Hawaii scientists find seafloor rock 2 billion years old.

All known life on Earth lives on the planet's solid crust, but below that, there is a roiling mass of molten rock known as the mantle.
Scientists have long considered the mantle to be a well-blended mix of rock—but a team of University of Hawai'i researchers recently found something new and different in rock three miles deep under the Arctic ice, near the North Pole.
There, beneath a feature called the Gakkel Ridge, they found some rock that had not mixed well, and which still retained the mineral signatures of two billion years ago.
UH geologist Eric Hellebrand was co-leader of an expedition aboard the German research icebreaker Polarstern. UH postdoctoral researcher Anette von der Handt also participated. Their research findings were printed in the March 20, 2008, edition of the journal Nature.
In the language of the geologists, when moltten mantle rock finds its way through the crust and erupts to the surface, it is expected to be well-mixed or homogeneous. What they found when they brought up samples from the ridge on the Arctic ocean floor was rock that was, instead, heterogeneous—not like everything else.
It's like biting into a plain cookie and coming across a chocolate chip. And now, scientists are wondering whether they'll find more surprises if they keep looking.
“The unprecedented discovery of these rocks indicates that mantle heterogeneity may turn out to be more widespread in mid-ocean ridge settings than inferred from the more commonly studied erupted lavas,” said a UH press release announcing their find. The results of the Arctic research are published in the March 20th edition of the prestigious journal Nature.
When they put their rocks under a microscope, Hellebrand and von der Handt—who were part of an international research team-- what they found was unexpected and “as rare and fascinating as moon rocks.”
It was rock that had not been significantly altered by mixing, and studies of isotopes of the rare metal osmium indicated the rock was 2 billion years old.
“We can’t exaggerate how important these rocks are – they’re a window into that deep part of the earth,” said paper co-author Jonathan Snow, an assistant professor of geosciences at the University of Houston.
They may, in fact, be a kind of ancient library, a technique for looking into the early geology of our planet.
That's not to say that there isn't any diversity within the molten rock of the mantle. There is.
“Compared to the varied and ancient continental crust, most geologists think of the mantle as a relatively homogeneous region of the deep Earth”, Hellebrand said.
“Some variations in composition, or heterogeneities, are well known, and are seen in volcanic rocks from Hawaii and Iceland.”
But to find rocks that hadn't participated in the vast global mixing—that was special, the researchers said.
© 2008 Jan W. TenBruggencate

Halema'uma'u erupting! First time since 1982.

Halema'uma'u Crater, the firepit of Kīlauea, is erupting for the first time in 26 years.
(Image: Hawaiian Volcano Observatory image of ash plume from Halema'uma'u. Credit: USGS.)
In a buildup that has lasted more than a week, Halema'uma'u first began pumping out increased amounts of sulfurous gas, then threw boulders across the landscape in what was described as a gas explosion. Sunday night, it began erupting small amounts of lava and large amounts of ash.
Much of the landscape around the Kīlauea Caldera is covered with ash from previous eruptions, so this is not unheard-of.
The implications of the ash plume are potentially severe. It can damage aircraft engines that fly through it. It can harm human lungs.
“There is now continuous emission of ash from the new gas vent in Halema`uma`u Crater, turning the formerly white cloud of fume a dusty-brown color. The top of the ash plume, which is currently being blown to the southwest of the Crater, reaches 0.5 to 1.0 mile above ground level. Hawai`i aviation agencies have been notified of the potential hazard to aircraft,” the Hawaiian Volcano Observatory said in its daily update Monday.
Observatory staffers began seeing glowing material erupting Sunday night from a 100-foot-wide vent that is within the crater and below the crater overlook. The overlook and parts of the Chain of Craters road are closed to the public because of the health and safety hazards.
The eruption as of the most recent update is not the classic fountain of lava, but more of a spattering of molten rock. Geologists searching the area yesterday found a range of volcanic products, including long, thin strands and small gobs, which are known as Pele's hair and Pele's tears. The biggest pieces, the observatory said, are gobs of about 4 inches across.
“The amount of lava erupted from the vent last night was small, but it represents the first lava erupted from anywhere in Halema`uma`u since 1982. Previous eruptions included lava flowing into the crater from fissure eruptions on its southwest rim in 1974 and 1971 and an 8 month eruption in Halema`uma`u in 1967-1968 that created a lake of lava that covered the entire crater floor,” the observatory said.
For more on the current eruption, see the RaisingIslands.com post at raisingislands.blogspot.com/2008/03/quiet-volcano-gets-explosive.html.
Updates are available at the observatory website at hvo.wr.usgs.gov.
© 2008 Jan W. TenBruggencate

