February 2, 2007, 4:38 AM CT

Algae Toxin And The Fish-kill Mystery

A team of scientists from the Hollings Marine Laboratory in Charleston, S.C., has uncovered a subtle chemical pathway by which normally inoffensive algae, Pfiesteria piscicida, can suddenly start producing a lethal toxin. The discovery, reported last week in Environmental Science and Technology,* could resolve a long-standing mystery surrounding occasional mass fish kills on the East Coast.

Pfiesteria has been implicated for years in a series of otherwise unexplained episodes of mass fish death throughout its range from roughly Delaware to Alabama, especially in the Neuse River in North Carolina and the Chesapeake Bay. The single-cell organism can experience explosive growth resulting in algae blooms in coastal waters. While it has been suspected not only in fish kills but in incidents of human memory loss and other environmental and health-related effects, no one has ever conclusively identified the actual mechanism. Attempts to grow lethal Pfiesteria in the laboratory have had inconsistent results.

The Hollings Marine Laboratory is a joint institution of the National Oceanic and Atmospheric Administration (NOAA), the National Institute of Standards and Technology (NIST), the South Carolina Department of Natural Resources, the College of Charleston, and the Medical University of South Carolina (MUSC). Lead researcher Peter Moeller of NOAA suspected that the presence or absence of heavy metals might be the missing factor accounting for Pfiesteria's lethality, and put together a multidisciplinary research team to identify the actual toxin and the conditions under which it is produced.........

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February 2, 2007, 4:20 AM CT

Human Link To Global Warming

Evidence presented in the first phase of the Intergovernmental Panel on Climate Change's 4th Assessment Report, released recently in Paris, paints the clearest picture yet that human-derived greenhouse gases are playing a significant role in observed global warming, says a Duke University scientist who co-authored one of the report's main chapters.

"We are now seeing, not merely predicting, effects of greenhouse warming on a scale and in ways that were not observable before," said Gabriele Hegerl, associate research professor at Duke's Nicholas School of the Environment and Earth Sciences, who also co-authored a summary of the report for policymakers.

"When you look at the changes in temperature, circulation, ocean warming, arctic sea ice reduction and glacial retreat together, it paints a much clearer picture that external drivers, especially greenhouse gases, are playing a key role," she said. "As a result, we can be much more confident that 20th century climate changes were not just associated with natural variability".

Hegerl was a coordinating lead author of the IPCC report's chapter on "Understanding and Attributing Climate Change." Francis Zwiers of the Canadian Centre of Climate Modeling and Analysis was also a coordinating lead author of the chapter.........

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January 31, 2007, 9:05 PM CT

Continuing Tomato Sequence Project

An international project led by Cornell and the Boyce Thompson Institute for Plant Research (BTI) at Cornell has received $1.8 million from the National Science Foundation (NSF) to continue sequencing the tomato genome and to create a database of genomic sequences and information on the tomato and related plants.

The grant for the International Tomato Sequencing Project, a collaboration of scientists from nine other countries, will enable U.S. scientists to continue their work. In 2004 the NSF provided $4 million for the U.S. part of the research.

Sequencing the tomato genome is the first step in creating the comprehensive International Solanaceae Genomics Project (SOL) Genomics Network database. This will tie together maps and genomes of all plants in the Solanaceae family, also called nightshades, which includes the potato, eggplant, pepper and petunia and is closely correlation to coffee from the Rubiaceae family.

The public database will help scientists ask fundamental questions: Have changes from a common ancestor brought about the attributes of crop species? What are the functions of specific genes? How has domestication changed genes? Which plants might be good candidates for genetically engineered improvements for growing crops?

Cornell scientists are close to completing a toolkit of resources about tomato and solanaceae species (some currently available in the database) to make the sequencing possible. These resources include genetic maps, DNA libraries, individual gene sequences, DNA markers and associated information, comparative mapping data to go from one species to another as sequences are added, and tools to query and search this information.........

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January 24, 2007, 7:40 PM CT

deep-sea fauna under Antarctic ice shelf

Under the former Larsen ice shelf east of the Antarctic Peninsula, deep-sea sea cucumbers and stalked feather stars were ubiquitously found in shallow waters. These animals usually inhabit far greater water depths.

