Great white sharks, much like humans, tend to stick to familiar turf, according to new research. Also like a lot of people, they like to hang out along the coastal waters of California. Sharks tagged with acoustic devices often spent up to 107 days at four key sites along the central and northern California coast where seals and sea lions are abundant: Southeast Farallon Island, Tomales Point, Año Nuevo Island and Point Reyes [LiveScience]. A few of the fearsome predators were tracked as far inland as the Golden Gate Bridge, apparently in search of snacks, say the researchers. The study, the largest and most detailed study of North American great white sharks, provides evidence contrary to the popular notion of great white sharks swimming aimlessly in the ocean.
The sharks under study divided most of their time between three locations: Northern California, Hawaii, and an area that the researchers called the white shark café, a spot in the open ocean about halfway between the Baja Peninsula and the Hawaiian Islands. Exactly what goes on at the café is still unknown–although researchers suspect it may be a hot spot for mating. Lead researcher Salvador Jorgensen explains that male white sharks “converge in a very specific area of the cafe,” Jorgensen said, while female sharks move in and out of the area. “It adds a little more evidence to the argument that this could be an important reproductive area” [Washington Post].
The scientists tracked the snaggly toothed predators between 2000 and 2008 from the Bay Area to San Diego, Hawaii and back as the sharks followed a route that was carried out with surprising precision and under a strict time frame [San Francisco Chronicle]. These great whites have been isolated from other great white sharks near Australia and South Africa for so long that they are now genetically distinct. The study was published in the journal Proceedings of the Royal Society B.
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In 2005, the earth cracked open in Ethiopia. Two volcanic eruptions shook the desert, and a 35-mile-long rift opened in the land, measuring 20 feet wide in some places. Now a new study adds weight to the argument that the opening of this crack marks the first step in the formation of a new sea that may eventually separate East Africa from the rest of the continent. Says lead researcher Atalay Ayele: “The ocean’s formation is happening slowly, likely to take a few million years. It will stretch from the Afar depression (straddling Ethiopia, Eritrea and Djibouti) down to Mozambique” [ABC News].
The study, to be published in the journal Geophysical Research Letters, explains that the seismic movements observed in Ethiopia are very similar to the changes wrought by faults and fissures on the seafloor, where the processes that move tectonic plates usually begin.
Seismic data from 2005 shows that the rift opened in a matter of days. Dabbahu, a volcano at the northern end of the rift, erupted first, then magma pushed up through the middle of the rift area and began “unzipping” the rift in both directions, the researchers explained in a statement today. “We know that seafloor ridges are created by a similar intrusion of magma into a rift, but we never knew that a huge length of the ridge could break open at once like this” [LiveScience], says study coauthor Cindy Ebinger.
The active volcanic region in Ethiopia’s Afar desert sits at the boundary of the African and Arabian tectonic plates, which have been gradually spreading apart for millions years; the new study shows that large-scale seismic events can speed up that process. The gradual separation has already formed the 186-mile Afar depression and the Red Sea. The thinking is that the Red Sea will eventually pour into the new sea in a million years or so [LiveScience].
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Image: University of Rochester
The tsunami that struck the South Pacific islands of Somoa, American Somoa, and Tongo yesterday has resulted in at least 108 deaths, according to early reports.
Experts monitoring the underwater earthquake that triggered the tsunami have issued various reports of its magnitude, ranging from 7.8 to 8.3. The powerful quake struck early on Tuesday morning, local time, as island residents were getting ready for work and school. About ten minutes after the shock, ten-foot-high waves hit American Somoa’s shore. “American Samoa is a small island, and most of the residents are around the coastline,” [said Filipo Ilaoa, deputy director of the American Samoan office in Honolulu]. “There was no warning or anything at all. By the time the alert was out of the Pacific Tsunami Warning Center, it had already hit” [The New York Times].
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A 8.3 magnitude earthquake in the South Pacific triggered a tsunami early Tuesday morning local time (5:48 pm Greenwich Mean Time), sending residents of the Samoan Islands running to the hills. At this time there are unconfirmed reports of scattered deaths in American Samoa. The powerful waves reportedly swept into Pago Pago, American Samoa’s capital city.
To the west, in the independent state of Samoa, at least one coastal village was leveled, according to eyewitness Graeme Ansell of New Zealand. “It was very quick. The whole village has been wiped out,” Ansell told National Radio from a hill near Samoa’s capital, Apia. “There’s not a building standing. We’ve all clambered up hills, and one of our party has a broken leg. There will be people in a great lot of need ’round here” [AP].