The quiet volcano gets explosive

The world's great drive-in volcano showed its darker side this week—and not for the first time.
Kīlauea is known for its calm eruptions and flows, which visitors often can approach close enough to feel the heat.
But as the week's activities showed, the volcano also has a history of violence, of catastrophic explosions capable of destroying property and taking lives.
Earlier, the firepit within the Kīlauea began producing prodigious amounts of nasty fumes. On March 19, 2008, a blast just before 3 a.m. strewed rocks and gravel over an estimated 75 acres. It followed several days of concerns over toxic sulfur dioxide gas emissions from the volcano, including the discussion that Volcano Village might need to be evacuated if gas clouds moved in its direction.
Parts of Crater Rim Drive continued to be closed due to danger from the gas, and the Hawaiian Volcano Observatory said further explosions—driven by steam or underground gas—were possible.
Elevated toxic gas levels continued after the explosions, and parts of the region remained closed to human activity several days after the explosion.
For many folks, the violence of the volcano seemed uncharacteristic, but it certainly was not unheard-of.
In its multi-day events of May 1924, the Halema'uma'u firepit rumbled and roared, its activity punctuated by powerful blasts that threw rocks from the size of sand grains to small cars. They landed, sizzling in the rain, hundreds and occasionally thousands of feet from the edge of the pit. Showers of yellow mud fell 25 miles away.
That event ended in a spectacular eruption. During the events, one observer, a photographer, was killed by rocks and hot mud.
Scientists said much of the pre-eruption activity was steam-driven—the result of water underground meeting magma. In these conditions, water flashes to steam, expanding dramatically in volume, and creating immense pressures that can drive explosive results.
And the 1924 events were predated by an even more catastrophic explosion.
In 1790, another explosion of ash from Kīlauea trapped the passing army of Keoua, and killed 80 or more people who were trapped. It has been suggested that it was the toxic gas rather than the ash that overcame the Keoua supporters. The volcano observatory said the ash eruption dumped 100 million cubic yards of ash on the landscape, some of it more than 35 feet thick.
For updates on what's happening at the volcano, see volcano.wr.usgs.gov/kilaueastatus.php.
© 2008 Jan W. TenBruggencate

Bottomfish: closed season increased imports

It's not surprising: When the first closed season for bottomfish in the main Hawaiian Islands took effect last summer, ratio of imports of the same fish increased dramatically.

(Image: An 'ōpakapaka swims by a BotCam used for monitoring the health of Pacific fish stocks. National Marine Fisheries Services photo.)

The Western Pacific Regional Fishery Management Council reported that in previous summers, there were about 1.8 pounds of imported bottomfish for every pound caught locally. During the closed season from May 15 to Sept. 31, 2007, the percentage climbed to 4.5 pounds per locally caught pound.

The fishery council, in its winter 2008 newsletter, expressed surprise that the situation did not result in an increase in the prices of locally caught bottomfish. I concluded that this may have been because folks didn't realize that some Hawai'i bottomfish were still available.

There are several explanations required here.

First, bottomfish are considered to be seven species of prized eating fish caught in relatively deep waters around the islands. They include the grouper hāpu'upu'u, and the snappers lehi, onaga, gindai, 'ehu, kalekale and 'ōpakapaka.

Second, the reason there were still some locally caught bottomfish in the mix (the 1 pound of local catch compared to the 4.5 pounds of imports) is that the Northwestern Hawaiian Islands (NWHI) bottomfishery remained open. The closed season only applies to the depleted stocks in the main Hawaiian Islands. The new NWHI Bottomfishing Hui, has launched an educational program to let Hawai'i residents know that there is still legal local bottomfish available during the closed season.

Third, the situation changes further in 2011, when all commercial fishing in the Northwestern Hawaiian Islands will be terminated, a part of the law established with President Bush's creation of what came to be known as the Papahānaumokuākea Marine National Monument.

The next closed season will be from May 1 to Aug. 31, 2008. The next fishing season, starting Sept. 1, 2008, may include special reporting requirements, bag limits for non-commercial anglers, vessel markings and other features.

