Among all animals, amphibians are in the worst shape; fully 30 percent are classified as threatened or endangered. Amphibians – including frogs, toads and salamanders — are under attack by a deadly fungus. They are losing habitat to farms and cities, and collected as food or pets. Amphibians are suffering from chemical pollution and the warming climate.

The present is harsh enough, but the future seems worse.

This week, Nature publishes the first global attempt to forecast the impact of three big threats to amphibians by 2080 – a year chosen to be one century after the study’s baseline data.

By comparing areas with plenty of amphibian species with projections of climate change, land use change and the chytridiomycosis fungus, the researchers forecast a grim future for these cold-blooded, four-legged vertebrates. “The bad news is that more than two-thirds of all high-richness regions will probably be affected, to a high intensity, by one of these three threats,” said lead author Christian Hof, who did the work as a Ph.D. student and post-doctoral fellow at the University of Copenhagen.

The geographic study of data on 5,527 amphibian species found little overlap between the cool, moist areas afflicted by fungal serial killer chytridiomycosis, and the places likely to suffer the worst effects of changes in climate and land use.

And the losers win!

In forecasting the future of amphibians, the study coined two technical terms: “losers” — species that are expected to suffer due to disease or changes in climate or land use, and the less numerous “winners,” which are expected to prosper by 2080.

The projection hinged on whether an expected change would make a habitat more or less suitable to the species, says Hof, who’s now at the Biodiversity and Climate Research Center in Frankfurt, Germany. “We ran a number of climate-change models and based on them, calculated a change in climate suitability for each region across the globe.”

Based on these changes in suitability due to climate, land use and disease, Hof adds, “We calculated the number of species that would probably decline due to a decline in habitat suitability. We classify the species as a loser in a particular region, but that does not mean it will decline across its whole range.”

Overall, the researchers found an increasingly dire future for amphibians. For example, 54 percent of frogs are likely to be “climate losers” in the average grid cell of their model. And heavy impacts are projected for about two-thirds of the regions with the highest species richness in frogs and salamanders.

In fact, the future could be even worse, since the study ignored a number of potentially damaging factors, including chemical pollution from cities, factories and agriculture.

Photo: Robert Fletcher, Ohlone Preserve Conservation Bank

Tougher times might await this prowling California tiger salamander, an endangered California native.

Going down!

It’s frustrating but understandable that the study could not predict rates of decline among amphibians. “For many species, we are not sure about the actual distribution, many have tiny ranges and we don’t know where they occur, so we can’t relate historic changes to, say, climate change. We were very careful not to predict extinctions, based on these uncertainties.”

Data are scarce in the study of amphibians, agrees Anna Pidgeon, an assistant professor of forest and wildlife ecology at University of Wisconsin-Madison. “It’s frustrating, amphibians are out at night, often in remote areas, they are small and many are cryptic, so it’s a huge challenge” to understand their populations and ecologies. “We work with the best data we have all the time … and try to make inferences from what we know about close relatives.”

Pidgeon, an expert on habitat needs of vertebrates, says predicting 70 years into the future is always dicey, but that the study’s analysis of multiple threats and global scope are major accomplishments. “They did a lot of things to make sure they were using consensus data, and that makes it a pretty solid approach.”

Although the study looked at overlapping threats, it did not actually look at interactions between those threats, Hof says. “What needs to be done, and we could not do that with our model, is to look at, for example, how climate change would affect susceptibility to the fungus. How would habitat fragmentation affect susceptibility to climate change?”

Although the study does not suggest practical changes that could sustain amphibians in the short run, “The general conclusion is that it’s very important, when thinking about the future for amphibians, to consider different threats together,” says Hof. “Just looking at one threat will not give us the whole picture.”

– David J. Tenenbaum

In Africa, elephants trample farms. Some traditional herders are prohibited from grazing their herds on land occupied by tourist-magnets like lions, leopards, giraffes and gazelles.

And buffalo, zebras and antelopes eat grass that could feed cattle.

In the East African savannas, the interactions between wildlife and the people whose livelihood depends on cows and goats, are complicated, critical and contentious.

