Sunday, October 21, 2012

Permian Extiction

Fascinating article below on the Permian Extinction, one of if not the most lethal in the earth's history.  Yes, this is the same article as the I put on the ES blog.  It has very much to do with oceanography as well.

 Read on...


Tropical Collapse in Early Triassic Caused by Lethal Heat: Extreme Temperatures Blamed for 'Dead Zone'

ScienceDaily (Oct. 18, 2012) — Scientists have discovered why the 'broken world' following the worst extinction of all time lasted so long -- it was simply too hot to survive.
The end-Permian mass extinction, which occurred around 250 million years ago in the pre-dinosaur era, wiped out nearly all the world's species. Typically, a mass extinction is followed by a 'dead zone' during which new species are not seen for tens of thousands of years. In this case, the dead zone, during the Early Triassic period which followed, lasted for a perplexingly long period: five million years.
A study jointly led by the University of Leeds and China University of Geosciences (Wuhan), in collaboration with the University of Erlangen-Nurnburg (Germany), shows the cause of this lengthy devastation was a temperature rise to lethal levels in the tropics: around 50-60°C on land, and 40°C at the sea-surface.
Lead author Yadong Sun, who is based in Leeds while completing a joint PhD in geology, says: "Global warming has long been linked to the end-Permian mass extinction, but this study is the first to show extreme temperatures kept life from re-starting in Equatorial latitudes for millions of years."
It is also the first study to show water temperatures close to the ocean's surface can reach 40°C -- a near-lethal value at which marine life dies and photosynthesis stops. Until now, climate modellers have assumed sea-surface temperatures cannot surpass 30°C. The findings may help us understand future climate change patterns.
The dead zone would have been a strange world -- very wet in the tropics but with almost nothing growing. No forests grew, only shrubs and ferns. No fish or marine reptiles were to be found in the tropics, only shellfish, and virtually no land animals existed because their high metabolic rate made it impossible to deal with the extreme temperatures. Only the polar regions provided a refuge from the baking heat.
Before the end-Permian mass extinction, Earth had teemed with plants and animals including primitive reptiles and amphibians, and a wide variety of sea creatures including coral and sea lillies.
This broken world scenario was caused by a breakdown in global carbon cycling. In normal circumstances, plants help regulate temperature by absorbing Co2 and burying it as dead plant matter. Without plants, levels of Co2 can rise unchecked, which causes temperatures to increase.
The study, published Oct. 19 in the journal Science, is the most detailed temperature record of this study period (252-247 million years ago) to date.
Sun and his colleagues collected data from 15,000 ancient conodonts (tiny teeth of extinct eel-like fishes) extracted from two tonnes of rocks from South China. Conodonts form a skeleton using oxygen. The isotopes of oxygen in skeletons are temperature controlled, so by studying the ratio of oxygen isotopes in the conodonts he was able to detect temperature levels hundreds of millions of years ago.
Professor Paul Wignall from the School of Earth and Environment at the University of Leeds, one of the study's co-authors, said: "Nobody has ever dared say that past climates attained these levels of heat. Hopefully future global warming won't get anywhere near temperatures of 250 million years ago, but if it does we have shown that it may take millions of years to recover."
The study is the latest collaboration in a 20-year research partnership between the University of Leeds and China University of Geosciences in Wuhan. It was funded by the Chinese Science Foundation.
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The above story is reprinted from materials provided byUniversity of Leeds, via EurekAlert!, a service of AAAS.
Note: Materials may be edited for content and length. For further information, please contact the source cited above.
Journal Reference:
  1. Yadong Sun, Michael M. Joachimski, Paul B. Wignall, Chunbo Yan, Yanlong Chen, Haishui Jiang, Lina Wang, and Xulong Lai. Lethally Hot Temperatures During the Early Triassic Greenhouse. Science, 2012; 338 (6105): 366-370 DOI: 10.1126/science.1224126
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 MLA
University of Leeds (2012, October 18). Tropical collapse in Early Triassic caused by lethal heat: Extreme temperatures blamed for 'Dead Zone'.ScienceDaily. Retrieved October 21, 2012, from http://www.sciencedaily.com­/releases/2012/10/121018141844.htm
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Tuesday, October 16, 2012

Coral Reefs

Given today's class discussion about the stages in coral reef development, I think this photo essay from National Geographic is rather timely.

 As always, National Geographic's photos are unparalleled in their quality.  Gorgeous images.  Each has a quality caption, too.

 Enjoy.

