Copper levels, below those recorded around inshore reefs, could be enough to prevent the mass spawning of corals, says a report in New Scientist.
A currently unpublished study by Melbourne University PhD student Claire Bennett, which investigated spawning in captive corals collected from the Great Barrier Reef, found that copper levels as low as 5 ppb (parts per billion) resulted in 30% fewer larvae developing. At copper levels of 30 ppb the number of larvae that developed was reduced by 70%.
Although copper levels of up to 30 ppb had no effect on the number of larvae produced, those larvae that did survive in copper-rich waters took longer to mature.
Copper is a common marine contaminant and has been recorded at levels of over 8 ppb in some reefs. It is also common in tapwater.