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Title: Ecological risk assessment of oviparous wildlife from Hong Kong and southeastern coast of China due to environmental contaminants
Other Titles: Huan jing wu ran wu dui Xianggang ji Zhongguo dong nan yan an luan sheng ye sheng dong wu de sheng tai feng xian ping gu
Authors: Lam, James Chung Wah (林忠華)
Department: Dept. of Biology and Chemistry
Degree: Doctor of Philosophy
Issue Date: 2005
Publisher: City University of Hong Kong
Subjects: Coastal ecology -- China -- Hong Kong
Coastal ecology -- China, Southeast
Ecological risk assessment -- China -- Hong Kong
Ecological risk assessment -- China, Southeast
Notes: CityU Call Number: QH541.15.R57 L35 2005
Includes bibliographical references (leaves 194-218)
Thesis (Ph.D.)--City University of Hong Kong, 2005
xviii, 218 leaves : ill. ; 30 cm.
Type: Thesis
Abstract: Marine pollution has been a problem for the coastal waters of Hong Kong Special Administrative Region (HKSAR) since the 1970s. More recently, the adjacent Pearl River Delta (PRD) region has also become a significant pollution source. Persistent toxic contaminants, including a suite of organochlorine compounds, trace elements and metals, have been recorded in the coastal environment of HKSAR at concentrations that may have an adverse impact on the integrity of our marine ecosystem. Hong Kong’s marine waters are home for a wide variety of marine life. Deterioration in water quality will not only threaten wildlife, but may cause deleterious effects on human health. Indeed, wildlife has been the sentinels of human health effects for a long time. Many marine lives have been used as bioindicators for a wide range of environmental contaminants. The primary objective of this study is to monitor a broad spectrum of pollutants present in marine wildlife namely waterbirds and marine turtles, with a view to evaluate the potential risks on assessment targets exposed to these environmental contaminants. Waterbirds and marine turtles were selected as the assessment targets in the present study because of their importance in the marine ecosystem, as well as, their susceptibility to the effects of marine pollutants. Throughout the world, birds are influenced by environmental contaminants including organochlorines, organophosphorous insecticides, metals and petroleum. Among the trace organic pollutants, DDTs are well known for their role in causing a decline in populations of fish-eating birds. A previous investigation has already demonstrated the potential hazard of DDTs present in the eggs of Ardeids from Mai Po, Hong Kong. In this investigation, eggs of three species of waterbirds, namely, Little Egret (Egretta garzetta), Black-crowned Night Heron (Nycticorax nycticorax) and Bridled Terns (Sterna anaethetus) were examined and the results revealed significantly higher levels of organochlorines in the eggs of little egret collected from northwestern part of Hong Kong as compared to the northeastern coastal region, indicating that the western waters of Hong Kong are more contaminated by organochlorines. Preliminary ecological risk assessment indicated potential risks of total PCBs, dioxin-like halogenated aromatic hydrocarbons, heptachlor epoxide and endrin to waterbirds inhabiting the northwestern coastal areas of Hong Kong, based on the levels of these contaminants detected in eggs. Hazards of trace elements to the waterbirds were also evaluated and the results suggested that mercury and selenium might pose some risk to certain waterbirds in Hong Kong. Sea turtles are threatened by a variety of anthropogenic disturbances and are vulnerable to human impacts at all life stages. Green turtle (Chelonia mydas) is the only recorded sea turtles nesting in Hong Kong. Apart from the loss and degradation of habitats, marine pollution is another factor that may cause direct effects on the green turtles. To assess the risks of environmental pollutants, including organochlorine pesticides, PCBs and a number of trace elements, were measured in the green turtles. Results of a screening ecological risk assessment suggested that total PCBs, p,p’-DDE, selenium and nickel were likely to cause adverse effects to the turtle hatchings. Our study also found that concentrations of several trace elements (Ag, Ba, Se, As, Zn and Hg) in the shell of the green turtle eggs were significantly correlated with levels in the whole egg contents (yolk + albumen). It is conceivable that if the precise relationships for specific elements are established, egg shell concentrations may be used as a non-lethal and non-invasive surrogate for predicting whole egg burden of these contaminants in marine turtles. Polybrominated diphenyl ethers (PBDEs) are one of the environmental contaminants recently detected in significant quantities in various environmental compartments such as sediment, wildlife, food and even human beings. They were created as flame retardants for broad applications in products, such as textiles, electronics, plastics and other materials, to help prevent property damage and fire-related injuries. These new emerging chemicals have entered the marine environment and, due to their persistence and lipophilic characteristics, have bioaccumulated in the tissues of organisms, particularly those at higher trophic levels, e.g. fish-eating birds. South China is one of the fast-growing regions in the world in terms of population growth, economic and industrial activities. Through the discharge of municipal sewage and industrial effluents, large quantities of PBDEs may have accumulated in our coastal environment. To assess the status and trends of PBDE contamination, PBDEs in eggs of waterbirds were monitored in South China. Waterbirds selected in the current study included Little Egret (Egretta garzetta), Black-crowned Night Heron (Nycticorax nycticorax), Cattle Egret (Bubulcus ibis) and Chinese Pond Heron (Ardeola bacchus). Eggs of these waterbirds were collected from Hong Kong, Xiamen and Quanzhou, three important port cities of South China. The results indicated relatively higher concentrations of total PBDEs in eggs of waterbirds in Hong Kong as compared to Xiamen and Quanzhou. Such inter-site variations may be attributed to the different developmental phases and the amount of PBDEs technical mixtures used in and around the various sampling locations. The toxicological effects of PBDEs in bird eggs were estimated and the findings suggested potential hazards to certain waterbirds, though the “actual” risk still needs to be further evaluated. Overall, the present study has provided the baseline information on a range of environmental contaminants and has assessed the ecotoxicological effects of these pollutants in a number of oviparous wildlife in Hong Kong. These results will make a contribution towards an optimal use of sentinel wildlife in the evaluation of the ecological integrity of important ecosystems.
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