What does a coral reef look like 50 years after being nuked? Not so bad, it seems. Coconuts growing on Bikini Atoll haven't fared so well, however.
Three islands of Bikini Atoll were vapourised by the Bravo hydrogen bomb in 1954, which shook islands 200 kilometres away. Instead of finding a bare underwater moonscape, ecologists who have dived it have given the 2-kilometre-wide crater a clean bill of health.
"It was fascinating – I’ve never seen corals growing like trees outside of the Marshall Islands," says Zoe Richards of the ARC Centre of Excellence for Coral Reef Studies in Australia.
Richards and colleagues report a thriving ecosystem of 183 species of coral, some of which were 8 metres high. They estimate that the diversity of species represents about 65% of what was present before the atomic tests.
The ecologists think the nearby Rongelap Atoll is seeding the Bikini Atoll, and the lack of human disturbance is helping its recovery. Although the ambient radiation is low, people have remained at bay.
"Apart from occasional forays of illegal shark, tuna and Napoleon Wrasse fishing, the reef is almost completely undisturbed to this day," says Maria Beger of the University of Queensland in Australia. "There are very few local inhabitants and the divers who visit dive on shipwrecks, like the USS Saratoga, and not on the reef."
Beger took a Geiger counter with her on dives and says that the background levels were similar to that at any Australian city. The same could not be said of coconuts growing on the islands.
"When I put the Geiger counter near a coconut, which accumulates radioactive material from the soil, it went berserk," says Beger.