Study On Rapid Assessment Of Bay Ecosystem Health

Bays have unique geographical environment,where human activity is highly intensive.The bay ecosystems have been destroyed due to unreasonable development and construction activities for a long time,and ecological problems have become unfavorable factors restricting the development of social economy.Ecosystem assessment is the foundation of bay ecological protection and management.However,index system method,widely used to assess ecosystem health,has some drawbacks,for instance,there are too many parameters,and it's difficult to acquire the data.To solve these problems,on the basis of related research of domestic and overseas ecosystem heath assessment,this paper attempted to establish a method of bay ecosystem health rapid assessment by screening structure indices of marine biological community,simplifying the assessment indicators and analyzing taxonomic sufficiency.The main results were as follows:(1)Based on the correlation analysis of different community indicators,the indicator community was selected.The results showed that there was significantly positive correlation between community indicators of phytoplankton,zooplankton and benthos.Benthos was selected as the indicator community,in view of the fact the habits and characteristics of benthos reflected strong indication of eco-environment,.(2)The rapid assessment indicators of benthos were selected through the analysis of connotation of biodiversity indices,the correlation analysis of different indices and PCA analysis.The results showed that there was strong correlation between differnt benthos biodiversity indices(including traditional diversity indices and taxonomic diversity indices).Besides,combined with the connotation of each index and the results of each index's empowerment of PCA analysis,Taxonomic diversity index(?)and Pielou's evenness index(J)were selected as rapid assessment indices.(3)The taxonomic identification of benthos was simplified,based on the analysis of correlation between indices on different levels,the measurement of multidimensional scaling(n MDS)method and 2-STAGE(Second-STAGE)method.According to the high similarity of three community structures(on species level,genus level,and family level respectively)and the results of calculation which showed that compared with the species level,certain information was missed at the genus level(8%)and family level(20%).Therefore,benthos were supposed to be identified to the genus level rather than the species level for the monitoring and assessing benthos in case that identification to species level is unrealizable.(4)On the basis of research above,the method of rapid assessment of bay ecosystem health has been established,including indicator system of assessment,estimation model of comprehensive health index,reference standard of index,index standardization,etc..The established method was applied in Daya Bay,and the scores of comprehensive health index of rapid assessment and conventional assessment were81.76 and 79.98 respectively and the health grades were both sub-health,which showed that the result of rapid assessment of ecosystem health was consistent with the conventional assessment,with only 2.2% difference in scores,and the method of rapid assessment of bay ecosystem health established on this paper is feasible.