MIT's ocean model precisely mimics microbes' life cycles

MIT's ocean model precisely mimics microbes' life cycles

Scientists at MIT have created an ocean model so realistic that the virtual forests of diverse microscopic plants they "sowed" have grown in population patterns that precisely mimic their real-world counterparts.

This model of the ocean is the first to reflect the vast diversity of the invisible forests living in our oceans-tiny, single-celled green plants that dominate the ocean and produce half the oxygen we breathe on Earth. And it does so in a way that is consistent with the way real-world ecosystems evolve according to the principles of natural selection.

Scientists use models such as this one to better understand the oceans' biological and chemical cycles and their role in regulating atmospheric carbon dioxide, an important greenhouse gas.

The output of the new model, the brainchild of oceanographer Mick Follows, has been tested against real-world patterns of a particular species of phytoplankton, called prochlorococcus, which dominates the plant life of some ocean regions.

Follows and co-authors report this work, part of the MIT Earth System Initiative's new Darwin Project, in the March 30 issue of Science. The Darwin Project is a new cross-disciplinary research project at MIT connecting systems biology, microbial ecology, global biogeochemical cycles and climate.

"The guiding principle of our model is that its ecosystems are allowed to self-organize as in the natural world," said Follows, a principal research scientist in MIT's Department of Earth, Atmospheric and Planetary Sciences (EAPS), lead author on the paper and creator of the model. "The fact that the phytoplankton that emerge in our model are analogous to the real phytoplankton gives us confidence in the value of our approach."

One of Follows' collaborators, Penny Chisholm, the Lee and Geraldine Martin Professor of Civil and Environmental Engineering and Biology and director of the Earth Systems Initiative, has made prochlorococcus her focus of study for 20 years. Stephanie Dutkiewicz, a research scientist in EAPS, and Scott Grant, a graduate student at the University of Hawaii, who was an MIT physics undergraduate during this project, collaborated with Chisholm and Follows on the new model.

Chisholm believes that because previous ocean models did not convey the diversity of phytoplankton, they did not well represent the systems they modeled. The new model remedies that.

"Now we are finally modeling the ocean systems in a way that is consistent with how biologists think of them-water filled with millions of diverse microbes that wax and wane in relative abundance through interactions with each other, and the environment, as dictated by natural selection," said Chisholm.

Indeed the guiding principle of the new model is natural selection. It simulates the physical and chemical characteristics of the oceans, but adds to the virtual soup about 100 random types of phytoplankton. The model randomly generates the single-celled plants, which differ primarily in their size, and in their sensitivity to light, temperature and nutrient availability, then allows the ocean to self-select those most fit for survival in any particular area.

What emerged after the model completed its 10-year virtual evolution -which took four to five days on a cluster of parallel computers-is a phytoplankton community with members that are characteristic of observed phytoplankton communities, including plants similar to prochlorococcus that are extremely abundant in the warm mid-latitude Atlantic and Pacific oceans.

Chisholm said this is the first major change in the way scientists approach ocean models in many years. She believes it will serve to break down disciplinary barriers between the physical and biological ocean sciences.

Follows attributes this new approach to three factors: the emergence of new information about the genetic diversity of marine microbes, recent advances in computational capability and a simple recognition of his own bias.

"Physicists, like myself, have a bit of a reductionist view. We often shy away from the complexity of the real world in our models and prefer to reduce things to the simplest case with fewest factors," said Follows, who went through a sort of conceptual evolution after collaborating with Chisholm for several years. "I finally said, 'Yes, real world ecosystems are messy and complex. But let's embrace it.'"

The Paradigm Consortium of the National Ocean Partnership Program, the National Science Foundation, the Department of Energy, the Gordon and Betty Moore Foundation, and the MIT Global Habitat Longevity Award provided funding for the research.

Chisholm, Follows and Dutkiewicz plan to use this new type of model to look in more detail at what shapes the habitats of the phytoplankton and to link this to other, larger scientific issues about oceans, the plants and creatures living in them and global climate.

"This is just the beginning," said Chisholm. "Now we can begin to ask the model questions and test hypotheses about the role of oceanic microbes in global processes. This will help guide decisions about responsible use of the oceans in this era of global change."

Green Counsel: San Francisco Bans Plastic Bags

Green Counsel: San Francisco Bans Plastic Bags

San Francisco just passed a law -- the first in the United States -- that bans petroleum-based plastic bags by large grocery and drug chains. According to the city, plastic bags litter the streets and are responsible for choking marine life. As an alternative, stores may offer paper bags or compostable plastic.

According to Craig Noble, a San Francisco-based spokesperson for NRDC, "America consumes 30 billion plastic bags and 10 billion papers ones each year," he says, which use up 14 million trees and 12 million barrels of oil. The biodegradable bags, he says, "give consumers a way out of making this false 'paper or plastic' choice."

The California Grocers Association opposed the ban, partly because of cost, and supported recycling. They argued that plastic bags cost pennies, while paper bags cost 4 to 5 cents, and compostable plastic bags run from 6 to 10 cents; and these costs will have to be passed on to consumers.

Shark disappearance threatens sea life: Report

TheStar.com - News - Shark disappearance threatens sea life: Report

HALIFAX – The near extinction of several species of sharks is causing a dangerous ripple effect through the marine food chain, according to a new study that links their virtual disappearance to depletions of other sea life.

The report by a team of researchers at Dalhousie University in Halifax has found that species that were once the primary food source for certain types of large sharks are undergoing a population boom because there aren't as many sharks to prey on them.

