Deep-sea Corals May Be Oldest Living Marine Organism

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ScienceDaily (Mar. 25, 2009) — Deep-sea corals from about 400 meters off the coast of the Hawaiian Islands are much older than once believed and some may be the oldest living marine organisms known to man.

Researchers from Lawrence Livermore, Stanford University and the University of California at Santa Cruz have determined that two groups of Hawaiian deep-sea corals are far older than previously recorded.
Using the Lab's Center for Accelerator Mass Spectrometry, LLNL researchers Tom Guilderson and Stewart Fallon used radiocarbon dating to determine the ages of Geradia sp., or gold coral, and specimens of the deep-water black coral, Leiopathes sp. The longest lived in both species was 2,740 years and 4,270 years, respectively. At more than 4,000 years old, the deep-water black coral is the oldest living skeletal-accreting marine organism known.
“And to the best of our knowledge, the oldest colonial organism yet found,” Guilderson said. “Based on the carbon 14, the living polyps are only a few years old, or at least their carbon is, but they have been continuously replaced for centuries to millennia while accreting their underlying skeleton.”
The research appears in the March 23 early online edition of the Proceedings of the National Academy of Sciences.
Using a manned deep-sea research submersible, the team used samples that were individually collected from the Makapuu and Lanikai deep-sea coral beds off the coast of Oahu, Keahole Point deep-sea coral bed off the coast of the Big Island and Cross Seamount about 100 miles south of Oahu.
Carbon dating uses radiocarbon (carbon 14) to date the age of an object. Radiocarbon is the most widely used geochronological tool in the earth sciences for the late Quaternary (the last 50,000 years).
Earlier radiocarbon studies showed that individual gold coral colonies from the Atlantic and Pacific oceans have life spans of 1,800 to 2,740 years, but the results remain contentious with some biologists. In particular, some have questioned whether the corals feed on re-suspended sediment (which could be old) and not on recently photosynthesized carbon that falls through the water column, or that they grew faster and then stopped growing when they reached a certain size.
To answer these questions, the group analyzed not only polyps (the living animals that make up corals) but a branch of one specimen.
The living animals had the same carbon 14 concentration as the overlying surface water. This shows that the carbon in the polyps was recently photosynthesized in the surface prior to being “eaten” by the polyps. The skeleton's carbon 14 concentration mimicked that of the overlying surface water's 'post-bomb' time series: the time since the late 1950s when the testing of nuclear weapons augmented the natural abundance of carbon 14 in the atmosphere.
The radial growth rate during the last 50 years is similar to the long-term growth rate of the 300-year branch. The radial growth rate also is consistent with that derived from larger fossil samples. The radial growth rate is similar within a rather small range of tens of microns per year for all specimens analyzed.
In the recent research, the Geradia coral was assumed to be much younger when amino acid and growth band methods were used. With radiocarbon dating, the average life span of the analyzed specimens is 970 years and ranges from about 300 years for a small branch (with a radius of 11 millimeters) to about 2,700 years (with a radius of 38 mm).
“These ages indicate a longevity that far exceeds previous estimates,” Guilderson said. “Many of the Geradia samples that we have analyzed are branches, not the largest portions of the colony and so the ages may not indicate how old the entire individual is.”
Hawaiian deep sea corals face direct threats from harvesting for jewelry and from commercial fisheries that trawl the ocean bottoms. In addition, the close relationship between deep sea corals (and the mid-water ecosystems) and ocean's surface means that they can be affected by natural and manmade changes in surface ocean conditions including ocean acidification, warming and altered stratification.
The antiquity of the coral is an additional call for action, Guilderson said.
“The extremely long life spans reinforce the need for further protection of deep-sea habitat” he said. “The research has already had an impact for activities in Hawaiian waters where a harvesting and fishing moratorium has been enacted to protect certain areas. There are similar habitats in international waters and it is hoped that the results will provide the scientific basis for agreements under the Law of the Sea, and United Nations Environment Programme.”
Journal reference:
E. Brendan Roark, Thomas P. Guilderson, Robert B. Dunbar, Stewart J. Fallon, and David A. Mucciarone. Extreme longevity in proteinaceous deep-sea corals. Proceedings of the National Academy of Sciences, 2009; DOI: 10.1073/pnas.0810875106
Adapted from materials provided by DOE/Lawrence Livermore National Laboratory.

Earliest Evidence Of Domesticated Maize Discovered: Dates Back 8,700 Years

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ScienceDaily (Mar. 25, 2009) — Maize was domesticated from its wild ancestor more than 8700 years according to biological evidence uncovered by researchers in the Mexico's Central Balsas River Valley. This is the earliest dated evidence -- by 1200 years -- for the presence and use of domesticated maize.

According to Ranere, recent studies have confirmed that maize derived from teosinte, a large wild grass that has five species growing in Mexico, Guatemala and Nicaragua. The teosinte species that is closest to maize is Balsas teosinte, which is native to Mexico's Central Balsas River Valley.
"We went to the area where the closest relative to maize grows, looked for the earliest maize and found it," said Ranere. "That wasn't surprising since molecular biologists had determined that Balsas teosinte was the ancestral species to maize. So it made sense that this was where we would find the earliest domestication of maize."
The study began with Piperno, a Temple University anthropology alumna, finding evidence in the form of pollen and charcoal in lake sediments that forests were being cut down and burned in the Central Balsas River Valley to create agricultural plots by 7000 years ago. She also found maize and squash phytoliths -- rigid microscopic bodies found in many plants -- in lakeside sediments.
Ranere, an archaeologist, joined in the study to find rock shelters or caves where people lived in that region thousands of years ago. His team carried out excavations in four of the 15 caves and rock shelters visited in the region, but only one of them yielded evidence for the early domestication of maize and squash.
Ranere excavated the site and recovered numerous grinding tools. Radiocarbon dating showed that the tools dated back at least 8700 years. Although grinding tools were found beneath the 8700 year level, the researchers were not able to obtain a radiocarbon date for the earliest deposits. Previously, the earliest evidence for the cultivation of maize came from Ranere and Piperno's earlier research in Panama where maize starch and phytoliths dated back 7600 years.
Ranere said that maize starch, which is different from teosinte starch, was found in crevices of many of the tools that were unearthed.
"We found maize starch in almost every tool that we analyzed, all the way down to the bottom of our site excavations," Ranere said. "We also found phytoliths that comes from maize or corn cobs, and since teosinte doesn't have cobs, we knew we had something that had changed from its wild form."
Ranere said that their findings also supported the premise that maize was domesticated in a lowland seasonal forest context, as opposed to being domesticated in the arid highlands as many researchers had once believed.
"For a long time, I though it strange that researchers argued about the location and age of maize domestication yet never looked in the Central Balsas River Valley, the homeland for the wild ancestor," said Ranere. "Dolores was the first one to do it.'
In addition to Ranere and Piperno, other researchers in the study included Irene Holst of the Smithsonian Tropical Research Institute, Ruth Dickau of Temple, and Jose Iriarte of the University of Exeter. The study was funded by the National Science Foundation, National Geographic Society, Wenner-Gren Foundation, Smithsonian National Museum of Natural History, Smithsonian Tropical Research Institute and the Temple University College of Liberal Arts.
Journal references:
Anthony Ranere, Dolores Piperno et al. The Cultural and chronological context of early Holocene maize and squash domestication in the Central Balsas River Valley, Mexcio. PNAS, March 24, 2009
Anthony Ranere, Dolores Piperno et al. Starch grain and phytolith evidence for early ninth millennium B.P. maize from the Central Balsas River Valley, Mexico. PNAS, March 24, 2009
Adapted from materials provided by Temple University.

Mount Redoubt Volcano In Alaska Erupts Explosively

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ScienceDaily (Mar. 23, 2009) — Alaska's Mount Redoubt Volcano has erupted, spewing ash thousands of feet into the air.

The volcano, 106 miles southwest of Anchorage, erupted explosively on March 22, 2009, at approximately 10:38 PM AKDT, sending a cloud of volcanic ash to an estimated 50,000 feet above sea level. Scientists from the Alaska Volcano Observatory (AVO) are monitoring the volcano closely as the eruption continues.
Ash plumes generated by the explosive bursts are drifting north-northeast. Ash fall has been reported in Skwentna and the Chuitna area.
The eruption follows an increase March 15 of seismic activity at Mount Redoubt, when approximately four hours of continuous volcanic tremor ensued. The onset of the tremor was associated with a small explosion that produced a plume of gas and ash that rose to about 15,000 feet above sea level and deposited a trace amount of ash over the summit-crater floor and down the south flank of the volcano to about 3,000 feet.
AVO's dynamic website (http://www.avo.alaska.edu/) contains extensive information about present and past volcanic activity in Alaska and is increasingly popular as a destination for real-time data about Alaska's restless volcanoes.
The Alaska Volcano Observatory is a cooperative program of the U.S. Geological Survey, the University of Alaska Fairbanks Geophysical Institute, and the Alaska Division of Geological and Geophysical Surveys.
Adapted from materials provided by U.S. Geological Survey.

