Modeling changes in the coastal ecosystem of the Pearl River Estuary from 1981 to 1998

摘要: Abstract The coastal ecosystem of the Pearl River Estuary (PRE) has been overfished and received a high level combined pollution since 1980s. Ecopath with Ecosim was used to construct two models (for 1981 1998) characterize food web structure functioning ecosystem. Pedigree work simple sensitivity analysis were carried out evaluate quality data uncertainty models. seem reliable regards input good quality. Comparing variations outputs these aimed facilitate assessment changes during past decades. trophic changed an increase in biomass proportion lower (TL) organisms decrease top predator proportion. All indices maturity examined show that system more mature condition than 1998, although stress due anthropogenic disturbances, such as environmental habitat destruction 1981. aggregated into six seven integral TLs respectively, using aggregation routine Ecopath. Most total catch took place at TL II III both years. But distribution different decreasing proportions higher 1998. mean transfer efficiency 9.1% 10.2% respectively. Comparative network allowed quantification importance direct indirect interactions among functional groups. Moreover, method derived from mixed impact (MTI) estimating groups terms “keystoneness” identifying keystone species over results indicate there no clear 1998 but medium levels identified located low phytoplankton, zooplankton benthic invertebrates have relatively keystoneness