ScienceNow Daily News: Warming seas and ocean acidification aren't the only hazards facing the world's coral reefs. A new study suggests that the communities can be thrown quickly and seriously out of balance by the iron from sunken ships. Scientists hope the findings will encourage the prompt removal of derelicts before they can damage the fragile ecosystems.The problem with shipwrecks appears to be a particularly aggressive reef-dwelling creature called Rhodactis howesii, a type of sea anemone. When nutrients are abundant and there are no predators, R. howesii thrives. Unfortunately, it also eats coral, threatening the foundation of the ecosystem.
Several previous studies have linked shipwrecks and reef degradation, but researchers in Hawaii decided to measure the effect in detail. They surveyed a coral reef off Palmyra, an isolated atoll in the middle of the Pacific Ocean. There they found high densities of R. howesii near a longline fishing boat that sank in 1991. Those densities steadily declined with distance from the wreck; and within about 100 meters, they dropped to zero--with a few exceptions. The exceptions, the team reports today in PLoS ONE, involve navigation buoys installed on the atoll in 2001....
Alexey Bogolyubov (1824-1896) painted this shipwreck. Wikimedia Commons
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