American Birds Sending Troubling Message About The Environment

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ScienceDaily (Mar. 23, 2009) — A new report based on 40 years of data analysed by the U.S. Fish and Wildlife Service, U.S. Geological Survey, state government wildlife agencies, and non-governmental organizations including Audubon (BirdLife in the USA), shows that birds are sending an important and troubling message about the state of the environment.

The report also shows that investment in conservation works, exemplified by the remarkable recoveries of waterfowl after more than 30 million acres of wetlands were restored and managed.
The U.S. State of the Birds report offers heartening evidence that strategic land management and conservation action can reverse declines of birds.
Wetlands: Although many wetland birds show troubling declines, conservation programs have protected millions of acres and contributed to thriving populations of hunted waterfowl, herons, egrets, and other birds. Lesser Scaup Aythya affinis, Northern Pintail Anas acuta, and several sea ducks are showing troubling declines, but most geese are increasing dramatically and many ducks have held steady.
Waterfowl: On the whole, 39 species of hunted waterfowl have increased by more than 100% during the past 40 years. Successful waterfowl conservation is a model for widespread habitat protection.
"By bringing together the data, the analytical expertise and the combined voices of government and non-governmental organisations, this new U.S. State of the Birds Report brings new power to the essential message the birds are conveying", said John Flicker, President, National Audubon Society.
The report also reveals sobering declines of bird populations during the past 40 years - a warning signal of the failing health of ecosystems.
Hawaiian Islands: Threatened by habitat destruction, invasive species, and disease, nearly all native Hawaiian bird species are in danger of extinction if urgent conservation measures are not implemented immediately. Since humans colonized the islands in 300 AD, 71 Hawaiian bird species have gone extinct; 10 others have not been seen in as long as 40 years.
Oceans: At least 39% of U.S. bird species restricted to ocean habitats are declining and almost half are of conservation concern, indicating deteriorating ocean conditions. Management policies and sustainable fishing regulations are essential to ensure the health of oceans.
Coasts: Half of all coastally migrating shorebirds have declined, indicating stress in coastal habitats besieged by development, disturbance, and dwindling food supplies.
Grasslands: The grassland bird indicator shows nearly a 40% decline in the past 40 years, based on birds that breed exclusively in grasslands. Farm conservation programs provide millions of acres of protected grasslands that are essential for the birds in a landscape where little native prairie remains.
Flicker concludes, "The birds are sending us a wake-up call that the habitat destruction, climate change and shortsighted environmental policies of the past are combining to take a serious toll. We must address the warming of our climate and the loss of vital habitat through policy and on-the ground action at every level. This report makes clear the need and for urgent individual, collective and government action, but leaves little doubt that taking that action can make a difference. Audubon has sent this message before, and now, thanks to all who played a role in the 2009 U.S. State of the Birds Report, the birds’ warning will be heard by more Americans than ever before – including our representatives in Congress and in our state capitols, and policy-makers in our communities."
Full report.
Adapted from materials provided by BirdLIfe International.

New 'Green' Pesticides Are First To Exploit Plant Defenses In Battle Of The Fungi

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ScienceDaily (Mar. 23, 2009) — Exploiting a little-known punch/counterpunch strategy in the ongoing battle between disease-causing fungi and crop plants, scientists in Canada are reporting development of a new class of "green" fungicides that could provide a safer, more environmentally-friendly alternative to conventional fungicides.

They will report on the first pesticides to capitalize on this unique defensive strategy March 23 in Salt Lake City, Utah, at the 237th National Meeting of the American Chemical Society.
Developed with sustainable agriculture in mind, the new fungicides — called "paldoxins" — could still do the work of conventional pesticides, helping to protect corn, wheat and other crops. These crops increasingly are used not just for food, but to make biofuels. The new fungicides also could help fight the growing problem of resistance, in which plant pests shrug off fungicides, the researchers suggest.
Most fungicides today are made based on chemicals that can kill potentially beneficial organisms and have other adverse environmental effects. The new materials are more selective, stopping fungi that cause plant diseases without harming other organisms. They work in a unique way, disrupting a key chemical signalling pathway that the fungi use to breakdown a plant's normal defenses. As a result, the plants boost their natural defenses and overcome fungal attack without harming people and the environment, the researchers say.
"Conventional fungicides kill constantly," explains study leader Soledade Pedras, Ph.D., a professor of chemistry at the University of Saskatchewan in Canada. "Our products only attack the fungus when it's misbehaving or attacking the plant. And for that reason, they're much safer."
Researchers have known for years that many plants have a defense mechanism that involves production of natural chemicals, called phytoalexins, to kill disease-causing fungi. The fungus, however, fights back. It releases enzymes that detoxify, or destroy, the phytoalexin, leaving the plant vulnerable to the fungi's attack.
To take advantage of that punch-counterpunch strategy, Pedras and her colleagues proposed the development of new anti-fungal agents to block the fungi's destruction of phytoalexins. They termed these new agents paldoxins, short for phytoalexin detoxification inhibitors.
Pedras discovered those agents after screening broccoli, cauliflower, mustard greens and other plants in the so-called "crucifer family." They discovered the most powerful phytoalexin in a flowering plant called camelina or "false flax." In laboratory tests, camelina phytoalexins blocked detoxifying enzymes produced by a wide variety of fungi.
"We found that many fungi couldn't degrade this chemical," says Pedras. "So that's what we used to design synthetic versions that were even stronger than the original."
The researchers now have developed six different synthetic versions of the paldoxins, which are essentially potent inhibitors of fungal enzymes.
The researchers have successfully tested the synthetic paldoxins in the lab on several crucifer plants, including rapeseed plants and mustard greens. Pedras' group plan field tests of their new fungicides on other important crop varieties. In the future, a similar strategy will be applied to grasses such as wheat, rye, and oat. These grassy plants tend to be more difficult to protect with fungicides than broccoli and related veggies, the researchers say.
If studies continue to show promise, the paldoxins could be marketed quickly, within a few years, Pedras says. The new fungicides could be applied like conventional pesticides.
The Natural Sciences and Engineering Research Council of Canada and the University of Saskatchewan funded the study.
Adapted from materials provided by American Chemical Society, via EurekAlert!, a service of AAAS.

Flies May Spread Drug-resistant Bacteria From Poultry Operations

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ScienceDaily (Mar. 23, 2009) — Researchers at the Johns Hopkins Bloomberg School of Public Health found evidence that houseflies collected near broiler poultry operations may contribute to the dispersion of drug-resistant bacteria and thus increase the potential for human exposure to drug-resistant bacteria. The findings demonstrate another potential link between industrial food animal production and exposures to antibiotic resistant pathogens.

Previous studies have linked antibiotic use in poultry production to antibiotic resistant bacteria in farm workers, consumer poultry products and the environment surrounding confined poultry operations, as well as releases from poultry transport.
“Flies are well-known vectors of disease and have been implicated in the spread of various viral and bacterial infections affecting humans, including enteric fever, cholera, salmonellosis, campylobacteriosis and shigellosis,” said lead author Jay Graham, PhD, who conducted the study as a research fellow with Bloomberg School’s Center for a Livable Future. Our study found similarities in the antibiotic-resistant bacteria in both the flies and poultry litter we sampled. The evidence is another example of the risks associated with the inadequate treatment of animal wastes.”
“Although we did not directly quantify the contribution of flies to human exposure, our results suggest that flies in intensive production areas could efficiently spread resistant organisms over large distances,” said Ellen Silbergeld, PhD, senior author of the study and professor in the Bloomberg School of Public Health’s Department of Environmental Health Sciences.
Graham and his colleagues collected flies and samples of poultry litter from poultry houses along the Delmarva Peninsula—a coastal region shared by Maryland, Delaware and Virginia, which has one of the highest densities of broiler chickens per acre in the United States. The analysis by the research team isolated antibiotic-resistant enterococci and staphylococci bacteria from both flies and litter. The bacteria isolated from flies had very similar resistance characteristics and resistance genes to bacteria found in the poultry litter.
Flies have ready access to both stored poultry waste and to poultry houses. A study by researchers in Denmark estimated that as many as 30,000 flies could enter a poultry house over the course of six week period.
Additional authors of “Antibiotic-resistant enterococci and staphylococci isolated from flies collected near confined poultry feeding operations” are Lance Price, Sean Evans and Thaddeaus Graczyk. The study is published in the April 2009 issue of Science of the Total Environment.
The research was funded by a grant from the Johns Hopkins Center for a Livable Future.
According to Robert Lawrence, MD, director of the Center for a Livable Future, confined animal feeding operations—where thousands of animals are crowded together and are fed antibiotics for growth promotion—create the perfect environment for selection of bacteria that are resistant to antibiotics. “Antimicrobials are among the most important developments of the twentieth century in managing infectious diseases in people. We can’t afford to squander them by using them as growth promoters in industrial food animal production. The increase in antibiotic-resistant bacteria is a major threat to the health of the public, and policymakers should quickly phase out and ban the use of antimicrobials for non-therapeutic use in food animal production,” said Lawrence.
Adapted from materials provided by Johns Hopkins University Bloomberg School of Public Health.

