GALVESTON, Texas (AP) — Research by several universities has found that thousands of tons of methane gas released into the Gulf of Mexico by the epic 2010 oil spill lingered longer than expected.

The study by researchers from Texas A&M University at Galveston and other universities found that microbes expected to consume almost all of the gas released into the deep Gulf didn’t remove the gas as quickly and efficiently as expected. The natural process has eliminated much of the gas, but at a slower rate than expected.