Grazing is about the only way to make a living in this hot, dry land, but livestock and many wild herbivores eat similar vegetation.

And so the competition is obvious: How can a cow eat forage that a zebra ate first?

The question answers itself, and so nobody studied the issue.

Not so obvious after all

But in other realms, ecologists have found that organisms that seem to compete may actually aid each other. “We are just beginning to understand that the relationship between species is highly contextual,” says Truman Young, a professor of plant sciences at the University of California at Davis, “and this interaction includes competition and facilitation. Once, people thought if two species were similar, they always competed, but years ago, it became clear that facilitation exists in certain situations.”

Young is senior author of new study showing that in Kenya’s highland savannas, competition is partly offset by facilitation; although during the dry season wildlife steal food from the mouths of cattle, so to speak, the situation is reversed during the wet season.

When the rains come, wild ungulates (mammals with hooves), particularly zebras, seem to benefit cattle by eating fibrous, woody grasses and revealing the more delectable, higher-protein grasses beneath.

This gives cattle access to forage with more protein, and their wet-season weight gains nearly counterbalance the dry-season losses inflicted by wildlife.

Well done

The study was performed during 2007 and 2008, on nine fenced plots, or “exclosures,” each 4 hectares in size. The researchers placed four young, unbred females of an African breed called Boran on each plot for 16-week periods, and measured their eating habits and weight gain in three conditions:

First author Wilfred Odadi, a postdoctoral researcher at Princeton University and the African Wildlife Foundation, wrote us to explain that facilitation nearly equaled competition. “Wildlife-driven depression of cattle weight gain in the dry season is 35 to 40 percent. In the wet season, cattle put on weight faster by about the same percentage when they forage with wildlife.” The real-world situation, he added, would “depend on the lengths and frequencies of dry and wet seasons.”

This was the first experimental evidence that wildlife and livestock are engaged in facilitation and competition, Young says. “There is a basic-science excitement here. With this large-vertebrate system, we have shown that you can actually sometimes have competition and sometimes facilitation.”

It’s possible that the 15-year history of experiments on the site has changed the vegetation enough to weaken the results. But the continuous grazing of cattle kept the site’s vegetation similar to the surrounding savanna, Young says. “If we had excluded all large herbivores, the rangeland would become very different, and our inferences would be skewed. But because cattle are the dominant herbivores … the plots were not that different. My belief is if we had started the exclosures last year, we would have gotten the same result.”

What are the practical implications?

Killing wildlife, except for rogue animals, is illegal in Kenya, but it still happens, Odadi told us. “Because in Kenya wildlife belongs to the state, and not to the land owner, some livestock keepers still show a negative attitude towards wildlife because of perceived ‘detrimental’ effects on livestock including competition, livestock depredation and disease transmission. Some people react by fencing off their properties to keep wildlife away. There are also situations where water sources are fenced off by pastoralists to make them inaccessible to wildlife. In extreme cases, wild animals are actually killed, albeit illegally.”

And so in a region with unreliable rainfall and few resources, it’s good news for advocates of biodiversity conservation that the competition between domestic and wild ungulates, at least on savannas, may be more apparent than real.

Good news for conservation

Indeed, large mammal ecologist Johan du Toit of Utah State University, wrote in Science that the new information should eventually “provide managers with opportunities to capitalize on facilitative interactions, intervene against competitive ones, and enhance animal production overall.”

Rangeland managers often mix native and non-native plants, du Toit added. And after “bold experimentation and a break from orthodoxy,” a similar approach with animals could boost production while conserving biodiversity.

Odadi says better knowledge of cattle-wildlife interactions could support short-term changes, such as slaughtering or marketing livestock “at the end of the wet season, when they have recovered from competition in the preceding dry season, and also to minimize competitive effects (by reducing densities) in the next dry season.”

Conservationists in East Africa and elsewhere are seeking “to manage land for ecosystem biodiversity and short-term extractive value,” says Young, “but it’s pretty hard to find good examples, other than assertions about the profitability of ecotourism. We were able to show that wildlife and cattle have a complex interaction; that wildlife is not uniformly bad for cattle, and that allows us to be a little more lenient toward wildlife.”

