Mystery earthquake south of Hawai'i

A mysterious earthquake shook the seafloor between Hawai'i and the Marquesas Islands this morning, in a spot that's not known for temblors.
(Image: Image provided by Google Earth and USGS, annotated by the author.)

It wasn't a huge event, just a 5.4, but it was enough to set up a chatter between the folks at the U.S. Geological Survey who watch these things. They said there is no reason to believe it could presage another, bigger event.

The quake happened at 5:40 a.m. Hawai'i time on Friday, February 29, a little more than an hour before this posting.

The site was below the surface of the ocean floor, at 3.08 degrees north and 140.34 degrees west longitude. That's just northwest of the Marquesas and southeast of Hawai'i, a little north of the Equator.

It is an odd and unusual place for a quake, although such events are not unheard-of, said Barry Hirshorn, a geophysicist with the Pacific Tsunami Warning Center.

Most of the earthquakes around the Pacific occur at the edges of the vast Pacific Plate, one of the chunks of the earth's crust that are constantly in movement, shoving up against each other, rising up or slipping under each other, or sliding alongside each other. The perimeter of the Pacific Plate is familiarly known as the Ring of Fire, because of all the volcanic activity that is associated with the plate fringe.

There are also frequent quakes around Hawai'i, associated with both the activity of the volcanoes and the weight of the islands on the center of the plate.

But at the site of this morning's event, there are no islands, no volcanoes, no fault lines, and it's nowhere near the edge of the Pacific Plate. Hirshorn said he had discussed the event with folks at the Alaska warning center, who had also seen it on their instruments.

“You can have false readings, but this is a real quake. It's the middle of the plate. It's pretty rare to have that happen, but you can have residual areas of stress that build up” and cause an event, he said.

The quake was comparatively shallow, about 4 miles deep.

For information on the quake, see earthquake.usgs.gov/eqcenter/recenteqsww/Quakes/us2008pabx.php.

© 2007 Jan W. TenBruggencate

Airborne dust over Hawai'i impacts climate change

That dust that appears magically on your windowsill in Hawai'i?

It may be better-traveled than you are.

(Image: Here, airborne dust from the Sahara is seen as a brown haze over the Caribbean. The same thing happens in the Pacific, with dust from both Asia and South America. NOAA photo from the GOES8 satellite.)

There's a fair chance some of the material on the windowsill is Asia dust, lately resident of Chinese deserts or the smokestacks of China industry.

“Each year, long-distance winds drop up to 900 million tons of dust from the deserts and other parts of the land into the oceans,” write a team of researchers who have studied the issue.

Earlier work suggests Asian dust storms may have dumped enough material on the Islands to increase the fertility of worn-out volcanic soils. The most recent studies, looking at ocean sediments, suggest that dust volume is associated with climate change.

Researchers led by geochemist Gisela Winckler, of Columbia University's Lamont-Doherty Earth Observatory, studied seafloor sediments across 6000 miles of the Pacific south of Hawai'i—along the Equator from New Guinea to the Galapagos.

“Dust from Asia travels long ways, including Hawai'i and the West coast of the U.S., for example. In our study we present geochemical evidence that the dust in the central and western tropical Pacific (at the equator) is of Asian origin while the dust in the eastern equatorial Pacific is predominantly

derived from South America,” Winckler said in an email to RaisingIslands.

The paper, with the unfortunate title “Covariant glacial-interglacial dust fluxes in the equatorial Pacific and Antarctica,” was written by Winckler, Martin Fleisher, Robert Anderson and David McGee, all of Columbia, and Natalie Mahowald of Cornell. It was to be published today (Feb. 28) at the ScienceExpress website.

The dust is high in a range of nutrients—more on that later.

They used the isotope thorium 232 to track land dust—if you find this isotope in the remote ocean, it's generally from land-sourced dust. And they used various other isotopes to identify where the dust came from. Most on the western side of the Pacific came from Asia. On the Galapagos side, it tended to come from South America.

They also compared their data with information from previous cores done in Antarctica, where the main source of dust is Patagonia. Both sets of cores showed that during ice ages, there's a spike in the amount of continental dust deposited in the oceans.

Why do we care about dust? Because, as the paper says, “dust affects climate.” It may even be acting as a kind of feedback mechanism.

With more dust in the air, sunlight (and heat) is radiated back into space—helping keep the Earth's temperatures cool.

Dust has considerable amounts of iron, and it may fertilize the oceans, causing them to grow more plants and to suck carbon-dioxide out of the atmosphere. The reduced carbon-dioxide would lessen the atmosphere's ability to hold heat, and would further support cooling.

Other researchers have considered dumping iron into the oceans as a way of fertilizing them, causing themto take up more carbon-dioxide, all in hope that the stuff would sink to the deep sea and be hidden away for a long time. Winckler and her team, in a press release, say the jury is still out on how well that would work.

“A dozen early experiments in different regions have shown that plankton growth increases when iron is artificially added, but scientists have yet to show that this could lock significant amounts of CO2 into the ocean...The new data gives us a natural experiment to see what might have happened in the past.

They plan to study their sediment cores to see if they also include high levels of carbon, which might indicate carbon was effectively being sequestered.

The scientists say it's not entirely clear why there's more dust during ice ages, but it seems clear that there is a relationship between more cold and more dust.

Or, to let them use their own words:

“Although there is uncertainty concerning the complex interplay of the factors influencing dust generation in any particular region, we infer from the synchronous changes in dust fluxes seen in our records that in each of the source areas, i.e. Asia, northern South America and Patagonia, the dominant processes regulating dust generation experienced a coherent response to global climate change.”

© 2007 Jan W. TenBruggencate

Oh, the slime! Slugs a threat to native ecosystems

Gardeners have long known the threat of garden slugs to their seedlings, but natural resources managers are only now recognizing that the slimy critters are also significant threats to rare native plants.

(Images of slugs in the Hawaiian environment courtesy Stephanie Joe. The spotted character at the top is a large European native named Limax maximus. She's a pet, and Joe calls her Destiny.)

“Slug herbivory may be skewing species abundance in favor of certain non-native and native plants,” wrote University of Hawai'i botanist Stephanie Joe and UH botany professor Curtis Daehler, in an article in the journal Biological Invasions.

Their article is entitled “Invasive slugs as under-appreciated obstacles to rare plant restoration: evidence from the Hawaiian Islands.”

Garden stores sell slug bait, which home gardeners use to keep slugs from munching their new seedlings right down to the ground. But this is not something the first residents of the Islands had to face.

