Thursday, June 15, 2017

The bend in the Hawaiian-Emperor Chain--we know it happened, but why?

You might wonder whether there’s any value in learning about things that happened millions of years ago.

And maybe there isn’t any value…or maybe there is, at least in the sense of, if it happened then, maybe it can happen now.

THE BEND IN THE CHAIN

(Image: The line of volcanoes forming the Hawaiian-Emperor Chain. note the 60-degree bend halfway--which has been dated at 47 milliion years ago. Credit: NOAA.)

So there’s the question of the distinct but odd bend in the Hawaiian-Emperor chain—that series of volcanic mountains that runs from Lo`ihi and Hawai`i to the southeast, to Detroit Seamount to the northwest—way up by Kamchatka.

The rocks of the chain have been dated, and the oldest ones--up near Russia--are 80 million years old. At the bend, 47 million. Kaua`i is at about 5 million. And the Big Island is downright new.

The Emperor half of the chain is a series of volcanoes whose peaks are underwater. The Hawaiian half has peaks mainly above the surface—from Kure Atoll, through Midway, Pearl and Hermes, Lisianski, Laysan, Maro, Gardner, French Frigate, Mokumanamana, Nihoa--and then Kaua`i, Ni`ihau and the rest.

If you follow the line of volcanoes from the Hawai`i end to just beyond Kure they take a sharp 60-degree bend to the right.

What’s that about?

A new paper suggests that the bend is pretty clearly the result of two things, but that one of them—tectonic plate drift—is the main one.:

One, the whole floor of the Pacific Ocean, which had been drifting northward, suddenly changed direction 47 million years ago and began drifting westward.

Two, the volcanic hot spot—which had been piercing the ocean floor to create volcanoes—was drifting itself, and was drifting generally southward.

The paper in Nature, written by a team led by Trond Torsvik, of the University of Oslo, says it’s pretty clear what dynamics are at work.

“While southward hotspot drift has resulted in more northerly positions of the Emperor Seamounts as they are observed today, formation of the HEB (Hawaiian-Emperor Bend) cannot be explained without invoking a prominent change in the direction of Pacific plate motion around 47” million years ago, the paper says.

It’s pretty clear you need both factors to explain the bend, Torsvik’s team said.

“After more than two decades debating hotspot drift versus Pacific plate motion change to explain the HEB, we must realize that neither of these two end-member options is able to accurately reproduce the geometry and age progression of the Hawaiian-Emperor Chain.”

THE MORE INTERESTING ISSUE

The paper gets a little testy about the continuing debate, and says there’s a better place to focus our attention.

“We can stop going in circles and move forward, focusing new research on understanding the processes that resulted in the change in the direction of the Pacific plate motion at around 47 Ma, which we conclude is a prerequisite for explaining the formation of the HEB,” the paper says.

At this point, we know what happened. What we still don’t know is why.

Why did the largest geological feature on the planet—the Pacific Ocean floor—suddenly change directions. What exactly happened 47 million years ago that made the Pacific Plate turn its steering wheel right?

There was lots of stuff going on back then.

Australia was in the process of ripping itself away from the Mainland, a process that started about 45 million years ago.

The massive meteor impact that formed the Chicxulub Crater was 18 million years earlier.

On the land, there were tiny early mammals that seem lemur-like. A fossil find from the period of the HEB was named Darwinius masillae--a cute little mammal with a tail.

On both land and sea there were whales that could both swim and walk on land.

In 2012, a team of researchers collected deep sediment samples from the Pacific Ocean that were able to track the climate back 53 million years.

It says that the planet was coming off a period of extreme warming at the beginning of the sample, and cooled right through the 47 million-years-ago period when the Pacific Plate changed directions.
Interesting, but what could that have done to planetary geology?

Or what else was happening on our planet?

Which takes us back to the big question: Why did the Pacific Plate take its right turn?

And how does that information help us live our lives today?

BACK TO THE LITTLE 47 MILLION YEAR-OLD MAMMAL

This is a diversion, but I was fascinated by that little warm-blooded critter that populated our world at the time of the Hawaiian-Emperor Bend. It was named Darwinius masillae. 