– David J. Tenenbaum

Burning of the Alaskan tundra can release massive amounts of carbon dioxide, the major greenhouse gas, according to a study published in Nature this week. The Arctic is warming faster than the rest of the planet, causing scientists to wonder what will happen to the carbon that plants have stored in Arctic soils and plant matter, both living and dead.

The new study looked at the aftermath of the Anaktuvuk River wildfire, which burned more than 1,000 square kilometers of tundra on Alaska’s North Slope in 2007. Anaktuvuk burned for almost three months, and by itself, accounted for two-thirds of the total area burned in Alaskan tundra since 1950.

The immediate cause was lightning, but weather played a major role. Between July and September, 2007, the North Slope had the hottest weather in a 129-year record. When the fire was really roaring, daily highs were 5°C to 10°C above average. The Slope also received less than 20 percent of the average rainfall that summer, leaving the tundra abnormally arid.

In 2008, Michelle Mack, an associate professor of biology at the University of Florida and her colleagues visited the area and took samples from 1-square-meter quadrants both inside and outside the fire zone. Mack was in the field in Alaska, alas, and did not answer our emails, but her group calculated that the fire oxidized more than 2 million tons of carbon, which entered the atmosphere as carbon dioxide.

Accounting for carbon

The movement of carbon through soils, ecosystems, waters and the atmosphere is critical to the issue of global warming. Releasing carbon to the atmosphere as carbon dioxide speeds warming; and storing carbon compounds can slow or potentially reverse warming.

The moist acidic tundra under study covers as much as one-third of a billion square kilometers of the global Arctic – making it a major “sink” for carbon dioxide. The 2 million-ton release of carbon was equal to at least 50 percent of the amount of carbon stored annually in the Alaskan tundra, meaning this one fire almost cancelled the anti-warming benefit of photosynthesis in the region.

Chilling news about a burning issue

The link between global warming and fire also appeared in a new analysis of Yellowstone National Park. “Large, severe fires are normal for this ecosystem,” said Monica Turner, a Yellowstone expert and professor of ecology at the University of Wisconsin-Madison. Historically, the entire Yellowstone landscape has burned every 100 to 300 years, but Turner and company calculated that current trends toward hotter, drier summers, mean fires could consume the entire area every 30 years by 2050.

Wildfires are also becoming more common in the normally fire-resistant tundra of Alaska, and for reasons related to permafrost, reflectivity and feedback, the consequences could be dire:

And feedback moves us from the additive realm to the multiplicative one. In the Arctic, feedback also plays a central role related to the release of methane, which has even more warming potential than carbon dioxide. Many warming Arctic habitats have started releasing larger amounts of methane, which could warm the planet, feed back, and stimulate the release of yet more methane.

This feedback, like the one that may be affecting burning tundra, paints a darker picture of what could happen if we ignore the atmosphere and blithely assume that the future will be just like the present.

– David J. Tenenbaum

Southwest fires still ablaze

Last week, New Mexico’s famous Los Alamos National Laboratory, home of the atomic bomb, was shut down when a wildfire exploded from 2,000 acres to 49,000 acres over 24 hours, forcing the evacuation of the town of Los Alamos.

A wildfire that started May 29 in droughted Arizona scorched 538,000 acres – the largest in the state’s history.

Historically, wildfires have been usually battled as threats to life, limb and property. But scientists and land managers now see them as a part of nature that can be postponed but not denied.

This edition of The Why Files examines the ecology of fire in the forest.

For a century, the highly successful Smokey the Bear ad campaign fueled fear and loathing of wildfires in the United States. Embezzlers have been more popular than wild fires, which scourged the landscape, burned the birds and rendered Bambi homeless. But in recent decades, ecologists have come to three startling conclusions about fire:

Forests afire

One touchstone for the reconsideration of fire was the “catastrophic” conflagration in Yellowstone National Park in 1988 — which, despite the frightening photos, turned out to be a temporary setback for the ecosystem. Still, even ignoring the human toll for a moment, scientists have found that massive debris flows from denuded slopes can permanently alter the landscape.