Gliding Bristletails Give Clues On Evolution Of Flight

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ScienceDaily (Mar. 23, 2009) — Dr. Stephen P. Yanoviak of the University of Arkansas at Little Rock has published new research in the Royal Society’s Biology Letters providing insight on the evolution of winged flight.

Yanoviak and his co-authors, Mike Kaspari of the University of Oklahoma and Robert Dudley at the University of California-Berkeley, observed how arboreal bristletails -- evolutionary precursors to insects -- in the Amazon Forest can leap tree trunk to tree trunk by manipulating a filament on their bodies as a primitive rudder system.
“Directed aerial descent, such as gliding and maneuvering, may be an important stage in the evolution of winged flight,” Yanoviak said.
The scientists conducted drop tests in tropical forests in Peru, the Smithsonian Tropical Research Institute at Barro Colorado Island, Panama; and Gamba, Gabon, from 2005 to 2007. They quantified the directed descent behavior of jumping bristletails by dropping individuals from tree branches while perched high above the ground in the rainforest canopy.
The bristletails were dusted with orange fluorescent power to track their movement. Approximately 90 percent of them successfully landed on an adjacent tree branch. When the median caudal filament – the structure thought to control its gliding ability – was removed, the percentage of tree trunk landings was significantly reduced.
“The existence of aerial control ability in a wingless insect and its habitat in trees is consistent with the hypothesis of a terrestrial origin for winged flight in insects,” Yanoviak said.
Last year, Yanoviak, Kaspari and Dudley, in collaboration with nematode specialist George Poinar, Jr. at Oregon State University, made waves in the bug world with their research about a parasite that can so dramatically transform the look of its host – an ant – that the ant comes to resemble a juicy red berry, ripe for the picking in the jungles of Central and South America.
Their research, first published in the American Naturalist, may be the first example of how a lowly parasite can manipulate the look of a host to such an extent that birds can’t tell the difference between a red berry and an ant.
Journal references:
Stephen P Yanoviak, Michael Kaspari, Robert Dudley. Gliding hexapods and the origins of insect aerial behaviour. Biology Letters, 2009; DOI: 10.1098/rsbl.2009.0029
S. P. Yanoviak, M. Kaspari, R. Dudley, and G. Poinar Jr. Parasite%u2010Induced Fruit Mimicry in a Tropical Canopy Ant. The American Naturalist, 2008; 171 (4): 536-544 DOI: 10.1086/528968
Adapted from materials provided by University of Arkansas at Little Rock.

New Tracking Tags Are Providing Fish-eye Views Of Ways To Manage Depressed Fisheries

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ScienceDaily (Mar. 21, 2009) — New tracking and observing technologies are giving marine conservationists a fish-eye view of conditions, from overfishing to climate change, that are contributing to declining fish populations, according to a new study.

Until recently, scientists provided fishery managers only such limited data as stock counts and catch estimates, said Charles Greene, Cornell professor of ocean sciences and lead author of the study published in the March issue (Vol. 22, No. 1) of the journal Oceanography.
But new advances in miniature sensors and fish-tracking tags, ocean observing systems and computer models are providing much more insight into environmental changes and how fish are responding behaviorally and biologically to such changes, thereby enabling better modeling to predict fish populations. As a result, researchers are making more informed recommendations for strategies to address falling fish populations.
Obtaining real-world data is essential, stressed Greene. "Many of the commercial fish populations in the world are pretty highly depressed. It's a bleak picture in terms of the status of many wild marine fish populations."
For example, the Atlantic bluefin tuna fishery, which can garner more than $15,000 per fish, is managed as two separate stocks, one in the eastern Atlantic basin, with a breeding ground in the Mediterranean, and another in the western basin, with a breeding ground in the Gulf of Mexico. Both stocks are not sustainably harvested, and the western population has declined by roughly 90 percent over the last 25 years, despite strict quotas.
A project known as Tag A Giant (TAG) uses an implanted tag in the tuna to record external pressure, internal and external temperature and ambient light, though the tuna must be recaptured to recover these data. TAG also uses a pop-up tag that is attached to the tuna but self releases, floats to the surface and transmits data on each tuna's external conditions via satellite. The tags help researchers estimate geo-locations and track each fish's daily movements.
According to the study, new TAG data have revealed that as tuna grow, they swim all over the Atlantic, and that the fish from the two stocks commingle. Past failure to account for this mixing of the two stocks has led to unsustainable management practices, especially for tuna originating in the Gulf of Mexico, Greene said. New strategies must account for mixing stocks, since fishing in the eastern basin has undermined the quotas and recovery plans for the western basin stock.
With regard to Pacific salmon, fishery managers have assumed that juveniles traveling from spawning grounds to the ocean face great mortality along heavily dammed rivers, like the Snake-Columbia river system, than in undammed rivers. Thus, they collected juveniles and transported them past the Snake-Columbia river system's eight dams before releasing them downstream. However, adult salmon numbers returning from the ocean did not increase.
The Pacific Ocean Shelf Tracking project, which tagged juvenile fish, showed that the smaller, less developed fish were dying in high numbers in the lower river and coastal ocean. This kind of knowledge will help managers test and adapt their strategies in wild-fish systems, which historically have been hard to monitor.
This work was supported by more than a dozen entities, including the Gordon and Betty Moore, Packard, Monterey Bay Aquarium and Sloan foundations, and the Bonneville Power Administration.
Adapted from materials provided by Cornell University.

Carbonated Oceans

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ScienceDaily (Mar. 20, 2009) — Like a sinkful of hard water deposits suddenly doused with vinegar, the shells of tiny marine snails in Victoria Fabry’s test tanks don’t stand a chance.