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The tiny island nation of Palau has taken a big step to protect the ocean’s endangered sharks, by designating all of its territorial waters a shark sanctuary within which all commercial shark fishing is prohibited. Palau’s president, Johnson Toriboing, announced the plan at a meeting of the UN General Assembly last Friday. Sharks are increasingly under threat as the demand for shark-fin soup—a delicacy in many Asian countries—has risen worldwide. “The need to save the ocean and save sharks far outweighs the need to enjoy bowls of soup,” Toriboing said [National Geographic News].
Palau consists of about 200 small islands in the Pacific Ocean to the east of the Philippines; its expansive marine territory spans 230,000 square miles, an area about the size of Texas. About 130 species of rare sharks either make their homes or pass through these waters, including hammerheads, leopard sharks, and reef sharks, as well as the related stingrays.
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One day, the most advanced ships may not have steel hulls that slice cleanly through the water, but instead may sort of ooze along, leaving a wake of slime and microbes. Researchers are trying to design a ship that continuously exudes slime to form a coating around its hull that steadily wears away, taking hangers-on like barnacles with it.
Barnacles and the other sea creatures that accumulate on boats’ undersides create drag, and therefore reduce speed and energy-efficiency. The problem is an expensive one, as it requires vessels to be brought into dry dock every couple of years to remove plants and animals from the hull. It has been made worse by the banning last year of antifouling paints based on tributyltin, which is toxic to marine life [New Scientist].
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In an ambitious attempt to assess how humans are doing as stewards of planet earth, 28 leading scientists have drawn up a list of nine “planetary boundaries” that must not be crossed if we want to avoid drastically changing the global environment and imperiling our own existence. The only problem is, we’ve already crossed three of those thresholds.
The paper, published in Nature (and available for free), aims to define a “safe operating space” for human life on the planet. It’s a first-draft users’ manual for an era that scientists dub the “anthropocene,” in which nearly seven billion resource-hungry humans have come to dominate ecological change on Earth [Wired.com]. What follows is a list of the nine environmental factors, and how we’re doing on living within each limit.
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Arctic sea ice melting, which scientists have linked to global warming, may be a boon for the shipping industry. As the sea ice continues to melt a shipping passage to Russia’s north is becoming more navigable, and now two German ships are close to completing the first trip from Asia to Europe via the Arctic shortcut. However, walruses that live in the Arctic could care less, since their sea ice habitat is rapidly disappearing.
Thousands of walruses are congregating on Alaska’s northwest coast, a sign that their Arctic sea ice environment has been altered by climate change. Chad Jay, a U.S. Geological Survey walrus researcher, said Wednesday that about 3,500 walruses were near Icy Cape on the Chukchi Sea, some 140 miles southwest of Barrow [AP]. Walruses wear themselves out diving for clams, and need to rest on the sea ice between meals. Since the sea ice is disappearing, they are turning to the shore for a break. Federal managers and researchers worry that so many walruses in one location could lead to a deadly stampede or could drive off prey. Highlighting the animals’ peril, the Obama administration is considering adding walruses to the endangered species list.
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Here’s the good news: Plastic may break down in the ocean in as little as a year, not 500 to 1,000 years as scientists previously thought. Now, the bad news: This degradation could be releasing harmful compounds such as bisphenol A (BPA) into the ocean, according to research presented at the American Chemical Society meeting on Wednesday.
Ocean-borne plastic, such as that in the vast Great Pacific Garbage Patch, has traditionally been viewed as an environmental hazard due to the danger it can pose to sea life and birds. But to find out more about how plastic behaves when in the ocean, researchers acquired water samples from Japan, India, Europe, the United States, and other locations. The results? All the water samples were found to contain derivatives of polystyrene, a common plastic used in disposable cutlery, Styrofoam, and DVD cases, among other things [National Geographic News].
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In the depths of the Pacific Ocean, several never-before-seen species of worm have been found that have a remarkable defense mechanism. Take, for example, the newly named species Swima bombiviridis. Thousands of meters below the sea, a tiny worm wriggles through the darkness, its dozens of paddle-shaped bristles moving in beautiful coordination. Suddenly, a hungry predator appears. The worm releases a glowing green sac, and the fish homes in on this bright new trophy. By the time the fish realizes the sac is no meal, the worm is long gone [ScienceNow Daily News].
Of the seven new species described in a paper in Science, five drop luminescent “bombs” that researchers think distract their predators, allowing the worms enough time to wriggle away backward. Study coauthor Greg Rouse explained that a common ancestor of the species had gills that appeared to be “in exactly the same places as the bombs”, from which the bombs could have evolved. “The gills (of their relatives) can fall off very easily so there’s a similarity of being detachable, but for some reason the gills have transformed to become these glowing little detachable spheres” [BBC News].
