Underwater wonder of the Spratly Islands under threat

Updated 11:36 PM ET, Wed March 29, 2017
South China Sea Spratlys underwater 3South China Sea Spratlys underwater 3
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The Spratly Islands are an archipelago of atolls and reefs that support 600 coral species and 6,000 fish species -- but they are under threat from large-scale land reclamation in the contested waters of the South China Sea. This photo of a sea turtle in a coral garden was taken at Swallow Reef in the southeast of the archipelago. All photos by Greg Asner. Greg Asner
In 2016, researcher Greg Asner ventured into the Spratlys to better understand the ecological cost of the land reclamation. A scalloped hammerhead shark is pictured here near Swallow Reef. Greg Asner
Each reef in the region is a submerged biodiversity hotspot, with millions of reef creatures, haphazardly stacked atop one another, competing for space, light, nutrients and prey, says Asner. Greg Asner
Nearly invisible are each atoll's factory of coral polyps, which circulate over thousands of kilometers of open ocean to seed and support distant reefs, says Asner. Greg Asner
Asner said the reef supports huge schools of batfish, bumphead parrotfish, whitetip and scalloped hammerhead sharks, and dolphins. Greg Asner
Asner said that fieldwork on the reef wasn't a peaceful experience. During dives, he could hear the hammering of ocean piles into the seabed -- likely from land reclamation work. Greg Asner
Asner and his team also saw numerous military ships and the team once surfaced to encounter a submarine. Greg Asner
A school of barracuda on a Spratly Island atoll. Greg Asner