The scientists contend that the explosive increase in about a dozen types of smaller sharks, rays and skates has caused a cascading effect throughout the ecosystem as they begin to deplete limited nutrient sources and alter nature's complex food web.

"It's incredibly serious," said Julia Baum, who co-wrote the report to be released Friday in the journal Science. "Everyone knows that the oceans are being overfished and it's the top predators that are being disproportionately hit by overfishing.

"Because they structure everything underneath them in the food web, we may be drastically changing and restructuring how the oceanic food web functions and operates."

The report states that shark populations off the eastern United States are in an even steeper decline that originally thought. Using data from fisheries logs and research surveys from 1970 to 2005, the team discovered that the abundance of several types of so-called great sharks has dropped by more than 99 per cent.

The bull and dusty sharks are verging on extinction, while hammerheads and great white sharks are in dangerously low numbers, Baum said, due largely to overfishing.

The controversial practice of finning – slicing the shark's fin off and then tossing the carcass overboard – has led to precipitous drops in most strains of the large predators globally, the report said.

"What we're seeing is a higher risk of extinction of these species in these areas, and the term we use as ecologists is functional elimination," Baum said, adding that finning kills as many as 73 million sharks a year worldwide for an industry that supplies fins for soups and other uses.

"It means that these great predators can no longer play their roles in the ecosystem as top predators. So they're no longer controlling the species in the food web below them."

The researchers, including the late Ransom Myers who passed away Tuesday, cited a specific example of how the removal of sharks is affecting other species.

Baum, a marine biologist, said they have for the first time linked the decimation of bay scallops in waters off North Carolina to an increase in cownose rays, which eat the delicacy. Sharks feed on the rays, but because there are now so few sharks, the ray population has been allowed to grow to more than 10 times what it was a decade ago.

Cownose rays have wiped out scallop beds to the point that the fishery has been closed every year off North Carolina since 2004.

"This ecological event is having a large impact on local communities that depend so much on healthy fisheries," said Charles Peterson, a professor of marine sciences and biology at the University of North Carolina and co-author of the report.

Baum said it's not clear what the increase in the other species will mean for the food chain and the wider ecosystem, but it's likely skates, rays and smaller sharks are disrupting the wider natural order in oceans around the world.

The loss of the bay scallop has already caused disruptions to seagrass, an important habitat for other marine life, because rays plow through the growth in search of scallops. Rays may also be inhibiting the recovery of oysters, hard clams and soft-shell clams.

Ken Frank, a fisheries scientist with the federal Fisheries Department, said the findings add to what he had discovered in an earlier research paper that looked at how the disappearance of cod affected the food chain.

Frank, whose study was published in Science in 2005, found that the collapse of cod and other large species led to a cascade effect. As the number of large predators declined dramatically, the fish they preyed on – herring, capelin, shrimp and snow crab – experienced a population explosion.

"There are interdependencies among the species, and when you cause these imbalances, you're going to get some effect elsewhere," he said from his office in Halifax.

"For many decades, it was thought this type of cascade effect was possible only in simplified systems like ponds, so seeing this occur in the marine system is alarming. It means we're modifying the way energy is flowing through these systems."

This latest scientific paper follows groundbreaking research Myers and Baum did in 2003 that found shark populations in the Atlantic had plunged dramatically since the mid-1980s.

"We know better now why sharks matter," Baum said. "Keeping top predators is critical for sustaining the health of the ocean."

Arctic sea ice decline may trigger climate change cascade

Arctic sea ice decline may trigger climate change cascade
 

Arctic sea ice that has been dwindling for several decades may have reached a tipping point that could trigger a cascade of climate change reaching into Earth's temperate regions, says a new University of Colorado at Boulder study.

Mark Serreze, a senior research scientist at CU-Boulder's National Snow and Ice Data Center who led the study synthesizing results from recent research, said the Arctic sea-ice extent trend has been negative in every month since 1979, when concerted satellite record keeping efforts began. The team attributed the loss of ice, about 38,000 square miles annually as measured each September, to rising concentrations of greenhouse gases and strong natural variability in Arctic sea ice.

"When the ice thins to a vulnerable state, the bottom will drop out and we may quickly move into a new, seasonally ice-free state of the Arctic," Serreze said. "I think there is some evidence that we may have reached that tipping point, and the impacts will not be confined to the Arctic region."

A review paper by Serreze and Julienne Stroeve of CU-Boulder's NSIDC and Marika Holland of the National Center for Atmospheric Research titled "Perspectives on the Arctic's Shrinking Sea Ice Cover" appears in the March 16 issue of Science.

The loss of Arctic sea ice is most often tied to negative effects on wildlife like polar bears and increasing erosion of coastlines in Alaska and Siberia, he said. But other studies have linked Arctic sea ice loss to changes in atmospheric patterns that cause reduced rainfall in the American West or increased precipitation over western and southern Europe, he said.

The decline in Arctic sea ice could impact western states like Colorado, for example, by reducing the severity of Arctic cold fronts dropping into the West and reducing snowfall, impacting the ski industry and agriculture, he said. "Just how things will pan out is unclear, but the bottom line is that Arctic sea ice matters globally," Serreze said.

Because temperatures across the Arctic have risen from 2 degrees to 7 degrees F. in recent decades due to a build-up of atmospheric greenhouse gases, there is no end in sight to the decline in Arctic sea ice extent, said Serreze of CU-Boulder's Cooperative Institute for Research in Environmental Sciences. Arctic sea ice extent is defined as the total area of all regions where ice covers at least 15 percent of the ocean surface.

