South China Sea island building impacts marine life

Dredging boats raised material from the seafloor to build an artificial island on Mischief Reef in the South China Sea. This satellite image from 16 March 2015 shows that the sediment released by dredging spread across and affected an area much larger than the island itself. Credit: DigitalGlobe/ScapeWare3d/DigitalGlobe/Getty Images

A recent study has concluded that the dredging of the seafloor to build new islands in the South China Sea has had a significant impact on the surrounding waters, both during and after the island building.

Peter Cornillon, oceanographer from the University of Rhode Island, USA, and co-author of the study , Evidence of Environmental Changes Caused by Chinese Island-building, which was published in Scientific Reports on 28 March 2019 commented, “not only is it impacting the biological activity in the reef, but it’s impacting it out to about eight kilometers away from the reef … to me, that’s sort of a smoking gun of a real problem.”

Kilometres long sediment plumes and altered biological markers were seen from satellite imagery taken during the building of the artificial island on Mischief Reef.

Mischief Island itself, a five-kilometre, ring-shaped atoll, was built by dredging up the seafloor and fortifying shallower areas. The Chinese-built atoll was part of the 2016 legal dispute of sovereignty between China and the Philippines.

Satellite imagery emerged from January 2014 and December 2017, which “documents exactly when the dredging started and when it ended,” Cornillon explained. The study team could ascertain that the highest dredging activity took place between February and May 2015, with some sediment plums exceeding 250 km2.

The levels of nutrients in the sea in the periods of pre- and post-dredging have been key to the environmental impact of the marine life and environment in the South China Sea. With the study team concluding that the sinking of sediment, from when the dredging stopped, likely damaged to ecosystem’s health and smothered the marine life on the seafloor.

There are 600 types of coral that can be found in the area with a diversity of marine life that rivals the Coral Triangle in the western Pacific.

Despite the speculation that the dredging up of the coral reefs in the South China Sea to build these islands, would cause immense environmental damage, obtaining data has been extremely difficult. Leland Smith, lead author of the study commented, “there are no in situ reading for anything,” as the exact data about the timing of the beginning of construction, the extent and the processes is non-existent.

The South China Sea is a known hotbed of geopolitical conflict among all the nations that share its shores. It is not only an important fishing ground, but also of strategic political and economic significance, with oil and methane reserves and important shipping lanes.

The team involved in the study is hopeful that the data collected from the long-term environmental damage of island building could lead to more evidence-based policies, regarding the construction phase and help protect vital marine resources.