A sea turtle covered in oil from the Deepwater Horizon oil spill swims off Grand Terre island, Louisiana. Oceana, the ocean conservation organisation, released a new report this week warning that the spill is proving extremely dangerous for sea turtles. Turtles can become coated in oil or inhale volatile chemicals when they surface to breathe, swallow oil or contaminated prey, and swim through oil or come in contact with it on nesting beachesPhotograph: Lee Celano/Reuters