Deep Sea Methane Ecosystem Found in Atlantic

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Deep-sea explorers recently found a rare methane-based ecosystem nearly one mile beneath the waves of the Atlantic Ocean.

The National Oceanic and Atmospheric Administration explorers used Jason, the remotely operated vehicle, to plunge 1,600 meters (5,200 feet) deep south of Norfolk Canyon, 35 miles off Virginia’s coast. Jason found mussel beds stretching as far as his cameras could see. While deep sea vent and methane seep ecosystems have been explored around the world, few have been found along the U.S. Atlantic coast.

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The mussel-bound ecosystem thrives on methane seeping from the ocean floor, which bacteria devour. Those methane-munching bacteria make their home in the gills of mussels. The mussels and bacteria form a symbiotic relationship in which the mussels dine on products released from the bacteria in exchange for providing the microorganisms with a home.

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Fish swam among the mussel beds along with sea cucumbers and lithodid crabs, but other species were conspicuously absent. Other methane seep ecosystems in the Gulf of Mexico hosted tube worms and galatheoid crabs. However, the NOAA research team exploring the Atlantic seeps didn’t encounter these two species.

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Last year, a seafloor survey by the NOAA ship Okeanos Explorer found telltale bubbles rising from the depths, which suggested the methane seep ecosystem was waiting to be discovered. This year, the NOAA research vessel Ron Brown returned with Jason to take a look.

The NOAA team took sediment, rock and dead mussel shells up from the bottom of the ocean for analysis. Several live mussels were also recovered for use in genetic and reproductive studies.

IMAGE 1: A lithodid crab seen on the mussel bed at 1,600 meters. Image courtesy of Deepwater Canyons 2013 – Pathways to the Abyss, NOAA-OER/BOEM/USGS.

IMAGE 2: An unidentified deep-sea fish, perhaps a relative of Brotulas, rests among the mussels. Image courtesy of Deepwater Canyons 2013 – Pathways to the Abyss, NOAA-OER/BOEM/USGS.

IMAGE 3: Jason collects a sea urchin and a few mussels from the expansive mussel bed with its manipulator arm. Image courtesy of Deepwater Canyons 2013 – Pathways to the Abyss, NOAA-OER/BOEM/USGS.

IMAGE: 4: Methane gas bubbles rise from the seafloor – this type of activity, originally noticed by NOAA Ship Okeanos Explorer in 2012 on a multibeam sonar survey, is what led scientists to the area.Image courtesy of Deepwater Canyons 2013 – Pathways to the Abyss, NOAA-OER/BOEM/USGS.