Saturday, July 19, 2014

Hawaiian koa seed made 10,300-mile voyage, 1.4 million years ago, to Réunion Island


If you as a Hawaiian resident wander into a forest on the remote island of Réunion Island, you might feel at home.

That’s because the koa trees are nearly the same genetically as the Hawaiian koa—and must have originated in the Hawaiian Islands.

That’s a remarkable thing, because it happened before humans got involved—more than a million years before. 

And it’s a significant distance—10,300 miles. Réunion is half a world and two oceans away, tucked in the west Indian Ocean between Madagascar and Mauritius.

Scientists in a paper in the journal New Phytologist report that the Acacia koa of Hawai`i and the Acacia heterophylla of Réunion are very closely related. The Hawaiian koa are older, and are the source of the Réunion trees. The authors called it “one of the most exceptional examples of such dispersal.”

Indeed, some Hawaiian and Réunion trees are even more closely related to each other than some Hawaiian koas are related to each other. Furthermore, all the Hawaiian and Réunion acacias are more closely related than any of them is to their presumed ancestral species in Australia.

Their best guess is that a koa seed from Hawaiian forests arrived on a bird’s body or in a bird’s gut at Réunion. It is unlikely to have drifted because a koa seed won’t remain viable after soaking in in salt water. 

The researchers used molecular techniques to determine that the genetic differences between the Hawaiian and Réunion acacia trees all occurred within the past 1.4 million years. That suggests that the koa seed traveled to Reunion about that long ago. 

The journal Nature reviewed the story in one of its June issues.

Citation: Relatedness defies biogeography: the tale of two island endemics (Acacia heterophylla and A. koa, Authors Johannes J. Le Roux, Dominique Strasberg, Mathieu Rouget, Clifford W. Morden, Megan Koordom, David M. Richardson. New Phytologist. First published: 18 June 2014. DOI: 10.1111/nph.12900

© Jan TenBruggencate 2014

Friday, July 4, 2014

Massive Kaua`i landslide--neither unique nor even rare

Volcanic eruptions are impressive, but massive erosion events are right up there on the breathtaking scale.


When a chunk of the side of Wai`ale`ale/Kawaikini sloughed off this week, it sent a catastrophic debris flow down a tributary of the Wailua River. 

A flash flood of water, rocks, dirt and logs scoured the river bed and its banks, destroying all vegetation and any wildlife in the area.

(Image: A screenshot of the Wailua streambed after the debris flow. The image is taken from a Kaua`i Fire Department video taken from a helicopter.)

The event turned the Wailua River a yellowish milk chocolate color, as the mud mixed with the flow from myriad streams feeding Wailua.

This isn’t new. It happens fairly frequently, though mostly in smaller events. You frequently see vertical brown streaks against the green steep cliffs of the older islands, indicating similar events.

The Wailua event appears considerably smaller than a massive slide at the back of Olokele Canyon around 1980, when an immense chunk of material plunged down a towering basalt wall, hit the bottom, and surged downstream. An image of that event is visible on the first page of this site from the Association of American State Geologists

In that case, the Makaweli River flowed milk chocolate in color for months. A most interesting view was where Makaweli and Waimea joined, and you could see swirling and mixing of the the tea-tinted Waimea water mix with the café-au-lait of the Makaweli River.

This landslide process is sometimes called mass wasting, the downward movement of soil and rock under the influence of gravity, often lubricated by water. It is an entirely natural process that has been going on for millennia.

Indeed, just as periodic volcanic eruptions are responsible for building the Islands, periodic landslide events are significant features in unbuilding them.

“Volcanoes are particularly prone to massive rock slope failure and can experience very large scale sector collapse or much smaller partial collapse,” says a 2006 paper, “Landslides from massive rock sloped failure and associated phenomena.” 

What is often far more dangerous—sometimes catastrophic—is the water, mud, rock and debris flow and lunges downstream as part of the collapse. It can rip out everything in its path, scouring the valley floor to bare mud and rock.

Such events also have significant impacts on nearshore waters, dumping tons of sediment into the coastal ocean, often temporarily blanketing reefs.

© Jan TenBruggencate 2014

Wednesday, July 2, 2014

Schatz: Congressional climate deniers can't hide any more

Many of Congress’s Republicans have shifted their public stances on climate change, Sen. Brian Schatz said at a debate Tuesday night in Līhu`e.