More recently, discussion has shifted to reducing the intensity of wildfires, and to their interaction with a warming climate. How effective is controlled burning? Are global warming and the likely increase in drought already accelerating wildfires? Will more wildfires turn arid parts of Australia, the American West and Asia to desert?

An old debate

Each fire is shaped by weather, geology, plant life, and topography, which makes them hard to study, let alone control. Beyond harming or killing plants and animals, fires force a broad range of changes in chemistry, pH, microbial activity, moisture, water flows, soil structure and erosion.

The debate over wildfire is old, according to Stephen Pyne, a fire historian at Arizona State University. Although it’s impossible to know for certain the prevalence of fire five centuries ago, for a 1998 Why Files, Pyne estimated that before Columbus, wildfires, often set to clear land for planting, burned five times as much area as today.

Pyne said the debate over wildfire in the United States when the first national parks opened a century ago “mirrored an earlier argument in Europe over the role of fire” in natural landscapes. The European emigrants to the New World associated fire with “primitive” agriculture, and the U.S. government sought to eradicate fire from its parks and forests. The policy of fighting pretty much all fires succeeded at first, Pyne said. “Absolute suppression will work for a number of years, even a few decades, but you are always going to have fires.”

In the long run, he contended, total suppression is futile or counterproductive, since it allows a buildup of fuel that makes future fires larger, fiercer and even harder — or impossible — to fight.

Controlled burns — a forest fire you can love!

In response to this fuel buildup, controlled (“prescribed”) burns have been used for decades to reduce the chance of a catastrophic fire and return forests to a condition adjudged to be more natural. Prescribed burns reduce the amount of fuel, try to remove the “ladder trees” that can carry a creeping ground fire into the treetops, and are the “primary management tool” in the Forest Service region that covers 18 national forests in California.

USDA Forest Service, Rocky Mountain Research Station

Watch this piece of Montana’s Bitterroot National Forest grow denser as fire is excluded and trees are harvested. Before 1895, low-intensity fires burned through this forest every three to 30 years, until people began logging and suppressing fires. Click the link for a more complete explanation.

But prescribed burns are expensive, difficult to pull off (as they require a forest that is dry enough to burn, but not so dry that a raging fire will result), and studies of their efficacy conflict:

Do controlled burns damage trees?

Despite some successes from these deliberate burns, scientists have noted that they are sometimes followed by outbreaks of destructive bark beetles, or that fire in the heavy layer of organic matter left after a century of firefighting can kill tree roots – and trees. In a 2007 report, Sharon Hood of the U.S. Forest Service wrote that prescribed burning “is causing significant mortality of these high-value trees even with low intensity fires.”

In a 2005 test in Lassen National Forest and Lassen National Volcanic Park in California, Hood and colleagues looked at the effect of raking litter and duff away from ponderosa and Jeffrey pine trees before a controlled burn. Raking did not confer a survival advantage, perhaps because trees survived well in both the treatment and control groups, but raking did confer some advantage against beetle attack.

Bigger ecological picture

In the search to find out how fires affect forests, one theme stands out: The aftermath of fires is as varied as their weather conditions, biology and landscapes. In some cases, as we’ll see for Yellowstone, the ecosystem bounces back after a fire. But the results vary, even in one fire in one location. For example, the 2002 study of the Rodeo-Chediski Wildfire (which set an Arizona record at 189,000 hectares) found that about half the area was severely burned, and that many more years would be needed to restore the area despite efforts to replant vegetation and contain erosion. The mildly burned half section, however, had reverted to pre-fire conditions by 2009.

In the Arctic, the aftermath of a fire was much more serious: A report after the 1,000-square kilometer Anaktuvuk River fire in Alaska in 2007 documented a dramatic reduction in stored carbon. The researchers concluded that the growing frequency and intensity of fire would cause major changes in the ecosystem, climate and “the well-being of humans and other animals that inhabit Alaska’s North Slope.” After a severe burn, soil carbon, a key indicator of fertility, is “unlikely to recover to pre-fire levels over the next millennia.”

