Trophic assessment in chinese coastal systems

Xiao, Yongjin

http://hdl.handle.net/10400.1/257

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Authors

Xiao, Yongjin

Advisor(s)

Ferreira, J.

Abstract(s)

Coastal eutrophication, mainly defined as ―the enrichment of nutrient stimulating algal growth‖ in coastal water, has started to be one of the main threats to the Chinese coastal areas since last two decades. The huge amount of nutrient loads from the human activities has modified the natural background of water quality in estuaries, bays and other coastal zones. As a result of elevated eutrophic status, coastal systems are subject to a series of negative and undesirable consequences, such as fish-kills and interdiction of shellfish aquaculture. While much attention is focused on managing this issue, there is a need to assess the eutrophic level in coastal systems and to identify the extent of danger. In this thesis, a variety of traditional Chinese assessment methods are discussed and compared with western ways, such as OSPAR COMPP and ASSETS. Afterwards, ASSETS was chosen to carry out two case studies (Changjiang Estuary and Jiaozhou Bay) due to its solid theory and successful applications. As a process-based method, it set up a pressure-state-response model based on three main indices, i.e., Overall Human Influence, Overall Eutrophic Condition and Future outlook. In spite of the lack of enough data, the results from applying ASSETS to Changjiang Estuary and Jiaozhou Bay are ―Bad‖ and ―Low‖ respectively, while the traditional methods only obtain more ambiguous results. The comparisons of the rationalities behind the methodologies and the results suggest that ASSETS could be a more reasonable and applicable method to assess Chinese coastal systems.