Fabry, a biological oceanographer and visiting researcher at Scripps Institution of Oceanography at UC San Diego, studies the effects of ocean acidification on the molluscs known as pteropods. In one experiment, only 48 hours of exposure to slightly corrosive seawater caused normally smooth shells to become frayed at the edges on their way to eventual dissolution, severely diminishing their owners’ chances of survival.
The acidity of the water in Fabry’s lab had been ratcheted up to levels that might not be seen until the end of the century, but she and other scientists fear that ongoing acidification of ocean water could be causing a slow-motion destruction of ocean ecosystems now.
The loading of carbon dioxide into oceans is a consequence of fossil fuel use that has only begun to be widely recognized as problematic in the past decade. Its subsequent effects on seawater chemistry have the potential to spread ecological disaster to a variety of industries dependent on the seas.
To understand what the world might expect, several Scripps research teams are drawing on the institution’s expertise in long-term climate data collection and on new technologies that will help them understand when, where, and how ocean chemistry changes when the seas are overwhelmed by increasing infusions of carbon dioxide. They are joining a growing number of international scientists who are turning their attention to the issue. Their collective hope is to understand whether the oceans are approaching a tipping point of widespread damage and to see what can be done to prevent it.
“We know the oceans are getting more acidic. We know lab experiments have shown that organisms find living more difficult as the CO2 increases,” said Scripps marine chemist Andrew Dickson, who is collaborating with Fabry to build a network of observing stations off the California coast. “Studies that can clarify how important this is for ecosystems remain to be designed and done.”
As humans burn oil and coal, carbon dioxide is released and accumulates in the atmosphere. A little less than half of it stays in the sky and about a third enters the oceans, dissolving into seawater at the ocean surface.
When ocean water absorbs CO2, the two react to form carbonic acid. The acid reacts with carbonate ions, making the ions less available in ocean waters to shell-forming organisms. Robbed of sufficient quantities of a main ingredient for their shells, these organisms may become less hardy and less able to replenish their numbers.
The trend scientists are seeing might seem small. The average pH of water at the ocean’s surface has fallen from 8.16 to 8.05 since the beginning of the Industrial Revolution and the advent of fossil fuel use. Pure water in comparison has a pH of 7.
But marine organisms that build shells have grown accustomed to a certain chemical background and they do not take such a decrease well — especially at the pace scientists are documenting. The rate of change that marine creatures have endured in fewer than three centuries is 100 times faster than the rate of change over the preceding 850,000 years. And once the lower pH water is present, it will be there for a long time because of the slow pace of ocean circulation. Dickson likens it to pouring cream in a cup of coffee and stirring it once every 1,000 years.
As a relatively well-studied example of acidification’s effects, the pteropod has become what ocean acidification researchers consider their canary in the coal mine. The snails, however, are not the only organisms that are sensitive. Nearly all marine life forms that build calcium carbonate shells are jeopardized by the rising acidity of the oceans. That long list includes corals as well as commercially important marine invertebrates such as abalone, sea urchins, clams, and mussels.
Even fishes might be susceptible to problems as carbonic acid amasses in their tissues. A new study led by Australia’s James Cook University found that acidification diminishes the ability of larval clownfish, the colorful species popularized in the film “Finding Nemo,” to use the olfactory cues they need to locate suitable habitats.
And though they are not themselves harvested as food, pteropods and other vulnerable zooplankton and phytoplankton have an indirect but profound value to fisheries, being a key part of the diet of pink salmon, mackerel, and cod.
Scientists are concerned less about a sudden mass die-off of shelled organisms than about a persistent assault on their health that won’t relent for centuries. Coral reefs, for instance, may reach the point at which they erode faster than they grow by the mid-21st Century, according to some estimates.
“These organisms are likely to have difficulty in secreting their shells in a fully functional way which could alter their reproductive success and their population abundances,” said Mark Ohman, a Scripps biological oceanographer who recently added carbon dioxide measurements to the data he regularly collects through the California Current Ecosystem Long-Term Ecological Research (LTER) program led by Scripps.
But at this point, only the chemical basics of acidification are well-understood. New discoveries have the feel of breaking news. Richard Feely and other researchers at NOAA’s Pacific Marine Environmental Laboratory made headlines in 2008 when they discovered that masses of acidic water were encroaching on the continental shelf off the West Coast to a surprising extent. The onslaught appears to change throughout the year and scientists still do not understand fully how much pH fluctuates seasonally in coastal waters. They also aren’t sure how far masses of lower pH water stretch geographically.
Acidification’s potential threat to the California Current, which encompassed most of the area studied by Feely, is making the economically vital ocean region a research target zone. Because Scripps is the home of a key repository of long-term data about the current and greenhouse gases, the institution is becoming a center of ocean acidification studies.
Two key monuments to fastidious long-term data gathering reside at Scripps. The California Cooperative Oceanic Fisheries Investigations (CalCOFI) was launched just after World War II after the West Coast sardine fishery collapsed. It provides a continuous record of temperature, plankton abundance, and other key indicators of the state of the ocean. For most of the program’s existence, these data have been gathered quarterly. In 1958, Charles David Keeling initiated measurements of atmospheric carbon dioxide levels at a weather station atop Hawaii’s Mauna Loa. Monthly averages are plotted to this day on the iconic graph known as the Keeling Curve.
Both time series and their offshoots help characterize trends in ocean acidification that were present before scientists knew to look for them. Ohman notes that records from CalCOFI are providing “six decades of context” in the form of proxy data ranging from temperature to nutrient concentration. This information will help scientists reconstruct the rate of change in the California Current’s acidity. Scientists also hope that the record can tell them not only about acidity trends but how climate cycles like El Niño cause such trends to fluctuate.
The Keeling Curve provides indirect evidence that not all human carbon dioxide emissions remain in the atmosphere and present-day researchers credit that record for prompting scientists to look for signs of acidification in the oceans. Papers about the phenomenon first started appearing in the 1970s and a decade later, Keeling started a similar time-series of seawater carbon dioxide content and alkalinity levels near Bermuda. Subsequent work by Dickson established the reference standards for measurements of carbon dioxide content and alkalinity of ocean water that have helped researchers uniformly measure trends in acidification.
“The Mauna Loa CO2 time series is the most famous example of what impact you get if you collect very long time series,” said Uwe Send, a Scripps physical oceanographer collaborating with Ohman, Fabry, and Dickson, “and we are trying to do the same kind of thing in the ocean in important and representative or critical locations.”
Last November, Send, Ohman and NOAA researcher Chris Sabine deployed a mooring with carbon dioxide sensors 250 kilometers (155 miles) southwest of Point Conception, Calif. Contributions from those sensors and several others attached to the mooring feed into data collected by the LTER project, a National Science Foundation-supported program building from CalCOFI that aims to answer scientists’ questions about the interplays between California Current organisms and their changing ocean environment.
Fabry and Dickson are leading efforts to deploy two more carbon dioxide sensors this year, one in Carlsbad, Calif., and the other off the Northern California city of Trinidad. The latter launch is part of a California Ocean Protection Council-funded project in which Fabry will conduct complementary tests in the lab to understand how varying pH levels affect marine organisms at different stages of development.
The moored sensors off California are a small contribution to much larger efforts on the global scale. Send is co-leading the international OceanSITES program, which is building a network of stations around the world oceans to collect long time series of changes in ocean climate, carbon, and ecosystems, including acidification.
It took 50 years of case-building on the part of scientists before the world began to respond aggressively to the global warming threat resulting from atmospheric CO2 increases. Because the chemical consequences of adding fossil fuel-derived greenhouse gases is indisputable, Fabry and Dickson hope that the wait for prudent actions will be a shorter one when it comes to the seas.
“What we’re doing now will have impacts in our lifetime,” said Fabry. “We are certainly leaving a legacy to our children and grandchildren and they’re going to ask what did we do about it.”
Adapted from materials provided by University of California, San Diego, via Newswise.

Not All Bats Land The Same Way

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ScienceDaily (Mar. 21, 2009) — People have always been fascinated by bats, but the scope of that interest generally is limited to how bats fly and their bizarre habit of sleeping upside down. Until now, no one had studied how bats arrive at their daytime perches.

A Brown University-led research team is the first to document the landing approaches of three species of bats — two that live in caves and one that roosts in trees. What they found was surprising: Not all bats land the same way.
“Hanging upside down is what bats do,” said Daniel Riskin, a postdoctoral researcher in the Ecology and Evolutionary Biology department at Brown and lead author on a paper published in the Journal of Experimental Biology. “We've known this. But this is the first time anyone has measured how they land.”
Using sophisticated motion capture cameras in a special flight enclosure, the team filmed each species of bat as it swooped toward a latticed landing pad and landed on it. Cynopterus brachyotis, a tree-roosting bat common in tropical parts of southeast Asia, executed a half-backflip as it swooped upward to the landing site, landing as its hind legs and thumbs touched the pad simultaneously — a four-point landing, the group observed.
The landing is hard, Riskin noted, with an impact force more than four times the species’ body weight.
The team then turned its attention to two cave-roosting species, Carollia perspicillata and Glossophaga soricina. These bats, common in Central and South America, approach their landing target with a vertical pitch and then, at the last instant, yaw to the left or to the right — executing a cartwheel of sorts — before grasping the landing pad with just their hind legs.
The two-point landing is much gentler than the impact force exerted by the tree-roosting bats, the researchers observed; the cave-roosting bats have a landing impact force of just one-third of their body weight.
There are about 1,200 recognized bat species worldwide, so Riskin was cautious about not drawing any grand conclusions. Still, he said, the fact that the team has documented that bats land differently could open new insights into a species that makes up roughly one-fifth of all mammals on earth.
Other Brown researchers who worked on the paper include Sharon Swartz, associate professor of biology; Tatjana Hubel, a postdoctoral researcher; and Joseph Bahlman, a graduate student. John Ratcliffe, a biologist at the University of Southern Denmark, and Thomas Kunz, a biologist at Boston University, contributed to the paper.
The research was funded by the U.S. National Science Foundation, The U.S. Air Force Office of Scientific Research, Sigma Xi in the United States, The Natural Sciences and Engineering Research Council of Canada, and the Danish Natural Sciences Research Council.
Journal reference:
Daniel K. Riskin, Joseph W. Bahlman, Tatjana Y. Hubel, John M. Ratcliffe, Thomas H. Kunz, and Sharon M. Swartz. Bats go head-under-heels: the biomechanics of landing on a ceiling. Journal of Experimental Biology, 2009; 212 (7): 945 DOI: 10.1242/jeb.026161
Adapted from materials provided by Brown University.

New View Of Oceanic Phytoplankton

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ScienceDaily (Mar. 21, 2009) — Phytoplankton comprise the forests of the sea, and are responsible for providing nearly half of the oxygen that sustains life on Earth including our own. However, unlike their counterparts on land, the marine plants are nearly exclusively microscopic in size, and mostly out of human sight. Consequently, we are still in a very early stage of understanding even the most basic aspects of phytoplankton biology and ecology.