"While the Arctic is losing a great deal of ice in the summer months, it now seems that it also is regenerating less ice in the winter," said Serreze. "With this increasing vulnerability, a kick to the system just from natural climate fluctuations could send it into a tailspin."

In the late 1980s and early 1990s, shifting wind patterns from the North Atlantic Oscillation flushed much of the thick sea ice out of the Arctic Ocean and into the North Atlantic where it drifted south and eventually melted, he said. The thinner layer of "young" ice that formed it its place melts out more readily in the succeeding summers, leading to more open water and more solar radiation being absorbed by the open ocean and fostering a cycle of higher temperatures and earlier ice melt, he said.

"This ice-flushing event could be a small-scale analog of the sort of kick that could invoke rapid collapse, or it could have been the kick itself," he said. "At this point, I don't think we really know."

Researchers also have seen pulses of warmer water from the North Atlantic entering the Arctic Ocean beginning in the mid-1990s, which promote ice melt and discourage ice growth along the Atlantic ice margin, he said. "This is another one of those potential kicks to the system that could evoke rapid ice decline and send the Arctic into a new state."

The potential for such rapid ice loss was highlighted in a December 2006 study by Holland and her colleagues published in Geophysical Research Letters. In one of their climate model simulations, the Arctic Ocean in September became nearly ice-free between 2040 and 2050.

"Given the growing agreement between models and observations, a transition to a seasonally ice-free Arctic Ocean as the system warms seems increasingly certain," the researchers wrote in Science. "The unresolved questions regard when this new Arctic state will be realized, how rapid the transition will be, and what will be the impacts of this new state on the Arctic and the rest of the globe."

Global warming is very real and very serious

http://www.da.wvu.edu/XMLParser/printstory.phtml?id=27022

Global warming is very real and very serious

By Travis Doyle
Columnist

It has recently been brought to my attention that global warming is a very serious problem and that we, as human beings, must treat it with all the seriousity that we can muster. First and foremost, we must destroy all volcanoes. After that, we have to consider the facts.
The biggest fact is that carbon dioxide, or CO2, causes global warming. We all have seen this on television, we all have heard the disaster reports, and it really doesn't matter that at times in Earth's history there have been three to 10 times as much CO2 in the atmosphere without the world coming to an end, because now it will cause the world to end. There are no hidden agendas, there is no propaganda in regards to this subject, there are just people dying from global warming. And those people could be you.
Another big fact that people should know is that Al Gore supports efforts to reduce global warming, and he was almost president. Why would anyone who isn't president lie to us? Why would his ice core samples show a correlation between CO2 in the atmosphere and warming temperatures, yet fail to comment on the fact that the correlation is skewed in the opposite direction? Just because CO2 levels in his core samples rise 800 years later than global temperatures themselves have raised doesn't mean we shouldn't believe him. After all, he was almost president.
Furthermore, just because in the post-war economic boom between 1940 and 1970, when our nation was increasing its CO2 emissions by the greatest leaps and bounds in history, and global temperatures were lowering, doesn't mean that global warming isn't happening now. Even though the same types of environmental scientists who are propagating global warming now are the ones that were predicting global cooling in the '70s, they have it right this time, and we need to listen to them or die.
Look, I know what a lot of you are thinking: ''But I went on Google Video and watched the UK documentary called, 'The Great Global Warming Swindle,' which clearly points out, with the aid of scientists from around the world, that global warming really isn't feasible.''
Well, there are a lot of scientists supporting global warming as well, and they're getting a lot of grant money for doing it. Who are you going to trust: scientists ��?or scientists? I am going to put my life in the hands of scientists. Do whatever you want with yours.
And I'm sure that there are some people out there are going to say, ''But I read the article in The New York Times by Frederick Seitz, the former president of the National Academy of Sciences, and he said that there were a great deal of omissions in the global warming report shown to the UN, and that scientists who dropped out of the project still had their names added to it, despite the fact that they didn't support the text within.'' Do I really have to ask if you're going to put stock in what the former president of the National Academy of Sciences says about anything scientific? Just because he has all the credibility a man could ever need on the subject doesn't mean that he is right. And he is not right, and if you believe him, you will die.
But the real issue that I'm going to encourage people to take up, in writing this column, is to destroy volcanoes. Volcanoes produce more CO2 than any man, machine or industry on the planet combined. Volcanoes are going to kill us if we don't kill them first. Everyone needs to look around, grab something pointy and start stabbing at the nearest volcano.
Remember, folks, if you don't agree with me, then you don't believe in global warming.
And if you don't believe in global warming, then nobody is going to die because of it, and the world will probably be a better place without all that grant money being wasted and all that media airtime being spent on the same footage of a glacier cracking.

Bioenergy pact between Europe and Africa

Bioenergy pact between Europe and Africa

According to a new study by researchers at the Carnegie Institution and Lawrence Livermore National Laboratory, warming global temperatures have already caused annual losses of roughly US$5 billion for major food crops over the past two decades.

From 1981-2002, warming reduced the combined production of wheat, corn, and barley—cereal grains that form the foundation of much of the world's diet—by 40 million metric tons per year. The diagram with scatter plots ( click to enlarge ) shows first-differences of yield (kg ha–1) and first-differences of average monthly minimum and maximum temperatures (°C) and precipitation (mm) during the growing season, along with best-fit trend lines (in grey). Each decade is shown with a different colour, indicating that the relationships do not appear to change through time.

The study, titled "Global scale climate–crop yield relationships and the impacts of recent warming" [*abstract], is published in the current online edition of the journal Environmental Research Letters, and demonstrates that this decline is due to human-caused increases in global temperatures. The article is freely accessible [ *.html version / *.pdf version]. Do check it out, as the evidence is represented in a very straightforward way, and it offers a - scaringly clear - signal of the potential disaster climate change has in store for global agriculture.

