BANGKOK – One of the best Pacific Ocean locations to witness a stunning abundance of tropical fish, sharks and corals is also the least expected – Bikini Atoll, site of U.S. nuclear tests in the middle of the last century.
The surprising recovery of the atoll’s reef in the decades after experiencing sea-surface temperatures of 55,000 degrees Celsius and forces that obliterated islands underlines the capacity of marine life to heal, under certain circumstances, from even stupendous assaults.
Researchers say the 187 square kilometers (72 square miles) of remote reef is in good health compared with many other locations in the Pacific – a backhanded compliment that’s an indictment of the toll taken by overfishing, pollution and other human activities in the region.
National Geographic’s Pristine Seas conservation program surveyed Bikini as well as Bikar and Bokak atolls in the Marshall Islands, halfway between Australia and Hawaii, in 2023.
Their recently released report contributed to the Pacific island country’s declaration last month of a marine protected area around Bikar and Bokak – remote atolls that are a window into pristine ocean conditions of a millennium ago. Yet what they observed at Bikini Atoll was also remarkable.
“What we found was incredible,” said Enric Sala, director of Pristine Seas.
Scientists are able to compare the reef today to its pre-nuclear tests condition because of detailed surveys carried out by the U.S. in the 1940s.
“In the places where the explosions had destroyed the reef of course the habitat is gone, it’s rubble and sand. It’s not a coral reef anymore,” Sala told Radio Free Asia.
“In the places near the explosions where the reef remained in place, but where everything was obliterated, everything died because of the heatwave and the blast, what we found was the same thing that they found in 1946 before the tests. The reef has recovered fully.”
Research published in 2010 – the first on Bikini’s reef in decades – indicated that about 70% of coral species at Bikini atoll repopulated the reef in the decades following the 23 nuclear tests carried out between 1946 and 1958. It also found new coral species, probably carried by currents from Rongelap Atoll to the east.
A Pristine Seas team of 18 people spent a week at Bikini Atoll. With dives, remote cameras and a submersible they investigated from the surface to depths of about 2,000 meters.
It is safe to visit the atoll but nuclear contamination of its soil and groundwater poses risks for long-term habitation.
Before the nuclear tests, the U.S. moved the entire Bikinian population of 167 people to the much smaller Rongerik Atoll, which, with scarce water and land, resulted in their near starvation.
It was part of a series of resettlements and injustices that continue to stain relations between the Marshall Islands and the U.S. A U.S.-directed resettlement of Bikini Atoll in the late 1960s was abandoned a decade later when the population was found to have dangerous levels of Cesium-137 from consumption of local foods.
In 2010, the Lawrence Livermore National Laboratory, which has a radiation monitoring program for Bikini as well as Rongelap and Utrok atolls to its east, said radiation could be reduced to safe levels by treating crops with potassium and removing about 15 centimeters of topsoil.
The nuclear tests also forever changed Bikini’s lagoon. It is polluted by the wrecks of ships that were purposely placed in the path of the detonations, which also deposited millions of tons of sediment.
Sala said the extent of coral at Bikini is less than at Bikar and Bokak atolls but it has a greater abundance of reef fish and sharks. The presence of apex predators is a sign of a healthy reef.
The reef, Sala said, “is in really good health compared with most places in the Pacific.”
However, its ability to bounce back from nuclear explosions doesn’t imply it will be similarly resilient in the face of a “continuous and increasing stressor”– warming caused by greenhouse gas emissions, he said.
“If ocean temperatures continue rising and marine heatwaves occur on a yearly basis, corals will simply not have any time to bounce back,” Sala added.
“This is like someone who’s been kicked in the face, falls on the ground, and is kicked again and again before having a chance to stand back up.”
Edited by Mike Firn and Taejun Kang.