There were no native slugs in Hawai'i before humans arrived. The slugs' relatives, tree snails like the famed and generally endangered Achatinella, were animals that did not appear to eat plants. They crawl on leaves of forest plants but don't eat the leaves themselves. Rather, they feed on the algae and fungi that grow on plants.

But a dozen or more species of slugs have appeared in the Islands over time. They are not well studied, Daehler said, and it's not really clear how many species there are, or exactly where they are.

However, “they are pretty widely distributed. Everywhere we've looked, we find evidence of them,” he said.

There are warm-weather slugs in the lowlands, and slugs from temperate regions in the cooler high forests.

To determine what their impact on native plants might be, Joe and Daehler developed experiments that involved growing seedings of two endangered native plants, Cyanea superba and Schiedea obovata, a non-endangered native, Nestegis sandwicensis (Olopua), and two weeds, Psidium cattleianum (strawberry guava) and Clidemia hirta (Coster's curse).

They planted the seedings out in the forest in the Waianae mountains, and watched what happened.

It wasn't pretty.

“In our field study, both of the critically endangered species had 50 percent higher mortality when exposed to slugs,” they wrote. The greehouse-grown plants were comparatively large when they were planted in the forest, and the authors feel the loss could be higher for tiny naturally germinating seedings.

The slugs did not appear to similarly damage the weedy alien species, or even the non-endangered Olopua, which may give these plants a competitive advantage at the same time the rarest Hawaiian natives are being knocked down by slugs.

And it's not just seedings that are affected.

“We've seen that they climb up on larger plants and burrow into the plant. A lot of them can climb up defoliate a bush-sized plant,” Daehler said.

The research has serious implications for the protection of native plant communities. For a time, it seemed enough to fence out deer, goats and pigs. Then scientists found that rats were a major problem, and they used both traps and poisons to control them. Now it appears slugs will also need to be controlled.

“Slug and snail control measures have generally not been used in the management of rare plants in Hawaii, nor have published studies documented their use to facilitate rare plant restoration on other islands around the world, where endemic plants might be expected to be highly susceptible to introduced herbivores,” The Joe-Daehler paper says.

“The implications are especially relevant for rare plant outplantings and population restoration efforts... Outplanted seedings that are unprotected from slug predation may suffer from high mortality.”

Hawai'i's native tree snails are not known to be herbivores. They crawl on leaves but don't eat the leaves themselves. Rather, they feed on the algae and fungi that grow on plants.

© 2007 Jan W. TenBruggencate

New Kauai shoreline erosion bill among nation's most conservative

Kaua'i County has adopted the most aggressive shoreline building setback law in the state, a powerful policy that aims to protect coastal structures against 70 to 100 years of erosion.

(Image: Kaua'i map with red boxes showing areas where erosion studies have been completed. This interactive image is available online at www.soest.hawaii.edu/asp/coasts/kauai/index.asp. Courtesy Chip Fletcher.)

Coastal geologist Chip Fletcher, of the University of Hawai'i's School of Ocean and Earth Science and Technology, said the Kaua'i legislation may represent the most conservative coastal erosion position in the nation.

The new law, passed by the County Council and signed by the mayor, declares its provisions to be both a public safety and a planning measure.

Pushing buildings back from eroding waterlines, the law says, “is critical to the protection of life and property, the mitigation of coastal hazards, and the preservation of coastal resources.”

The issue, in part, is that if government allows people to build within a few dozen feet of the shore, and erosion threatens to undermine foundations, then there are powerful financial incentives to protect the structures—and you end up with rock walls instead of sandy beaches. Coastlines where people can't pitch their beach umbrellas, where anglers can't set up poles and beach chairs and coolers, where monk seals and turtles can't haul out, and where the classic look of a tropical beach is destroyed.

Under the new legislation, there are two potential ways of calculating how close to the water a structure can be erected.

On shallow lots whose depth from the certified shoreline to the back of the lot averages 100 feet or less, a building could be built as near as 40 feet. On deeper lots, the setback grows. If the lot depth is 130 feet, the setback is 60 feet. If it's 180 feet, the setback is 80 feet.

On larger lots, a coastal erosion study would be required, and it would establish the rate at which the shoreline is eroding.

For structures of less than 5,000 square feet, the setback would be 40 feet plus 70 times the annual erosion rate. The goal is that 70 years from now, if the erosion continues, the building would presumably be near the end of its useful life, and would still be 40 feet from the water.

For bigger buildings, with square footages greater than 5,000, the setback would be 40 feet plus 100 times the erosion rate.

So, on a coastline that's eroding at a foot a year, a normal-sized house would require a 110-foot setback, and a big hotel would require a 140-foot setback.

The Kaua'i bill is considerably stronger than the state's first such legislation, Maui's bill. The Maui setbacks are 25 feet plus 50 times the erosion rate.

For comparison, on a beach with one foot of erosion per year, a Maui home would be set back 75 feet from the certified shoreline (25 feet plus 50), while the same house on Kaua'i would be set 110 feet back (40 feet plus 70).

To learn more about coasts, see the University of Hawai'i Coastal Geology website at http://www.soest.hawaii.edu/coasts.

Erosion maps, showing coastlines where the erosion rates have been determined, are available:

For O'ahu: www.soest.hawaii.edu/asp/coasts/oahu/index.asp.

For Maui: www.soest.hawaii.edu/asp/coasts/maui/index.asp.

For Kaua'i: www.soest.hawaii.edu/asp/coasts/kauai/index.asp.

One of the interesting features of the maps is that they indicate that on many shorelines, land is actually building up. Accretion and erosion both are features of Hawaiian shorelines, and some shores have some of both, depending on where along the coast you look.

As a result of this, on many coastlines, the dramatic Kaua'i setback legislation would not take effect. If there's no documented erosion, then the issue doesn't come into play.

© 2007 Jan W. TenBruggencate

"Earth: The Sequel," a positive view of the environmental future

“Earth: The Sequel,” a new book coming out in March 2008 from Environmental Defense Fund, provides one of the most hopeful views yet of the possible future of the planet.

And while Hawai'i isn't specifically in the book, most of the technologies it reviews have Hawaiian analogues.

Its subtitle is “The race to reinvent energy and stop global warning,” and unlike virtually every other environmental book you will read, it is unfailingly positive in its outlook.

The message: human ingenuity and technology can save us, if only we let them.

“Earth: The Sequel,” written by Environmental Defense Fund president Fred Krupp and Miriam Horn, is at its core is a compilation of the some of the most forward-looking energy initiatives that are either under design or being built.

Scientists modifying microorganisms to make fuels that can be used in existing cars—does this sound like the recently announced program to make biofuels out of algae on the Big Island? .

Wave energy technologies—nothing new to Hawaii, which has one in place already off O'ahu and a different one scheduled to be installed off Maui.