Since the fishery reopened after last summer's closed season, anglers by late February had caught close to two-thirds of the established total allowable catch for the open season. The total allowable catch is 178,000 pounds for the cumulative weight of the seven bottomfish species. If the catch reaches that number before the scheduled end of the open season, the fishing will be immediately halted for bottomfish in the main Hawaiian Islands.

For more information, see www.hawaiibottomfish.info, a site jointly operated by the state Division of Aquatic Resources, the Western Pacific Regional Fishery Management Council and the National Marine Fisheries Service.

© 2008 Jan W. TenBruggencate

Pacific Menehune traditions: new "small people" in Palau

Researchers have discovered a clan of Menehune-sized humans in caves on the island of Palau.

It is the second recent example in the Pacific of what appears to be a miniature race.

(Image: Views of adult skulls found in the Palau caves. Credit: PLoS One.)

The previous finding—reported in 2004—on the Indonesian island of Flores, was of a group of small people, who have been described as a separate species from humans, under the name Homo floresiensis. (As opposed to modern humans, Homo sapiens.)

It raises the question of whether the actual existence of miniature people in the Pacific may have generated the traditions in the Islands of a race of small forest people, among them the Hawaiian Menehune. There have been no discoveries of similarly small human-like remains in Hawai'i.

Palau lies in western Micronesia. The Hawaiian voyaging canoe Hokule'a visited Palau in 2007 on its extended voyage through the eastern Pacific and on to Japan.

The new Palau finding was published in the online journal PloS One, under the title, “Small-Bodied Humans from Palau, Micronesia.” The authors are Lee Berger and Bonita De Klerk of South Africa's Institute for Human Origins and the Bernard Price Institute for Palaeontology, School of GeoSciences, University of the Witwatersrand, along with Steven Churchill of Duke University's Department of Biological Anthropology and Anatomy, and Rhonda Quinn of Rutgers University's Department of Earth and Planetary Sciences.

The authors do not suggest that the Palau samples necessarily represent a different species from humans. Rather, they argue that these might be pygmies—humans whose size has diminished over time, just as other species can sometimes dramatically change size in island environments.

But there are odd things about the findings.

“First, individuals from the older time horizons are small in body size even relative to 'pygmoid' populations from Southeast Asia and Indonesia, and thus may represent a marked case of human insular dwarfism. Second, while possessing a number of derived features that align them with Homo sapiens, the human remains from Palau also exhibit several skeletal traits that are considered to be primitive for the genus Homo,” they write.

The remains were found in limestone cave environments in the rock islands of Palau. The small individuals represent remains found in two separate burial caves. The caves apparently were only used for burials, since there was no associated material suggesting they were also habitation caves.

And they appear to come from a period well after normal-sized humans first arrived at Palau, which is estimated at 3,000 to 4,500 years ago. Radiocarbon dates on the bone of the Palau Menehune suggested the miniature individuals lived between 1420 and 2890 years ago, or roughly 900 BC to 600 AD.

(The Flores remains are graybeards by comparison—well in excess of 10,000 years old.)

Wave action or other disturbance had moved the Palau bones around, and the researchers were unable to recover complete skeletal remains. They cautioned that “these limitations make it impossible for us to make definitive statements about critical aspects of skeletal morphology in these ancient Palauans—namely brain size and body proportions.”

But they were able to determine that while a few of the remains were of children, many were of mature individuals. And from what they found, they concluded that some of the individuals when alive may have weighed from less than 70 to nearly 100 pounds, that they had small faces, and brains that are the smaller end of the normal range for humans.

The Palau small folks were similar in some ways to the Flores “hobbits,” but not identical to them.

Scientists left many of the remains in place, encased in hardened sediment, and they said further investigation might reveal more about the Palauan small people.

It is clear that under certain circumstances, forms of life can dramatically change size. Sometimes they can get larger, like sheep-sized Hawaiian flightless ducks that evolved from small migrant flying ducks. And sometimes, things shrink.

Among humans, this is not unknown.

“Pygmy populations are known from mainland tropical forests and tropical island settings in Africa and Southeast Asia, reflecting parallel cases of dwarfing in response to the combined factors of relative genetic isolation, a reduced resource base, hot and humid climates, hilly topography, thick undergrowth of vegetation, and (in certain island contexts) an absence of terrestrial predators,” the authors of “Small-Bodied Humans” write.