"Most people tend to think of climate change as something that will impact the future," says Christopher Field, co-author on the study and director of Carnegie's Department of Global Ecology in Stanford, Calif. "But this study shows that warming over the past two decades has already had real effects on global food supply."

The study is the first to estimate how much global food production has already been affected by climate change. Field and David Lobell, lead author of the study and a researcher at Lawrence Livermore National Laboratory, compared yield figures from the Food and Agriculture Organization with average temperatures and precipitation in the major growing regions.

They found that, on average, global yields for several of the crops responded negatively to warmer temperatures, with yields dropping by about 3-5 percent for every 1 degree F increase. Average global temperatures increased by about 0.7 degrees F during the study period, with even larger changes in several regions:
  "Though the impacts are relatively small compared to the technological yield gains over the same period, the results demonstrate that negative impacts are already occurring," said Lobell.

The researchers focused on the six most widely grown crops in the world: wheat, rice, maize (corn), soybeans, barley and sorghum—a genus of about 30 species of grass raised for grain. These crops occupy more than 40 percent of the world's cropland, and account for at least 55 percent of non-meat calories consumed by humans. They also contribute more than 70 percent of the world's animal feed.

The main value of this study, the authors said, was that it demonstrates a clear and simple correlation between temperature increases and crop yields at the global scale. However, Field and Lobell also used this information to further investigate the relationship between observed warming trends and agriculture.

"We assumed that farmers have not yet adapted to climate change—for example, by selecting new crop varieties to deal with climate change. If they have been adapting—something that is very difficult to measure—then the effects of warming may have been lower," explained Lobell.

Most experts believe that adaptation would lag several years behind climate trends, because it can be difficult to distinguish climate trends from natural variability. "A key moving forward is how well cropping systems can adapt to a warmer world. Investments in this area could potentially save billions of dollars and millions of lives," Lobell added.

Global warming or not, CO2 levels threaten marine life

Global warming or not, CO2 levels threaten marine life

 

Like a piece of chalk dissolving in vinegar, marine life with hard shells is in danger of being dissolved by increasing acidity in the oceans.

Ocean acidity is rising as sea water absorbs more carbon dioxide released into the atmosphere from power plants and automobiles. The higher acidity threatens marine life, including corals and shellfish, which may become extinct later this century from the chemical effects of carbon dioxide, even if the planet warms less than expected.

A new study by University of Illinois atmospheric scientist Atul Jain, graduate student Long Cao and Carnegie Institution scientist Ken Caldeira suggests that future changes in ocean acidification are largely independent of climate change. The researchers report their findings in a paper accepted for publication in the journal Geophysical Research Letters, and posted on its Web site.

"Before our study, there was speculation in the academic community that climate change would have a big impact on ocean acidity," Jain said. "We found no such impact."

In previous studies, increasing levels of carbon dioxide in the atmosphere led to a reduction in ocean pH and carbonate ions, both of which damage marine ecosystems. What had not been studied before was how climate change, in concert with higher concentrations of carbon dioxide, would affect ocean chemistry and biology.

To investigate changes in ocean chemistry that could result from higher temperatures and carbon-dioxide concentrations, the researchers used an Earth-system model called the Integrated Science Assessment Model. Developed by Jain and his graduate students, the model includes complex physical and chemical interactions among carbon-dioxide emissions, climate change, and carbon-dioxide uptake by oceans and terrestrial ecosystems.

The ocean-surface pH has been reduced by about 0.1 during the past two centuries. Using ISAM, the researchers found ocean pH would decline a total of 0.31 by the end of this century, if carbon-dioxide emissions continue on a trajectory to ultimately stabilize at 1,000 parts per million.

During the last 200 years, the concentration of atmospheric carbon dioxide increased from about 275 parts per million to about 380 parts per million. Unchecked, it could surpass 550 parts per million by mid-century.

"As the concentration of carbon dioxide increases, ocean water will become more acidic; which is bad news for marine life," Cao said. "Fortunately, the effects of climate change will not further increase this acidity."

There are a number of effects and feedback mechanisms built into the ocean-climate system, Jain said. "Warmer water, for example, directly reduces the ocean pH due to temperature effect on the reaction rate in the carbonate system. At the same time, warmer water also absorbs less carbon dioxide, which makes the ocean less acidic. These two climate effects balance each other, which results in negligible net climate effect on ocean pH."

The addition of carbon dioxide into the oceans also affects the carbonate mineral system by decreasing the availability of carbonate ions. Calcium carbonate is used in forming shells. With less carbonate ions available, the growth of corals and shellfish could be significantly reduced.

"In our study, the increase in ocean acidity and decrease in carbonate ions occurred regardless of the degree of temperature change associated with global warming," Jain said. "This indicates that future changes in ocean acidity caused by atmospheric carbon-dioxide concentrations are largely independent of climate change."

That's good news. The researchers' findings, however, call into question a number of engineering schemes proposed as mitigation strategies for global warming, such as lofting reflective balloons into the stratosphere or erecting huge parasols in orbit. By blocking some of the sunlight, these devices would create a cooling effect to offset the warming caused by increasing levels of greenhouse gases.

"Even if we could engineer our way out of the climate problem, we will be stuck with the ocean acidification problem," Caldeira said. "Coral reefs will go the way of the dodo unless we quickly cut carbon-dioxide emissions."

Over the next few decades, we may make the oceans more acidic than they have been for tens of millions of years, Caldeira said. And that's bad news.