There's the Alaskan inventor using subterranean heat to keep his ice hotel frozen in summer—a technology that won't be new to those familiar with the geothermal plant on the Big Island.

But the book goes beyond technologies familiar to the Islands as well, to new battery systems, improved and cheaper photovoltaics, kite wind systems, carbon sequestration research and much more.

The book's message is that the great inventors and their great ideas are out there. All they need is a fair playing field. As long as tax subsidies and government policies favor petroleum and coal, inventiveness will be inhibited and climate change will roll over us.

It is, authors Krupp and Horn say, a “near certainty that unless the United States acts as a nation to give these innovators the chance to compete fairly in the worlds biggest business, they will fail to avert the crisis in time.”

Their proposal is to recognize the cost of carbon emissions.

“Policymakers are only just beginning to confront the huge hidden subsidy for fossil fuels: that no financial account is taken of the use of the atmosphere as a dumping ground for the pollutants that cause global warming,” they write.

Read more about the book at earththesequel.environmentaldefense.org.

© 2007 Jan W. TenBruggencate

Endangermint: A little recognition for an exceedingly rare plant

It may be the rarest plant in Hawai'i—so rare that at times biologists thought it might already be extinct—and the federal administration has concluded it ought to be placed on the federal endangered species list.

(In this NASA photograph taken from the International Space Station, Moloka'i is the island to the upper left, and Phyllostegia hispida has only been found in the mountains under the clouds on its right—east—side in this image.)

The plant is Phyllostegia hispida, and it's found only in the wet forests of the mountains of east Moloka'i. It grows in a botanical wonderland, among the 'ōlapa with their trembling leaves, spreading hāpu'u tree ferns, the Hawaiian hydrangea kanawao, the native raspberry 'ākala, the red-tinted ama'u ferns.

There, rooting pigs appear to be the most serious threat to the plant, although its very rarity is also a concern. Alien grasses and potential competitors like the invasive clidemia and other weeds are also a threat.

The plant presumably has always been somewhat rare. It has no native name. It's a member of the mint family, but is a mint without the aroma.

National conservation organizations are making something of a big deal about the proposed listing, in part because it is such a rare event for the Fish and Wildlife Service under the current federal administration.

Said the Center for Biological Diversity: “The agency has not protected a single new species in 650 days, which includes the entire tenure of Dirk Kempthorne as Secretary of the Interior and is by far the longest period without a new species being protected since the landmark federal law (The endangered species act) was passed.”

The Fish and Wildlife Service in the Federal Register on Feb. 19, 2008, announced its proposal to list Phyllostegia hispida as an endangered.. The agency will accept public comments on the filing through April 21. The Hawai'i contact is Patrick Leonard, a field supervisor with the service at its Honolulu office, 300 Ala Moana Boulevard, Box 50088, Honolulu HI 96850, telephone 808-792-9400.

The filing describes the exceedingly rare plant as “a loosely spreading, many-branched vine that often forms large tangled masses.” It has six to eight white flowers in a cluster.

Biologists have managed to collect seeds and samples, and living material is being maintained in the Lyon Arboretum. On several occasions, botanists believed the last plants had died out in the wild, but over time, they would find a handful of individuals growing, generally within the Kamakou Preserve of The Nature Conservancy of Hawai'i. Whenever a plant has been found, it's been fenced to protect it from pigs and other threats. Two dozen captively grown specimens have been planted in the wild within the past year, although previous outplanting efforts have not been particularly successful.

The Phyllostegia hispida has been a candidate for endangered species status since 1997, and in 2004, the Center for Biological Diversity included it on a list of 225 plants and animals it petitioned the Fish and Wildlife Service to protect with listing as endangered species. The Fish and Wildlife Service, in its Federal Register filing, said it has been working on a number of plants, including ones with higher priority than Phyllostegia hispida, but eventually had the resources available to launch the listing of the species.

One of the problems for the species is that so little is known about it.

“The poor reproduction and survivorship...clearly indicate that the current conditions are less than optimal for this species, although we do not yet fully understand the specific mechanisms that are undermining its viability,” the service said in its notice.

In part because of that uncertainty, the service is not proposing the designation of critical habitat for the mint.

© 2007 Jan W. TenBruggencate

The flip side of photovoltaics

It's a hot time for solar energy, and in the middle of the solar frenzy, a new report is arguing that it all makes no financial sense.

Solar stock prices are up, solar arrays are sweeping across rooftops, there are even shortages in the supply of solar panels. Smart folks are clocking the savings and racking up the tax breaks by installing photovoltaics.

But Severin Borenstein, in a January 2008 report for the Center for the Study of Energy Markets, says none of this makes makes any sense from a society-wide perspective. His paper is entitled “The Market Value and Cost of Solar Photovoltaic Electricity Production.”

“My analysis,” he writes, “suggests that the actual installation of solar PV (photovoltaic) systems in California has not significantly reduced the cost of transmission and distribution infrastructure, and is unlikely to do so in other regions.”

He says the society-wide benefit of installing solar electrical generation is considerably smaller than the cost, and that “the difference is so large that including current plausible estimates of the value of reducing greenhouse gases still does not come close to making the net social return on installing solar PV today positive.”

Borenstein is a professor of business adminstration and public policy at the Haas School of Business at the University of California.

The paper makes you wonder. What does Borenstein know that accountants and businesses, who are banking the savings from installing photovoltaics, don't know?

The answer is that he's looking at the issue from an entirely different perspective—the utility's perspective, or what he calls the “social valuation.” He admits this up front.

“I do not analyze here the private valuation of solar PV for the end-use customer,” he writes.

One key to his analysis: You can't count on solar to be there when you need it. At night, or when cloudy weather inhibits PV production, or when the sun's angle reduces a panel's effectiveness, a utility needs to have alternative generation capacity standing by. And that often means installing and maintaining a big, high-cost, oil-fired, peaking generator.

Borenstein says photovoltaic installation tends to be disorganized. People install it where they want, or where they have property and roof space—not necessarily where it will do the power grid the most good.

“The experience in California is that solar PV has been installed broadly across the state, with no focus on transmission-constrained areas or minimizing line losses. The same is true in the more than 30 other states that have programs subsidizing solar PV installation,” he writes.

One upshot of this is that a utility can't use solar to justify cutting the cost of its grid.

“One might ask how much less a distribution system for a new housing development would cost to install if the developer were putting solar PV on all the houses than if it were not. The answer seems to be that the difference is negligible,” he writes.

