海湾生态系统健康评价方法构建及在大亚湾的应用

根据海洋生态系统的压力-结构-响应框架模型,从压力指标、结构指标、响应指标等几个方面构建了海湾生态系统健康评价的指标体系,提出了基于GIS的海湾生态系统健康综合指数法.以春季大亚湾海洋生态系统为例进行实证研究.结果表明:大亚湾海湾生态系统春季的健康综合指数平均值为0.57±0.08,从总体看来,生态系统健康状态处于“较好”水平,浮游植物丰度、浮游植物多样性和生态缓冲容量是其主要健康负面因子,健康状况可能面临着向“临界”状态转化的危险.实证研究表明该方法适用性强、结果客观准确、形象生动,是一种值得推广的定量评价方法.

Establishment of integrated methodology for bay ecosystem health assessment and its application in Daya Bay

Bay ecosystem health, recently, has faced a growing interference and disturbance by anthropogenic activities, which has also caused challenges to ecosystem management. Ecosystem health assessment, a new methodology of ecosystem assessment, could obtain the current situation both of ecosystem structure and function and provide a great of necessary information for ecosystem management. An integrated assessment methodology for bay ecosystem health was established based on geographical information system (GIS) technology, which was on basis of a "pressure-structure-response" frame model for marine ecosystem and an ecosystem health assessment indicator system constructed by external pressure, ecosystem structure and response parameters. This paper also presented a case study of Daya bay in spring by employing GIS technology.The results showed that the average ecosystem health integrated index was 0.57 in Daya Bay ecosystem in spring. Detailedly, organic pollutant index ranged from 0.36 to 1, with the average value at 0.87, was at "very good" level of Daya Bay ecosystem. Eutrophic level index value ranged from 0.17 to 1, with the average of 0.77, indicated "better" level of the ecosystem. Furthermore, phytoplankton abundance index was at a "worse" level because of the ranges from 0.33 to 1 and the average of 0.21. Zooplankton biomass index ranged from 0.16 to 1, with the average of 0.88, suggested the ecosystem was at a "very good" level. Zoobenthos biomass index was at "critical state", as the index value ranged from 0 to 1 and the average value at 0.59. Moreover, phytoplankton diversity index was also "critical state" level, as the index ranged from 0.39 to 0.75 and the average of 0.55. Primary productivity index, ranged from 0.21 to 1 and the average of 0.77, illustrated the "better" level of the ecosystem. However, ecological buffer capacity index was at a "worst" level, as the index value ranged from 0 to 0.39 and the average value of 0.06. Resumptively, spatial distribution of the assessed sea area could be divided into three zones according to the grade of integrated assessment index, namely "good health zone", "critical health zone" and "bad health zone". The percentages of three zones were 46.56%, 47.97% and 5.47%, with the average integrated health index of 0.64, 0.54 and 0.35, respectively.In general, the status of the Daya Bay ecosystem health was at a "better" level according to the above indexes. However, the health status of the ecosystem was potential to change to "critical state" by the negative influences by factors including phytoplankton abundance, phytoplankton diversity and buffer capacities of the ecosystem. The "bad health zone" in the Daya Bay ecosystem distributed at or near the area with the intensive anthropogenic activity. Consequently, the special distribution of Daya Bay ecosystem health status was mostly affected by anthropogenic activity around the bay. The established methodology has been ultimately proved to be a valuable quantitative assessment method and to be worth widely popularizing in marine ecology due to the characteristics of wide applicability, high accuracy and good expression.