In a new paper published in Nature, an international team of scientists, including two University of Hawaii at Manoa (UHM) microbial oceanographers, describe a novel strategy for phytoplankton growth in the vast nutrient-poor habitats of tropical and subtropical seas. The research team was led by Benjamin Van Mooy of the Woods Hole Oceanographic Institution on Cape Cod, MA, with key contributions by UHM scientists Michael Rappé and David Karl of the School of Ocean and Earth Science and Technology (SOEST) and UH's new Center for Microbial Oceanography (C-MORE).
Until now, it was thought that all cells are surrounded by membranes containing molecules called phospholipids – oily compounds that contain phosphorus, as well as other basic elements including carbon and nitrogen. These phospholipids are fundamental to the structure and function of the cell and for this reason had been thought to be an indispensable component of life. Phospholipids are one of several classes of molecules that contain the element phosphorus, which has been shown to be in very short supply in many marine ecosystems. The deep sea contains ample phosphorus but delivery to the surface waters where photosynthesis occurs is limited by temperature-induced stratification and the inability to mix the ocean to depths where phosphorus is available. Indeed, research conducted at Station ALOHA near Hawaii during the past two decades has shown that phosphorus is rapidly becoming less abundant in the stratified regions of the North Pacific Ocean, possibly a result of changes in the marine habitat due to greenhouse gas warming.
Van Mooy and colleagues discovered that phytoplankton in the open ocean may be adapting to the low levels of phosphorus by making a fundamental change to their cell structure. Rather than synthesizing the phosphorus-requiring phospholipids for use in their membranes, the plants appear to be using non-phosphorus containing "substitute lipids" that use the nearly unlimited element sulfur also found in seawater instead of phosphorus. These substitute sulfolipids apparently allow the plants to continue to grow and survive under conditions of phosphorus stress, a unique strategy for life in the sea.
To test the generality of this biochemical strategy, the authors compared the response of the phytoplankton communities in different ocean basins that experience varying levels of phosphorus stress. In regions where phosphorus stress is extreme, such as the area dubbed the Sargasso Sea in the central North Atlantic Ocean, phospholipids were nearly nonexistent. By comparison, in the South Pacific Ocean, where sufficient phosphorus exists, there were large amounts of phospholipids. The region around Hawaii was intermediate, which is consistent with the long-term data sets from the Hawaii Ocean Time-series program showing that phosphorus is still measurable but is disappearing from the surface waters at an alarming rate.
One prediction from this initial study is that the phytoplankton in Hawaiian waters are likely to become more like those in the Sargasso Sea over time as phosphorus supplies dwindle further. To date, the ability to synthesize substitute lipids appears to be restricted to the phytoplankton; heterotrophic bacteria and other organisms must have a different strategy for survival, or none at all. This has implications for the future structure, biodiversity and function of Hawaiian marine ecosystems, including fish production and long-term carbon dioxide sequestration.
Journal reference:
Benjamin A. S. Van Mooy, Helen F. Fredricks, Byron E. Pedler, Sonya T. Dyhrman, David M. Karl, Michal Koblíek, Michael W. Lomas, Tracy J. Mincer, Lisa R. Moore, Thierry Moutin, Michael S. Rappé & Eric A. Webb. Phytoplankton in the ocean use non-phosphorus lipids in response to phosphorus scarcity. Nature, 2009; 458 (7234): 69 DOI: 10.1038/nature07659
Adapted from materials provided by University of Hawaii at Manoa, via EurekAlert!, a service of AAAS.

One Quarter Of The World’s Population Depends On Degrading Land

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ScienceDaily (Mar. 20, 2009) — A new study published in the journal Soil Use and Management attempts for the first time to measure the extent and severity of land degradation across the globe and concludes that 24% of the land area is degrading – often in very productive areas.

Land degradation - the decline in the quality of soil, water and vegetation – is of profound importance but until now there have been no consistent global data by which to assess its extent and severity. For nearly thirty years the world has depended on the Global Assessment of Soil Degradation (GLASOD) based on the subjective judgement of soil scientists who knew the conditions in their countries. GLASOD indicated that 15 per cent of the land area was degraded, but this was a map of perceptions, rather than measurement of land degradation.
The new study by Bai et al. measures global land degradation based on a clearly defined and consistent method using remotely sensed imagery. The results are startling. The new assessment indicates that 24 per cent of the land has been degraded over the period 1981-2003 - but there is hardly any overlap with the GLASOD area that recorded the cumulative effects of land degradation up to about 1990.
One of the authors, Dr David Dent of ISRIC - World Soil Information explains: “Degradation is primarily driven by land management and catastrophic natural phenomena.
Our study shows the extent and severity of land degradation measured in terms of loss of net primary productivity, making allowance for climatic variability. Overall, a quarter of the world’s population depends directly on these degrading areas. The worst-hit areas are Africa south of the Equator, SE Asia and S China. The worst-affected countries, with more than 50 per cent of territory degrading are, in Africa, the Congo, Zaire, Equatorial Guinea, Gabon, Sierra Leone, Zambia and the most affected (95 per cent degrading) Swaziland; in Asia, Myanmar, Malaysia, Thailand, Laos, Korea and Indonesia. In terms of the rural population affected, the greatest numbers are in China, with nearly half a billion, India, Indonesia, Bangladesh and Brazil. The usual suspects, such as the African Sahel and around the Mediterranean are much less affected.”
The resulting loss of carbon fixation from the atmosphere over the measured period amounts to a thousand million tonnes. At a shadow price of $50 per tonne, the loss of carbon fixed amounts to $50 billion – and the real cost is far greater in terms of emissions to the atmosphere through loss of soil organic carbon.
Comparison with land use reveals that 19% of the degrading area is cropland and 43% forest. Cropland occupies 12% of the land area and forest 28%, so both are affected disproportionately.
The study found only weak correlations between degrading land and rural population density and with biophysical factors such aridity. The researchers conclude that more detailed analysis of land use history is needed to uncover the underlying social and economic drivers of land degradation.
Adapted from materials provided by Wiley - Blackwell, via AlphaGalileo.

Biodiversity Found In Unexpected Regions: More Than 200 Plant Species Found In Semi-arid Rivers In South Eastern Spain

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ScienceDaily (Mar. 20, 2009) — The prevailing belief to date has been that the streams of south eastern Spain contained nothing of interest. However, a research project by the University of Murcia has shown that these ecosystems, which are unique in Europe, are home to great plant and animal biodiversity. This has enabled the research team to explode the myth that arid systems do not contain any organisms of interest, and to call for them to be protected because of their ecological value.

In general, semi-arid streams have low flow volume and little vegetation, and can seem to have minimal ecological value or interest. However, the reality is very different. Spanish scientists who have studied how they function at a global scale have found them to contain a greater number of species than those in wetter areas.
"We encountered a very high level of biodiversity, much higher than what we expected at the outset, and we realised that these systems function as refuges for biodiversity. In fact they contain a large variety of environments at micro-environment level", Marina Aboal, lead author of the study and a researcher at the University of Murcia, tells SINC.
The study is focused on the study of algal communities, and particularly of diatomeae (a class of microscopic, unicellular algae), since these organisms form the foundations of the entire ecosystem.
The biologists discovered more than 200 species of micro algae (which cannot be seen with the naked eye), some of which may be new to Science.
This finding is important because of the exceptional nature of this habitat in Europe. The south east of Spain, one of the most arid regions on the continent, is one of the few areas in Europe where semi-arid streams can commonly be found. These shelter "an extremely significant number of species, many of which are characteristic of these environments", says Aboal.
A unique ecological richness
The research team believes that these species of algae "deserve to be studied and included within conservation strategies", since they can adapt themselves to extreme conditions such as very high temperatures and high levels of evaporation and water salinity.
Failure to protect these ecosystems, which has been the situation to date, will mean "species will become extinct before we can even find and study them, or find out if they have any uses for us", says the botanist.
The experts stress that, since these are "humble and little known" ecosystems, information about the species that inhabit them is being lost. "The loss of species completely changes the way in which the river functions, and can cause chain reactions that lead to mini ecological catastrophe, with the loss of an ecosystem," warns Aboal.
Aside from being of ecological interest as the first link in the trophic chain, micro algae could also have "interesting" biotechnological applications. The expert says that if these are not protected and studied "we will never know whether they are useful". This is the great drama of extinction, with species disappearing before they can even be discovered.
The functioning of the entire system rests upon algae. These photosynthesising organisms are the primary producers, and form the foodstuff underpinning the entire ecological system in aquatic ecosystems. From an environmental point of view, they help to control the environmental quality of aquatic systems, and are essential for assessing their ecological status, or health.
Journal reference:
Ros et al. Biodiversity of diatom assemblages in a Mediterranean semiarid stream: implications for conservation. Marine and Freshwater Research, 2009; 60 (1): 14 DOI: 10.1071/MF07231
Adapted from materials provided by Plataforma SINC, via AlphaGalileo.

Major Losses For Caribbean Reef Fish In Last 15 Years

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ScienceDaily (Mar. 20, 2009) — By combining data from 48 studies of coral reefs from around the Caribbean, researchers have found that fish densities that have been stable for decades have given way to significant declines since 1995.

"We were most surprised to discover that this decrease is evident for both large-bodied species targeted by fisheries as well as small-bodied species that are not fished," said Michelle Paddack of Simon Fraser University in Canada. "This suggests that overfishing is probably not the only cause."
Rather, they suggest that the recent declines may be explained by drastic losses in coral cover and other changes in coral reef habitats that have occurred in the Caribbean over the past 30 years. Those changes are the result of many factors, including warming ocean temperatures, coral diseases, and a rise in sedimentation and pollution from coastal development. Overfishing has also led to declines of many fish species, and now seems to also be removing those that are important for keeping the reefs free of algae.
"All of these factors are stressing the reefs and making them less able to recover from disturbances such as hurricanes, which also seem to be occurring more frequently," Paddack said.
Scientists had previously documented historical declines in the abundance of large Caribbean reef fishes that probably reflect centuries of overexploitation. However, effects of recent degradation of reef habitats on reef fish had not been established before now.
In the new study, the research team compiled data on reef fish densities from 48 studies representing 318 reefs across the Caribbean from 1955 to 2007. Their analysis found that overall reef fish density has been declining significantly for more than a decade, at rates that are consistent across all sub-regions of the Caribbean basin. Specifically, they show losses in fish density of 2.7 to 6 percent per year.
Paddack said her study, which involved a very large team of scientists from around the globe, should serve as a call to action.
"If we want to have coral reefs in our future, we must ensure that we reduce damage to these ecosystems," she said. "On a personal level, this may mean not buying wild-caught aquarium fish and corals, not eating reef fish species that are declining, taking care not to anchor on reefs, and reducing our carbon emissions to help control climate change. But importantly, we need to let lawmakers and resource managers know that we care about these ecosystems and we need to push for changes in how they are managed."
The study appears online on March 19th in Current Biology, a Cell Press publication.
Journal reference:
Paddack et al. Recent Region-wide Declines in Caribbean Reef Fish Abundance. Current Biology, 2009; DOI: 10.1016/j.cub.2009.02.041
Adapted from materials provided by Cell Press, via EurekAlert!, a service of AAAS.

