September 9, 2015 — NORWAY — A recent study found that using dispersants moderately decreased the number of cod eggs and larvae affected by spills off the Norwegian coast.
Oil spills at sea can be catastrophic events, with oil and discharged toxins, including polycyclic aromatic hydrocarbons, threatening marine wildlife and coastlines, damaging healthy ecosystems and harming livelihoods, reports Science for Environment Policy.
Efforts to stop widespread damage from oil spills typically involve burning or collecting surface spills, or using dispersants. Dispersants are chemicals that help to break up the oil into smaller droplets, reducing or preventing the ascent of oil droplets from seabed spills, enhancing the mixing of the oil into the water column and making it easier for naturally occurring bacteria to break it down.
The use of dispersants has been controversial, particularly as earlier types were sometimes more environmentally damaging than the oil itself. Newer types of dispersants though are considered less toxic to the environment and are useful in preventing oil slicks travelling to sensitive areas, such as fish spawning grounds or places where there are stationary organisms, like mussels, which cannot escape.
Fish eggs and larvae are highly sensitive to oil toxins, especially polycyclic aromatic hydrocarbons (PAHs). Using dispersants to break up surface slicks increases the concentration of total PAHs (TPAHs) in the water column where the cod eggs and larvae are found, which may increase the toxic effects of an oil spill.