Effects of reclamation and natural changes on coastal wetlands bordering China's Yellow Sea from 1984 to 2015

Abstract

Coastal wetlands are rapidly disappearing worldwide, which is posing a substantial threat to the integrity of coastal ecosystems. In addition to the direct area reduction caused by reclamation, coastal wetlands experience natural changes due to sediment transport in coastal regions. Arguably, the reclamation rates must be less than the net accretion rate to guarantee the restoration of coastal wetlands. By applying an automatic and replicable shoreline algorithm to all available Landsat imagery from 1984 to 2015 using the Google Earth Engine Cloud Platform, we developed distribution maps of coastal wetlands and reclamation in China's Yellow Sea (CYS) at 4‐ or 5‐year intervals. In addition, we divided coastal wetlands into saltmarshes and mudflats and analysed their trends separately. Over the past 30 years, the area of coastal wetlands decreased by 53% (from 6,463 to 3,036 km2), including a 67% decrease in saltmarshes (from 1,471 to 489 km2) and a 49% decrease in mudflats (from 4,992 to 2,547 km2). Meanwhile, the reclaimed area was 7,696 km2 (including 1,276 km2 of saltmarshes and 3,002 km2 of mudflats), which exceeded the area of newly formed coastal wetlands (852 km2). The natural state of mudflats gradually changed from accretion to erosion, but without considering the natural state of coastal wetlands, reclamation will continue at a high rate in CYS according to China's national marine functional zoning (MFZ) for 2010–2020. In view of their important ecological services, there is an urgent need to revise the national MFZ to achieve ‘no net loss’ of coastal wetlands.

Remote Observations in China’s Ramsar Sites: Wetland Dynamics, Anthropogenic Threats, and Implications for Sustainable Development Goals

“…In terms of evident wetland loss and diverse anthropogenic threats (Figure 4), protection efficacy for most Ramsar sites in China could be improved. Even after the designation of Ramsar sites, agricultural activities still encroached into large areas of Ramsar wetlands, especially in NEC [18,29], while infrastructure construction with urbanization and industrialization occurred in areas such as the YAR [30,31]. Moreover, aquaculture development and invasive S. alterniflora had encroached upon large areas of natural wetlands in coastal Ramsar sites that are known to be important for migratory waterbirds [32,33].…”

The southern Jiangsu coast is a critical moulting site for Spoon-billed Sandpiper Calidris pygmaea and Nordmann’s Greenshank Tringa guttifer

“…The intertidal flats of southern Jiangsu Province are of global importance as a moulting and staging area for threatened shorebird populations. The rapid loss of intertidal habitats elsewhere in Jiangsu (Cai et al 2017, Chen et al 2019 means that it is highly unlikely that Spoon-billed Sandpipers and Nordmann's Greenshanks would be able to find a nearby alternative moulting and refuelling ground if our study areas were to be destroyed. Currently, these areas still face multiple threats including invasion by exotic smooth cordgrass Spartina alterniflora (Zhou et al 2009), pollution (Melville et al 2016, Yao et al 2018, incidental shorebird capture by fishnet (Crighton 2016) and further land reclamation (Melville 2018).…”

Long‐term monitoring and evaluation of land development in a reclamation area under rapid urbanization: A case‐study in Qiantang New District, China

“…For example, Wang et al (2014), Tian et al (2016), Ren et al (2019), and Li et al (2020) analyzed the changing spatial extent of coastal land reclamation at a national scale. At regional scales, many researchers focused on the reclamation of three major economic zones from north to south along the coast, including Bohai Bay (Chen et al, 2019; Xu et al, 2019), Yangtze River Delta (Li, Lu, et al, 2018; Li, Yin, et al, 2018), and Pearl River Delta (Li & Damen, 2010). Many studies also focused on land reclamation dynamics and its impacts on the ecological system at the individual city scale, such as Yantai (Yu et al, 2013), Lianyungang (Li et al, 2014), Shanghai (Wu et al, 2018), and Shenzhen (Yi et al, 2018).…”