Their conclusion suggests that the Flores Menehune and the Palau Menehune may simply represent examples of what happens to humans in certain difficult environmental situations:
“Based on the evidence from Palau, we hypothesize that reduction in the size of the face and chin, large dental size and other features noted here may in some cases be correlates of extreme body size reduction in H. sapiens. These features when seen in Flores may be best explained as correlates of small body size in an island adaptation, regardless of taxonomic affinity. Under any circumstances the Palauan sample supports at least the possibility that the Flores hominins are simply an island adapted population of H. sapiens, perhaps with some individuals expressing congenital abnormalities.”

The paper is online at www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0001780#pone.0001780-Brown1.

© 2007 Jan W. TenBruggencate

Hawai'i coral capitol discovered

It may seem counterintuitive to many residents, but new studies show that the island with the most live coral cover in Hawai'i is the Big Island.

(Image of Big Island corals courtesy NOAA)

Most would think of the reef flats of 'Anini on Kaua'i, or O'ahu's Kāne'ohe Bay, or perhaps the vast reef flats of South Moloka'i—but of course there are reasons for the Big Island's pre-eminence.

“Live coral covers 57 percent, or 29 square miles, of the waters surrounding the Big Island of Hawaii,” said Timothy A. Battista, an oceanographer with NOAA’s Center for Coastal Monitoring and Assessment. “That is the most live coral coverage of any of the main Hawaiian islands.”

The conclusion is based on a remarkably thorough new mapping study of the coral communities of the coasts of all the islands.

The new NOAA reef mapping study is available on the Web at http://ccma.nos.noaa.gov/products/biogeography/hawaii_cd_07/startup.html.

It is entitled “Shallow-water benthic habitats of the Hawaiian Islands 2007.” The report has zoomable maps of the entire coastline of each island.

NOAA's press release on its report is here: http://www.noaanews.noaa.gov/stories2008/20080116_hawaiicoral.html.

Here's what NOAA says about its new maps:

“The maps are the result of the most comprehensive assessment of the extent and types of shallow-water seafloor habitats in Hawaii to date. In all, the NOAA mapping effort covered 506 square miles of ocean habitat on Hawaii, Kahoolawe, Maui, Lanai, Molokai, Oahu, Kauai, Niihau and Kaula. The Hawaii survey was part of a larger effort by NOAA and partners to map all U.S. shallow water coral reef ecosystems and associated deeper reefs.”

Why would the Big Island's reefs have more coral than other islands? Perhaps because the waters around much of the state's youngest island are cleaner, less contaminated with sediment from runoff. But also because the waters there are generally warmer, and reef corals tend to do better in warmer water.

On most of the islands in the Hawaiian Archipelago, the reefs are largely constructed of coralline algae, a plant, rather than reef corals, which are an animal that lives in a symbiotic relationship with single-celled algae.

© 2007 Jan W. TenBruggencate

Air drops eradicate Hawaii islet rat population

State and federal agencies believe they have wiped out the rat population on a small island off north Moloka'i.

(Images: Helicopter dropping rat bait on Mōkapu Island. Heather Eijzenga photos.)

The rat control program is aimed at allowing the native species of Mōkapu Island to recover from decades of rat predation. Rats are not native to the Hawaiian Islands.

Similar rat eradication efforts have been or are being conducted at several locations throughout the Hawaiian archipelago, after the recognition that rats are among the major predators of native species, eating chicks and eggs of native birds, as well as seeds and small native plants.

Among the native species on the island are three seabird species: wedge-tailed shearwaters, red tailed tropicbirds, and white-tailed tropicbirds. The island also has most of the state's remaining wild specimens of the plant hoawa, or Pittosporum halophilum, and a small group of the rare Hawaiian fan palm, loulu lelo, or Pritchardia hillebrandii.

The steep-sided little island is a challenging location for conducting an invasive species program, and the program involved helicopter drops of fish-flavored pellets of a rodenticide called diphacinone.

“This aerial application of the rodenticide diphacinone is the first of its kind for offshore

islands in Hawai‘i,” said Chris Swenson, Pacific Islands Coastal Program Coordinator for the

U.S. Fish and Wildlife Service. “Similar rat eradication methods have been successfully used in other parts of the world since the early 1990s.”

The Mōkapu program was a joint effort of the service, along with the state Department of Land and Natural Resources' Division of Forestry and Wildlife, and the U.S. Department of Agriculture's APHIS-Wildlife Services agency. Others involved included Hacco Inc., Moloka‘i/Maui Invasive Species Committee, the Moloka'i branch of The Nature Conservancy of Hawai'i and United Agriproducts

Black rats, also known as roof rats, are the primary problem in many forest ecosystems in Hawai'i, but on Mōkapu, the predator of native seabirds and rare plants was the Polynesian rat, Rattus exulans.