The creature had fingers and nails, not claws. It had opposable big toes, like humans and monkeys. It was about two feet long, like a lemur or a big squirrel. It lived near what is now Germany. 

Seen here is an image of the fossil, from the American Museum of Natural History.



© Jan TenBruggencate 2017

Saturday, June 10, 2017

How to tell if an extinct Hawaiian bird was flightless: now there's a tool.

A lot of the early birds of Hawaii were believed flightless due to big bodies and small wings, but until now there hasn’t been a real good way to measure.

(Image:  The fossil bones of Ptaiochen pau otherwise known as a small-billed moa nalo—a big duck that looks more like a goose. Bones like these could be used to determine whether the bird could fly. Credit: Junya Watanabe.)

Today, using a new system developed by Japanese researcher Junya Watanabe of Kyoto University, we can be far more confident that the moa nalo and other big extinct ducks and geese had given up flight in these islands that lacked a lot of the predators of continents.

Helen James, an expert in Hawaiian fossil birds, said Watanabe’s work, published in the journal Auk: Orinthological Advances, said Watanabe’s work is a big step forward.

"Dr. Watanabe has developed a valuable statistical tool for evaluating whether a bird was capable of powered flight or not, based on measurements of the lengths of only four different long bones. His method at present applies to waterfowl, but it could be extended to other bird groups like the rails," said James, Curator of Birds at the Smithsonian Institution's National Museum of Natural History.

Many times, fossil birds must be described from only a few bones, and Watanabe’s method provides a new tool for learning more about them.

"Other researchers will appreciate that he offers a way to assess limb proportions even in fossil species where the bones of individual birds have become disassociated from each other. 

"Disassociation of skeletons in fossil sites has been a persistent barrier to these types of sophisticated statistical analyses, and Dr. Watanabe has taken an important step towards overcoming that problem," James said.

Watanabe studied hundreds of skeletons of relatives of ducks, including both flightless and known not-flighted species. And developed a methodical assessment using such data as the size of leg bones, size of wing bones, body size and an assessment of pectoral muscle development from the keel or breastbone.

In part, Watanabe said, the work was challenging because ducks are so different.

"What is interesting in fossil flightless anatids is their great diversity; they inhabited remote islands and continental margins, some of them were specialized for underwater diving and others for grazing, and some were rather gigantic while others were diminutive."

His paper, "Quantitative discrimination of flightlessness in fossil Anatidae from skeletal proportions" is here

Eurekalert's report on the paper, from which the quotations in this report were taken, is here. 

© Jan TenBruggencate 2017

Monday, May 22, 2017

Waikiki awash, Svalbard melting--Oh, is climate change still a hoax?

King tides are threatening to wash into Waikiki hotel lobbies this week—a combination of unusual sea heights around Hawaii corresponding with super spring tides, plus climate change.

And in the Arctic, just to the left of Superman’s Fortress of Solitude, the global seed bank at Svalbard is melting,

So, how’s it working for you, that “climate change is a hoax” business?

The Honolulu Star-Advertiser picked up the king tide story here

For planning purposes, the king tides are scheduled for May 24-28, June 22-26, and July 20-25, with very high tides a day or two before and after those peaks.

Meanwhile, in the distant north, Svalbard is a global seed bank established high in the Arctic at 78 degrees north latitude, where it stays frozen all the time. Or did. 

There are tens of millions of crop seeds stored there, to protect the planet in case of catastrophe. But now, instead of saving the planet, Svalbard itself is at risk.

Umthinkably, Svalbard is melting. The seeds are still safe—they’re deep enough that it’s still frozen where they are, but the permafrost near the surface is melting, and officials are now planning to waterproof that part of the great vault.

Here’s what the blog Live Science had to say about it. 

Climate change denial remains well entrenched in Washington, including among the deniers the President and the head of the Environmental Protection Agency. As for Congress, the blog ThinkProgress put it this way:

“Of the 180 climate science deniers in the 115th Congress, 142 are in the House and 38 are in the Senate. That’s more than 59 percent of the Republican House caucus and 73 percent of Republicans in the Senate that deny the scientific consensus that climate change is happening, human activity is the main cause, and it is a serious threat. No Democrats publicly deny the science behind climate change.”

