The study on the vulnerability of the ecosystem in Yueqingwan Bay

With the exploitation and development of marine economy,destruction of the marine ecological environment becomes more and more serious,and the ecosystem becomes more and more fragile.Marine ecosystem has become a restricting factor for the sustained development of the marine economy or if the marine economy continues to develop in the present pattern the marine ecosystem will be threatened.Both the ability of interference-resistance and self-stability of the ecosystem are poor.The main feature of the ecosystem is sensitive to outer disturbance and instable for its own inner structure.Starting with a typical bay named Yueqingwan Bay in Zhejiang province,the formation mechanism of the vulnerability of the ecosystems is analyzed.It is resulted from joint action of many natural and man-made dynamic factors.Its vulnerability can be divided into two categories of inherent and special vulnerability.Inherent vulnerability is mainly formed by land-sea dynamics such as runoff,air temperature,precipitation,wave,tide and other environmental factors.Special vulnerability is formed by human activities,including marine engineering,beach reclamation,aquaculture,pollution,and other non-environmental factors.Integrating above factors shows that the ecosystem of Yueqingwan Bay is at sub-healthy condition and close to the edge of unhealthy,and the ecosystem is extremely fragile.Although the major service function of the ecosystem services is still working,it can no meet the requirements of marine functional zoning and seriously affect the sustainable development of marine economy.In addition,the tolerance of the fragile ecological environment to interferential factors and interference process and the self-plasticity or flexibility has decreased,or the sensitivity is strong.It is prone to degradation or deterioration.The ecosystem vulnerability in Yueqingwan Bay incorporates following aspects:(1) The water is badly polluted by inorganic nitrogen and active phosphate.The degree of eutrophication is notable,and the ratio of nitrogen and phosphorus is imbalanced.The water quality of the whole Bay is of inferior to four categories in spring,and 76 percent of the whole Bay is of four categories or inferior to four categories in summer. (2) The actual area of natural water has reduced by nearly a quarter,and the quantity of receiving tide decreased by nearly 5.79 percent. (3) The biodiversity has reduced,and the total biomass and the count of species are decreasing year by year.The marine food chain has been severely damaged,and the structure of biological communities has obviously changed. (4) The quality of sediments has declined in the aquaculture zone,and it is easy to be secondly polluted under hydrodynamic action. (5) The fishery economic is in downturn around Yueqingwan Bay.The individual of the catchable fish becomes smaller and low-value fish is more and more.Finally,measures and suggestions for the rehabilitation of the fragile ecosystem in the bay are proposed:(1) Implement the responsibility system of objective management of marine environment;(2) Strengthen the control of pollutants entering the sea;(3) Use ecological principles and technology to control mariculture pollution;(4) Use large algae to remedy water eutrophication;(5) Build up a system of marine ecological environment monitoring,forecasting and management and law enforcement.All these will make the marine ecosystem re-enter a benign circle,and provide basis for the sustainable utilization of marine sources.