It might be argued that the photovoltaics arguments Borenstein makes are flawed, because they compare the cost of PV with fossil fuel power, and fail to account for the massive subsidies the fossil fuel industry gets. Borenstein responds with a remarkable footnote, which argues that oil and coal subsidies have little impact on actual fuel costs.

“The huge subsidies that fossil fuel companies in the U.S. receive through favorable tax treatment are often used to justify offsetting subsidies for renewables. While the argument is correct in some cases, it must be applied carefully. For instance, the billions in tax breaks that oil companies receive for domestic exploration benefit owners of the oil companies, but they do not substantially affect the price of oil, because oil is traded in a world market and the impact of these subsidies on world supply is negligible. While this points out the disturbing lack of a rational basis for such gifts to oil company shareholders, it also means that oil exploration subsidies do not put alternative energy sources at a financial disadvantage in the marketplace.”

In other words, the paper is saying that when your legislator passes a big tax break for an oil company, it doesn't keep your cost of oil down—it just diverts money into the pockets of the oil company owners.

Borenstein does concede that the cost of photovoltaics is going down, and that at some point, it will make economic sense from a society-wide perspective to install it.

His paper is notable for what it doesn't count in its analysis.

Borenstein says his research is purely economic, and does not make judgments on the various other values of going solar, including environmental (such as reduced pollution from fossil fuel sources), geopolitical and security (such as reduced risk that an attack on a power plant will wipe out all generation, or that a foreign fuel disruption will threaten local power supplies).

He also does not inspect the value of storage technologies, like batteries, which could turn solar from an intermittent source to a steady one, and minimize many of his objections to it.

So, given all that, does solar photovoltaic power make sense for you? The Borenstein paper really seems to have no applicability in making that determination.

Many residents and businesses have found that PV is an economic plus, even without considering environmental and other issues, particularly once solar installation tax credits and other incentives are counted. The reduced contribution of greenhouse gases, for example, is simply another plus for environmentally minded consumers.

From a public policy perspective, the paper may be an argument for changing some of the existing incentives to promote their installation in specific localities and in specific ways in which they'll do the society and the grid the most good.

Borenstein's paper is available here: www.ucei.berkeley.edu/PDF/csemwp176.pdf.

© 2007 Jan W. TenBruggencate

Monk seal volunteer opportunities on O'ahu

Scientific teams are working year-round to solve the mystery of the decline in Hawaiian monk seal numbers, and they're asking the public to help, too.

(Photo courtesy NOAA Fisheries Pacific Islands Fisheries Science Center.)

Residents can join the effort by becoming monk seal volunteers. Their mission is to assist monk seals that show up in the main Hawaiian Islands, including pregnant moms and young seals born on Hawaiian beaches.

The Hawaiian native seal has been on the federal endangered species list for three decades, but its numbers continue to decline. About 1,200 are left, according to the National Ocean and Atmospheric Administration.

O'ahu residents interested in becoming monk seal volunteers or learning about the program can attend orientation meetings on the following schedule:
• February 26th from 6-8 pm at the Ewa Beach Library;
• February 28th from 6-8 pm at the Waikiki Aquarium;
• February 29th from 6-8 pm at the Kailua Rec Center;
• March 1st from 10 am to 12 pm at the Waimea Bay Visitor’s Center.

For more information, call 944-2268. Neighbor island residents can call that number for information on monk seal programs on their islands.

Alien invasion at high levels in Hawaiian waters

Wander through your backyard or other places in the urban environment, and most of the plants you find are aliens—from the grass in your lawn to the weeds infesting the lawn.

The coastal environment has many of the same issues--weeds by the dozens.

(Photos: Divers feed invasive gorilla ogo into the mouth of the Super Sucker. In photo below, the alien seaweed is inspected as it comes aboard. Kanako Uchino images courtesy The Nature Conservancy of Hawai'i.)

A new study by The Nature Conservancy, published in the journal Frontiers in Ecology and the Environment, reports that Hawaiian waters have 73 species of marine invasives, and while most are comparatively benign, a full 42 percent are harmful and are disrupting the natural environment.

The report, entitled, “Assessing the Global Threat of Invasive Species to Marine Biodiversity,” lists Hawai'i as an ecoregion with “high levels of invasion.”

At some level, if you ever get in the water with a mask on, you know the stuff that's causing the problems. It's the seaweeds like gorilla ogo that are growing like, well, weeds on the reefs. It's the schools of imported yellow taape fish.

Where do they come from? Those two examples were both brought here on purpose. But most arrive as hitchhikers on the bottoms or in the bilgewater of shipping. Before humans were here, a bit of drifting debris might carry an invader, or the larval form of an alien species might wash ashore during unusual sea conditions. But that would happen in small amounts and infrequently.

Today, big ships whose bottoms are covered with living material arrive daily from exotic ports around the world. And some of that stuff drops off to find an initial home clinging to a harbor piling, in a nearby estuary or on an adjacent reef.

The Nature Conservancy study estimates that 68 percent of invasive species in the Islands came on or in or under ships.

Nationwide, there are 800 invasive marine species.

“The scale of this problem is vast. Every day, thousands of vessels cross our oceans with invasive species hitchhiking on their hulls. Because of this, as many as ten thousand species are estimated to be in transit at any one time,” said Jennifer Molnar, lead author of the study. She is a conservation scientist with The Nature Conservancy.

The Conservancy report estimated it costs the nation $120 billion each year to deal with the invasives, which cause disease, clog pipelines, foul ships, damage the productivity of fisheries and do other sorts of damage.

And it can be impossible with current technology to reverse the damage.

“Once alien species become established in marine habitats, it can be nearly impossible to remove them. The best way to address these invaders is to prevent their arrival or introduction in the first place,” Molnar said.

In Hawai'i, one of the techniques being employed to address the problem of weeds already here is the regular vacuuming up of some of the most aggressive alien seaweeds, using a device known as the Super Sucker. It is essentially a barge fitted with a pump and a hose, and divers use the hose to suck up fast-growing unwanted limu off the reefs—presumably giving native reef creatures room to grow.

"The Super Sucker is an essential component of a comprehensive management strategy for controlling these alien algae. The research we’ve done shows that we can efficiently remove mass quantities of algae from impacted reefs. In some cases, we can restore the reef to a condition that native fishes are able to maintain in an algae-free state, which allows corals to recover,” said Eric Conklin, marine science advisor with The Nature Conservancy of Hawai'i.

The Hawai'i State Legislature is at this writing considering two bills, HB 2828 and SB 2638, which would fund the full-time use of the Super Sucker a Kāne‘ohe Bay for a year, as well as to pay for another unit that would be more portable.

For more on the marine invasives report, see www.nature.org/marineinvasion.