Is The Hippopotamus The Closest Living Relative To The Whale?

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ScienceDaily (Mar. 19, 2009) — Hippos spend lots of time in the water and now it turns out (or researchers argue), they are the closest living relative to whales. It also turns out, the two are swimming in a bit of controversy.

Jessica Theodor, an associate professor in the Department of Biological Sciences at the University of Calgary, and her colleague Jonathan Geisler, associate professor at Georgia Southern University are disputing a recent study that creates a different family tree for the hippo.
That research was published in Nature in December 2007 by J. G. M. Thewissen, a professor at Northeastern Ohio Universities College of Medicine, and his colleagues. Thewissen says that whales are more closely linked to an extinct pig-like animal, often known as India's pig or Indohyus, while hippos are closely related to living pigs.
But this isn't accurate according to Theodor.
"What Thewissen is saying is that Indohyus is the closest relative of whales - and we agree. Where we think he is wrong, is that he is saying that that hippos are more closely related to true pigs than they are to whales," says Theodor. "This contradicts most of the data from DNA from the last 12 or 13 years. Those data place hippos as the closest living relative to whales."
She says Thewissen did not use DNA evidence, instead used fossil evidence alone to create a family tree and reach the conclusion that hippos have more in common with pigs than whales.
"And the reason their tree is so different is simple: by excluding all the DNA information they left out all the data that shows a strong relationship between whales and hippos."
Theodor's rebuttal of Thewissen's work will appear in Nature on Thursday, March 19.
The controversy began after the new fossil of Indohyus, was discovered and written about by Thewissen and his group. This animal lived around 48 million years ago, lived in the water and fed on land.
When biologists study family trees, they traditionally rely on morphology, in other words, the shape of bones. More recently, the DNA revolution means that scientists can use DNA data as another tool to reconstruct family trees, but DNA data can't be used all the time because DNA is not available for most fossils.
"In order to get the best understanding, researchers combine the two sources of data in a single analysis. But what Thewissen and his group did, was leave one of the major ones out," says Theodor.
Before the widespread use of DNA data, hippos had been thought to be closely related to pigs, but DNA data show that whales are closely related to hippos. Geisler and Theodor argue that leaving out the DNA data not only ignores important information, it implies that the evolution of swimming evolved independently in hippos and whales, when it may have evolved only once in a common ancestor.
Adapted from materials provided by University of Calgary, via EurekAlert!, a service of AAAS.

Killing Young Fish Paradoxically Results In Population Growth, Study Finds

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ScienceDaily (Mar. 19, 2009) — If you kill more fish, the total population of the species declines. However, kill only small, young fish, the total number of small, young fish increases. This seemingly paradoxical conclusion has far reaching implications for the sustainable management of oceans, and is the result of a theoretical study conducted by a research team led by Prof. André de Roos of the Institute for Biodiversity and Ecosystem Dynamics (IBED), University of Amsterdam.

A follow up study conducted by the same team now provides experimental evidence to support their initial findings.
When fish are killed, by fishing or predation, a first obvious effect is that the total number of fish of the species in question declines. However, the removal of fish also results in less competition for food among the remaining individuals. For example, young, small fish, one can imagine that when a certain percentage of young small fish is selectively removed, the remaining ones have more food available to grow into bigger and stronger adults. These adults in turn, are able to produce more offspring, i.e. more young small fish, to compensate for the ones that were killed. In fact, the increased reproduction more than compensates for the number of small fish that were selectively removed in the first place.
This is a simplified version of the type of relationships that Prof. De Roos and his team revealed in a theoretical study that was published in the American Naturalist in 2007. The modeling study indeed predicted that selectively removing specimens of certain size classes not only results in compensation induced by changes in competition for resources, but in fact results in over-compensation.
The seemingly paradoxical implication is that selectively fishing away small, young fish results in an increase in the number of small, young fish. In a similar manner, the modeling study also predicted that the selective removal of large, adult individuals can lead to an increase in small, young fish densities. To test their predictions, Prof. De Roos and his team performed an experimental follow up study in Sweden that was recently concluded and supports their theoretical conclusions in all respects. This includes the specific example of selectively culling a certain percentage of small, young fish, which indeed was found to lead to an increase in their total numbers.
The results of the experimental study were published in the Proceedings of the National Academy of Science in February 2009.
Together, both studies show once more that marine food webs are very complicated and that interfering with them may lead to unanticipated results. However, they also show that by carefully studying the relationships, they can be understood and modeled. Both these conclusions have far reaching implications for the sustainable management of oceans. For example, in a forthcoming publication in the Canadian Journal for Fisheries and Aquatic Sciences it is shown that this type of overcompensation may prevent a marine reserve from functioning as a source of young fish. This latter is one way in which marine reserves were believed to contribute to a sustainable exploitation of marine fish stocks.
Journal references:
A. Schröder, L. Persson, and A. M. de Roos. Culling experiments demonstrate size-class specific biomass increases with mortality. Proceedings of the National Academy of Sciences, 2009; 106 (8): 2671 DOI: 10.1073/pnas.0808279106
Tobias van Kooten, Lennart Persson, and André M. de Roos. Size-Dependent Mortality Induces Life-History Changes Mediated through Population Dynamical Feedbacks.. The American Naturalist, 2007; 170 (2): 258 DOI: 10.1086/518947
Adapted from materials provided by Universiteit van Amsterdam (UVA), via AlphaGalileo.

Long, Sexy Tails Not A Drag On Male Birds

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ScienceDaily (Mar. 18, 2009) — The long tails sported by many male birds in the tropics look like they're a drag to carry around and a distinct disadvantage when fleeing predators, but experiments by University of California, Berkeley, biologists shows that they exact only a minimal cost in speed or energy – at least in hummingbirds.