Nat Geo - Mesoamerican Reef Article
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Sunday, October 14, 2012

The Gulf Stream


News Release

Scientists Uncover Diversion of Gulf Stream Path in Late 2011

Warmer waters flowed to shelfbreak south of New England

FOR IMMEDIATE RELEASE
Media Relations Office
October 11, 2012
(508) 289-3340
At a meeting with New England commercial fishermen last December, physical oceanographers Glen Gawarkiewicz and Al Plueddemann from the Woods Hole Oceanographic Institution (WHOI) were alerted by three fishermen about unusually high surface water temperatures and strong currents on the outer continental shelf south of New England.
“I promised them I would look into why that was happening,” Gawarkiewicz says.
The result of his investigation was a discovery that the Gulf Stream diverged well to the north of its normal path beginning in late October 2011, causing the warmer-than-usual ocean temperatures along the New England continental shelf.  
The researchers’ findings, “Direct interaction between the Gulf Stream and the shelfbreak south of New England,” were published in the August 2012 issue of the journal Scientific Reports.
To begin to unravel the mystery, Gawarkiewicz and his colleagues assembled data from a variety of sources and recreated a record of the Gulf Stream path during the fall of 2011.  First, they tapped into data collected by a program called eMOLT, a non-profit collaboration of fishing industry, research, academic and government entities, run by James Manning of National Oceanic and Atmospheric Administration’s Northeast Fisheries Science Center. For more than a decade the program has recorded near-bottom ocean temperatures by distributing temperature probes to lobstermen. 
Manning and scientists from WHOI, including Robert Todd and Magdalena Andres, analyzed a time series of temperatures from two eMOLT sites, OC01 and TA51, which were located over the outer continental shelf near the shelfbreak, and identified two events when temperatures suddenly increased by 6.2 and 6.7°C, respectively, to highs of more than 18°C.
“These are very dramatic events for the outer continental shelf, at least 2°C warmer than we’ve seen since 2001,” says Gawarkiewicz. “Near-bottom temperatures of 18°C on the outer shelf are extremely high for late autumn.” The maximum recorded temperature in December 2011 was the warmest bottom temperature recorded in 6 years of records at the OC01 site.
In typical years, the warm Gulf Stream waters only indirectly influence ocean currents and temperatures near the continental shelfbreak south of New England when eddies, called warm core rings, pinch off from the Gulf Stream and drift toward the outer continental shelf. Such rings normally drift past a site after a few weeks, and therefore cause only limited warming of the water on the outer shelf.
Gawarkiewicz and his colleagues collected additional data on water temperature and salinity from December 4, 2011 through January 4, 2012, from instruments on temporary test moorings placed 12 km south of the shelfbreak by the Ocean Observatories Initiative (OOI). The researchers compared those salinity measurements to historical data, and discovered that high salinity levels – consistent with the salinity of waters carried by the Gulf Stream – coincided with the warming periods. 
The extent and duration of the two 2011 warming events combined with the high salinity observed by the researchers suggested the cause was not a transient warm core ring, but the Gulf Stream itself that carried warm, salty water to the outer shelf.
To solidify that finding, Gawarkiewicz received serendipitous help from students in the Marine Advanced Technology Education (MATE) program at Cape Fear Community College in Wilmington, NC, who had deployed a surface drifter during the period coinciding with the two warming events. Drifters use satellites to transmit their positions roughly every six hours, key information for the WHOI scientists, who analyzed the drifter tracks and speeds.
“Drifters around the edges of warm core rings drift toward the continental shelf at about 1 knot,” Gawarkiewicz says. “But we saw the drifter cut across the slope towards the shelf at about 2.5 knots. It only took it eight days to travel from Cape Fear, North Carolina, to a point 40 miles south of Georges Bank, a total distance of 580 miles.”
The periods of high speeds for the drifters coincided with the records for high temperatures on the outer shelf, which told the scientists that the core of the Gulf Stream had diverted to 39.9°N at 68°W – 125 miles north of its mean position, further north than had ever been recorded by satellite altimeters at this particular longitude.
The temporary shift in Gulf Stream path observed last fall potentially has significant longer-term implications. Studies have shown that temperature increases of 2°C have caused major shifts in silver hake populations, for example, and in spring 2012, migratory bluefish and striped bass were observed off the coast of Cape Cod much earlier than in previous years. But, the scientists say, more research is needed to determine just how the Gulf Stream’s behavior in 2011 affected the continental shelf ecosystem and marine organisms.
It is unclear what might have caused this shift in the Gulf Stream path.  It occurred shortly after Hurricanes Irene and Katia drenched the east coast with rain, and this might have impacted the Gulf Stream separation from the continental shelf near Cape Hatteras. Another possibility is that a cold core ring, an eddy south of the Gulf Stream core, might have deflected the Gulf Stream.  Further research will be necessary to determine exactly how and why this occurred, which will be helpful in the long term in predicting Gulf Stream motions.
In the meantime, Gawarkiewicz and his colleagues will be keeping an eye on what the Gulf Stream does this fall, with the hope of someday being able to predict such a shift. “We’re checking in from time to time to monitor it. We’ll be talking to the fishermen, and academics, and keeping an eye on things,” he says.
Fishermen David Spencer, Fred Mattera, and Norbert Stamps first alerted the researchers to the anomaly. Profile data were made available by the OOI, which is funded by the National Science Foundation and managed by the Consortium for Ocean Leadership. Tim Shaw and David Calhoun at Cape Fear Community College provided drifter data. WHOI scientists on this project were supported by the NSF, the Cooperative Institute for the North Atlantic Region, the Penzance Endowed Fund in Support of Assistant Scientists, and the Postdoctoral Scholar Program at WHOI.

