Areal Ecosystem Healthassessment Of Daya Bay

In recent years, the world's major bays are suffering by the impact from human activities in different degrees, undering the landing and sea-source sewage, coastal and marine construction, over-farming and fishing and other external pressures, ecosystem health has declined markedly. Daya Bay is located at east of the Pearl River estuary, near Hong Kong, is a type of drowned valley bay which is very rich with biological resources and the provincial nature reserve aquatic resources in Guangdong Province, but since the late 80s last century, around the Gulf are more and more impact of human activities, especially in the South China Sea petrochemical project started, upstream and downstream industries, has led to increasingly serious eutrophication Gulf, decreased biodiversity, fisheries continue to decline, ecosystem lose it balance.To evaluate the ecosystem health of Daya Bay, this paper build a of ecosystem health assessment index system and comprehensive health assessment model by used analytic hierarchy process and comprehensive indexing method, and then made three typical regional ecosystem which are the artificial reef sea area in Yangmei Delve of Daya Bay, Dapeng Cove mariculture sea area and the Daya Bay Eastern Petrochemical sewage zone as the research object, using the established model of ecosystem health assessment of their health status was assessed. The paper is divided into theoretical parts and practical parts. The main results are as follows:The overall ecosystem health situation of artificial reef sea area are all sub-healthy. Ecosystem health index of Six survey voyages are: 0.713,0.807,0.830,0.841,0.759 and 0.815,according to the grading standards of ecosystem health, the ecosystem health of the background survey is in a sub-healthy level, five following survey voyages are in the basically-healthy level. Phytoplankton, zooplankton biomass and primary productivity of sea waters are at a high level, biodiversity is more extensive, the main factors which affecting the health of marine ecosystem are total inorganic nitrogen in sea waters and inorganic carbon in sediments.The overall ecosystem health situation of marine culture sea area is sub-healthy. Four seasonal voyage's comprehensive index of ecosystem health are: 0.880,0.809,0.719,0.610, according to ecosystem health grading standards, ecosystem health situation of the spring and summer's survey voyage is in the basically-healthy level, fall and winter seasons are in a sub-healthy level. The main factors which affecting the health of marine ecosystem are active phosphate, total inorganic nitrogen and sulfide in deposits.The overall ecosystem health situation of petrochemical sewage sea area is sub-healthy. Two seasonal(summer and winter) survey voyage's comprehensive index of ecosystem health are 0.759 and 0.739, in accordance with the grading standards of ecosystem health, the marine ecosystem health of the summer season's survey voyage is in the basically-healthy level and winter is sub-healthy. The main factors which affecting the health of marine ecosystem are phosphate and sediment sulfide.