Human Threats to Coral Reefs and Coral Damage (Continued)

The twentieth century introduced another threat to coral reefs, in the form of weapons testing. However, opinions differ as to whether testing does in fact have a long term detrimental effect to reefs. After World War 2, between 1946 and 1958, testing of the nuclear bomb was carried out in the atolls of the Pacific Ocean by the US (Reuther, 1997). Atolls are circular coral islands that enclose a central lagoon, often occurring on top of submerged mountains or volcanoes. The most notable nuclear testing was carried out on the Marshall Islands, or the ‘Pacific Proving Grounds’. It is thought 67 bombs were tested in this period, and clearly had direct effects on the surrounding reefs. One bomb, codenamed Castle Bravo, was detonated in 1954 at the Bikini Atoll, the first testing of the more powerful hydrogen bomb. Its yield was underestimated by the military by two and a half times and as a result had significantly high impacts on the environment, spreading nuclear fallout over thousands of kilometres, infringing on many other reefs and inhabitants (Reuther, 1997). Some data, however, shows that the ecosystem in these areas is in pristine condition, and that species that were affected at the time have quickly recovered. For example, in France, despite direct damage to coral caused by explosions, there is little evidence to suggest the balance of species has been affected long term. Data shows that loss of fish species was complete in the area most affected by the bomb. However, recovery of the populations, initially via immigration followed by reproduction, was very swift, lasting just 1-5 years (Planes et al., 2005). In this case the coral habitats for species were not badly damaged, so it seems as though as long as the habitats are not badly damaged, and niches remain free, coral communities may recover fairly quickly in the case of nuclear weapons. Another study on coral reef gastropods in French Polynesia gave similar results. Populations of gastropod fell immediately after nuclear testing, but they were quickly able to recolonise empty niches left as a result of the bombs (Lanctot et al., 1997).