"We estimate that having a long tail increases a bird's daily metabolic costs by 1 to 3 percent, which means the bird has to visit 1 to 3 percent more flowers in its territory," said Christopher J. Clark, a graduate student in UC Berkeley's Department of Integrative Biology. "Is that a lot? It's hard to say, but we argue that it's not, especially when compared to the costs of things like molting and migration."
As a way to attract admiring females, in fact, long tail feathers may be one of the easiest ornamentations to evolve with the least consequences, the researchers say.
Clark and Robert Dudley, UC Berkeley professor of integrative biology, report the results of their study in the March issue of the journal Proceedings of the Royal Society B, which appeared online this week.
Male birds of numerous species have evolved elaborate colors and decorations to attract females, many of them involving tail feathers. The peacock's eye-popping display, the broad, gauzy tail of the male lyre bird and the two-foot-long, iridescent green tail of the quetzal are but three examples.
Some biologists have made computer models of elongated tails, like those of the Jamaican red-billed streamertail hummingbird, the scissor-tail hummingbird or the marvelous spatuletail hummingbird, and have predicted as much as a 50 percent greater energy cost when flying with a long tail.
In his experiment, Clark outfitted short-tailed Anna's hummingbirds (Calypte anna) with long tail feathers from a red-billed streamertail (Trochilus polytmus), giving the hummingbirds two tail feathers that were five times the normal length for an Anna's, and put the hummers through their paces in a wind tunnel. He and Dudley found that the hummingbirds with enhanced tail feathers suffered only a 3.4 percent drop in their maximum speed. This corresponded to an 11 percent increase in energy needed to fly at high speeds.
For moderate and low speeds – the speeds at which hummingbirds typically flit from flower to flower and hover the long-tailed birds expended considerably less extra energy.
While other studies are needed to establish whether the same holds true in all bird families, Clark said, "I think that in most birds with long tails, the long tail is not costly."
Clark is writing his Ph.D. thesis on tail feather variation among the 330 known species of hummingbirds, which occur only in the Americas. Last year, he and fellow student Teresa Feo described how the Anna's hummingbird flares its tail feathers to generate a chirp at the bottom of its display dive.
In this new experiment, Anna's hummingbirds were the controls to discover whether very long tail feathers create enough drag to significantly affect flight performance. In visits to Jamaica, Clark collected five pairs of long tail feathers from red-billed streamertails, which molt their feathers once a year and then re-grow them. Eight of a streamertail's 10 flight tail feathers, called rectrices, are of moderate length – slightly more than an inch long – but the two feathers next to the outside pair are about 19 centimeters (7 ½ inches) long. (Of the approximately 60 hummingbirds with long tails, all but the red-billed streamertail have the outer pair of tail feathers elongated, as opposed to the next-to-outer pair.)
He first glued two streamertail shafts to two of an Anna's own feather shafts and placed the bird in a wind tunnel to see how its metabolism was affected by hovering or flying into a breeze of up to 35 miles per hour, or 15 meters per second. He enticed the hummingbird to feed in flight at a plastic tube that allowed him to collect its breath, which was analyzed for oxygen content. Of six birds tested, all expended more metabolic energy when equipped with long tail feathers. At high speeds (12 meters per second or 27 mph), they expended, on average, 11 percent more energy.
Based on these metabolic measurements, Clark and Dudley predicted that long-tailed birds would show a 3 to 4 percent decrease in maximum flight speed, which is what they found: 3.4 percent, on average.
As an extra control, Clark tested the flight abilities of birds without rectrices and of birds without either rectrices or covert feathers (the short feathers that cover the bases of the rectrices, both above and below). Birds lacking both rectrices and covert feathers showed a 2 percent drop in maximum air speed, but those lacking only rectrices were unaffected.
Given that elongated tails in birds have evolved at least 26 times, if not hundreds of times, it seems as if tail feather variation is easier to live with than, for example, wing feather elongation, which would more likely affect flight and is rare in nature, Clark said. Tail feathers streamline the bird's body and reduce drag, but when folded in flight, the length of tailfeathers appears to be less important than having at least some tail feathers.
"We propose ... that sexual selection has generated enormous diversity in avian tail morphology because, by 'hiding' in the wake of the body, such modifications can be relatively cost free," they wrote in their paper.
Although most biologists think that extreme ornamentation, like long tails, arise because females select males based on that trait, there is still much debate about the evolutionary details. Some suggest that females have an innate bias that is exploited by males to win over females. Others suggest that long feathers are a good indication of a healthy male, and thus stand out like "tall, dark and handsome" in human males.
"The energetic costs of a long tail are not high, but it remains to be seen if there are any benefits of a long tail, other than the indirect benefit of helping to pass on one's genes," Clark said.
The work was supported in part by the Department of Integrative Biology. Field work in Jamaica was supported by the American Museum of Natural History, the American Ornithologist's Union, Sigma Xi, UC Berkeley's Center for Latin American Studies, the Museum of Vertebrate Zoology and the Department of Integrative Biology.
Adapted from materials provided by University of California - Berkeley, via EurekAlert!, a service of AAAS.

Rock Rose Leaves And Olive And Date Pits Make Up New Anti-pesticide Formula

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ScienceDaily (Mar. 18, 2009) — A Spanish-Moroccan research team has developed an ecological means of reducing pesticide-related water pollution by using natural organic waste materials, such as olive and date stones, and the leaves of plants such as the rock rose and radish. This new formula could help to reduce this problem that causes damage to health and the environment.

A group of experts in Analytical and Environmental Chemistry from the University of Seville (US), working with researchers from the University of Abdelmalek Essaadi in Morocco, has shown that date and olive stones, as well as the leaves of certain Mediterranean plants, can act to absorb pesticides.
The scientists studied the absorption of 22 different types of pesticides by 10 natural substances - five of which were organic waste materials (peanut shells, bamboo, and olive, avocado and date stones), and five of which were the leaves of plants (eucalyptus, radish, oregano, oleander and rock rose), which had been previously crushed.
The results of this study, published in the Journal of Hydrology, show that date and olive stones had the greatest absorption capacity, at 93% and 90% respectively, while the values for rock rose and radish leaves stood at 80%.
"Directly applying natural organic absorbents to cultivated soil not only helps to stop the pesticides leaching away and thus reduce their use, but also helps to improve soil fertility," Hicham El Bakouri, one of the study's co-authors and a researcher in the Department of Chemical and Environmental Engineering at the US, told SINC.
El Bakouri said that using this crushed organic matter on the soil also helps pollutants to biodegrade by increasing levels of microbiological activity and reducing the vertical movement of pesticides from the surface down into the groundwater - which is used for irrigation and human consumption.
Cooperation between Spain and Morocco
The analytical studies during this research project were carried out in the laboratories of the University of Abdelmalek Essaadi and the Higher School of Engineers of the US, and the samples were taken in Loukkos, in the north west of Morocco. The researchers tested the decontamination techniques in a number of fields throughout the region, and also carried out an information and awareness-raising campaign among the local population.
A large part of the groundwater in the Loukkos region suffers from pesticide pollution, with an average contaminant load per cultivated hectare of 6kg - a very similar figure to that in some Spanish autonomous regions, such as Extremadura, the Balearic Islands and Madrid.
El Bakouri stressed that the contamination of water resources by pesticides used in agriculture or harmful substances from industry is a problem worldwide.
"In many countries around the world, especially those with fewer resources, this type of water contamination represents a serious problem, and we need to find economical, environmentally-sustainable solutions, which are easy to put into use, such as the method we have proposed," said the researcher.
The project was financed by the Ministry of Science and Innovation (MICINN) and the Spanish Agency for International Development Cooperation (AECID).
Journal reference:
Elbakouri et al. Natural attenuation of pesticide water contamination by using ecological adsorbents: Application for chlorinated pesticides included in European Water Framework Directive. Journal of Hydrology, 2009; 364 (1-2): 175 DOI: 10.1016/j.jhydrol.2008.10.012
Adapted from materials provided by Plataforma SINC, via AlphaGalileo.

Eutrophication Of Lake Constance Led To Genetic Changes In A Species Of Water Flea

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ScienceDaily (Mar. 18, 2009) — Ecological changes caused by humans affect natural biodiversity. For example, the eutrophication of Greifensee and Lake Constance in the 1970s and 1980s led to genetic changes in a species of water flea which was ultimately displaced.

Despite the fact that water quality has since been significantly improved, this species has not been re-established. This was demonstrated by researchers from Eawag and from two German universities (Frankfurt and Konstanz), who analysed genetic material from Daphnia eggs up to 100 years old.
Evolutionary biologist Nora Brede explains, animatedly: “In the laboratory, we were able to revive resting eggs over 40 years old isolated from Greifensee sediment.” For Eawag, this Jurassic Park-style method has a serious purpose: it makes it possible to determine retrospectively which Daphnia species was dominant in the lake around 1960, and whether the species that prevailed in the 1970s and 1980s became more tolerant of pollutants. Daphnia, which are crustaceans, can produce diapausing (resting) eggs – e.g. when food supplies are inadequate – which develop into a living organism when environmental conditions subsequently become more favourable. As these eggs are deposited in datable layers of anoxic sediments, their DNA can be analysed even after the passage of 100 years or more.
What makes this biological archive particularly interesting is the fact that conditions in the lake have undergone dramatic changes since 1960. In the 1970s and 1980s, inputs of phosphate detergents and fertilizer runoff led to eutrophication, with the development of algal blooms, including toxic cyanobacteria (blue-green algae). Fish died as a result of oxygen depletion.
As reported in the latest edition of the Proceedings of the National Academy of Sciences, the results of the genetic analysis of Daphnia eggs indicate that genetic diversity was also affected by the excessive nutrient levels. At the beginning of the 20th century, only one species of water flea (Daphnia hyalina) occurred abundantly in the two lakes studied. As eutrophication developed, this was displaced by another species (Daphnia galeata). In the transitional periods before and after peak nutrient inputs, hybrids also developed. However, although the lakes are now once again much cleaner (thanks to major efforts in the urban wastewater management sector), the original species has yet to recover.
According to Nora Brede, “This demonstrates that anthropogenic changes, such as eutrophication, can have major and not fully reversible effects on animal species.” In addition, the research project also showed how rapidly evolutionary processes can unfold in the animal kingdom. Brede comments: “In a mere 50 years, there have been measurable changes in the genome structure of a species, which is amazing, given that this is an extremely short period on the timescale of the Earth’s history.”
Biological archives such as the resting eggs of Daphnia in lake sediments are a valuable tool for investigating how organisms respond to changes in the ecosystem. Together with its partners, Eawag is therefore making the most of these opportunities to study and gain a better understanding of evolutionary processes. Research is focusing in particular on the question of how quickly plants and animals adapt genetically to the alterations in temperature associated with global climate change.
Journal reference:
Brede et al. The impact of human-made ecological changes on the genetic architecture of Daphnia species. Proceedings of the National Academy of Sciences, 2009; DOI: 10.1073/pnas.0807187106
Adapted from materials provided by EAWAG: Swiss Federal Institute of Aquatic Science and Technology, via AlphaGalileo.

Elephant Shark Genome Sequence Leads To Discovery Of Color Perception In Deep-sea Fish

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ScienceDaily (Mar. 18, 2009) — The elephant shark, a primitive deep-sea fish that belongs to the oldest living family of jawed vertebrates, can see color much like humans can.