The Woods Hole Oceanographic Institution is a private, non-profit organization on Cape Cod, Mass., dedicated to marine research, engineering, and higher education. Established in 1930 on a recommendation from the National Academy of Sciences, its primary mission is to understand the oceans and their interaction with Earth and humanity, and to communicate an understanding of the ocean’s role in the changing global environment.
Originally published: October 11, 2012
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Wednesday, October 10, 2012

Drones and Marine Mammal Research

Up until recently, the use of unmanned drones has been strictly the domain of the US Military.  Recently several southern US states and the US Border Patrols have begun using them to finally better enforce our southern border.

 Now the use of drones has expanded into the realm of scientific research.  The article below, from NOAA, chronicles a novel approach to marine mammal surveys in isolated areas.  The drone can be useful especially when monitoring dangerous animals.


Aerial Drones Give NOAA Scientists a New Perspective

Wayne Perryman with a group of penguins on Livingston Island in Antarctica.  
A hovering aerial drone.

Additional Information
Leopard seal on Livingston Island bares its teeth at researchers. Using a drone to get close to these aggressive predators might be a good idea. Credit: Ray Buchheit. 

October 3, 2012 
From a rare rocky outcrop on the otherwise ice-covered surface of Livingston Island, near the end of the peninsula that Antarctica extends like a tentacle toward South America, a team of scientists from NOAA's Southwest Fishery Science Center is about to launch a whole new era in marine mammal research. They just have to wait for the wind to die down.
When it does, biologist  Wayne Perryman flips a switch, and an unmanned aerial vehicle the size of a hubcap shoots straight up into the sky, its sharp insect buzz fading quickly as it races away. This drone has 6 helicopter rotors, allowing it to take off vertically and hover motionlessly, and a high-resolution digital camera. Perryman maneuvers it into position above a small group of leopard seals hauled out onto the rock, and then starts taking pictures.
Very little is known about the role of leopard seals in this ecosystem, and the drone, which Perryman also uses to study penguins and fur seals, will provide a better look. “You can tell a lot about the reproductive and nutritive condition of an animal based on its shape,” he says. From the photos, scientists can measure the length and width of individual animals and so generate estimates of their weight. By monitoring weight gain among the seals, scientists hope to better understand the energetics of the species and how they structure their ecological community through predation.
A typical season of fieldwork involves anaesthetizing a sample of animals on the ground and physically examining them. “The reason you want to work with them remotely is that it’s safer for the human and safer for the seal,” says Perryman. “A leopard seal is about a thousand pound animal, it’s mostly teeth, and it’s a very dangerous animal to work with.” They’re also particularly sensitive to anesthesia, which means that there’s a very fine line between using too much, which can be dangerous for the animal, and using too little, which can be dangerous for everyone."
Perryman served as a hydrographic surveyor in the Navy during the Vietnam War. Soon after, he joined NOAA and helped pioneer the use of aerial surveys to monitor dolphin populations in the Pacific. He’s spent most of his career working with high-end military equipment, but the digital revolution has moved consumer technology to the cutting edge. Equal parts biologist and hacker, Perryman now flies drones that are custom built out of readily available parts.
During the upcoming field season, Perryman will hand the controls of the drone to NOAA scientist Doug Krause, the lead researcher on the leopard seal study. Krause and his team will collect data both by air and on the ground, allowing them to calibrate the method for converting remote measurements into weight estimates. Although these methods are still being developed, aerial drones will soon be a standard tool in the marine mammal biologist’s field kit.
Richard Merrick, the Chief Science Advisor for NOAA Fisheries, expects drones to expand the reach of science. “Unmanned aerial systems will open the door for us to conduct research in a wider range of environments. These technologies are going to help us do this research more safely, and they are very cost-effective,” said Merrick, citing the example of remote islands where surveys from manned flights are ineffective and dangerous due to low cloud cover.
Perryman also has some ideas about where the new technology will take him, such as inside the plume of a whale as it blows. By following closely above a whale, then swooping in to sample the plume at just the right moment, a drone can yield data on hormone levels, genetic markers, and other clues to the animal’s condition. “We’ve got a technology that works really well,” Perryman says, and he and other NOAA scientists are quickly imagining new ways to use it.