In general, animals get less consideration than plants in research on the aftermath of fires, but several studies of birds describe changes for better and for worse:

Open-air experiment in Yellowstone…

Much of what we know about the ecological impact of fire has come from Yellowstone National Park, where a giant blaze burned about 45 percent of the 1-million hectare park in 1988. Photos of towers of flame and exhausted firefighters became symbolic of nature run amok. Yet long-term studies of the aftermath produced surprising results, says Monica Turner, a landscape ecologist at the University of Wisconsin-Madison.

By 1998, 10 years after the blaze, Yellowstone was already on the rebound. Fish and mammals had survived the holocaust surprisingly well, and lodgepole pines—which dominated the park for 10,000 years — were poking through the shrubs and weeds, heralding a return of the park’s old ecosystem.

• While it looked catastrophic, Yellowstone’s infamous 1988 fire turned out to be a regular stage of ecological change.
  Photo: Jeff Henry, U.S. National Park Service, 12120
  
• Before: A stand of lodgepole pines tower above spruce and fir in Yellowstone 1965.
  Photo: RG Johnsson, , U.S. National Park Service, 08161
  
• 10 years after: The forest restored itself, as lodgepole pines sprout between dead ones in 1998.
  Photo: Jim Peaco, U.S. National Park Service, 15995
  

On cone-y island?

Why the quick rebound? Although the horrific photos from 1988 suggested that the vast sections of Yellowstone were uniformly charred, the severity varied from place to place. While intense crown fires killed all above-ground vegetation in some areas, trees and plants survived milder ground fires elsewhere, and the “mosaic” destruction allowed rapid, but patchy, regeneration. “In some places, very few trees are coming back, in other we see hundreds of thousands per hectare,” says Turner.

These extremes of tree density after a fire reflect that pattern of fire severity, Turner explains, and the biology of the dominant lodgepole pines. Many of these trees produce cones that, in a fire, open and release their seeds, which confront ideal growing conditions: Bare soil with little competition, plenty of sun, and the weather they are adapted to.

Other lodgepoles, however, release their seeds essentially on schedule, giving them less advantage after a fire. As the difference in tree density plays itself out over the decades, the fire’s imprint on the landscape can persist for more than 150 years, Turner says.

A flowering success

Because the soil was charred only to an average depth of 2 centimeters, and never more than 6 centimeters, some plants resprouted from roots or underground structures called rhizomes. By 1990, wildflowers were already abundant, Turner said. “Regeneration of these plants was very rapid, and it came from within the burned area. Even the really big fires leave a legacy of the plants that were there before the fire.”

In contrast, invasive species, did unexpectedly poorly after the fire, Turner said. “We had hypothesized that there might be an invasion by non-natives; the fires had created so much expansive, disturbed habitat, but the invasives have not appeared to spread, and are still where they used to be, along roads and trails.”

Burn and revive — or not

Over all, the fires had surprisingly little impact on wildlife, says Turner, who studied survival of elk and bison in Yellowstone, and the fire may even have given elk an advantage over the reintroduced wolf. “The young forest that is coming back after the ’88 fires provides quite a bit of cover for elk; the young pines are super-dense, it’s difficult to see your hand in front of your nose.” Furthermore, logs from the fallen trees killed by the fire can conceal elk and interfere with the wolf attempts to run down elk in open fields.

The summary word for Yellowstone is resilience, Turner says. The natural fire regime in the Yellowstone area includes a hot, crown fire “that replaces the whole forest and the cycle begins again about every 120 to 300 years. Big fires at the historic intervals are not detrimental to the system in any way.” Although these fires threaten homes and businesses, “from the perspective of plants and animals, fire is a normal event.”

Wildfires can carry other hazards, however. For example, a 2010 study of dry regions of Southeast Australia noted heavy erosion and debris flows after a big fire, mirroring what has been seen in the arid American Southwest. The debris flows were not seen in wetter forests, however.

Fire in a changing globe

Fire, obviously, removes stored carbon from the forest, making it a potential source of greenhouse warming. But the opposite is also true: global warming seems to cause more fires. According to experts on Western water and climate⁵ rapid climate change is underway in the American West, with:

The “signature” of global warming is already appearing in western forests, agreed a 2006 study⁶ which identified a change starting in the mid-1980s toward “higher large-wildfire frequency, longer wildfire durations, and longer wildfire seasons. The greatest increases occurred in mid-elevation, Northern Rockies forests, where land-use histories have relatively little effect on fire risks and are strongly associated with increased spring and summer temperatures and an earlier spring snowmelt.”