Tracking sperm whales and jumbo squid

Tracking sperm whales and jumbo squid

The sperm whale and its large prey, the jumbo squid, are among the deepest divers in the ocean, routinely reaching depths of 3,000 feet or more. Now, in a new study, a team of marine scientists reports the successful tagging of sperm whales and jumbo squid swimming together off Mexico's Pacific coast—the first time that electronic tracking devices have been applied simultaneously to deep-diving predators and prey in the same waters.

The research team included principal investigator William Gilly, professor of biological sciences at Stanford University, and lead author Randall Davis, professor of marine biology at Texas A&M University-Galveston. Their results, published in the March 12 edition of the journal Marine Ecology Progress Series (MEPS), raise new questions about the diving behavior of both species.

"Sperm whales (Physeter macrocephalus) and jumbo squid (Dosidicus gigas) are both major predators that spend much of their lives in one of the world's largest ecosystems, the mesopelagic zone [650 to 3,300 feet below sea level]," the authors wrote. "How sperm whales search for, detect and capture their prey remains uncertain."

To find out, the researchers traveled to the Gulf of California, also called the Sea of Cortez—a narrow stretch of ocean that separates the Mexican mainland from the Baja Peninsula.

"The central Gulf of California is a uniquely advantageous location to study the behavioral ecology of sperm whales and their squid prey," the authors wrote. "Sperm whales are abundant year-round and appear to feed heavily on jumbo squid, a species that is easily captured and amenable to tagging. To our knowledge, this is the first attempt to simultaneously study a mesopelagic predator and its prey using electronic tagging techniques."

Size matters

The jumbo (or Humboldt) squid is a large cephalopod species found only in the Pacific. A mature jumbo squid can weigh more than 100 pounds and grow more than 6 feet long. Sperm whales, the biggest of all toothed whales, inhabit every ocean. An adult male can reach nearly 60 feet in length and weigh 57 tons.

The sperm whale was immortalized by Herman Melville in his novel Moby-Dick. Heavily hunted for their oil during Melville's time, the sperm whale population today ranges somewhere between 360,000 to 1 million. These giants have a voracious appetite for squid. According to one estimate, worldwide sperm whale predation on squid may exceed 100 million metric tons a year—roughly equivalent to the entire annual harvest of all the commercial fisheries on Earth.

Humans also are big consumers of squid, including jumbo squid, now the target of a thriving commercial fishery in Baja California. "Even though this species is found only in the eastern Pacific, it reaches from Alaska to Chile and supports the largest cephalopod fishery in the world," said Gilly, an authority on squid who is based at Stanford's Hopkins Marine Station.

"It's very rare to find a place like the Gulf of California where you can actually see sperm whales together with their prey," added Davis, an expert on marine mammal behavior. "I can't think of another place in the world where this would be possible."

Despite the vital role that jumbo squid and sperm whales play in oceanic ecosystems and fisheries, many aspects of their lifestyle—including feeding and hunting—are as mysterious today as they were when Melville made the following observation in Moby-Dick: "For though other species of whales find their food above water, and may be seen by man in the act of feeding, the spermaceti whale obtains his whole food in unknown zones below the surface; and only by inference is it that any one can tell of what, precisely, that food consists."

The sperm whale remains a challenging research subject for scientists today, Davis noted. "Adult sperm whales can stay underwater for more than an hour, but nobody knows exactly what they're doing down there," he said.

"We also know relatively little about the behavior of jumbo squid in the wild," Gilly added. "For example, it was only a couple of years ago that we discovered an area in the central Gulf of California where spawning and mating of these animals probably take place."

Electronic tags

The MEPS study was conducted in fall 2004 near Santa Rosalia, a coastal Baja California town that is the center of Mexico's jumbo squid fishery.

During six days at sea, the research team identified 74 individual sperm whales in a 27-square-mile area. To locate whales, researchers towed an array of hydrophones from the back of a boat and listened for the animals' distinct clicking vocalizations. When they finally encountered a whale, the scientists carefully approached the animal and attached an electronic depth recorder to its back. Later, whenever the tagged whale surfaced for a breath of air, the device would transmit recorded data about the animal's movements to an orbiting satellite.

Jumbo squid also were abundant, with numerous small fishing boats hauling in a total catch of about 10,000 squid per night throughout the six-day study. Captured squid were outfitted with a pop-up archival transmitting tag, which periodically sampled the animal's depth. Unlike the instruments used on whales, the squid tags were designed to detach at a predetermined time, then float to the surface and transmit stored data to the satellite.

Results

During the study, electronic tags were placed on five whales and three jumbo squid swimming nearby. Analysis of the tagging data showed that the whales were traveling up to 60 miles a day within a relatively small area, suggesting that they had found an abundant supply of food.

The tagged predators and prey must have crossed paths at some time during the experiment, Gilly noted. "Based on the locations of where the squid tags first appeared on the surface, all three squid had to have moved from the Santa Rosalia fishing grounds right through the area where the whales were patrolling," he said.

As for diving behavior, the majority (91 percent) of sperm whale dives recorded during the study ranged from 300 to 1,600 feet below sea level and were 15 to 30 minutes in duration. Only 13 dives (3 percent) exceeded 3,200 feet.

These results closely mirrored the diving data collected from the squid. "Tagged squid in our study occupied the 100-500 meter [300 to 1,600-foot] zone, the same region to which the whales dove over 90 percent of the time, consistent with the idea that whales were primarily preying on jumbo squid of large body size," the authors wrote. "Whales did occasionally dive beyond 500 meters, especially during daytime when the squid were deep, and we assume these also represent foraging dives."

