Abstract
This paper quantifies environmental effects of island-building operations in the South China Sea, which result from dredging and can negatively impact marine flora, fauna, and ecosystems. The extent of the damage caused by island-creation is believed to be large, as the South China Sea reefs support the largest concentration of marine biodiversity on Earth. Through use of satellite imagery, we investigate the island-construction on Mischief Reef in the South China Sea, showing backscatter increases of up to 350% in waters surrounding the reef, with plumes of excess sediment exceeding 250 km2 at times during island-construction, and the cumulative area impacted by dredging exceeding 1,200 km2. Comparison of satellite-derived chlorophyll-a, backscatter, absorption and remote sensing reflectance at 412 nm suggest that dredging activities led to a decrease in biological health of the region resulting from the smothering of natural benthic habitats and reef complexes with sediment. We anticipate this ex post facto quantification of the connectivity between island-construction, large particulate plumes and a decrease in absorption related to marine life in the water column to establish a starting point for further study into ecosystem impact. The potential associations between these damages and a long-term reduction in ocean life and resources could serve inter-governmental bodies with a baseline metric for evaluating the level of damage caused. This may result in both forward-looking deterrent policies that limit island-building as well as backward-looking compensation.
Highlights
Artificial island-creation generally involves cutter suction dredging (CSD) and/or trailing hopper dredging (THD) often followed by airfield construction[1,2]
Dredging and island building on Mischief Reef began in late January 2015 and the reef had reached it’s maximum area (20.94 km2) by May 30, 2015 (Fig. 4)
Dredging was observed after May but no increase in land area was detected, it is assumed that this activity was focused on increasing the height of the land, a dimension not measured by this study
Summary
Artificial island-creation generally involves cutter suction dredging (CSD) and/or trailing hopper dredging (THD) often followed by airfield construction[1,2]. In the South China Sea (SCS) between 2013 and 2017, China built 3,200 acres of new land, Vietnam built 120 acres of new land, and Taiwan built eight acres of new land[4] Given this level of activity in the SCS and the fact that environmental alterations resulting from dredging can include the loss of species in the benthic community[5], it is natural to ask: what impact do these activities have on the surrounding ocean? 2014, above the waterline in 2015 following commencement of dredging, and inhabited by living quarters and an airstrip in 2016 (Fig. 1a–c from the Mischief Reef Tracker web). These observations are consistent with the increase in area of impacted water documented below
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