For more on the Super Sucker, see www.nature.org/wherewework/northamerica/states/hawaii/projectprofiles/art22268.html

One of the issues for the rest of the Pacific is that while Hawai'i may have the financial strength to keep some of its worst invasions at bay, small, fragile economies may not be able to fund such efforts.

“Many in Hawai‘i have seen what alien algae have done to some of our reefs. We need all the tools that can be provided for wise management of our coasts. Our next concern is that reefs in other parts of the Pacific may be similarly impacted but have no scientists there to help.” said University of Hawai'i botany professor Celia Smith.

© 2007 Jan W. TenBruggencate

Snakes! Interception, or search-and-destroy? A million-dollar question.

Brown tree snakes may already be establishing a population in Hawai'i, but could be undetected.

That's because they are very secretive, and because while we are actively watching ports to prevent their arrival, nobody's actively looking for them.

(Photo: A brown tree snake in hand. Courtesy Coordinating Group on Alien Pest Species-Hawai'i.)

A new study suggests it is more cost-effective to add a search-and-destroy function to existing brown tree snake prevention efforts, than to expand the prevention alone.

The study compares current efforts to a drunk who only looks for lost car keys under the streetlight, rather than where he may have dropped them. Current tree snake monitoring is done primarily at places where cargo arrive, like airports. Once a snake slithers out of these areas, nobody's looking.

The paper, “Beyond the lamppost: Optimal prevention and control of the Brown Tree Snake in Hawaii,” was published in the journal Ecological Economics. Its authors are economists Kimberly Burnett of the University of Puget Sound in Tacoma, and Sean D'Evelyn, Brooks Kaiser, Porntawee Nantamanasikarn and James Roumasset, all with the University of Hawai'i at Mānoa. Kaiser is also associated with Gettysburg College in Pennsylvania.

The costs of getting the tree snake issue wrong are significant.

“Actively searching for a potential population of snakes rather than waiting for an accidental discovery may save Hawaii tens to hundreds of millions of dollars in future damages, interdiction expenditures, and control costs,” the paper says.

The losses from uncontrolled snake population in Hawai'i could run to billions of dollars.

Take the case of Guam, a comparatively small island where brown tree snakes became established in the 1950s. Today, the island has densities of 12,000 snakes per square mile. The paper lists thousands of hospital visits for snake bites each year, 90-minute power outages (the snakes span power lines, shorting them out) every other day, and the killing off of 11 of the island's 18 bird species.

Because of the large and growing amount of military and civilian travel between Guam and Hawai'i, it is considered the most likely source of a Hawai'i snake invasion.

Christy Martin, who heads Hawai'i's Coordinating Group on Alien Pest Species, conceded that Hawai'i has teams of snake hunters trained in Guam, but that they only come out after someone has made a confirmed snake sighting.

“I think it would be very prudent to do more searching, particularly around the ports of entry,” Martin said.

Since 1981, eight brown tree snakes have been caught in Hawai'i, mostly at the point of entry—near shipping containers or aircraft. What's the likelihood that some got away uncaught?

“Because interdiction is imperfect, we do not know how many snakes may have arrived without discovery. Given the abundance of local prey base (think birds, geckos, etc.) a small number of escaped snakes have a good chance of establishing,” Burnett said.

Martin said that's a valid concern.

“There have already been a few very credible sightings, with no snakes recovered,” Martin said.

Burnett said her study of the situation concludes “that more funds should be directed towards search, early detection and removal of the brown tree snake in Hawaii.

“While current interdiction efforts are impressive and agencies have done a remarkable job in this area with extremely limited funds, our results show that more attention needs to be given to searching for snakes that may have evaded detection at ports of entry,” Burnett said.

Current interception spending, the paper said, is at $2.6 million, and the scientists assume that even at that, there is a 90 percent chance of a snake arriving within 10 years. Increasing that to $9 million could cut the potential of a snake getting through to one in five.

The economists argue that there's more bang for the buck in expanding the scope of brown tree snake programs than simply beefing up port-of-entry monitoring.

““When the population has not been identified but there is a substantial probability that one exists, early detection is the appropriate strategy,” the paper says.

And there's good reason for doing it, they say.

“Based on Guam's experience, an established population has the potential to do millions of dollars in damage through disruptions to the state's power infrastructure, lost biodiversity, and medical damages due to snakebites.

For more information, see the Hawaii state brown tree snake site: www.state.hi.us/dlnr/Snake.html.

Or the U.S. Department of Agriculture brown tree snake site: www.invasivespeciesinfo.gov/animals/bts.shtml.

© 2007 Jan W. TenBruggencate

New Phoenix marine reserve dwarfs Hawaiian Papahānaumokuākea

Hawai'i's Papahānaumokuākea Marine National Monument now has a new southern sister—a whomping big chunk of coral and sea 1,400 miles directly to the south.
(Image courtesy Phoenix Islands Protected Area.)

While the Phoenix Islands Protected Area, just north of the Equator, is somewhat larger than Papahānaumokuākea, and also covers isolated islands and their associated reefs, it is in many ways quite different.

Each is a reserve that was comparatively simple for the decision-makers to produce, largely because there weren't many vested interests there. Both are made of up largely of uninhabited islands and a lot of remote ocean. The primary economic interest in each has been fishing.

But while the Northwestern Hawaiian Islands are subtropical and distinctly isolated, the Phoenix group is tropical and in a piece of ocean with many nearby groups of islands—the Line Islands to the east and northeast, the Gilberts to the west, and the Cook Islands and Samoa to the south.

Papahānaumokuākea was established by President George Bush June 15, 2006, reputedly at the urging of his wife, Laura. It created a new management overlay of the Northwestern Hawaiian Islands, which were already protected as state and federal wildlife reserves. The 10 islands and reefs of the monument stretch from Nihoa Island beyond Kaua'i to Kure Atoll, more than 1,000 miles to the northwest.

The Phoenix Islands reserve is an expansion of a previously announced refuge, and one might be forgiven for suspecting that its size was selected specifically so the financially challenged Pacific nation of Kiribati—formerly the Gilbert Islands—would be able to claim the title of the world's largest marine reserve.

Phoenix, whose boundaries enclose 164,000 square miles, is bigger than the two previous record-holders—Australia's Great Barrier Reef (135,000 square miles) and Papahānaumokuākea (140,000 square miles). (An earlier layout was smaller, and the reserve website's fact sheet still calls it the third-largest marine protected area in the world, after the Australian and Hawaiian reserves.)

One issue for Phoenix is that Kiribati admits it can't afford to manage a marine reserve of anywhere near that size.

