Nuked coral reef recovers


Scientists have found out that coral reefs recover astonishingly well 50 years after being nuked.

In a study published in a recent issue of the journal Marine Pollution Bulletin, Zoe Richards, Maria Beger, Silvia Pinca and Carden Wallace surveyed the corals living in Bikini Atoll in the Central Pacific about 50 years after the last nuclear tests were conducted there.

Between 1946 and 1958, the United States government detonated 23 nuclear devices (with a total yield of 76.3 megatons) on the reef, in the sea, in the air and underwater in the vicinity of Bikini Atoll.

The authors and found a total of 183 species of hard (scleractinian) coral around the atoll.

Comparing the results of their surveys with published surveys conducted prior to the nuclear tests, the authors found that an astonishing 70% of the coral species have re-established themselves on the atoll following the nuclear tests.

The authors offer an explanation for this astonishing recovery: he modern Bikini Atoll community may have been replenished by self-seeding from brooded larvae from surviving adults (e.g. in genera Pocillopora, Stylophora, Seriatopora and Isopora), survival of fragments of branching corals, and/or migration of new propagules from neighbouring atolls. The patchy nature of impacts may have mitigated the overall effect of disturbance at Bikini Atoll, with some patches surviving after each impact.

Corals living on deep exposed reefs on Bikini Atoll may also have escaped some of the direct impacts, and thus have played an integral role in mitigating the overall effect of the disturbance event.

We consider the extremely large and highly diverse Rongelap Atoll is likely to have contributed a significant proportion of new propagules to enable recovery of the Bikini coral community, as Bikini Atoll lies downstream of the prevailing surface current from Rongelap.

The authors conclude that in a twist of fate, the radioactive contamination of northern Marshall Island Atolls has enabled the recovery of the reefs of Bikini Atoll to take place in the absence of further anthropogenic pressure.

Today Bikini Atoll provides a diverse coral reef community and a convincing example of partial resilience of coral biodiversity to non-chronic disturbance events.

For more information, see the paper: Richards, ZT, M Beger, S Pinca and CC Wallace (2008) Bikini Atoll coral biodiversity resilience five decades after nuclear testing. Marine Pollution Bulletin 56, pp. 503"515.