Long-term influence of the Three Gorges Dam in the East China Sea ecosystem

Abstract

Since the impoundment of the Three Gorge Dam (TGD) in 2003, many researchers were concerned about the potential impact of the dam on the East China Sea ecosystem. However, long-term influence of the TGD on the adjacent coastal water has not been well examined. Here, we analyzed the seasonal and inter-annual variation of surface chlorophyll-a, photosynthetic active radiation, sea surface temperature, and euphotic depth in the East China Sea according to the three TGD periods using the SeaWiFS and MODIS-aqua merged satellite data Pre-TGD (1998-2002), Trans-TGD (2003-2007), and Post-TGD(2008-2012). The study area was divided into six regions based on the K-means clustering of empirical orthogonal function scores. Our result suggest that the area where a significant increase in chlorophyll-a attributable to TGD was confined to the vicinity of Changjiang river mouth while a decrease or no clear pattern was observed in the other part of the East China Sea. The consistent decrease in the chlorophyll-a in the continental slope region can be explained by the warming in the region over the period. been well examined. Here, we analyzed the seasonal and inter-annual variation of surface chlorophyll-a, photosynthetic active radiation, sea surface temperature, and euphotic depth in the East China Sea according to the three TGD periods using the SeaWiFS and MODIS-aqua merged satellite data Pre-TGD (1998-2002), Trans-TGD (2003-2007), and Post-TGD(2008-2012). The study area was divided into six regions based on the K-means clustering of empirical orthogonal function scores. Our result suggest that the area where a significant increase in chlorophyll-a attributable to TGD was confined to the vicinity of Changjiang river mouth while a decrease or no clear pattern was observed in the other part of the East China Sea. The consistent decrease in the chlorophyll-a in the continental slope region can be explained by the warming in the region over the period.