In other words, the increase in large, intense forest fires was more likely due to global warming than to the increased fuel load left by a century of fire-fighting.

Data: National Interagency Fire Center

In the United States, the area burned has gradually increased since 1983.

These changes are evident in Yellowstone, says Erica Smithwick, an assistant professor of geography and ecology who studies the aftermath of wildfires at Penn State. Historically, the “fire regime” — the average time needed to burn the entire area — is 120 to 300 years, but the lodgepole pines that dominate the plateau recover within a century, so the forest has survived regular large fires.

But Smithwick, Turner and colleagues came to an alarming conclusion when they compared projections for temperature and rainfall timing and intensity in 2050 to the history of fires when those conditions prevailed in the past.

Near Ryazan, Russia, 8 May 2011, mcsdwarken via Flickr

Record heat in Russia in 2010 led to a series of huge wildfires.

The interval between fires, they calculated, would be drastically shorter, and that is disturbing, Smithwick acknowledges. “If these projections are correct, there really might be a threshold in the vegetation where it would not be able to recover.”

Such a fire regime, she adds, is “more consistent with lower montane forests [with trees spaced far apart] or non-forests.”

What is the endgame of warmer, drier forests where fires are becoming more frequent? Could fires turn a forest to desert? Yes, according to a 2009 presentation by Daniel Neary of the Rocky Mountain Research Station in Flagstaff, Ariz. “Wildfire is now driving desertification in some of the forest lands in the western United States. The areas of wildfire in the Southwest U.S.A. have increased dramatically in the past two decades” from less than 10,000 hectares per year in the early 20th century to over 230,000 hectares today. “Individual wildfires are now larger and produce higher severity burns than in the past. A combination of natural drought, climate change, excessive fuel loads, and increased ignition sources have produced the perfect conditions for fire-induced desertification.”

It’s impossible to know the outcome in Yellowstone, a jewel of the U.S. national parks, Smithwick says. “I don’t think the ecosystem is doomed, but how do you manage a system like Yellowstone in that context? There should be some opportunity for the ecosystem to shift.” Eventually, grassland may replace forest, she notes. “Ecosystems are constantly shifting; that’s the kind of mindset we need to go forward. But this is a bit of a wakeup call. We are pushing the system, and we don’t know what is on the other side of the tipping point.”

– David Tenenbaum

Humans and cats go way back. The relationship sprouted around 2000 BC in Egypt, where humans first domesticated felines. Today, more than 90 million cats in the United States alone enjoy the companionship of humans, while another estimated 90 million are stray or feral.

As in most relationships, there are still secrets between humans and their feline friends. But a recent study published in the Journal of Wildlife Management shed light on one secret that may have been nagging cat owners: what do outdoor cats, otherwise known as “free-roaming,” do all day?

Since there are several cat enthusiasts at The Why Files, we, too, wondered about the answer to that question. And the answer belies a few thorny predicaments peculiar to the cat-human relationship.

A day in the life of a free-roaming cat

Decked with radio collars that tracked their every move, 42 free-roaming cats (18 of them pets, 24 of them owner-less) were the stars of the two-year University of Illinois study. The researchers’ goals were to compare what owned versus un-owned cats did all day, where and how far they wandered, and how likely they were to survive in the often risky outdoors.

Certainly, to no cat owner’s surprise, the felines spent much of their time lounging or sleeping, just like their strictly-indoor counterparts. However, the amount of time pet cats versus owner-less cats spent snoozing differed significantly. Pet cats lazed about for 80 percent of their days, while un-owned cats loafed for “only” 62 percent of the time.

“That alone is very interesting. It could be associated with their requirements. It’s possible that the cats without owners have to spend more time looking for resources to take care of themselves,” speculated Nohra Mateus-Pinilla, study co-author and wildlife veterinary epidemiologist at the Illinois Natural History Survey.

