Decadal changes in East China Sea and Southern Yellow Sea ecosystem

Abstract

The Three Gorges Dam on the Changjiang river discharge (CRD) is the largest hydropower project in the world, implemented in June 2003. Many researchers were concerned with the potential impact of the TGD on the marine ecosystem. Gong et al. (2003), for example, argued that this massive dam may cause reduction in marine primary productivity in the East China Sea by changing the supply of nutrients and sediment loading in the area. In this study, we examined the long-term trend of marine primary productivity (PP), chlorophyll-a (CHL), photosynthetically active radiation (PAR), sea surface temperature (SST) and euphotic depth (Zeu) in the East China Sea and Southern part of Yellow Sea during last 15-years (1998-2012). We also examined the correlation between the anomalies of Changjiang River discharge (CRD) and chlorophyll during pre-TGD (1998-2002) and post-TGD (2003-2007) to understand the sensitivity of the change and some potential cause of the trend in the primary productivity. Our result showed that the geographic extent of CRD influence was indeed greatly reduced after 2003. However, the large scale variability of the primary productivity did not show any correlation with the operation of the TGD nor show clear temporal trend in the ECS. Therefore, we conclude that the TGD has not reduced the primary productivity of the East China Sea as a whole. (2003), for example, argued that this massive dam may cause reduction in marine primary productivity in the East China Sea by changing the supply of nutrients and sediment loading in the area. In this study, we examined the long-term trend of marine primary productivity (PP), chlorophyll-a (CHL), photosynthetically active radiation (PAR), sea surface temperature (SST) and euphotic depth (Zeu) in the East China Sea and Southern part of Yellow Sea during last 15-years (1998-2012). We also examined the correlation between the anomalies of Changjiang River discharge (CRD) and chlorophyll during pre-TGD (1998-2002) and post-TGD (2003-2007) to understand the sensitivity of the change and some potential cause of the trend in the primary productivity. Our result showed that the geographic extent of CRD influence was indeed greatly reduced after 2003. However, the large scale variability of the primary productivity did not show any correlation with the operation of the TGD nor show clear temporal trend in the ECS. Therefore, we conclude that the TGD has not reduced the primary productivity of the East China Sea as a whole.