Night and day

During the day, whales and squid spent about 75 percent of the time at depths ranging from 600 to 1,300 feet, which is "consistent with the idea that the whales were foraging where the probability of encountering squid was highest," the authors wrote. At night, however, the tagged squid spent at least half of their time in shallower waters above 600 feet and the remainder at 600 to 1,300 feet. One likely explanation for this vertical movement is that the squid were following small fish and other prey that migrate toward the surface at night and then return to deeper waters during the day.

Unlike squid, however, the sperm whales did not alter their diving pattern at night. Instead, they continued to spend about three-fourths of their time at depths of 600 to 1,300 feet, according to nocturnal tagging data.

"These data show that sperm whales don't change their feeding behavior, day or night," Davis explained. "Instead, they keep going down to about 1,300 feet, whether squid are there or not. Perhaps it's the only way they can catch them, but no one has ever seen a sperm whale feeding in the wild, so nobody really knows how they capture their food."

Stressed squid

The study also revealed that the squid often made rapid nighttime dives from the surface to deeper waters preferred by whales. "One reason squid may be going down there at night is because water near the surface is really warm—up to 82 F—and they may be getting stressed," Gilly explained. "The squid is using energy all of the time, because it has to swim to breathe. So when it gets into really warm water, I think it gets out pretty quickly. These deep dives, therefore, may have some kind of recovery function. We think the stress may be temperature-related, but another factor could be oxygen. It's possible they could be negatively affected by long exposure to the higher oxygen levels found near the surface."

A stressed-out squid may be an easy target for hungry sperm whales waiting below, according to Gilly. "We propose that jumbo squid are more susceptible to predation while they are recovering at depth immediately after a deep nighttime dive," he explained.

In previous studies, Gilly found that jumbo squid are well adapted to the low-oxygen environment in deeper waters, where they spend most of their time. However, he added, at depths of 800 feet or more, where it's very cold and oxygen levels are extremely low, the squid's reaction time, visual acuity and swimming speed may be significantly impaired because of an inadequate supply of oxygen—a condition known as hypoxia.

"Squid need a constant supply of oxygen to support their metabolism," Davis added. "Sperm whales, on the other hand, take the oxygen down with them bound to the hemoglobin in their blood and the myoglobin in their muscles, so they don't have to worry about hypoxia at depth."

By spending most of their time in cold, deep waters, he noted, sperm whales can take advantage of a vulnerable squid, whether it's slowed down by hypoxia at depth during the daytime, or at night after it has made a deep dive to escape the warm, stressful conditions at the surface.

"By hunting deep in this cold, hypoxic environment at night, as well as during the day, sperm whales may favor jumbo squid that are in some way compromised and thus easier to capture," the authors wrote.

"This research provided a unique opportunity to learn more about two species that are very difficult to study in their natural habitat," Davis noted. "In the future, this co-tagging approach should yield new insights into predator-prey interactions with other pelagic species that are large enough to carry electronic tags."

Added Gilly: "Although human observers at the surface of the sea must still infer what the mysterious squid and the leviathan are doing at great depths, the use of modern electronic tagging methods will surely guide those inferences, leading to insights that even Melville might not have imagined."

Carbon dioxide levels threaten oceans regardless of global warming

Carbon dioxide levels threaten oceans regardless of global warming

 

 

Rising levels of carbon dioxide will have wide-ranging impacts on the world's oceans regardless of climate change, reports a study published in the March 9, 2007, issue of the journal

 

The study, authored by Ken Caldeira from the Department of Global Ecology at the Carnegie Institution at Stanford University and Long Cao and Atul Jain of the University of Illinois, shows the increasing absorption of carbon dioxide is acidifying global oceans, putting sea life at risk.

"Whether you believe in global warming or not, CO2 is going to run havoc in the oceans if unabated, " warned coauthor Dr. Caldeira. "Temperature increases from climate change affect salinity, circulation, and marine biology. When carbon dioxide dissolves in the ocean, some of it becomes carbonic acid—a corrosive agent, which can eat away shells of important species in the global food chain."

Oceans worldwide absorbed approximately 118 billion metric tons of carbon between 1800 and 1994 according to a report published last year by scientists at the National Center for Atmospheric Research and NOAA, resulting in increased ocean acidity, which reduces the availability of carbonate ions needed for the production of calcium carbonate structures. In the past, changes in ocean acidity have triggered mass extinction events. According to a study published in the September issue of Geology, dramatically warmer and more acidic oceans may have contributed to the worst mass extinction on record, the Permian extinction. During the extinction event, which occurred some 250 million years ago, about 95% of ocean's life forms became extinct. The same fate could befall modern day marine life.

Late last year a team of scientists writing in Nature warned that by 2100, the amount of carbonate available for marine organisms could drop by 60%. In surface ocean waters, where acidification starts before spreading to the deep sea, there may be too little carbonate for organisms to form shells as soon as 2050. The loss of these small organisms would have a disastrous impact on predators -- including salmon, mackerel, herring, cod -- that rely on them as a food source and could spell trouble for other species.

Carbon dioxide is a byproduct of fossil fuels combustion. Scientists estimate that the oceans have soaked up about half of all carbon dioxide produced from fossil fuel emissions over the past 200 years. Had oceans not absorbed this carbon, current atmospheric carbon dioxide would be much higher than the current 381 parts-per-million (ppm)--probably closer to 500-600 ppm say climatologists.

