09/20/2011 01:24 EDT | Updated 11/20/2011 05:12 EST

APNewsBreak: Tar balls on shore prove BP oil not degrading as quickly as expected, study says

BIRMINGHAM, Ala. - Researchers say tar balls washed on to Gulf of Mexico beaches by Tropical Storm Lee prove that oil left over from last year's BP spill isn't breaking down as quickly as some assume.

Auburn University said Tuesday that its study shows the tar that hit Alabama beaches earlier this month appeared relatively fresh and unchanged from when oil first poured into the Gulf during the spill.

The study concludes that mats of oil are still submerged on the seabed, and it says the material could pose a long-term threat to coastal ecosystems.

BP isn't commenting on the study. The company is cleaning the beaches.