The main aim of the current Polarstern expedition to Antarctica is the investigation of marine ecosystems under the former Larsen ice shelf. This "white spot" with regard to biodiversity research gave rise to the following questions: What kind of life actually existed under the former floating ice shelf which was up to several hundreds of meters thick? What are the prospects for the future after the collapse of the ice shelf? Obviously, prosperous life did not exist in the area where the Larsen B ice shelf broke off three years ago. This is surprising since Antarctica's seafloor communities are known for their rich assemblages of sessile sponges, cnidarians and moss animals. Instead, underwater video footage and catches of towed sampling gear revealed the dominance of typical deep-sea animals and corresponding life forms.

Here, sea cucumbers and stalked feather stars are the main representatives. These deep-sea inhabitants belong to a group called echinoderms. Until now, stalked feather stars have only been found sporadically and then only below 800m water depths in this sector of Antarctica. But locally in the Larsen B region, they occurred rather frequently at depths of merely 200m. "During my nine expeditions to Antarctica, the only time I have seen the two most abundant species of sea cucumbers was below the far bigger Filchner-Ronne ice shelf further south." This second encounter brought back chief scientist Julian Gutt's memories of his first trip to Antarctica and his PhD thesis 21 years ago. Preliminary results show that a unique macrofauna exists in conjunction with the ice shelf. The sea cucumber Elpidia is probably the most prominent deep-sea animal but is also known to occur in shallow Arctic waters. Maybe this is the reason why this animal is aptly named glacialis (icy) especially with regard to our confirmatory findings on the opposite pole - Antarctica.........

Posted by: Ashley      Read more         Source

January 15, 2007, 7:33 PM CT

Rubus thibetanus 'Silver Fern'

This bramble is the source of much recent photographic frustration for me. It beckons outside my second-floor office window with its tangled icy-blue mass of canes, asking to be photographed in pretty much the exact frame that I see through the window from my office chair - a window that only opens thirty degrees outwards, thereby requiring me to either 1) move furniture and lean out the window while undergoing unnatural contortions (which I suspect the safety folks might have something to say about); 2) take the photograph through the window glass (and accept some glare and reduced image quality); or 3) let it taunt me. I wonder if I can get away with propping a ladder against the side of the building.

This shot was from a much closer distance, with a new lens.

By Daniel Mosquin.........

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January 15, 2007, 5:19 AM CT

Hofmeyr-Skull supports the "Out of Africa"-Theory

Reliably dated fossils are critical to understanding the course of human evolution. A human skull discovered over fifty years ago near the town of Hofmeyr, in the Eastern Cape Province of South Africa, is one such fossil. A study by an international team of researchers led by Frederick Grine of the Departments of Anthropology and Anatomical Sciences at Stony Brook University in New York published recently in Science magazine has dated the skull to 36,000 years ago. This skull provides critical corroboration of genetic evidence indicating that modern humans originated in sub-Saharan Africa and migrated about this time to colonize the Old World. (Science January 12, 2007).

"The Hofmeyr skull gives us the first insights into the morphology of such a sub-Saharan African population, which means the most recent common ancestor of all of us - wherever we come from," said Grine.

Eventhough the skull was found over half a century ago, its significance became apparent only recently. A new approach to dating developed by Grine team member Richard Bailey and colleagues at Oxford University allowed them to determined its age at just over 36,000 years ago by measuring the amount of radiation that had been absorbed by sand grains that filled the inside of the skull's braincase. At this age, the skull fills a significant void in the human fossil record of sub-Saharan Africa from the period between about 70,000 and 15,000 years ago. During this critical period, the archaeological tradition known as the Later Stone Age, with its sophisticated stone and bone tools and artwork appears in sub-Saharan Africa, and anatomically modern people appear for the first time in Europe and western Asia with the equally complex Upper Paleolithic archeological tradition.........

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January 12, 2007, 5:04 AM CT

Soil Nutrients Shape Tropical Forests

Tropical forests are among the most diverse plant communities on earth, and researchers have labored for decades to identify the ecological and evolutionary processes that created and maintain them. A key question is whether all tree species are equivalent in their use of resources - water, light and nutrients - or whether each species has its own niche.

A large-scale study by scientists at the University of Illinois at Urbana-Champaign and eight other institutions sheds some light on the issue. It indicates that nutrients in the soil can strongly influence the distribution of trees in tropical forests. The finding, published this week in the Proceedings of the National Academy of Sciences, challenges the theory that at local scales tree distributions in a forest simply reflect patterns of seed dispersal, said James W. Dalling, a U. of I. professor of plant biology and a principal researcher on the study.

