http://www.livescience.com/39787-super-eruption-seeded-sky-diatoms.html

Super-Eruption Launched Algae Army Into the Sky

Slimy brown algae not only survived a wild ride into the stratosphere via a volcanic ash cloud, they landed on distant islands looking flawless, a new study finds.

"There's a crazy contrast between these delicate, glass-shelled organisms and one of the most powerful eruptions in Earth's history," said lead study author Alexa Van Eaton, a postdoctoral scholar at both the Cascades Volcano Observatory in Washington and Arizona State University.

The diatoms were launched by the Taupo super-eruption on New Zealand's North Island 25,000 years ago. More than 600 million cubic meters (20 billion cubic feet) of diatoms from a lake flew into the air, Van Eaton reported Sept. 6 in the journal Geology. Lumped together, the microscopic cells speckled throughout Taupo's ash layers would make a pile as big as Hawaii's famed Diamond Head volcanic cone.

Some diatoms drifted as far as the Chatham Islands, 525 miles (850 kilometers) east of New Zealand. "They just hitched a ride," Van Eaton said. The pristine shells in the Chatham Island ash suggest diatoms could infect new niches by coasting on atmospheric currents.

"If they made it there alive, this is one way microorganisms can travel and meet each other," Van Eaton told LiveScience's OurAmazingPlanet. "We know that ash from smaller events easily travels around the world." [5 Colossal Cones: Biggest Volcanoes on Earth]

World domination, cell by cell

Diatoms, a golden brown algae, rule Earth's waterways. From Antarctica's glacial lakes to acidic hot springs to unkempt home aquariums, diatoms are everywhere. It's a good thing. The tiny creatures pump out up to 50 percent of the planet's oxygen, said Edward Theriot, a diatom expert and evolutionary biologist at the University of Texas at Austin, who was not involved in the study.

The algae look like little petri dishes or footballs,depending on the species, and spend most of their lives drifting on currents. How diatoms manage to colonize new homes remains a mystery: They can't swim.

Yet diatoms get around. When Wyoming's Yellowstone Lake emerged from its mile-thick ice cover 14,000 years ago, diatoms quickly arrived, Theriot said. "They had to be blown in by some mechanism or carried in by water birds," he added.

Diatoms particularly love volcanic lakes, because they are the only creatures that build shells of glass. (Glass sponges, for instance, produce a skeleton of glass spicules — tiny spike-like structures — but not a hard shell.) Silica-rich magma often causes the volcanic explosions that leave behind lake-filled craters, and silica is the key ingredient in diatom shells. Yellowstone Lake, which sits in a caldera created by a super-eruption, contains so many diatoms that the lake sediments are mostly shells (85 percent by weight), Theriot said.

Now scientists know what happens to diatoms when a massive volcanolike Yellowstone blasts through a big lake.

Immaculate preservation

The Taupo Volcano super-eruption slammed through a deep lake that filled a rift valley, similar to the elongated lakes in East Africa. The combination of water and ash created a hellish dirty thunderstorm, with towering clouds and roaring winds. The detonation flung ash and algae upward at more than 250 mph (400 km/h), Van Eaton said. Volcanic hail (called accretionary lapilli) pelted the landscape for miles.

Van Eaton discovered the diatoms while examining the volcanic hail with a scanning electron microscope.

"The first time I ever saw them I was looking at these volcanic ashaggregates and, bam, these gorgeous little symmetrical shells were there," she said. "Their shells are immaculately preserved."

Van Eaton soon determined that one of the three diatom species entombed in the ash only lives on the North Island of New Zealand. This meant she could track the 25,000-year-old ash layers around the South Pacific with a unique biologic marker. The unique North Island diatoms turned up in a few inches of ash on the Chatham Islands. The diatoms' trip to the Chatham Islands took longer than it looks on a map. The prevailing winds blew west at the time, so the shells circled the Southern Hemisphere before landing on the islands, Van Eaton and her colleagues think.

Some of the diatoms even kept their color, both in ash close to the volcano and at the Chatham Islands. The color suggests they weren't cooked to extreme temperatures in the volcanic eruption, Van Eaton said.

Spores infect the sky

But even though the Taupo diatom shells are pristine, Theriot is doubtful any diatoms lived through the eruptions. Instead, he suspects diatom resting spores could travel the atmospheric currents, dropping out and colonizing new ecosystems. Diatoms fashion spores to ride out inhospitable changes in their environment. Two years ago, Danish researchers revived 100-year-old resting spores from muck in a local fjord. Resting spores have been found in clouds. The eruption could have launched spores from the lake bottom into the atmosphere, Theriot said.