(Image: Satellite-based map of sea level change from 1993 to 2010. Credit:  CLS/Cnes/Legos: http://www.aviso.oceanobs.com/en/news/ocean-indicators/mean-sea-level/)

Not that they’re now climate hawks, but they have gone from active climate denial to silence on the issue. Some are using the newly popular line, “I’m not a scientist, so…”

It’s a step in the right direction, Schatz said.

And why is it happening?

Well, the chickens have come home to the proverbial roost. Politicians can’t deny the impacts occurring in their own districts—and have trouble answering constituents who are feeling the heat.

Take Virginia. Storm surge is already a problem there. There’s already some flooding. Add rising sea level to low land elevations, add storm surge to storm waves, and add a high tide, and you’ve got a lot of formerly occupied land underwater. 

The National Hurricane Center has an excellent fact sheet onstorm surge here. That page doesn’t once mention sea level rise, but you can be sure the folks on the coastal lowlands are aware of it.

This site does mention sea level rise, and aggressively.  It is a Climate Central report, which includes these tidbits. 

1. Odds of a 100-year flood or worse by 2030, with sea level rise from global warming: 29%
2. Odds without global warming: 9%
3. Bottom line: global warming multiplies the odds by 3X
4. Historic local sea level rise rate: 1.7 inches/decade
5. Projected new sea level rise by 2050: 16 inches.

If you’re interested in this stuff, see Climate Central’sSurgingSeas report

Florida is pretty famous for its conservative politics, but the climate chickens are roosting there, too.

The Union of Concerned Scientists is certainly not a neutral source, but they’ve been paying attention. On reviewing the National Climate Report, UCS senior analyst Erika Spanger-Siegfried wrote: 

“What lies ahead for Southeast Florida, for example, is stark, shocking even, and it will take a sustained national response to begin to see Florida through to a future of sea level rise resilience.”


In Miami, where the land is pretty low, they’ve established the Miami-Dade Sea Level Task Force. They list some of the problems: Saltwater intrusion into the aquifer; Drainage and flood control compromised; Impacts to coral reefs; Impacts to public and private infrastructure; Beach erosion; Impacts to Everglades.

The Miami report notes that with even a modest one-foot sea level rise, you lose a lot of southern Miami.

In Hawai`i, you also lose low areas. A good site to review Hawaiian impacts is the University of Hawai`i School of Ocean and Earth Scienceand Technology sea level page.

© Jan TenBruggencate 2014
 

Tuesday, July 1, 2014

Oceanic plastic mystery: where's it all going?



It certainly isn’t news that the oceans are full of plastics; The news is perhaps how little we know about it.

(Image: plastics collected on the Malaspina Expedition. Credit: CSIC.)

“Our awareness of the significance of plastic pollution in the ocean is relatively recent, and basic questions remain unresolved. Indeed, the quantity of plastic floating in the ocean and its final destination are still unknown,” write scientists who participated in a recent Spanish science expedition.

They found plastics throughout the oceans, and a scientific paper on the results concluded that they’re getting into the marine food chain. 

The researchers emphasized how little is known about the impacts of the plastics—and even where some of the plastic goes. A lot of it is unaccounted for: “Resolving the fate of the missing plastic debris is of fundamental importance to determine the nature and significance of the impacts of plastic pollution in the ocean.”

The Malaspina Expedition of 2010, sent out by the Spanish National Research Council (CSIC), was named after an early Spanish scientific circumnavigation from 1789 to 1794, headed by Alessandro Malaspina and José de Bustamante y Guerra.

They collected plastics in all the world’s oceans. And they found plastic in both the North Pacific and Atlantic, where it was known to occur in large amounts, but they also found large amounts in the southern oceans: the South Pacific, South Atlantic and the Indian Ocean.

"Ocean currents carry plastic objects which split into smaller and smaller fragments due to solar radiation. Those little pieces of plastic, known as microplastics, can last hundreds of years and were detected in 88% of the ocean surface sampled during the Malaspina Expedition 2010,” said Andrés Cózar, of the University of Cadiz.

"These microplastics have an influence on the behavior and the food chain of marine organisms.

“On one hand, the tiny plastic fragments often accumulate contaminants that, if swallowed, can be passed to organisms during digestion; without forgetting the gastrointestinal obstructions, which are another of the most common problems with this type of waste.

“On the other hand, the abundance of floating plastic fragments allows many small organisms to sail on them and colonize places they could not access to previously. But probably, most of the impacts taking place due to plastic pollution in the oceans are not yet known,” Cózar said.

The amounts of plastic estimated to be in the oceans is stunning. The Malaspina 2010 paper middle estimates are that there are 4.8 thousand tons in the North Pacific, 2.7 in the North Atlantic, 2.2 in the Indian Ocean, 2.6 in the South Atlantic and 2.1 in the South Pacific.