Its lone patrol boat was donated by Australia, and the nation said it hopes Australia and New Zealand will provide aerial overflights for surveillance of its huge reserve.

Kiribati also immediately announced it is accepting donations to establish a $100 million trust fund. It would be used to help cover the cost of running its big refuge—and to reimburse the nation for the money it will actually lose by canceling fishing licenses in the Phoenix area.

Two United States organization, Conservation International and the New England Aquarium, assisted in setting up the protected area and will help manage it.

"Kiribati has taken an inspirational step in increasing the size of [the protected area] well beyond the original eight atolls and globally important seabird, fish and coral reef communities," said New England Aquarium vice president of global programs Greg Stone, in a press release.

The atolls in the reserve include Kanton or Abariringa Island, Enderbury Island, Rawaki or Phoenix Island, Birnie Island, McKean Island, Orona or Hull Island, Manra or Sydney Island and Nikumaroro or Gardner Island.

Several of the island have been inhabited in the past. Only Kanton Island is currently inhabited. Nikumaroro has some fame in part because it is one of the places where the famed missing aviator Amelia Earhart is reputed to have ended up. The protected area will also include both Winslow and Carondelet reefs.

The protected area has been proposed as a World Heritage Site.

The new boundaries contain an amazing natural community. The site claims 120 species of corals and 520 species of fish. Doubtless further scientific surveys will expand those numbers. Massive fleets of birds nest on the atolls. The reserve also contains significant amounts of deep sea habitat.

For more information see www.phoenixislands.org. (It includes information on the search for Earhart.)

© 2007 Jan W. TenBruggencate

Solar magnetic shift, a nearby star, celestial mayhem

Our sun switches magnetic poles every 11 years, to the accompaniment of a great deal of celestial mayhem that astronomers casually call the solar maximum.

(Image: The star tau Bootis is shown with its gas giant in close orbit, in this image by Karen Teramura of the University of Hawai'i Institute for Astronomy.)

Now, another star has been observed doing the same thing. The star is tau Bootis, which passes directly over Hawai'i and lies next to the navigational star Hokule'a or Arcturus, in the constellation Bootes. The star is about 51 light years away.

(By contrast, the North Star, Polaris, is 430 light years away, and the brightest star in our heavens, Sirius, is just 8.7 light years away--a light year being the distance in which something traveling at the speed of light goes in a year.)

The tau Bootis finding was made by University of Hawai'i astronomer Evgenya Shkolnik and an international team that included pair of French astronomers, Jean-Francois Donati, Claire Moutou, Rim Fares and Magali Deleuil, Moira Jardine and Andrew Collier Cameron of the United Kingdom and David Bohlender and Gordon Walker of Canada.

They used the Canada-France-Hawai'i telescope atop Mauna Kea on Hawai'i Island. Their work was published this week in the journal “Monthly Notices of the Royal Astronomical Society.”

The observation is important because it may provide insight into the magnetic shifts of our own sun. Those shifts can cause severe disruptions in communications, in the Earth's own magnetic field and may have other impacts, like the amount of ozone produced in the upper atmosphere and changes in wind patterns.

Scientists believe that an unusual period of low solar activity in the late 1600s and early 1700s may have been responsible for the 17th Century's Little Ice Age.

Shkolnik said tau Bootis may switch magnetic poles much more frequently than our sun does. And that may be caused by the presence of a massive, gas giant planet that whips around the star at amazing speed.

“The increased gravitational energy may have sped up its magnetic cycles,” Shkolnik said.

Tau Bootis is roughly the size of our own sun. But its planet is six times the size of Jupiter, and is in a very tight orbit—just one-twentieth the distance of the Earth to our sun, and an eighth of the distance of Mercury to the sun.

The big planet orbits its sun in just 3.3 days. The massive gravity of the spinning planet has speeded up the star's rotation, so that it spins in 3.3 days, and the same side constantly faces the planet, Shkolnik said. It's the same effect that causes the same side of the moon to constantly face Earth.

The astronomers had just been watching the star for two years when they detected the flipping of the magnetic field from north to south during the past year. They were in the process of mapping the magnetic field of stars. It was the first time such a magnetic change has been seen in another star. They're now watching to see when the next switch takes place.

In our solar system, the magnetic field switches poles on a schedule of every 11 years. While it is in the process of making the shift, the sun releases dramatic amounts of energy and has a peak in sunspot activity. The last such magnetic switch occurred in 2007.

The Earth switches magnetic poles too, but on a much longer time scale. And the Earth's geomagnetic shifts are far more irregular.

An article on the American Geophysical Union website, www.agu.org/sci_soc/hoffman.html, suggests that the planet's magnetic field is weakening and could reverse within 2,000 years.

See more on the tau Bootis reversal on the web at
www.ifa.hawaii.edu/info/press-releases/tauBootis2-08

© 2007 Jan W. TenBruggencate

Hawaiian lava--down to the core?

It's the one of the sad truths about science that someone develops a theory of why a thing occurs, and then someone else rejects the theory based on new information.

It's good for science, but can be tough on the person who put a lot of time and effort into the original theory.

Recently, there's been a controversy over the source of the Hawaiian Islands.

There is general consensus that the molten rock for the Hawaiian volcanoes comes from a hot spot that drives deep in the Earth.

But how deep?

At the Earth's surface is the crust, which is a few miles to a few dozen miles thick, depending on where you're checking. The mantle extends roughly another 2,000 miles down, and the core 2,000 miles more, until you reach the legendary “Center of the Earth.” (It would be hard to reach that center, since it's believed to be in the middle of an immense solid iron sphere.)

At the least, the plume of magma that forms the Hawaiian hot spot goes down into the planet's mantle.

The elements that make up different parts of the planet's interior come in different mixtures, and some folks have suggested that the detection of certain chemical signatures in Hawaiian lava indicate the plume may extend all the way down to the boundary between the mantle and the core.

One of the elements on which these calculations are made is Osmium, a hard, heavy metal often found in conjunction with iron—the main component of the planet's core.

The theory: If there is a fair amount of Osmium in certain proportions in Hawaiian lavas, it must be coming from somewhere near the planet's core, and this suggests that the plume reaches all the way down to the edge of the core.

Tossing a little cold water on that hot topic, an international team of researchers found that it's possible to get that proportion of Osmium isotopes from within the upper mantle—that you don't need to go all the way down to the core to get it.

The scientists, whose work was published in the journal Science, include Ambre Luguet, Graham Pearson, Geoff Nowell, Scott Dreher, Judith Coggon and Stephen Parman of the Northern Centre for Isotopic and Elemental Tracing at the University of Durham in the United Kingdom, and Zdislav Spetsius of the Russian Yakutian Research and Design Institute of Diamond Mining Industry, a part of the ALROSA Joint-Stock Company.