Another important finding, according to Mateus-Pinilla, were the differences in the cats’ ranges. While, not surprisingly, un-owned cats roamed further afield than owned cats, Mateus-Pinilla and her co-authors were surprised by how far the stray cats strayed and by the diversity of habitats they skulked in, as compared to pet cats. While most of the pet cats stuck close to home, the most itinerant stray cat wandered around a 547-hectare (1,351-acre) area.

From original map by Jeff Horn

Despite range differences, un-owned and owned cats’ territories can overlap. The red outline shows the largest range tracked for an un-owned cat in the study, and the yellow dot indicates one pet cat’s range.

“Because of the large home range sizes in the evidence of both cats without ownership and cats that are owned, their home ranges are overlapping. And because of the mortality evidence, these animals could be facing a certain amount of risks that we are unable to measure,” said Mateus-Pinilla.

Indeed, the risks of being a free-range cat are much higher than those of indoor cats, and if the cat has no owner, its fate is almost always bleak. In their study, six stray cats died, while only one owned cat died.

Mateus-Pinilla said their study raises many new questions. To The Why Files, however, it seems that living in the company of humans has its advantages for cats. But keeping this relationship indoors may have advantages for wildlife and people too—-implications that drive the otherwise curious research on free-roaming cats.

Too many kitties on the range

While the indoor-outdoor debate lives on in the cat owner community, and regardless of whether or not cats enjoy the out-of-doors, their secret lives outside entail some dirty secrets that are alarming scientists and laypeople alike.

The sheer number of free-range cats, owned or not, has become a conservation and health concern, some scientists say. Like any species, too many can spell trouble.

Cats, by nature, are superb predators. A cat stalking a bird or squirrel is simply doing what cats do. However, their prowess as hunters, combined with their overpopulation, has wildlife biologists and enthusiasts biting their nails over the potential endangerment or extinction of some prey species.

“There are a growing number of landscapes in which free-ranging cats are not only the most abundant mid-sized mammalian predator, but they can outnumber all of the native mammalian mid-sized predators combined. So they really do become the dominant mid-sized predator in many landscapes,” said Stanley Temple, an emeritus professor of forest and wildlife ecology at the University of Wisconsin-Madison, who was among the first to study the ecological impacts of free-roaming cats.

Because of their impacts on both native predators and prey, conservation scientists consider free-roaming cats invasive species. While not the greatest threat to wildlife, they add to the increasingly complex web of existing threats.

Species most at risk of death-by-kitty are birds that spend a lot of time on the ground, small mammals and reptiles, according to Temple. In fact, cats are second to habitat destruction as the cause of bird extinction. Thirty-three bird species have met their fate to the paws of cats since the 1600s.

The world’s ever-shrinking “islands” of wildlife habitat are hotspots of conservation concern over free-roaming cat populations, since the native species in these areas are the hardest hit by invading cats. For example, birds that live in America’s dwindling grasslands or on the increasingly crowded seashore are finding themselves in a precarious situation.

Open and fragmented landscapes, which also include forest outskirts and farmland, are the territories of choice for cats. And, except in subtropical locales, they tend to stick close to humans. Even if un-owned, most cats are still dependent on people for either food or shelter, or both.

“They are remarkably resourceful at taking advantages of the opportunities that we present,” said Temple, who clarified that free-roaming cats are only truly “feral” if they are completely independent of humans.

Their dependency on humans highlights another dilemma: free-range cats can easily spread diseases and parasites that can jump from cat to cat, cat to wildlife, and even cat to human. The list of contagions includes feline leukemia, feline immunodeficiency virus, worms, rabies and toxoplasmosis, a parasite-caused disease that can damage the developing brains of unborn human babies, if their mothers are infected.

Free-roaming cats’ close proximity to both humans and other animals thus creates a potentially strong reservoir for these diseases. While vaccinating both owned and un-owned cats can help reduce the spread of disease, vaccines are not 100 percent effective and the logistics of vaccinating every single cat may be impossible, especially since many vaccinations are annual.

Photo: Rodrigo Basaure

These street cats certainly benefit from a human handout, but do humans benefit from the cats’ potential disease threat?

