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February 20 (UPI) – Marine biologists have discovered a group of tanned crabs feeding vigorously on a seepage of methane in the seabed off the coast of British Columbia.
Tanning crabs are a kind of crab, sometimes called king crabs or spiders. The seven species of Chionoecetes Kinds are often marketed as "snow crabs" in the seafood markets. This discovery marks the first time that a commercially harvested marine species feeds on a methane vent.
Flat-bottomed animals such as tanning crabs – and the entire ocean bottom food chain – are assumed to rely exclusively on phytoplankton descending into the water column, but recent research suggests that seabed ecosystems harbor a variety of sources of energy and basic nutrition.
"Tanning crabs are probably not the only species to derive energy from methane seeps, which have not yet been much studied," said Andrew Thurber, marine ecologist at the University. of Oregon, in a press release. "We used to think that there were maybe five off the northwest Pacific coast and research shows that there are at least 1,500 sites around the world. infiltration – and probably a lot more. "
Efforts to map methane seeps have revealed the presence of vents in various environments, in deep and deep waters. Scientists estimate that there are probably thousands of undiscovered sources of methane in the Arctic.
Scientists first had to study crabs that congregated in methane chimneys after seeing a specimen literally carried away by the rise of the gases.
"This project was born from the observation of a crab raised from the seabed by an accumulation of ice-forming methane on the chest before the methane fled and drops the crab on its head "said Thurber. "This entertaining video was the genesis of this project and led us to deepen our understanding of the connection between depths and society."
Observations of the behavior of tanning crabs around the methane seeps did not reveal any uniform consumption pattern, but many crabs were seen digging through the sediments surrounding the vents. It is likely that crabs eat the carpets of methane-eating microbes that form around the seabed ventilation holes.
"Despite the observation of tanning crabs feeding at the sites over and over, there was not much evidence that animals ate methane using established methods," said Sarah Seabrook, lead author from the study, Ph.D. candidate. "So we have looked into it further and found some chemical evidence for the presence of methane tracers in the digestive tract and biogeochemical evidence in their tissues, which raises the question of whether we can apply these new techniques to other species and determine whether the use of methane seeps as a food source are more prevalent than tanning crabs. "
While plankton supplies vary with the seasons, the mouths of methane are constantly bubbling. Scientists predict that climate change will decrease the amount of phytoplankton that spreads in seabed food chains. If this is true, lowlanders such as tanning crabs will be forced to rely more on alternative sources of energy. Methane seepage could be a lifeline.
Scientists suggest that more work needs to be done to characterize the importance of methane vents for food chains and seabed ecosystems. The latest evidence – published this week in the journal Frontiers in Marine Science – suggests that more should be done to ensure that methane vents are protected and undisturbed by human development.
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