"I and many others have joked about Yellowstone blowing up again and dispersing the diatomite that is being created at the bottom of Yellowstone Lake," Theriot said. "This is the most thoroughly studied and best documented example of this phenomenon, and so it really says maybe we can add volcanoes to the list of possibilities [of how diatoms spread]. And volcanoes would be particularly effective." [Infographic: The Geology of Yellowstone]

Van Eaton hopes the discovery will prompt other scientists to search for microscopic life in "wet eruptions," where magma hit water.

"This is potentially another tool to pinpoint where ash deposits come from," Van Eaton said. "If the work is done to characterize the kinds of microbes that are unique to an area, then it could give you a biogenic fingerprint for your eruption deposits. This has likely been going on in modern eruptions, but no one has taken the time to look for them."

Ash travels hundreds of miles, but once it's far from its source, linking a few inches of glass back to a single volcano becomes difficult, particularly in regions like the South Pacific, where volcanoes pop off all the time.

But Theriot is skeptical that diatoms will prove to be a useful tool for tracking volcanic ash. Diatoms are so global that endemic species — known only to one place — are hard to find, he said. "If you found diatoms in ash deposits in a bog in Ohio, you would have no idea if it was from Yellowstone or from that bog," Theriot said. "It would take a really extraordinary set of circumstances, like this New Zealand [diatom] that is clearly out of place, to be convincing that the diatoms had blown in with the ash."

Kasatochi Volcano - Ocean Fertilization - 2008

http://earthobservatory.nasa.gov/IOTD/view.php?id=79525&src=eoa-iotd

Several researchers have proposed that we could “engineer” our environment to offset the rising concentrations of carbon dioxide in the atmosphere. One proposal is to “fertilize” the ocean to make blooms of phytoplankton,plant-like, microscopic organisms that are the “primary producers” of the seas. Phytoplankton use sunlight and nutrients to grow and then become food for other marine life; along the way, they absorb carbon dioxide. The geoengineers propose that by putting enough iron in the right places—the mineral is often in short supply in the open ocean—phytoplankton will bloom wildly and soak up a lot of CO₂.

Nature is very good at making prodigious blooms of phytoplankton. But as a recent “natural” experiment showed, the absorption of carbon dioxide is not always so prodigious.

On August 7, 2008, a stratovolcano in the Aleutian Islands began erupting just as a storm system was passing overhead. Over several days, the explosive eruption at Kasatochi Volcano sent ash and sulfur dioxide about 11,000 meters (35,000 feet) into the air and thousands of kilometers downwind. That iron-enriched ash spread out across a vast area of the North Pacific Ocean.

“Usually ash from volcanic eruptions is swept in one narrow direction by the wind,” said chemical oceanographer Roberta Hamme of the University of Victoria. “However, the ash from Kasatochi was caught in this forming storm system, which swirled over the ocean, depositing volcanic ash over an unusually large area.”

Downwind from Kasatochi, the concentration of chlorophyll in the ocean increased by 150 percent. Hamme and other scientists saw satellite observations of both the ash plume and of the jump in chlorophyll—the sign of a phytoplankton bloom. Instruments on oceanographic buoys and gliders also captured elements of the event, as did scientists who were cruising through the area on a Fisheries and Oceans Canada ship. Hamme and the team connected the dots and concluded that the eruption led directly to a vast bloom of phytoplankton.

The image at the top of the page shows the concentration of aerosol particles as they were dispersed in the atmosphere southeast of the Aleutian Islands in August 2008. Aerosols are airborne particles such as sea salt, dust, air pollution and, in this case, volcanic ash. The measurements were made by the Ozone Monitoring Instrument (OMI) on NASA’s Aura satellite.

The second map depicts the increase in chlorophyll in the ocean in the month after the eruption at Kasatochi. Chlorophyll is the pigment in plants and phytoplankton that harnesses energy from the Sun for food, and the abundance of chlorophyll (in milligrams per cubic meter) is a proxy for the abundance of plankton. The map does not show total concentrations; instead it shows how much chlorophyll rose above (green) or below (brown) the norm for August in that region. The data were acquired by the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s <Aqua satellite.

The data plot (third image) shows the total concentration of chlorophyll within the white inset box marked in the second map, including the significant increase in 2008.

In the aftermath of the eruption and bloom, Hamme and colleagues looked for the carbon impact of the event. Estimating the amount of carbon dioxide in the water before, during, and after the event, they found that the phytoplankton pulled about 0.01 Petagrams (10¹⁵ grams) of carbon out of the atmosphere. For scale, the burning of fossil fuels releases about 6.5 Pg of carbon annually, and about 2 Pg are absorbed naturally by the ocean.

