Assessment Of Coral Reef Ecosystem Health And Ecological Assets In Past Three Decades At Weizhou Island Reef,Beibu Gulf

Under the multiple disturbances of human activities and natural factors,the global coral reefs are rapidly declining.The habitat of coral reef is destroyed,coral cover reduced and macroalgae cover increased,biodiversity decline,and the ecological services such as fishery,coastal protection and recreation are degraded.However,the incomplete information provided by current assessments mostly based on single or several indicators,which may mislead policy makers.Our assessment on Weizhou Island reef of the Beibu gulf,revealed contrasting responses to ecosystem structure and functions.We select 27 indicators from six aspects of community structure,habitat structure,supporting services,provisioning services,regulating services and cultural services to establish a health assessment index system.The major contents and results are as follows:(1)From 1990 to 2015,the health status of the ecosystem has degraded significantly,with the ecosystem health index decreased from 0.96 to 0.62.Although the community structure,supporting services and regulating services remained at good states,with the health index were 0.80,0.91 and 0.75,respectively.The health indexes of habitat structure,provisioning services and cultural services are all less than 0.6,with degradation of 83%,45% and 49%,respectively,which are the main reasons for the deterioration of coral reef health.(2)Grey relational analysis was used to a quantitative analytical tool for assessing integrated adaptive responses in coral reef ecosystems to climate/human stress in a long-term scale.The relational degree of community structure and supporting services with climate index increased from 0.6 to 0.8 during the period between 1990 and 2015,and was higher than that with human index after 2005.The recoveries of the community structure and supporting services that benefited from wintertime warming,and their health indexes recovered from 0.56 and 0.86 to 0.8 and 0.92,respectively.However,habitat structure,provisioning services and cultural services have a high relational degree with human index between 0.7-0.8,and the degradation of the three is closely related to the increase of human pressure from local tourism activities and petrochemical industry.The anthropogenic disturbances have impaired the possibility of this area serving as a potential thermal refuge for reef-building corals in the South China Sea.(3)The assessment of coral reef ecological assets mostly focuses on economics,using direct market pricing and replacement cost methods.There is less research on the evaluation of without market assets,such as biodiversity.In this paper,the corresponding relationship between the ecological attributes of coral reefs and the value of goods/services was established,and explores a method to calculate the ecological assets based on the health status of coral reefs.Taking the Weizhou reef as a case,this paper quantifies the current situation of its ecological assets,which provides a reference baseline for the evaluation of ecological assets in Weizhou reef.This study provides a comprehensive method to evaluate the health status of coral reef ecosystem,analyze the factors affecting the health of coral reef,and quantify the ecological assets based on the health status of coral reef.