Two aerial drops of diphacinone were used to be sure the entire island was covered, and to ensure the bait was available to rats in adequate doses.

Diphacinone is particularly effective for rats, but not as dangerous to birds and other species that might come into contact with it. Water samples and tests from marine life will be made to ensure the compound has not spread in the environment.

“The success of the Mokapu Island rat eradication project will provide natural resource

managers throughout the state access to a proven method of bait application using a less toxic

and more environmentally friendly rodenticide,” said the eradication program's project manager, Peter Dunlevy.

The wildlife agencies said they believe the eradication effort was successful, but that they will monitor the island for a two-year period to be sure. They will also keep an eye on seabirds and the native plants of the island to attempt to confirm their recovery from the years of rat presence.

The program was conducted after an environmental assessment, and after public meetings on Moloka'i about the project. The results of testing on water and marine life is to be offered to Moloka'i media for publication.

A copy of the environmental assessment is available on the web at www.fws.gov/pacificislands/FinalEAMokapuRatEradication.pdf.

© 2007 Jan W. TenBruggencate

Mud kicks up daily on Moloka'i reef

A muddy shoreline can starve marine life of light—the equivalent of trying to grow a garden in a dark room.

(Image: South Moloka'i coastline, showing Kaunakakai Pier at right. NOAA/USGS aerial photo.)

Research on the south shore of Moloka'i suggests that the light deprivation can in some areas continue long after the rain has stopped, since the sediments remain on the reef, and are lifted into the water column each time the winds and currents come up.

The process is described in a new paper, “Diurnal variability in turbidity and coral fluorescence on a fringing reef flat: Southern Molokai, Hawaii,” by researchers Gregory Piniak of NOAA's Center for Coastal Fisheries and Habitat Research in North Carolina, and Curt Storlazzi, of the U.S. Geological Survey's Pacific Science Center in California.

The work is published in the Elsevier journal, Estuarine Coastal and Shelf Science.

Piniak, in an email, said that many people worry about runoff from the land into the sea only when it's happening, not recognizing that the damage can continue for an extended period of time.

“Generally runoff is thought of as a single event, like storms that deliver big pulses of sediment to the reef,” he said.

But on some leeward shores, where big onshore surf doesn't quickly dilute the muddy water and flush it out to sea, things can be different.

“On the Moloka'i reef flat sediment builds up over time and is constantly stirred up, so sediment events become more of a chronic issue.

“The reef flat on the southern coast of Moloka'i can be really turbid—the water can be calm and fairly clear in the morning, but when the trade winds and waves kick up it can be like swimming through coffee,” Piniak said.

And it's not just Moloka'i's wide, protected southern side. Citing previous research by others, Piniak and Storlazzi note that a 2002 runoff event at Honolua Bay on Maui left sediment on the reef for six months.

“Periodic sediment damage decreased coral cover in the bay by 33 percent between 1992 and 2002,” they write.

In the Maui situation, agricultural runoff is the prime culprit. On Moloka'i, it is generations of overgrazing on the slopes above the shore. Moloka'i's situation, at least near Kaunakakai, is made worse by the long Kaunakakai Pier, which blocks the movement of mud down the coast.

“The wharf at Kaunakakai further inhibits longshore transport and removal of sediment from the Molokai reef flat, resulting in some of the lowest coral cover in the state of Hawaii,” the paper says.

The researchers studied the impacts of the muddy water on the coral Montipora capitata.

Not surprisingly, perhaps, they found these corals were somewhat adapted to handle the pulses of sedment, and a daily regiment of being pounded by bright sunlight in the morning when the weather was calm, and then getting shaded out each afternoon as the tradewinds came up and disturbed the sediment.

“The coral species we studied tends to handle sediment pretty well, but our data suggest it would probably do better physiologically if the water were clearer,” Piniak wrote.

It may be that some corals are able to develop a tolerance for the sediment conditions, but the authors gave two examples of things the community could do to address the sedimentation issue.

One is to revegetate the Moloka'i hillsides to reduce sediment-filled, and another is to make changes to the Kaunakakai Pier, to promote water low from one side to the other.

© 2007 Jan W. TenBruggencate