Shenzhen Key Laboratory of Edible and Medicinal Bioresources, HKUST Shenzhen Research Institute, Shenzhen, and Department of Ocean Science, The Hong Kong University of Science and Technology (HKUST), Clearwater Bay, Kowloon, Hong Kong, PR China.
Shenzhen Key Laboratory of Edible and Medicinal Bioresources, HKUST Shenzhen Research Institute, Shenzhen, and Department of Ocean Science, The Hong Kong University of Science and Technology (HKUST), Clearwater Bay, Kowloon, Hong Kong, PR China.
Environ Pollut. 2019 Jul;250:175-185. doi: 10.1016/j.envpol.2019.04.019. Epub 2019 Apr 8.
Despite of much evidence of trace metal pollution in the Pearl River Estuary (PRE), the seasonal dynamics of metal bioavailability as well as the potential impacts of metal pollution on the local marine organisms in this estuary is poorly understood. In the present study, the accumulation of trace metals and reproductive states of three populations of oyster Crassostrea hongkongensis, a keystone bivalve species in the PRE, were for the first time investigated throughout a one-year field study. Significant temporal fluctuations of metal accumulation were observed in the somatic tissues of oysters, suggesting seasonal variations of metal bioavailability in the PRE. A major feature of the seasonal variations was the increased levels of metal bioaccumulation in the summer season for the contaminated sites nearby the major river inlets. High riverine inputs accompanied by relatively lower salinity in summer may greatly contribute to such variations. Furthermore, oyster populations from two contaminated sites had a poor reproductive condition in comparison with the reference oyster population, as reflected by a significant decrease of gonad-somatic index (GSI) and gonad cover area (GCA), as well as an obvious change of sex ratios. Gonadal metal accumulation of Cu, Zn, Ni, Co and Pb in the contaminated oysters was much higher than that in the relatively uncontaminated oysters. Especially, the concentrations of these metals in the gonad during the breeding season had significantly negative correlations with the gonad condition indexes (GSI and GCA). Our results suggested strong seasonal fluctuations of bioavailability of trace metals in this highly contaminated estuary as well as an adverse effect of metal pollution on the reproduction of local oyster populations.
尽管珠江口（PRE）存在大量痕量金属污染的证据，但金属生物可利用性的季节性动态以及金属污染对该河口本地海洋生物的潜在影响仍知之甚少。本研究首次通过为期一年的野外研究，调查了 PRE 三种牡蛎（Crassostrea hongkongensis）种群的痕量金属积累和繁殖状态。牡蛎体组织中的金属积累存在明显的时间波动，表明 PRE 中金属生物可利用性存在季节性变化。季节性变化的一个主要特征是，受主要河流入海口附近污染点的金属生物积累水平在夏季增加。夏季河流输入量高，盐度相对较低，可能是造成这种变化的主要原因。此外，与参考牡蛎种群相比，来自两个污染点的牡蛎种群繁殖状况较差，表现在性腺-体指数（GSI）和性腺覆盖面积（GCA）显著下降，以及性别比例明显改变。污染牡蛎的 Cu、Zn、Ni、Co 和 Pb 的性腺金属积累明显高于相对无污染的牡蛎。特别是，这些金属在繁殖季节在性腺中的浓度与性腺状况指数（GSI 和 GCA）呈显著负相关。我们的研究结果表明，在这个高度污染的河口，痕量金属的生物可利用性存在强烈的季节性波动，金属污染对本地牡蛎种群的繁殖也有不利影响。