Some of the plastic is at the surface but even if it is buoyant, some is carried down through the water column via the added weight of biofouling, or being contained in the feces of marine life forms that eat the plastic.

And there may be other methods for sinking the plastics.

“Our observations also show that large loads of plastic fragments with sizes from microns to some millimeters are unaccounted for in the surface loads. The pathway and ultimate fate of the missing plastic are as yet unknown. We cannot rule out either of the proposed sink processes or the operation of sink processes yet to be identified,” the paper says.

It could be that the plastic is being broken down into such small pieces that they’re not getting caught in the sampling nets of marine scientists: “Missing micro- plastic may derive from  nano-fragmentation processes, rendering the very small pieces undetectable to convectional sampling nets, and/or may be transferred to the ocean interior.”

The University of Hawai`i’s Dave Karl edited the paper, Plastic debris in the open ocean, which was published in the Proceedings of the National Academy of Sciences. The authors are
Andrés Cózar,  Fidel Echevarría, Ignacio González-Gordillo, Xabier Irigoien, Bárbara Úbeda, Santiago Hernández-León, Álvaro T. Palma, Sandra Navarro, Juan García-de-Lomas, Andrea Ruiz, María L. Fernández-de-Puelles, and Carlos M. Duarte.

If you’re conversant in Spanish, the Malaspina 2010 website is here. 


© Jan TenBruggencate 2014

Tuesday, June 24, 2014

Strange days in the Indonesian straits



Among the very strange and spooky impacts of climate change: changes in the behavior of massive oceanic current patterns.


(Image: The Indonesian Straits, which provide a conduit between the Pacific and Indian Oceans. They are described as the only place on the planet where oceans interact the way they do here, and the only place in the tropics where oceans are able to interact. Source: University of Hawai`i.)

New research suggests that climate change will alter the flow between the Pacific and Indian Oceans through the Indonesian straits. That’s on top of changes in the flow that are driven  by the alternating El Nino-La Nina climate cycles.


What this will mean longer-term is not yet entirely clear, but there are suggestions that the changing flow could change the climate in both oceans. A better understanding of the changes could result in better forecasts of climate activity, according to a new paper.

The flow of ocean water through the Indonesian strait appears to have become both shallower and stronger, according to a study published June 22 in the journal Nature Geoscience. The paper is entitled “The Indonesian seas and their role in the coupled ocean-climate system.”

UH Mānoa physical oceanographer James Potemra is a co-author. The lead author is Janet Sprintall of Scripps Institution of Oceanography at UC San Diego, and other co-authors are Arnold Gordon of Lamont-Doherty Earth Observatory at Columbia Unversity, Ariane Koch-Larrouy of LEGOS in France, Tong Lee of the Jet Propulsion Laboratory in Pasadena, Calif., Kandaga Pujiana of Oregon State University and Insitut Teknologi Bandung in Indonesia, and Susan Wijffels of the Commonwealth Scientific and Research Organization in Australia.

Eric Lindstrom, co-chair of NASA’s  Global Ocean Observing System Steering Committee, which funded part of the study, talked about its importance:

“This is a seminal paper on a key oceanographic feature that may have great utility in climate research in this century. The connection of the Pacific and Indian oceans through the Indonesian Seas is modulated by a complex circulation, climate variations, and sensitive ocean-atmosphere feedbacks.  It’s a great place for us to sustain ocean observations to monitor potential changes in the ocean’s general circulation under a changing climate.”

Lead author Sprintall said: “Now that we have a better understanding of how the Indonesian Throughflow responds to El Niño and La Niña variability, we can begin to understand how this current behaves in response to changes in the trade wind system that are brought on through anthropogenic climate change.  Changes in the amount of warm water that is carried by the throughflow will have a subsequent impact on the sea surface temperature and so shift the patterns of rainfall in the whole Asian region.”

Here’s some complex language from the paper on what’s going on with the currents: “A synthesis of observational data and model simulations indicates that the temperature, salinity and velocity depth profiles of the Indonesian throughflow are determined by intense vertical mixing within the Indonesian seas. This mixing results in the net upwelling of thermocline water in the Indonesian seas, which in turn lowers sea surface temperatures in this region by about 0.5 °C, with implications for precipitation and air–sea heat flux.”

A University of Hawaii press release discusses the paper. 


More information on this kind of stuff at the website of the International PacificResearch Center at University of Hawai`i at Mānoa. 
 
© Jan TenBruggencate 2014