This absorption has made the world's oceans significantly more acidic since the beginning of the industrial revolution. Research published last year by Mark Jacobson, an assistant professor of civil and environmental engineering at Stanford University, indicated that between 1751 and 2004 surface ocean pH dropped from approximately 8.25 to 8.14. James Orr of the Climate and Environmental Sciences Laboratory further estimated that ocean pH levels could fall another 0.3 - 0.4 units by 2100.

The new Geophysical Research Letters paper confirms Orr's forecasts, projecting a 0.31 drop in pH units by the end of this century "if CO2 emissions continue on their current trajectory to stabilize at atmospheric CO2 concentrations at 1000 parts per million." Caldeira says their new model shows that overall temperature change won't have much effect on ocean acidity.

"Since surface temperature increases affect how carbon is broken down in seawater, we wanted to quantify how the acidity of the water would be affected by temperature increases from CO2 emissions," he explained in a statement. "We found that the pH, or acidity, of the water wasn't significantly affected regardless of how much warming occurs over the next decades and centuries."

Their model further showed that a doubling of carbon dioxide levels would produce a pH decline of 0.48-0.51 units by the year 2500.

"Ocean acidification threatens all marine organisms that use calcium carbonate to make their shells," Caldeira added. "However even as the planet warms, our study shows that we can help the ecological balance in the oceans by curbing CO2 emissions now by using wind, solar, nuclear power, and other alternative energy sources."

The findings suggest strategies that focus solely on moderating global temperatures, while neglecting carbon dioxide emissions (i.e. injecting sulfates into the upper atmosphere to reflect sunlight) will not counter the negative impact of ocean acidity.

The big blue whale puts people and dinosaurs into perspective

The big blue whale puts people and dinosaurs into perspective | StarNewsOnline.com | Star-News | Wilmington, NC

The big blue whale puts people and dinosaurs into perspective

 

We all grew up learning how eons ago, great creatures roamed the earth, dinosaurs as big as the school bus that carried us to class. We'd gasp and shudder, yet secretly yearn to have lived back then to see such a sight.

Little did we realize that there are modern animals which, placed next to the mightiest dinosaur, would make them look like dwarves. Even stranger, these giants live virtually next door to us, in our ocean.

Biggest of the big is the blue whale approaching 100-feet in length. Imagine a half-ton heart beating in a 100-ton body. (Its tongue alone, by the by, weighs four tons.) Put in perspective, that mean reptilian machine Tyrannosaurus rex was a meager 20-feet tall, and just 40-feet long. Brachiosaurus came closer at 50-feet tall and 85-feet long, measuring down its back and including its tail.

Oddly, whales such as the big blues don't have teeth, and don't eat big game. Instead they have baleen, solid plates that sift their favorite food, tiny krill or shrimp. Call them gulpers rather than biters. It makes Jonah's perilous trip make more sense, right?

Other baleen whales are gray, finback, humpback and right whales. Toothed whales comprise 64 species, and here's where it gets tricky. Dolphins and porpoises are among this group, as well as the pilot, sperm whale and orcas. Although they are called killer whales, orcas aren't really whales at all, but toothed dolphins.

While blues often travel in pairs, they can fall prey to packs of smaller orcas. And speaking of travels, whales are the original ocean cruisers. They live in every ocean, inhabiting surface waters. But since they require depth, it's rare to see them along sloping beaches.

Babies lack the blubber bulk of adults, so whales journey to warmer waters to give birth. But they don't mind taking a global trip to colder seas to feed, frequently traversing the ocean nearly from pole to pole.

Blue whales are not only the biggest creatures on earth they are also the loudest. Their deep whistle travels hundreds of miles, with a frequency of 188-decibels. The finest jumbo jet only emits 140-decibels. Humans strain to hit 70, even that crying baby.

The humpback is famous for its hypnotic whale songs, mysterious since they have no vocal chords. Despite possessing the widest note range among whales, when they "sing," they don't project air bubbles, the way we would underwater.

For many years, giants like blues escaped whalers, being too fast and huge to capture. Sadly, innovations like exploding harpoons and inflating harpooned whales with air to "float" them home changed that. Despite laws to protect them, rebuilding whale numbers is painfully slow and some fear, too little too late.

Sperm whales, by the way, have the largest brain on earth. Right now, whales could be passing our shores and we wouldn't know, in ancient dances we hardly comprehend. Puts us in perspective, too, doesn't it?

Solar energy can help mitigate global warming

Solar energy can help mitigate global warming

 

Solar energy has the power to reduce greenhouse gases and provide increased energy efficiency, says a scientist at the U.S. Department of Energy's Argonne National Laboratory, in a report (view it online) published in the March issue of Physics Today.

Last month, the Intergovernmental Panel on Climate Change (IPCC) of the United Nations released a report confirming global warming is upon us and attributing the growing threat to the man-made burning of fossil fuels.

Opportunities to increase solar energy conversion as an alternative to fossil fuels are addressed in the Physics Today article, co-authored by George Crabtree, senior scientist and director of Argonne's Materials Science Division, and Nathan Lewis, professor of Chemistry at Caltech and director of its Molecular Materials Research Center.

Currently, between 80 percent and 85 percent of our energy comes from fossil fuels. However, fossil fuel resources are of finite extent and are distributed unevenly beneath Earth's surface. When fossil fuel is turned into useful energy through combustion, it often produces environmental pollutants that are harmful to human health and greenhouse gases that threaten the global climate. In contrast, solar resources are widely available and have a benign effect on the environment and climate, making it an appealing alternative energy source.

