King crabs threaten Antarctic marine ecosystem

This video is called King Crabs Invade Antarctica.

From Discovery News:

King Crabs Invade Antarctic Waters

A warmer Antarctica makes a hospitable home for these crabs, endangering an entire ecosystem that has no defenses against them.

By Eric Niiler

Tue Feb 8, 2011 07:00 AM ET


* Shell-crushing king crab are expanding their kingdoms into the Antarctic peninsula.
* Creatures living there for tens of millions of years have no defenses against these crustaceans.
* Warmer waters are facilitating the crabs’ advancement.

McMURDO STATION, Antarctica — Warming waters along the Antarctic peninsula have opened the door to shell-crushing king crabs that threaten a unique ecosystem on the seafloor, according to new research by a U.S.-Sweden team of marine researchers.

On a two-month voyage of the Swedish icebreaker Oden and U.S. research vessel Nathaniel B. Palmer, marine biologists collected digital images of hundreds of crabs moving closer to the shallow coastal waters that have been protected from predators with pincers for more than 40 million years. They are the same kind of deep-water crabs with big red claws that you might find at the seafood counter.

“Along the western Antarctica peninsula we have found large populations over like 30 miles of transects. It was quite impressive,” said Sven Thatje, an evolutionary biologist at the University of Southampton in England and chief scientist on the cruise.

Finding crabs on the bottom of the ocean isn’t that big a deal. But here in Antarctica, crabs haven’t lived in coastal waters for the past 40 million years. Until now, it’s been too cold.

Bottom-dwelling creatures like mussels, brittle stars and sea urchins have not developed any defenses. They have thinner shells, for example. For the same reason, filter feeders, like clams and worms, burrow underground in most regions. The lack of predators has led to a thick canopy of sorts, much like a submarine jungle comprised of flowery feather stars, tube worms and squirming sea spiders.

During an interview on board the Oden just after it docked at the main U.S. base in Antarctica, Thatje described how the crabs are moving closer to an ecosystem with no defenses.

“The Antarctic shelf communities are quite unique,” Thatje said. “This is the result of tens of millions of years of evolution in isolation.”

To explore this underwater world, Thatje and his team of U.S. and Swedish scientists towed an autonomous underwater vehicle (AUV) that scanned the seafloor with a digital camera. Along the way, they encountered thick packs of ice, rough seas and lots of feeding whales.

Even though Thatje predicted the crab invasion several years ago in a research paper, he was surprised at seeing so many so quickly.

“The pace of changes that we are observing here in the Antarctic, which is the remotest continent on this planet, is quite frightening,” he said.

What’s happened is that the waters around the Antarctic peninsula have begun to get warmer. The air temperature has jumped 6 degrees Celsius (10.8 degrees Fahrenheit) since the 1950s, while the average ocean temperature has increased by 1 degree Celsius (1.8 degrees Fahrenheit) over the same time.

That change in water temperature has lowered a physiological barrier that has kept the crabs in check. Crabs are unable to process magnesium in their blood below a certain temperature, and the result is a narcotic effect on the crabs’ movement. Magnesium is a mineral that they absorb from the surrounding sea water. Scientists say that barrier may soon fall, as global climate change continues to impact wildlife at the polar regions.

The crab research team will spend the next few months analyzing 120,000 images taken of the seafloor by the AUV, which was designed and operated by the Woods Hole Oceanographic Institution. They want to know whether the crabs will invade and leave, or permanently colonize the shallow areas. Will their presence destroy the existing community or simply alter it?

Previous cruises had only spotted one or two crabs, but now scientists are seeing entire populations, according to Rich Aronson, lead investigator in the crab project and a professor of biology at the Florida Institute of Technology. The crabs are moving from the deep ocean, up the continental slope to the shallower shelf areas.

“As the surface waters warm up, that will make it possible to come running over the top and raise hell with the bottom communities,” Aronson said.

Unlike most areas of the world, the shallower waters on the Antarctic continental shelf are actually slightly colder than the deeper waters of the Southern Ocean. That’s because of a clockwise current of water called the Antarctic circumpolar current. That flow of cold water keeps Antarctic marine life — especially the bottom-dwelling creatures — isolated. There are no sharks, rays or fish with bony jaws, for example, Aronson explained, in Antarctica.

“If you look at the warming trends on the peninsula, you would expect that the crabs would come back in 40 or 50 years,” Aronson said from his office in Melbourne, Fla. “But boom, they’re already here. This is the last pristine marine system on Earth and it could get destroyed.”

King crabs invade Antarctica: here.

Penguins beware: Voracious 1m-wide red crabs invade Antarctica: here.

Guardian: Warming Arctic brings invasion of southern species: here.

In a world first, the sex life of Antarctic Krill in the wild has been caught on camera revealing the shrimp-like creatures are able to mate deeper in the ocean than previously thought: here.

Creatures from the Arctic abyss – video. The Census of Marine Life is bringing to light extraordinary microscopic creatures never before seen by human eyes, dredged from their world of permanent darkness, freezing temperatures and crushing pressure: here.

