 are invading Antarctic seas, where they prey on local species.)
King crabs (Neolithodes yaldwyni) are invading Antarctic seas, where they prey on local species.
Image: Flickr/Travis S.
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On a dim February evening, seven people crowded around a row of television monitors in a shack on the rear deck of the RV Nathaniel B. Palmer. The research icebreaker was idling 30 kilometers off the coast of Antarctica with a cable as thick as an adult's wrist dangling over the stern. At the end of that cable, on the continental shelf 1,400 meters down, a remote-operated vehicle (ROV) skimmed across the sea floor, surveying a barren, grey mudscape. The eerie picture of desolation, piped back to the television monitors, was the precursor to an unwelcome discovery.
The ROV had visited 11 different sea-floor locations during this 57-day research cruise along the Antarctic Peninsula in 2010. Each time, it had found plenty of life, mostly invertebrates: sea lilies waving in the currents; brittlestars with their skinny, sawtoothed arms; and sea pigs, a type of sea cucumber that lumbers along the sea floor on water-inflated legs. But at this spot, they were all absent. After 15 minutes, the reason became clear: a red-shelled crab, spidery and with a leg-span as wide as a chessboard, scuttled into view of the ROV's cameras. It probed the mud methodically — right claw, left claw, right claw — looking for worms or shellfish. Another crab soon appeared, followed by another and another. The crowded shack erupted into chatter. “They're natural invaders,” murmured Craig Smith, a marine ecologist from the University of Hawaii at Manoa. “They're coming in with the warmer water.”
Cold temperatures have kept crabs out of Antarctic seas for 30 million years. But warm water from the ocean depths is now intruding onto the continental shelf, and seems to be changing the delicate ecological balance. An analysis by Smith and his colleagues suggests that 1.5 million crabs already inhabit Palmer Deep, the sea-floor valley that the ROV was exploring that night (see 'A warming welcome'). And native organisms have few ways of defending themselves. “There are no hard-shell-crushing predators in Antarctica,” says Smith. “When these come in they're going to wipe out a whole bunch of endemic species.”
Researchers are worried that rising crab populations and other effects of the warming waters could irrevocably change a sea-floor ecosystem that resembles no other on Earth. Scientists are racing to document these effects, even as they continue to explore this little-understood region. “This could have a really major reorganizing impact on these unique and endemic marine communities,” says Richard Aronson, a marine biologist at the Florida Institute of Technology in Melbourne, who was part of a team that found crabs on another part of Antarctica's continental shelf in December 2010. “It's a fascinating thing,” he says. “A little scary, because it's a very obvious footprint of climate change.”
Cut off by cold
Aronson has worried about the fragility of life on the Antarctic shelf for more than a decade. He spent December 1994 collecting fossils from Seymour Island, on the northeast fringe of the Antarctic Peninsula. The island's bare, crumbling hills contain the remnants of an ancient sea floor. In 200 meters of layered rock and fossils exposed by wind erosion, Aronson saw evidence of the most pivotal event in Antarctica's history: the continent's final separation from South America, starting around 40 million years ago. This event allowed the emergence of the circumpolar ocean current, which isolated Antarctica from warmer air and water masses farther north, and plunged it into perpetual winter. Aronson and his students analyzed 10,000 fossils from before and after that sudden cooling, and a striking pattern emerged.
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11 Comments
Add CommentBut...but I thought all global warming was based on flawed computer models by people who wanted to stay inside and make more computer models so I would have to shiver in the cold. Are you saying there are actual observations of change? /sarcasm
Reply | Report Abuse | Link to thisIn before the denialists...
Are these king crabs the same as caught in the northern waters for human food, If so then fishermen should be told that there is good fishing in the Antarctic and this might alleviate the menace some what,
Reply | Report Abuse | Link to thisI participated in the 2010 Antarctic research cruise and made a short film about the King Crab discoveries. It can be seen at www.crabnet.tv or at https://www.youtube.com/watch?v=cVNTfpDlPzE.
Reply | Report Abuse | Link to this“They're natural invaders, ... They're coming in with the warmer water.”
Reply | Report Abuse | Link to thisThe human species makes the water warmer and they are the invaders?
http://blogdredd.blogspot.com/2012/12/new-climate-catastrophe-criminality.html
King crabs are just one of many species shifting habitats, or rather shifting locals, as the climate changes. For instance, there is the lovely armadillo.
Reply | Report Abuse | Link to thishttp://mdc4.mdc.mo.gov/Documents/16308.pdf
I suspect the armadillo is having less impact that the king crabs are, but species shifts are not really a new thing. The effects of a changing climate are already under way.
Have Red Lobster lower the price on Crab Festival. Enlist the show Deadliest Catch. Problem solved.
Reply | Report Abuse | Link to thisOr, tell the Chinese King Crab helps with iron-rod erections. Problem solved twice.
Did these crabs move into these same waters during the last interglacial, when it was much warmer than now?
Reply | Report Abuse | Link to thisQuinn- LOL!
Comment by Carlyle on another article: "So although the West antarctic melted entirely 3 million years ago, the original authors claim the crabs MAY have been excluded for fourteen My, just for luck SIAM doubled it & then rounded up a further 2 My & when I challenged them they deleted my post. I hope you can begin to see that this is not aberant behaviour. It is typical. You can look up the Ice record for Antarctica yourself if you doubt me. There could even have been later melts & almost certainly numerous times that match the present."
Reply | Report Abuse | Link to thisI did not see the original post, but why would SA delete this?
There is an abundance of crab because we have killed most of their preditors, so there is no need for fishermen to go far to get crab.
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Reply | Report Abuse | Link to this1. SteveO
08:00 PM 12/12/12 writes...
......But...but I thought all global warming was based on flawed computer models by people who wanted to stay inside and make more computer models so I would have to shiver in the cold. Are you saying there are actual observations of change? /sarcasm...
Perhaps SteveO missed the comment in the article where Domack says the process started at the end of the Little Ice Age. (at the top of page 3 in the article)
The computer models referred to by SteveO such as the hockey stick put forth by Mann and others show that there was no such thing. Despite a multitude of historical references documenting said climate, people like Gore, Hansen and David Suzuki regularly use many computer models to show that _all_ climate variation in the last ten thousand years or so is anthropogenic.
The most amusing comment that I have read that justifies rejecting historical evidence in favor of computer models is the belief the Medieval Warming Period and subsequent Little Ice Age documentation was all part of a massive real estate scam run by the Vikings.(!!??!!)
http://evilbloggerlady.blogspot.com/2013/01/are-king-crabs-really-poised-to-kill.html Good comment. I linked it.
Reply | Report Abuse | Link to thisWhile I am skeptical of global warming alarmism, I do not want to see gentle sea pigs wiped out by giant crabs. I do not discount some global warming is taking place. It is, the planet is getting warmer (whether that is because of the natural cycles or is completely man made remains to be seen). But this has also happened in the past and I suspect these fluctuations in predator prey overlap in Antarctica have happened before too. But I would suggest we investigate further and see if that is the case (or not).