It’s now understood to be far too late to stop the warming, the acidification of our oceans, the sea level rise and all the rest for our lifetimes. So, we’re guaranteeing our grandkids a wild ride.


© Jan TenBruggencate 2017

Thursday, May 11, 2017

The Big Lie: You're safe from rat lungworm on O`ahu and Kaua`i. You're not. People getting sick everywhere.

You might read media reports and believe rat lungworm disease or angiostrongyliasis is restricted to one, two or no more than three Hawaiian islands—and that you’re safe for now eating fresh veggies on other islands.

That’s wrong—potentially dead wrong.

This is a pretty rare, but a very spooky disease, and if you read or listen to most media reports, you'd feel safe in thinking the danger is at the eastern end of the Hawaiian chain. That's false.

Media reports notwithstanding, rat lungworm disease has impacted humans on all six of the major islands, and the disease vector has been found on five of the Hawaiian islands.

The painful and sometimes fatal disease, for which there is no treatment, has been identified on Hawai`i and Maui, but also on O`ahu, Kaua`i and Molokai—thus far no confirmed reports have come from Lana`i and Ni`ihau.

The very first reported Hawai`i case of rat lungworm disease, caused by the organism known to science as Angiostrongylus cantonensis, was in 1960, not on Maui or the Big Island, but in a man in Honolulu on O`ahu.
  
University of Hawai`i student Jaynee Kim in 2013 conducted a statewide study for a master’s thesis and found the disease in slugs and snails across Hawai`i. 

“Numerous gastropod species (16 of 37 screened) tested positive for A. cantonensis, with a large range of parasite load among and within species. The parasite occurs on five of the six largest islands (not Lanai),” Kim wrote.

And people have gotten sick all across the state: “There have been cases on all six of the largest Hawaiian Islands (Kauai, Oahu, Maui, Molokai, Lanai and Hawaii), with a noticeable increase in the number of cases since around 2004,” Kim wrote.

How is it that someone on Lanai got sick even though the nematode has not been found there? Said Kim “It is possible that produce regularly shipped from Maui was contaminated and the victim was infected through consumption of such produce, or that the victim became infected while on another island.”

Rat lungworm disease is caused by a parasitic nematode whose life cycle goes through rats and slugs, and can be caught by humans who eat the slugs or nematode larvae in slime trails on fruits and vegetables. The worms migrate to the human brain, where they mature, die and can cause a massive reaction, described by medicine as eosinophilic meningitis.

Live snails can carry large numbers of rat lungworms, but even the snail slime trails can carry small amounts. Here is a UH-Hilo report on the infectiousness of snail slime. 

“The larvae die when they reach the central nervous system, primarily in the brain, which can lead to eosinophilic meningitis. In humans, the resulting symptoms include nausea and headache, and in more severe cases, neurologic dysfunction, coma, and death,” wrote the authors of this paper

The slugs can be tiny, and can be easy to miss on improperly washed food. Giant African snails, which are common pests in yards and gardens throughout the Islands, can also be carriers. So can lots of other garden slugs and snails. The species most commonly linked to the disease is the semislug, Parmarion martensi.

The state Department of Health today (Thursday May 11, 2017) reported a new case on Hawai`i Island, bringing to 15 the number of recent cases. But while the most recent cases of people getting sick have all been on Maui and Hawai`i Island, there have been earlier cases of human illness from each of the other islands as well, starting with the 1960 O`ahu case. Only Ni`ihau has been spared.

Rat lungworm cases have been an annual occurrence in the Islands for more than the last decade. (The Department of Health reported 2 cases in 2007, 8 in 2008, 6 in 2009, 9 in 2010, 7 in 2011 and so on, according to this report.) 

This doesn't mean you should stop eating fresh produce, but just like your mom taught you, wherever your fresh fruits and vegetables are from, they need to be washed carefully to remove contaminants.

Many people who are infected with rat lungworm can be symptom-free, but other infections can lead to weeks to months of severe pain, possible paralysis and even death.

