Researchers in Israel have found that the detergents commonly used to treat crude-oil spills may be more damaging to marine life and coral reefs than the spilt crude-oil itself.
Researchers at the Hebrew University of Jerusalem exposed thousands of coral fragments, taken from two important coral reef species, to crude oil and six types of commercial oil dispersants under lab conditions.
The study was reported in the 1 August issue of Environmental Science and Technology, an American Chemical Society publication.
They found that manufacturer recommended dispersant concentrations ended up being highly toxic, resulting in the death of all coral fragments, while the crude-oil proved less harmful to the coral.
Even at concentrations as low as 25 per cent of those recommended by the manufacturer, many of the dispersants proved fatal to the coral.
Noting that an estimated 40 per cent of global crude oil transport is conducted offshore, with much of the traffic taking place in tropical, coral-rich areas, the researchers called on the use of such oil dispersants to be banned in the vicinity of coral reefs, where possible.
According to the authors, chemicals, mainly oil dispersants, are probably the most common used methods for treating marine oil spills. They use solvents and/or surfactant compounds to break down floating oil into small droplets within the water column, making the spill less likely to reach the shore.
The study’s authors called on decision-making authorities to carefully consider their results when deciding whether to use oil dispersants near coral reefs in the future.
‘The results imply … that the use of any oil dispersants in coral reefs and its vicinity should be avoided,’ they said.
‘Chemical dispersants should be considered only in emergencies, when oil slicks are shore bound and threatens to smother the reef flats.’