But they concede that the idea of using lavas to try to prove where the hot spot originates is cool.

“The possibility of observing the chemical signature of core-mantle interaction in magmas erupted at the Earth's surface is one of the most exciting prospects in mantle geochemistry,” they write, in their article, “Enriched Pt-Re-Os Isotope Systematics in Plume Lavas Explained by Metasomatic Sulfides.”

But their research shows it is possible for the melting of existing rocks within the Earth's upper mantle to produce the same Osmium chemical signatures found in Hawaiian lavas on Hualalai, the submarine volcano Loihi and Mauna Loa.

It doesn't mean that the Hawaiian plume isn't reaching down to the interface between mantle and core, but just that this particular bit of Osmium-based information isn't sufficient to prove it.

The Osmium signature “observed in plume-related lavas can have an upper-mantle origin,” the writers say. And as a result, it “cannot be taken to be a unique signature of core-mantle interaction.”

As often happens in science, a theory bites the dust, but provides ample ground for new scientific inquiry.

© 2007 Jan W. TenBruggencate

Mystery of the Hawaiian-Emperor Bend, solved?

The Hawaiian Island chain, as most people know it, runs from Hawai'i to Kaua'i and Ni'ihau, but the islands are only the tail of a string of volcanoes that runs all the way to the Aleutians.

What baffles science is why this long string makes a distinct turn midway.

(Image: The Hawaiian-Emperor Chain extends 3,700 miles northwest from the main Hawaiian Islands, and then makes a right turn beyond Midway and Kure, continuing as a line of seamounts that eventually disappears at the northern edge of the Pacific tectonic plate. The blue line follows the course of the chain and the red arrow marks the right turn. Credit: Modified from Google Earth.)

Current geological thinking is that the massive Pacific plate, which forms part of the Earth's crust, is constantly moving, its edges sliding along or under or over other plates, or being shoved away from others by volcanic activity. And a feature called the Hawaiian hot spot punches volcanoes up through the plate.

Like a pencil marking a line of dots on a page, the hot spot under the moving plate leaves a line of volcanoes.

But what could have caused the bend in the line? Some movement of the hot spot? A dramatic change in the direction in which the plate moves? The question was tackled in a recent paper in Science Magazine by geologists David Clague, former director of the Hawaiian Volcano Observatory now working with the Monterey Bay Aquarium Research Institute, and Warren Sharp, of the Berkeley Geochronology Center.

They conclude that the bend in the 129-volcano Hawaiian-Emperor Chain (the name for the combination of the Hawaiian Archipelago south of the bend and the Emperor Seamounts north of it), occurred about 50 million years ago.

They carefully determined the ages at which rocks in the chain were created, using the latest dating techniques available. In many cases, they were using rock samples collected in the 1960s, but whose ages had been established years ago with less effective equipment. With the new technology, many dates changed.

They found that the rocks from Kimmei seamount, in the bend and 2,270 miles from the active Kīlauea volcano on the Big Island, are 47.9 million years old, give or take a couple of hundred thousand years. That's several million years older than earlier estimates.

Samples from seamounts to the north and south show a continual progression in age as the chain goes north. When they compared ages of rocks to distance from Kīlauea, Sharp and Clague found that the Pacific Plate appears to move steadily, although with some speed-ups and slow-downs.

And they concluded that the change in direction, as represented by the Hawaiian-Emperor Bend (HEB), didn't happen suddenly.

“The new ages reveal that the HEB formed over a period of several million years...Initiation of the HEB occurred north of Daikakuji, near Kimmei seamount, where the chain's trend rotates from nearly due south to southeasterly,” they write.

Elsewhere in the paper, they say the bend took as much as 8 million years.

So, what was going on in and around the Pacific 50 million years ago that might have been associated with the change?

There was new volcanic activity along more than 1,300 miles of the plate's western edge, an area called the Izu-Bonin-Mariana arc. Rocks from that area also date to 50 million years ago.

That new activity may have been part of the change in the planet's geology that allowed the plate to slide more westward than southward.

The association of the Hawaiian-Emperor Bend with the Izu-Bonin-Mariana activity has previously been discounted, because earlier dates of the rocks suggested they happened several million years apart. The new dates from the bend suggest the bend was happening at the same time the activity at the western end of the plate took place, and that the one may have helped cause the other.

As followers of murder mysteries know, just a slight change in the timeline can turn someone with an airtight alibi into a prime suspect.

In geology, the same thing can take place.

© 2007 Jan W. TenBruggencate

Whales crowd seamounts off Hawaii at night

Bumps on the ocean floor, the biggest ones called seamounts, are known to attract many kinds of marine life—and new research indicates that this includes whales.

(Image: Cuvier's beaked whale. Credit: National Marine Fisheries Service Southwest Fisheries Science Center.)

Seamounts seem to create changes in current flows, concentrate some kinds of marine life, and attract predators of that marine life to those concentrations.

Fishermen have long known that they could improve their catch of certain species by seeking out places where the ocean floor changes elevation.

Researchers recently furthered our understanding of what goes on at seamounts by putting microphones on seamounts and listening for who showed up.

They used Cross Seamount, a feature about 100 miles south of O'ahu. The seamount rises from ocean two miles deep all around it to a depth of just 1,200 feet. It has a flattish summit about three by four miles across.

A sound recording system, referred to as a high-frequency acoustic recording package, was installed at the seamount for six months in 2005. It recorded for five minutes at a time, turning on every 25 minutes.

The results of the recording study was published this week in the journal Biology Letters, in a paper entitled “Temporal patterns in the acoustic signals of beaked whales at Cross Seamount.” The team conducting the research included Dave Johnston of the University of Hawai'i's Joint Institute for Marine and Atmospheric Research, Mark McDonald of Whale Acoustics, Jeff Polovina and Reka Domokos of NOAA's Pacific Island Fisheries Science Center., and Sean Wiggins and John Hildebrand of the Marine Physical Laboratory at Scripps Institution of Oceanography.

Scientists have long known that things happen around seamounts.

“Seamounts can have profound effects on the local physical and biological environment,” the authors write. “They can structure the velocity and vorticity of ocean currents and alter the vertical structure of water properties. These changes in the physical environment can alter local biological and ecological phenomena.”

But while a lot is known about what can happen, there's not a lot known about what actually does happen around the 4600 or so seamounts in the Pacific Basin alone. Previous studies shows that tuna fitted with electronic data recorders visit seamounts frequently, as do sharks. Above the surface, seabirds congregate there.

The fact that all those predators show up at seamounts suggests they provide a food source.