This 2014 paper confirms that the disease is found in many different kinds of snails and slugs throughout the Hawaiian Islands.

“We have now shown that nearly a third of the non-native snail species established in the Hawaiian Islands are carriers … along with two native species (Philonesia sp., Tornatellides sp.),” the paper says.

All three of the rat species known to Hawai`i are carriers: the Norwegian, black and Polynesian rats.

Here is the Hawai`i State Department of Health fact sheet on the disease. 



© Jan TenBruggencate 2017

Wednesday, May 10, 2017

Hawaii's reefs are eroding, and eroding faster than elsewhere

The threat to Hawai`i’s reefs and coastlines from a changing climate keep growing.

The latest data point is actual evidence that reefs are eroding off Hawaiian shores, and eroding faster than other reefs studied. 

That’s on top of coral bleaching from superwarm water, a huricane season that now starts in May instead of mid-summer, and retreating shorelines due to rising sea levels.

A team of researchers went to five coastal locations in Hawai`i, Florida and the Caribbean, and found that the seafloor was eroding in all five locations. The Hawaiian location was off Maui.

They found the reefs eroding so severely that the water depth increased—potentially meaning that coastal protection that reefs provide was at risk.

“Regional-scale mean elevation and volume losses were observed at all five study sites and in 77% of the 60 individual habitats that we examined across all study sites,” the authors said. The researchers included Kimberly K. Yates, David G. Zawada and Nathan A. Smiley from the U.S. Geological Survey and and Ginger Tiling-Range from Cherokee Nation Technologies.

As reefs eroded, the sea floor got effectively lower—sometimes by as much as 2 to 3 feet in Hawai`i.over a few decades. The reefs off Maui were losing more than 20 millimeters per year, compared to two to five millimeters per year in Florida and the Caribbean. For Maui, that's nearly an inch a year.

“Current water depths have increased to levels not predicted until near the year 2100, placing these ecosystems and nearby communities at elevated and accelerating risk to coastal hazards,” they wrote.

“These greater losses may be caused by higher sediment export rates due to a combination of higher wave energy, physical erosion, and a narrow shallow shelf surrounding the island allowing sediment to be more easily transported offshore into deep water, as has been observed in other high-energy reef environments,” the paper says.

The team studied bottoms of many kinds from 7 to 50 feet in depth, including coral and hard bottom, sandy bottom, patch reefs, rubble and mud, coral pavement and more.

The only places off Maui that showed increases were areas with mud and rubble bottoms—perhaps due to sediment runoff from the island. Or, as the scientists phrased it: “Elevation and volume gains occurred in mud and rubble habitats and may be associated with terrigenous sediment transport from the island.”

Exactly why is this seafloor erosion happening? I’ll use the paper’s language, and then try to translate it.

“Our results include elevation and volume changes caused by chronic erosion and accretion processes that occur slowly over time frames of months to decades such as changes in carbonate production rates, bioerosion, chemical erosion from carbonate dissolution, degradation of large framework building coral colonies, and physical movement of reef sediments due to persistent oceanographic conditions such as waves and currents.”

Essentially, the authors say there are lots of factors at play. Among them are reductions in coral and coralline algae growth, damage by biological factors like coral-eating creatures, ocean acidification that dissolves corals and shells, and other things like changing weather and current patterns.

But while those are all possibilities, the authors say the focus of their paper was actually measuring the changes in ocean depth, and not so much figuring out why it happens: “Detailed analysis of the processes causing elevation change in these systems is beyond the scope of this paper and should be undertaken in future studies.”

But they make a key observation about Hawaiian reefs. On Maui, material is being transported off the reefs, and the reefs right now are not able to replace it. That’s bad news for the future.

“Our results indicate net export of sediments from the coastal seafloor of Maui and support… previous observations that reef and terrigenous sediment is transported offshore and no new sediment from the reef is contributed to coastal beaches.”

Hawai`i beaches on balance are eroding, and this study seems to indicate that the factors causing that erosion are continuing.

This is the news release from the European Geosciences Union that accompanied the publication of the study.

Here is a Miami Herald piece on the study. 

And here’s a Washington Post piece.


© Jan TenBruggencate 2017