The study reviewed three sites: two lowland forests, in central Panama and eastern Ecuador, and a mountain forest in southern Colombia. The scientists plotted every tree and mapped the distribution of soil nutrients on a total of 100 hectares (247 acres) at the sites. The study included 1,400 tree species and more than 500,000 trees.

The scientists compared distribution maps of 10 essential plant nutrients in the soils to species maps of all trees more than 1 centimeter in diameter. Each of the sites was very different, but at each the scientists found evidence that soil composition significantly influenced where certain tree species grew: The spatial distributions of 36 to 51 percent of the tree species showed strong associations with soil nutrient distributions.........

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January 10, 2007, 9:19 PM CT

Age Is More Than A Number

Fluctuations in weather and the environment affect survival and reproduction of animals. But are all individuals within a population equally susceptible? Theory on the evolution in age-structured populations suggests not - those life stages that are more important for overall fitness should be less susceptible to environmental variation than other life stages. Empirical support for this prediction is rare because detailed data need to be collected over many years, and true variation tends to be inflated through the way in which natural populations are sampled.

In the recent issue of The American Naturalist, Res Altwegg (University of Cape Town and University of Victoria), Michael Schaub (Swiss Ornithological Institute and University of Bern), and Alexandre Roulin (University of Lausanne), examined temporal variation in survival and reproduction of barn owls in western Switzerland that had been observed over the past fifteen years. Using recently developed statistical tools, they were able to show that those fitness components that experienced stronger selection were indeed less variable over the years.

"Our results help explain why certain age classes are more susceptible to adverse weather, and they will help us understand how climatic variation affects populations of organisms in nature. This is important for predicting the effect of climate change on populations," the authors said.........

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January 10, 2007, 4:55 AM CT

New Project To Protect Biodiversity

The world's biodiversity is vanishing at an unprecedented rate - around 100 species every day - due to factors such as land use change and pollution. Addressing this threat, world governments agreed through the UN Convention on Biological Diversity to reduce significantly the current rate of biodiversity loss by 2010. To support this initiative, ESA has kicked off its new DIVERSITY project.

Biodiversity, the variety of life including ecosystems, species, populations and genes, is of grave importance for sustaining the planet's six billion people. The loss of biodiversity threatens our food supplies, energy and medicines. For instance, up to 80% of the world's population currently relies on plant and animal-based medicines for their primary health care needs. The sustainable use of biodiversity's components will not only save ecosystems and species, but it may also save the foods and medicines of tomorrow.

"The United Nations Convention on Biodiversity (UNCBD) agreed on a set of headline indicators to assess the progress made towards this target. DIVERSITY will make a contribution to the required monitoring efforts that will help us to determine whether we are making progress and which management and policy measures are most effective and thereby support decision-making," the UNCBD Secretariat Robert Hoft said.........

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January 9, 2007, 9:05 PM CT

Forest Fires Release Mercury

Forest fires release more mercury into the atmosphere than previously recognized, a multidisciplinary research project at the University of Michigan suggests.

The study, which has implications for forest management and global mercury pollution, was published online today (Jan. 9) in the journal Global Biogeochemical Cycles.

Doctoral student Abir Biswas, the paper's lead author, came up with the idea for the project when he was a student at U-M's Camp Davis Rocky Mountain Field Station near Jackson Hole, Wyoming. Wildfires were burning all around the station that summer, and smoke blanketed the camp. Around that time, Biswas happened to read a new scientific paper suggesting the possible role of fires in global mercury emissions.

"There I was, watching forest fires around our field camp, and it seemed like the ideal place to study the problem," he said.

The study Biswas read investigated mercury emissions from the combustion of foliage at locations around the USA and extrapolated to estimate mercury release during forest fires. "I'm interested in earth surface geochemistry so I wanted to approach the question differently," Biswas said.

Over the next two summers, under the direction of U-M professor Joel Blum, Biswas collected core samples of forest soil from burned and unburned areas, using sections of PVC pipe sharpened at one end to obtain the cylindrical samples. He and Blum also collaborated with U-M professor Gerald Keeler and former research scientist Bjorn Klaue to take air samples at Camp Davis-measuring mercury and trace metals over two summers-which provided the researchers with a picture of the atmospheric background on which the fires were superimposed.........

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