Not much was known about whales and seamounts, although there have been studies showing baleen whales are found in the seamounts of the Mediterranean and blue whales travel between deep ocean canyons and seamounts.

The Cross Seamount sensors recorded the echolocation signals and feeding signals of beaked whales, possibly Cuvier's beaked whales and Blainville's beaked whales, both of which have been spotted in Hawaiian waters.

Previous research by Robin Baird of Cascadia Research Collective, has found that both species appear to be semi-permanent residents of Hawaiian waters. The smaller Blainville's whale grows to 14 to 15 feet in length and can weight a ton. The Cuvier's whale reaches 18 to 19 feet and can weight three tons.

The Cross Seamount studies indicated the whales were primarily working the summit of the seamount at night, and that their sounds included both echolocation and what are called “feeding buzzes.”

The animals were present during the entire April to October period during which the microphones were in place.

The researchers' best guess is that the whales are attracted to the seamount for its tendency to have higher quantities of food resources than the surrounding ocean.

These are fish, crustaceans and other forms of life that scientists call nekton.

Nekton are ocean creatures capable of movement, like shrimps, fish and whales themselves. The term distinguishes them from plankton, which are smaller creatures that mostly move with the water and lack the ability to travel independent of currents.

“Concentrations of micronekton (those roughly 1 inch to four inches in length) were aggregated over the seamount in near-surface waters at night, and dense concentrations of nekton were detected across the surface of the summit,” the paper says.

The seamount may also be a convenient feeding spot in part because predators can “trap” prey against the surface of the seamount summit, making feeding easier, they say.

© 2007 Jan W. TenBruggencate

Wave power Hawai'i, new energy technology off Maui

An Australian company will build off the coast of Maui a wave power plant capable of producing 2.7 megawatts of electricity from the rising and falling of the ocean.

(Images: (top to bottom) What the Oceanlinx platform will look like on the surface, how it works, how the power gets to shore. Graphics courtesy Oceanlinx and Hawaiian Electric.)

Oceanlinx has a technology that allows the waves to force a column of air through a turbine. A rising wave shoves the air through the turbine one way. A falling wave sucks it through the turbine the other. It's designed so the turbine keeps turning in the same direction.

(For more information see www.oceanlinx.com.)

The Oceanlinx system is just one of a broad range of wave power systems. Some are fixed to the coastline, sucking energy from the crashing of waves on the land. Others use big submerged buoys that bob up and down in the water column. Others have floaters on the surface. And there are lots more.

An existing system off the Marine air station at Kāne'ohe, operated by Ocean Power Technologies, uses its PowerBuoy system, in which mostly submerged buoys create electricity as they are rocked up and down by the waves. (For more information see www.oceanpowertechnologies.com.)

“Ocean energy today is where wind was 15 to 20 years ago—with many competing technologies,” said Michael May, president of Hawaiian Electric.

The $20 million Oceanlinx system is to be built more than half a mile from shore at Pa'uwela point in Maui's Ha'ikū district. The company is performing its environmental studies, and hopes to have three wave platforms installed and working by the end of 2009.

Maui Electric has agreed to buy the power, although a formal purchase power agreement has not yet been completed. The cost of the system will be borne by Oceanlinx and investors, and a Hawaiian Electric unregulated subsidiary, Renewable Hawaii Inc., has signed a memorandum of understanding to possibly invest in it.

Oceanlinx says that among the benefits of its wave system is that it can be used in many different depths of water, has few moving parts and can be readily scaled up by adding units.

A seafloor power cable carries the energy from the moored units to the island.

Hawaiian Electric's May credited state Rep. Cynthia Thielen with being a persistent voice in support of ocean energy. Oceanlinx chairman David Weaver said he hopes the technology will be expanded to other parts of Hawai'i.

“The Oceanlinx technology is an ideal fit for Maui, with its excellent wave climate, and we hope to be able to continue working with Hawai'i on wave energy projects in the future,” Weaver said in a press release.

© 2007 Jan W. TenBruggencate

Keeping limu: strategies and common sense

In ancient Hawai'i, seaweeds were a primary spice—a way of providing different flavors to foods. (Image: The invasive but edible seaweed Gracilaria salicornia. Source: Hawaii Coral Reef Initiative Research Program.)

Most folks know about the role of various limu in fish dishes like poke. Seaweeds also could be used as a condiment, eaten alongside other foods rather than mixed with them.

The early Hawaiians would often have eaten their limu fresh or salted, said University of Hawai'i botany professor emeritus Isabella Abbot, but the realities of today's world are that folks seek something that seems fresh even though it may be several days old—so it will require some storage technology. And that's the problem challenged by Robert E. Paull and Nancy Jung Chen, of the University of Hawai'i's College of Tropical Agriculture and Human Resources.

They conducted extensive studies with one of the most popular seaweeds, Gracilaria.

Gracilaria comes in several forms in Hawai'i, several of them native, but one, Gracilaria salicornia, an imported, invasive one. The most commercially desireable form is known in Hawaiian as limu manauea and in Japanese as ogo. It is Gracilaria coronopifolia.

In the journal Postharvest Biology and Technology, Paull and Chen outlined their results.

They found that the seaweeds change in many different ways after collection. Among the changes are color, production of ethylene, leakage of fluids, and changes in protein content.

They studied using different temperatures, keeping the limu in light and dark, heat treatments and more.

They found that when kept just above freezing, the samples went limp and changed color after just one night. At 18 degrees Fahrenheit above freezing, the color changes occurred after a couple of days. A little warmer than that made little difference.

Their conclusion was that the best way to store it without special treatment was to keep it in darkness at about 61 degrees Fahrenheit, which is about 29 degrees above freezing. This didn't keep the limu usable beyond about four days, but the quality was better during the storage period.

The authors said they found that a five-minute hot dip in seawater at about 108 degrees Fahrenheit, followed by storage in 60-degree water would extend the useful life of some samples.

They said one of the best ways to keep limu for an extended period is one that seems like common sense: keep it submerged in seawater in darkness. This can extend its useful life from four days to four weeks.

“Seaweed submerged in seawater in the dark had an extended postharvest life” of about a month, the scientists said in their abstract.

That system works in part because it takes advantage of a natural characteristic of many seaweeds. One of the ways they reproduce is for pieces to break off, drift in the ocean for a while, and settle elsewhere. In order for that to work, they need to remain alive after breaking off.

They are hard-wired to survive for a long time while drifting in salt water.

If you're not in a position to haul around a bucket of water for your seaweeds, the best thing is to do preserve it in salt.

“That's what the Hawaiians did,” Abbott said.

© 2007 Jan W. TenBruggencate