Photo of a leopard seal taken from an aerial drone. Scientists use these photographs to measure the seal.

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Friday, October 5, 2012

Chicken and Eggs? Isn't this oceanography?

Yes, indeed, this the an oceanography blog.  You may be wondering about the title of today's post...
What came first...the chick or the egg?

The reason I ask that qusestion is that scientists are coming closer to the mystery of the age old question..."What came first? Mollusks or their shells?"

The article below reposts back on the study results...

Which Came First, Shells or No Shells? Ancient Mollusk Tells a Contrary Story

ScienceDaily (Oct. 3, 2012) — A fossil unearthed in Great Britain may end a long-running debate about the mollusks, one of life's most diverse invertebrate groups: Which evolved first, shelled forms like clams and snails, or their shell-less, worm-like relatives?
The small new fossil, found in marine rocks along the English-Welsh border, provides the best fossil evidence yet that the simpler worm-like mollusks evolved from their more anatomically complex shelled brethren, rather than the other way around.
The discovery reinforces previous findings from molecular sequencing studies and helps clarify the evolutionary relationships of mollusks, a broad category that includes not only oysters and mussels but also slugs, squids and octopuses.
"This is a kind of missing link with a worm-like body, bearing a series of shells like those of a chiton or coat-of-mail shell," said Derek E. G. Briggs, director of the Yale Peabody Museum of Natural History and one of the paleontologists who studied the new fossil, Kulindroplax perissokomos. The researchers report their findings online Oct. 3 in the journal Nature.
The evolutionary relationships of worm-like mollusks, known as Aplacophora, has been a subject of controversy. Previously thought to be a product of the explosion of diversity during the early Cambrian period, they are now shown to have evolved probably 40-50 million years ago by losing shells like those onKulindroplax.
Kulindroplax represents the first mollusk with an unambiguous combination of valves, or exterior shells, and a worm-like body, said Mark D. Sutton of Imperial College London, the paper's lead-author.
The researchers found the specimen of Kulindroplax more than 10 years ago in the Herefordshire fossil deposit, a rich assemblage of ancient marine life forms more than 400 million years old. About 2 cm wide and 4 cm long, Kulindroplax was buried in volcanic ash deposited on the sea floor. The researchers later reconstructed its three-dimensional shape using computer software, revealing both form and structure in fine detail. In addition to its seven shells, Kulindroplax had a dense covering of spicules over the rest of the body, which it probably used to gain purchase as it crawled on the muddy sea bed.
Kulindroplax is coined from the Greek words for a cylinder and a plate, referring to the rounded body with its series of shells.
The other authors of the paper are David J. Siveter of the University of Leicester, Derek J. Siveter of the University of Oxford and Julia D. Sigwart of Queen's University, Belfast.
Support for the research was provided by the Natural Environmental Research Council.
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The above story is reprinted from materials provided byYale University.
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Journal Reference:
  1. Mark D. Sutton, Derek E. G. Briggs, David J. Siveter, Derek J. Siveter, Julia D. Sigwart. A Silurian armoured aplacophoran and implications for molluscan phylogeny. Nature, 2012; 490 (7418): 94 DOI:10.1038/nature11328
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 MLA
Yale University (2012, October 3). Which came first, shells or no shells? Ancient mollusk tells a contrary story. ScienceDaily. Retrieved October 5, 2012, from http://www.sciencedaily.com­/releases/2012/10/121003132326.htm
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Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.
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