ATHENS, Ga. (AP) — A research team will return to the Gulf of Mexico next month to map underwater plumes of oil and gas, a University of Georgia oceanographer said.

A team led by oceanographer Samantha Joye tracked one plume during research voyages in May and June. She said no one has made a systematic sweep around the massive oil spill in the Gulf to find other plumes.

“We could have totally missed something,” Joye said Tuesday at a news briefing.

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The plumes are a mixture of seawater and methane gas, oil and other hydrocarbons that are spewing from the broken well a mile below the water’s surface off the coast of Louisiana.

A federal report released Friday confirmed the existence of oil plumes. Joye said plumes of methane and other gases could be as big a threat to deep-sea life as oil.

Joye says it’s been about two months since anyone measured underwater oxygen in the area.

“We really don’t know how these things have changed since then. I suspect the plumes have spread out quite a bit,” she said.

Joye and other researchers plan to spend about four weeks looking for more oil and gas drifting from the well. They plan to use sound waves to map where methane from the broken well has moved.

“The presence of gas changes the speed that sound passes through the water,” Joye explained.