This discovery, published in the March 2009 issue of Genome Research, may enhance scientists' understanding of how color vision evolved in early vertebrates over the last 450 million years of evolution.
"It was unexpected that a 'primitive' vertebrate like the elephant shark had the potential for color vision like humans. The discovery shows that it has acquired the traits for color vision during evolution in parallel with humans," said Byrappa Venkatesh, Ph.D., who with David Hunt, Ph.D., headed the research team responsible for this surprising discovery.
Dr. Venkatesh is a scientist at Singapore's Institute of Molecular and Cell Biology (IMCB), while Dr. Hunt is based at the Institute of Ophthalmology at University College London (UCL).
The research team found that the elephant shark had three cone pigments for color vision and, like humans, it accomplished this through gene duplication.
Dr. Venkatesh said that the finding underscores the research utility of the elephant shark, which IMCB scientists proposed in 2005 as a valuable reference genome to understand the human genome.
In a separate paper titled, "Large number of ultraconserved elements were already present in the jawed vertebrate ancestor," published in the journal Molecular Biology and Evolution in March 2009, the research team reported that they had discovered that the protein sequences in elephant shark were evolving at a slower rate than in other vertebrates.
This finding indicates that the elephant shark had retained more features of the ancestral genome than other vertebrates belonging to the same evolutionary tree and hence was a useful model for gaining insight into the ancestral genome, in which the human genome also has its roots.
In several scientific publications, Dr. Venkatesh's team has described research showing that the human DNA sequence was more similar to elephant shark than to any other fish.
Dr. Venkatesh added, "We expect the sequencing of the whole genome of the elephant shark to be completed by early 2010, the availability of which will then enable scientists to explore the important functional elements in both the human and elephant shark genome that have remained unchanged during the last 450 million years of evolution."
The findings reported in Genome Research and Molecular Biology and Evolution were generated less than two years after IMCB secured National Institutes of Health funding to sequence the whole genome of the elephant shark.
Journal references:
Davies, W.L., Carvalho, L.S., Tay, B., Brenner, S., Hunt, D.M. and Venkatesh, B. Into the blue: gene duplication and loss underlie colour vision adaptations in a deep-sea chimaera, the elephant shark Callorhinchus milii. Genome Research, 2009; 19: 415-426 DOI: 10.1101/gr.084509.108
Wang, J., Lee, A.P., Kodzius, R., Brenner, S. and Venkatesh, B. Large number of ultraconserved elements were already present in the jawed vertebrate ancestor. Molecular Biology and Evolution, 2009; 26: 487-490 DOI: 10.1093/molbev/msn278
Venkatesh, B., Kirkness, E.F., Loh, Y.H., Halpern, A.L., Lee, A.P., Johnson, J., Dandona, N., Viswanathan, L.D., Tay, A., Venter, J.C., Strausberg, R.L. and Brenner, S. Survey Sequencing and Comparative Analysis of the Elephant Shark (Callorhinchus milii) Genome. PLoS Biology, 2007; 5 (4): e101 DOI: 10.1371/journal.pbio.0050101
Venkatesh, B., Kirkness, E.F., Loh, Y.H., Halpern, A.L., Lee, A.P., Johnson, J., Dandona, N., Viswanathan, L.D., Tay, A., Venter, J.C., Strausberg, R.L. and Brenner, S. Ancient Noncoding Elements Conserved in the Human Genome. Science, 2006; 314 (5807): 1892 DOI: 10.1126/science.1130708
Adapted from materials provided by Agency for Science, Technology and Research (A*STAR), Singapore.

Animal Families With The Most Diversity Also Have Widest Range Of Size

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ScienceDaily (Mar. 18, 2009) — Somewhere out there in the ocean, SpongeBob SquarePants has a teeny-tiny cousin and a humongous uncle.

That's just what one would expect from a new analysis of body sizes across all orders of animal life that was conducted by researchers at the National Evolutionary Synthesis Center (NESCent), in Durham, N.C. and the University of North Carolina, Chapel Hill.
Researchers Craig McClain and Alison Boyer created a giant database on body sizes across all orders of animal life and found that phyla -- families of animals grouped together by a similar body plan -- with the greatest diversity of species were also those with the largest range of body sizes.
The sponges, Poriferans, were found to have some of the greatest diversity of both body size and species, ranging from microscopic to the size of an automobile. Molluscs (snails, squid, clams, chitons), and Arthropods (crabs, insects, lobsters, copepods) also showed great diversity. So did our family, the Chordates, which ranges from a half-inch fish in the swamps of Borneo to the truly leviathan 100-ton Blue Whale, with all the fishes, birds and mammals in between.
On the one hand, it may seem obvious that diversity in size and diversity in species go together, acknowledges marine biologist McClain, assistant director of science at NESCent. But it also says something a little more subtle about how new species arise and adapt to all the available niches in the environment.
"This really comes down to understanding the diversity of life on Earth," McClain said.
The group's findings appear online in Proceedings of the Royal Society B. The research was conducted in part at the Monterrey Bay Aquarium Research Institute, funded by the David and Lucile Packard Foundation, and the Smithsonian National Museum of Natural History. NESCent is a National Science Foundation collaboration of Duke, UNC and N.C. State that is housed in buildings Duke leases.
The Blue Whale, incidentally, is the largest animal ever, but the Chordate group doesn't boast the smallest. That distinction belongs to animals with names like mud dragons, brush heads, jaw worms, stomach hair worms and water bears that are so small they live between individual grains of sediment in the ocean. But this smallest group's range doesn't reach up to the largest body size.
This is a pattern that repeated itself several times in the data, McClain said. There are apparently physical limits to the range of sizes that can work for some body plans. In worms, for example, it is impossible to slither along if the girth and weight become too large. (The largest worm, Riftia pachyptila, from deep-sea vents, doesn't move.)
Within the range of sizes that works for a given body plan, evolution creates new species and new sizes, McClain said. What this sweeping analysis hasn't solved is the riddle about how different body sizes emerge. One theory says that body sizes arise through random natural variation. A second says that size diversity is driven by the availability of unused niches in the environment.
The finding also points to areas where more species might be waiting to be discovered. For example, the little-studied priapulid worms (aka "penis worms") have only 16 species on the books, but with a very large range in size. McClain's guess is that there may be more undiscovered species within that range of sizes. "There are groups that definitely don't have a lot of people studying them," he said.
Knowing something about a body plan's size constraints also might allow for a ballpark estimate of its number of species, McClain said.
Adapted from materials provided by Duke University, via EurekAlert!, a service of AAAS.

American Carnivores Evolved To Avoid Each Other, New Study Suggests

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ScienceDaily (Mar. 17, 2009) — How do the many carnivorous animals of the Americas avoid competing for the same lunch, or becoming each other's meal?

A possible answer comes from a new study by a pair of researchers at the University of California, Davis. Their large-scale analysis shows that it's not just chance that's at play, but avoidance strategies themselves that have been a driving force in the evolution of many carnivores, influencing such factors as whether species are active daytime or nighttime, whether they inhabit forests or grasslands, or live in trees or on the ground.
The Americas are home to more than 80 species of terrestrial carnivores, including cats, dogs, bears, weasels, skunks and raccoons. Commonly, 20 or more species can occupy the same region.
"For the most part, these overlapping species all share the same prey base -- other animals -- which includes each other," said Jennifer Hunter, who conducted the study for her Ph.D. dissertation in ecology.
Hunter and co-author Tim Caro, professor of wildlife, fish and conservation biology, first plotted the known ranges of all of the American carnivores on one big digital map. Assuming that wherever ranges overlapped, competition and predation between those species was possible, they then compared those animals' behavioral characteristics, body sizes and coloration. By analyzing this huge matrix of information, they were able to tease out broad patterns of strategies employed by each family.
For example, their map showed that the bear and dog families shared ranges with the greatest number of potential competitors. Most species in these families are omnivores, which helps reduce competition for a meat diet.
Raccoon family members, although small, run the lowest risk of becoming prey, because most live out of harm's way in trees.
One of their most surprising findings, Hunter said, was that the most petite carnivores, skunks, along with some weasels, lack an avoidance strategy. "When you look at all these overlays of ecology, these guys share all the same space at the same time with other carnivores."
How do these animals manage to survive? All skunks and a number of weasel species in this exposed group have facial or body coloring with an abrupt demarcation between white and dark. For skunks, this contrasting coloration almost surely warns predators of their noxious spray, Hunter explained, while with some weasel family members -- the notoriously aggressive badgers and wolverines, for example -- it may warn of ferocity.
The work provides a body of evidence for why these behaviors have evolved that could not have been obtained in the field, Hunter said.
The findings were published in the December issue of Ethology, Ecology and Evolution.
Partial funding for the study came from the National Science Foundation.
Journal reference:
Hunter J. and Caro T. Interspecific competition and predation in American carnivore families. Ethology, Ecology and Evolution, 2008; 20 (4): 295-324
Adapted from materials provided by University of California - Davis, via EurekAlert!, a service of AAAS.