Antarctic researchers funded by the U.S. National Science Foundation (NSF) may need to throw on another blanket at night to ward off the chill. But Thursday’s agreement to lease a Russian icebreaker to help resupply NSF’s logistics hub at McMurdo Station should otherwise allow the agency to avoid any major curtailments to its Antarctic research schedule for the 2011-12 winter season: here.

Sea Urchins Turning into Cannibals: Discovery News: here.

August 2011. New research by scientists in the Department of Biology at the University of York shows that species have responded to climate change up to three times faster than previously appreciated. These results are published in the latest issue of the leading scientific journal Science: here.

Oldest Spider Crabs Discovered in Fossil Reef: here.

Using risk assessments, like those used for setting occupational safety limits in the workplace, researchers determined the winners and losers of climate change in the Antarctic. They show that marine animals associated with sea ice for food or breeding, such as some whales and penguins, are most at risk from the effects of climate change, while seafloor predators and open-water feeding animals like starfish and jellyfish will benefit from the opening up of new habitat: here.

2 thoughts on “King crabs threaten Antarctic marine ecosystem

  1. UAB: Invasion of king crabs in Antartica causes many concerns

    By Shannon Delcambre
    Published: April 08, 2011

    News release from UAB:

    It’s like a scene out of a sci-fi movie – thousands, possibly millions, of king crabs are marching through icy, deep-sea waters and up the Antarctic slope.

    “They are coming from the deep, somewhere between 6,000 to 9,000 feet down,” said James McClintock, Ph.D., University of Alabama at Birmingham Endowed Professor of Polar and Marine Biology.

    Shell-crushing crabs haven’t been in Antarctica, the Earth’s southernmost continent, for hundreds or thousands, if not millions, of years, McClintock said. “They have trouble regulating magnesium ions in their body fluids and get kind of drunk at low temperatures.”

    But something has changed, and these crustaceans are poised to move by the droves up the slope and onto the shelf that surrounds Antarctica.

    McClintock and other marine researchers interested in the continent are sounding alarms because the vulnerable ecosystem could be wiped out, he said.

    Antarctic clams, snails and brittle stars, because of adaptation to their environment, have soft shells and have never had to fight shell-crushing predators. “You can take an Antarctic clam and crush it with your hands,” McClintock said. They could be the main prey for these crabs, he said.

    Loss of unique mollusks could jeopardize organisms with disease-fighting compounds, McClintock said.

    Sea squirts, for example, produce an agent that fights skin cancer. If the crabs eat them, it could bring McClintock’s research with that organism to a halt.

    McClintock’s chemical ecology program has published more than 100 papers on species researchers have discovered, including the compound that combats skin cancer and one to treat flu, that are being explored by drug companies.

    “I am very concerned that species could disappear, and we could lose a cure to a disease,” he said.

    McClintock’s colleague Sven Thatje, Ph.D., an evolutionary biologist at the University of Southampton in England, saw the first signs of the king crab invasion in 2007.

    He spotted a lone crab climbing up the slope.

    McClintock and Rich Aronson, Ph.D., a paleoecologist at Florida Institute of Technology, put together a proposal to launch the first systematic search for king crabs in Antarctica.

    With Sven as chief expedition scientist, the team headed back with two ships and a submarine earlier this year.

    “We ran transects up the slope and discovered hundreds and hundreds of king crabs, which could translate into millions across broad expanses of coastal Antarctica,” he said. “They are adults, males and females. They appear healthy and have all the ingredients needed to produce a healthy population.”

    The king crabs’ large numbers on the slope suggest that they are increasing in number at a rate faster than anticipated, McClintock said. “Before long, they could be in shallow water and on the shelf,” he said. “This is a very visual, visceral way of thinking of an impact of climate change.”

    McClintock and his fellow researchers are exploring causes for the invasion, which they believe is linked to human-induced climate warming.

    Around 40,000 tourists visit the area each year.

    “Antarctica has become a popular destination for tourists,” McClintock said. Cruise ship companies have seen it as an opportunity to take visitors to “one of the most stunningly beautiful areas on our planet.”

    After cruising along the waters, tourists can then take a rubber boat called a zodiac to a beach covered with penguins as far as the eye can see. “The penguins will come right up to you,” McClintock said.

    And, now that the king crabs are on the Antarctic slope, some fishermen are anxious to head to Antarctica as well.

    McClintock has already gotten an email from a fisherman asking when he can come.

    But the icy waters and dangerous logistics make fishing difficult, McClintock said. “There is a TV show called the ‘The Deadliest Catch,’” he said. “Well this is the deadliest, deadliest catch.”

    For now, McClintock and his team are reviewing the thousands of images they captured during their submarine exploration.

    His team is analyzing the data and plans to have its findings published in a major journal within a year.

    “The whole ecosystem could change,” McClintock said. “And this is just one example of a species expanding its range into a new territory. There will certainly be more as the climate warms up.”


  2. Pingback: Clever octopus steals crab, video | Dear Kitty. Some blog

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