Methane-munching crabs suggest they are adapting: researchers

VICTORIA — Crabs that have a normal diet of a type of plankton have been seen munching on methane-filled bacteria off British Columbia’s coast in what experts say could be their way of adapting to climate change.

Researchers with Oceans Networks Canada and Oregon State University discovered the snow crabs using other food sources because their main meal may be disappearing with a warmer climate.

The crabs were previously thought to exclusively eat phytoplankton but researchers said in a study published this month in the journal Frontiers in Marine Science that there is first evidence that the commercial species is finding some of its nutrition from other food sources.

Senior scientist at Oceans Networks Canada, an initiative of the University of Victoria, and the study’s co-author Fabio De Leo said by collecting these specimens, researchers can learn how a variety of sea-dwelling species are adapting to ongoing changes linked to climate change.

“It was really funny when we first saw this,” he said.

“The crab had accumulation of methane under its body and was sifting through the mud trying to collect the bubbles and they got trapped under its (shell) and then it got a lift off from the sediment.”

Phytoplankton are single-celled micro algae. When they die they sink to the sea floor and form a carpet making up the main food source for these crabs.

Climate change models show that as the oceans get warmer there will be less of that food for the crabs.

“The crab might be eating more of the methane-filled bacteria and less of the phytoplankton,” De Leo said.

Snow crabs are found from California to Alaska at depths ranging from 300 to 2,000 metres.

The researchers have watched these crabs on seeps, areas on the ocean floor where methane gas seeps out.

These methane seeps support a variety of species including clams and mussels that rely directly on the energy provided by the seep bacteria, he said.

CP/HO, UNIVERSITY OF VICTORIA’S OCEAN NETWORKS CANADA A Tanner crab is seen at 1,250 metres below the surface at Barkley Canyon in the northeast Pacific Ocean in a June 2016 handout photo. A new study from the University of Victoria shows tanner crabs feasting and snacking on methane-filled bacteria in the deep seafloor bed, which scientists say may be an adaptation to climate change.