"Sunlight is not only the most plentiful energy resource on earth, it is also one of the most versatile, converting readily to electricity, fuel and heat," said Crabtree. "The challenge is to raise its conversion efficiency by factors of five or ten. That requires understanding the fundamental conversion phenomena at the nanoscale. We are just scratching the surface of this rich research field."

Argonne carries out forefront basic research on all three solar conversion routes. The laboratory is creating next-generation nanostructured solar cells using sophisticated atomic layer deposition techniques that replace expensive silicon with inexpensive titanium dioxide and chemical dyes. Its artificial photosynthesis program imitates nature using simple chemical components to convert sunlight, water and carbon dioxide directly into fuels like hydrogen, methane and ethanol. Its program on thermoelectric materials takes heat from the sun and converts it directly to electricity.

The Physics Today article is based on the conclusions contained in the report of the Basic Energy Sciences Workshop on Solar Energy Utilization sponsored by the U.S. Department of Energy. Crabtree and Lewis served as co-chairs of the workshop and principal editors of the report. The key conclusions of the report identified opportunities for higher solar energy efficiencies in the areas of:

Electricity – important research developments lie in the development of new, less expensive materials for solar cells, including organics, thin films, dyes and shuttle ions, and in understanding the dynamics of charge transfer across nanostructured interfaces.

Fuel – solar photons can be converted into chemical fuel more resourcefully by breeding or genetically engineering designer plants, connecting natural photosynthetic pathways in novel configurations and using artificial bio-inspired nanoscale systems.
Heat – controlling the size, density and distribution of nanodot inclusions during bulk synthesis could enhance thermoelectric performance and achieve more reliable and inexpensive electricity production from the sun's heat.

The nation's first national laboratory, Argonne National Laboratory conducts basic and applied scientific research across a wide spectrum of disciplines, ranging from high-energy physics to climatology and biotechnology. Since 1990, Argonne has worked with more than 600 companies and numerous federal agencies and other organizations to help advance America's scientific leadership and prepare the nation for the future. Argonne is managed by UChicago Argonne, LLC for the U.S. Department of Energy's Office of Science.

Global warming or not, CO2 levels threaten marine life

Global warming or not, CO2 levels threaten marine life

 

Like a piece of chalk dissolving in vinegar, marine life with hard shells is in danger of being dissolved by increasing acidity in the oceans.

Ocean acidity is rising as sea water absorbs more carbon dioxide released into the atmosphere from power plants and automobiles. The higher acidity threatens marine life, including corals and shellfish, which may become extinct later this century from the chemical effects of carbon dioxide, even if the planet warms less than expected.

A new study by University of Illinois atmospheric scientist Atul Jain, graduate student Long Cao and Carnegie Institution scientist Ken Caldeira suggests that future changes in ocean acidification are largely independent of climate change. The researchers report their findings in a paper accepted for publication in the journal Geophysical Research Letters, and posted on its Web site.

"Before our study, there was speculation in the academic community that climate change would have a big impact on ocean acidity," Jain said. "We found no such impact."

In previous studies, increasing levels of carbon dioxide in the atmosphere led to a reduction in ocean pH and carbonate ions, both of which damage marine ecosystems. What had not been studied before was how climate change, in concert with higher concentrations of carbon dioxide, would affect ocean chemistry and biology.

To investigate changes in ocean chemistry that could result from higher temperatures and carbon-dioxide concentrations, the researchers used an Earth-system model called the Integrated Science Assessment Model. Developed by Jain and his graduate students, the model includes complex physical and chemical interactions among carbon-dioxide emissions, climate change, and carbon-dioxide uptake by oceans and terrestrial ecosystems.

The ocean-surface pH has been reduced by about 0.1 during the past two centuries. Using ISAM, the researchers found ocean pH would decline a total of 0.31 by the end of this century, if carbon-dioxide emissions continue on a trajectory to ultimately stabilize at 1,000 parts per million.

During the last 200 years, the concentration of atmospheric carbon dioxide increased from about 275 parts per million to about 380 parts per million. Unchecked, it could surpass 550 parts per million by mid-century.

"As the concentration of carbon dioxide increases, ocean water will become more acidic; which is bad news for marine life," Cao said. "Fortunately, the effects of climate change will not further increase this acidity."

There are a number of effects and feedback mechanisms built into the ocean-climate system, Jain said. "Warmer water, for example, directly reduces the ocean pH due to temperature effect on the reaction rate in the carbonate system. At the same time, warmer water also absorbs less carbon dioxide, which makes the ocean less acidic. These two climate effects balance each other, which results in negligible net climate effect on ocean pH."

The addition of carbon dioxide into the oceans also affects the carbonate mineral system by decreasing the availability of carbonate ions. Calcium carbonate is used in forming shells. With less carbonate ions available, the growth of corals and shellfish could be significantly reduced.

"In our study, the increase in ocean acidity and decrease in carbonate ions occurred regardless of the degree of temperature change associated with global warming," Jain said. "This indicates that future changes in ocean acidity caused by atmospheric carbon-dioxide concentrations are largely independent of climate change."

That's good news. The researchers' findings, however, call into question a number of engineering schemes proposed as mitigation strategies for global warming, such as lofting reflective balloons into the stratosphere or erecting huge parasols in orbit. By blocking some of the sunlight, these devices would create a cooling effect to offset the warming caused by increasing levels of greenhouse gases.

"Even if we could engineer our way out of the climate problem, we will be stuck with the ocean acidification problem," Caldeira said. "Coral reefs will go the way of the dodo unless we quickly cut carbon-dioxide emissions."

Over the next few decades, we may make the oceans more acidic than they have been for tens of millions of years, Caldeira said. And that's bad news.