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At the bottom of the Arctic Sea lie vast deposits of methane gas trapped in frozen, icy forms called methane hydrates, and climate scientists would very much prefer that it remains trapped down there. Methane is a powerful greenhouse gas, and some researchers worry that a warming ocean may melt the icy structures, allowing the gas to travel up through the water to the atmosphere, where it could further contribute to global warming. Now, scientists who have been scanning the seas for signs of trouble say they may have found some.
The researchers spotted 250 plumes of methane gas bubbling up through the sea north of Norway. The region where the team found the plumes is being warmed by the West Spitsbergen current, which has warmed by 1 °C over the past 30 years. “Hydrates are stable only within a particular range of temperatures,” says [study coauthor Tim] Minshull. “So if the ocean warms, some of the hydrates will break down and release their methane” [New Scientist]. However, the scientists couldn’t prove that the methane is being released as a direct result of the warming, and say it’s possible there have always been methane seeps like these.
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A new documentary film that has all the intrigue of a thriller is giving the world its first glimpse of what goes on in the scenic waters near the coastal town of Taiji, Japan. The Cove tells the story of a skilled group of activists who reveal the slaughter of dolphins by Japanese fisherman, with scenes so bloody that the cove’s waters are dyed red. This killing may be legal — dolphins and other small marine mammals are not protected by the ban on commercial whaling — but … the methods used are so nonchalantly brutal and gut-churningly primitive that Taiji officials are understandably publicity-shy [The New York Times].
In an effort to keep the dolphin killing off film, mysterious individuals follow, harass, and confront the filmmakers. The cove where the slaughter takes place is private property and strictly off-limits, but the movie makers are more than willing to break the law for their cause. To ensure they get their footage, the team includes a “clandestine operations” organizer, two of the world’s best free-divers, and a former avionics expert with the Canadian Air Force. This cloak-and-dagger crew makes use of such tools as a military infrared camera for night cinematography, unmanned aerial drones, a blimp and fake rocks specially designed by George Lucas’ Industrial Light & Magic to hold secret cameras [Los Angeles Times].
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Scientists will venture this summer to the Eastern Pacific Garbage Patch–a blob of discarded plastic twice the size of Texas that’s floating in the Pacific Ocean–in an extensive effort to assess just how detrimental the patch is to the marine ecosystem.
Two boats push off this month to examine and analyze the patch of plastic; one left from San Diego yesterday, the other is set to leave from San Francisco tomorrow. The expeditions will last four weeks and will cost $1.1 million. Researchers from the Scripps Institution of Oceanography in San Diego will conduct a wide range of experiments on the debris’ impact on phytoplankton, zooplankton, fish, whales, birds, salts and fouling communities – groups of organisms that live on the debris. They will spend 10 days traveling to and from the remote region [San Diego Union-Tribune]. Once the researchers are back on dry land, it will take months to fully analyze the samples collected during the voyage.
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The Chesapeake Bay was once carpeted with oysters, but that was before centuries of overfishing, pollution, and disease took their toll: Today the oyster population has been reduced to less than 1 percent of its historical population. But a new restoration effort has shown unprecedented progress in bringing the bivalves back. In the Great Wicomico River, a tributary of the Bay, researchers have created a 87-acre oyster colony that contains about 185 million oysters.
The Chesapeake’s oyster reefs were destroyed by centuries of watermen towing rakelike metal “dredges” and silted over by dirt flowing from the mid-Atlantic’s farms and growing cities. The final blow came in the mid-20th century: A pair of new diseases killed oysters by the millions. Now, in many places, the bay bottom is a flat expanse of green mud. “Just picture, you know, a clear-cut forest,” said Kennedy Paynter, a biology professor [Washington Post].
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The world’s fisheries may be seriously depleted, but a comprehensive new study shows that all is not lost–and suggests that when humans really put the effort into turning the tide, fish stocks can be returned to good health. The researchers found that efforts introduced to halt overfishing in five of the 10 large marine ecosystems they examined were showing signs of success. A combination of measures – such as catch quotas, no-take zones, and selective fishing gear – had helped fish stocks recover [BBC News].
The new study sprang from another report from marine ecologist Boris Worm in 2006, in which he made an alarming prediction: if current trends continue, by 2048 overfishing will have destroyed most commercially important populations of saltwater fish. Ecologists applauded the work. But among fisheries management scientists, reactions ranged from skepticism to fury over what many called an alarmist report [The New York Times]. Eventually the two groups agreed to collaborate on a study that would bring both their perspectives to the table, and which would determine the best ways to revive and manage the ocean’s fish stocks.
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