Unrefined – or “crude” – oil has been spilled into the sea in massive amounts following ecological disasters such as the Exxon Valdez or the Sea Empress spills. Moreover, oil is also routinely released into the environment in moderate volumes due to extraction and transportation activities. According to a new study led by the University College Cork (UCC) in Ireland, oil pollution poses a significant threat to many already endangered seabird populations.
The experts found that even tiny amounts of crude oil on the water surface – less than one percent of the thickness of a hair – could severely damage seabird feathers. After collecting feathers from the Manx shearwaters – a species considered to be at-risk from oil pollution – the scientists examined them to asses how quickly water would pass through after exposure to increasing concentrations of oil. Moreover, they also studied the feathers under high-powered microscopes to examine structural changes occurring after contamination.
The analyses revealed that even very thin oil sheens, between 0.1 and three micrometers in thickness, were enough to have a significant effect on feather structure and impacted waterproofing. Thus, seabirds exposed to oil are more likely to become waterlogged, cold, and less buoyant, as several other studies have already shown.
“Chronic small-scale oil pollution is commonly overlooked in the marine environment, though it has been shown to have serious implications for the fitness and survival of seabirds,” said study lead author Emma Murphy, a graduate student in Environmental Science at UCC. “This study examined one species, but the results can be extended to other species that rely on waterproofing to stay healthy when at sea for long periods.”
Murphy and her colleagues concluded that even when oil is released in moderate amounts from extraction and transport infrastructure, it can spread quite quickly across the surface of the sea, causing large marine areas to be coated by oil in concentration that are harmful for seabirds.
The study is published in the journal Royal Society Open Science.
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