Before the 2002 Prestige oil tanker spill off the coast of Spain, colonies of European shags produced roughly the same number of chicks. For at least 10 years after the spill, however, the reproductive success of the coastal seabirds dropped by 45 percent in oiled colonies, researchers report April 30 in Biology Letters.
The team did not report the underlying causes of the reduction in reproductive success. But the scientists argue that the birds suffered nonlethal health effects from oil exposure and also had access to less food after the spill, which could influence reproductive success. The results offer additional evidence that major oil spills have long-lasting effects on marine life, the scientists say.