 2% and 1.5% dry tissue weight after two-month of exposure; (2) there were opposite correlations between the Cu or Zn accumulation and catalase or superoxide dismutase, indicating the adjustments of oyster antioxidant systems induced by hyper-accumulation of Cu and Zn in tissues; (3) the tissue metallothionein concentration decreased after an initial increase; and (4) the lysosomal membrane stability gradually recovered after the initial strong inhibitions. The overall study validated the multiple biomarker technique coupling with tissue metal concentration measurements as a useful approach to evaluate the biological impacts of metal pollution in two estuaries of Southern China. However, the evolution of biomarker responses needs to be considered.
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