“Despite the huge area of iron addition and the optimal time of year when there was plenty of sunlight, the impact of this August 2008 event was quite small in terms of carbon absorption,” Hamme added. “This tells us that iron fertilization would have to be performed on a truly gigantic scale to have an impact on our climate.”

1. References

2. Alaska Volcano Observatory (n.d.) Kasatochi Introduction. Accessed January 23, 2013.
3. Global Volcanism Program (n.d.) Kasatochi. Accessed January 23, 2013.
4. Hamme, R. C., et al. (2010) Volcanic ash fuels anomalous plankton bloom in subarctic northeast Pacific.
Geophysical Research Letters, 37, L19604.
5. NASA Earth Observatory (2008) Natural Hazards: Aleutian Islands' Kasatochi Volcano Erupts.
6. Oceanus (2007, November 13) Fertilizing the Ocean with Iron. Accessed January 23, 2013.
7. Science Now (2010, October 6) How Volcanoes Feed Plankton. Accessed January 23, 2013.

NASA Earth Observatory images by Jesse Allen, use OMI aerosol data provided by the Aura science team, MODIS chlorophyll anomaly data from the Ocean Color team, and chlorophyll data from NASA Earth Observations (NEO) courtesy of Kevin Ward. Caption by Michael Carlowicz.

Underwater desert surrounds Aleutian volcano

http://www.sitnews.us/0410news/042310/042310_sitnews.html

Underwater desert surrounds Aleutian volcano
By NED ROZELL

April 23, 2010
Friday


Stephen Jewett has dived in ocean waters from one end of Alaska to the other, but he has never seen an underwater landscape as barren as one he saw last summer.

"Diving off Nome where they were doing offshore dredging (for gold) was close, but nothing compares to what we found around Kasatochi," said Jewett, who dives as part of his job with the University of Alaska Fairbanks' School of Fisheries and Ocean Sciences.

Kasatochi is an 800-acre island in the Aleutians that destroyed itself with an eruption in August 2008. Its 40,000-foot ash cloud disrupted Alaska Airlines flights from Seattle to Anchorage. Almost nothing on the island survived its transformation from lush and green to gray and muddy.



A mature kelp forest offshore of an Aleutian Island that resembles the offshore environment of Kasatochi Island prior to its August 2008 eruption.
Photo by Shawn Harper

Jewett visited the island twice in 2009, once in June and once in August, to perform dives around the island and see what became of the lush kelp forests that had formerly ringed the island. He recently gave a presentation at UAF to discuss his team's findings.

During Kasatochi's violent eruption, the island "blooped out," as one biologist put it, becoming 31 percent bigger as sand and ash flowed out to sea. That sand was mostly what Jewett and fellow divers Héloïse Chenelot and Max Hoberg found off Kasatochi.

A diver samples the sands offshore of Kasatochi Island in June 2009.
Photo by Héloïse Chenelot.

"There is absolutely nothing there it is barren," Jewett said of some of the spots in which they dove. "There were no fishes, no large invertebrates, and plants were rare. There were no crabs, sea stars, or urchins that you would see at any other site in the Aleutians."

The erupted ash and mud created an apron of gray that now surrounds the island.

"The lights probably went out underwater (during the eruption)," Jewett said. "Mobile organisms might have been able to get out of the way, but the sponges, kelp, and urchins were buried."

The thick beds of kelp that used to make motoring ashore in a skiff difficult were gone around most of the island, but Jewett and the others eventually saw something other than sand on their dives.

"We were delighted to see rocks, and then we found barnacles - our first sign of animal life," Jewett said.

The barnacles were large enough that Jewett and Hoberg decided they had survived the eruption, which probably heated the sea just offshore considerably.

They also found living diatoms - single-celled algae with cell walls made of glass. The diatoms were a species that is often one of the first colonizers of bare rock after a disturbance.

Another discovery was amphipods, tiny creatures that look somewhat like shrimp. They are also among the first creatures to return to a barren, undersea landscape.

Like the island itself, the shallow waters offshore of Kasatochi are still a desert, but recovery is underway. Jewett expects that a few healthy strands of kelp the divers found - the fastest growing kelp in the world that can grow a meter a day in the summer - will continue to prosper as the fine sediments erode away.

"There is a remnant of algae for future recolonization," Jewett said. "There is seed to replenish this otherwise sterile environment."