It’s complicated

Indeed, solutions to these predicaments aren’t easy. While the science may seem to imply that rounding up every cat on the range may be the best solution, the ubiquity of free-roaming cats and the emotions wrapped up in some people’s relationship with felines complicate the matter.

Studies suggest that many free-range cats are people’s beloved pets that are allowed outside, said Temple. But, while keeping every pet cat indoors would significantly and immediately cut the number of free-range cats, not every cat owner agrees that indoor life is best for kitty.

To further complicate things, one of the often promoted “humane” methods of attempting to reduce un-owned cat populations — trap, treat, neuter, release — repeatedly fails. Not only are there always the cats that get away, but releasing the cats back into the “wild” still does not eliminate the risks to wildlife.

Temple believes that for a cat-control method to work, three criteria must be met: the strategy must actually control cat numbers over large areas, it can’t harm any other part of the ecosystem, and it is socially acceptable. The last criteria can be the trickiest to meet and often creates tension between humans.

Photo: Flickr

Is this outdoor kitty taunting his indoor pal? But who has the better life?

“The divide over how to deal with cat overpopulation, in one way, can be simplified as the group of people who are really concerned about ecological impacts of cats versus those that are really concerned about the welfare of individual animals,” said Temple, based on his years of experience conducting public outreach on the issue. He clarified that he likes cats and is actually the owner of a 21-year-old feline.

Temple believes solutions that meet both factions on common ground do exist. Keeping pet cats inside and trapping, treating, neutering and confining un-owned, free-roaming cats are two strategies that meet his criteria. Though, for some people, it will take some convincing.

Mateus-Pinilla was careful to emphasize that their study did not seek to evaluate management options. They were focused on adding to the science and remaining neutral in the debate about solutions to the issue of free-roaming cats.

– Jenny Seifert

For controlling agricultural insects, bats are worth at least $3 billion a year to U.S. agriculture, according to a 2011 study from Boston University. “People often ask why we should care about bats,” said study co-author Paul Cryan, a research scientist with the U.S. Geological Survey in Fort Collins, Colo. “This analysis suggests that bats are saving us big bucks by gobbling up insects that eat or damage our crops. It is obviously beneficial that insectivorous bats are patrolling the skies at night above our fields and forests—these bats deserve help.”

As conservation officials scramble to respond to white nose, they are enacting quarantines to prevent people – cavers, bat-lovers and scientists alike – from transporting the fungus between caves. Last year, for example, the National Wildlife Refuge System halted public access to all caves and mines on its refuges, and set protocols to prevent scientists from spreading the infection.

In May, 2011, the Fish and Wildlife Service rolled out a national plan for confronting and controlling white nose syndrome.

But bats can do plenty of transportation on their own. Even non-migratory bats may fly 200 miles between their hibernation site and their summer range, says David Blehert, a microbiologist at the U.S. Geological Survey National Wildlife Health Center in Madison, Wis., and a leader of white nose studies. “They can move large distances, across state lines, so there is potential for significant disease spread based on bat-to-bat interactions.”

What is the white nose syndrome situation now? Why is it so deadly? What bright ideas are afoot to preserve insect-eating bats, and what is the likely end game?

Why deadly?

In the short time since white nose syndrome appeared in 2006, scientists have pinpointed a fungus called G. destructans as the killer. But how does G. destructans do its work? One clue comes from the fact that it only kills during hibernation, when bats live in mines and caves at a rather chilly 7°C. “The fungus only grows in the cold, and when insectivorous bats hibernate in a temperate region, they drop their core body temperature to the ambient level,” says Blehert.

(The fungus is not likely to attack fruit-eating bats, says Blehert, because they do not have long periods of “torpor,” the slow-metabolism hibernation state that is conducive to the white-nose fungus.)

A low body temperature allows the bats to survive winter without eating, but it could also curtail the immune system, Blehert says. “Studies of bat immunology are in their infancy, but based on what is known about the physiology of other hibernating mammals, especially the 13-lined ground squirrel it’s likely that the immune system becomes suppressed, and that leaves them particularly vulnerable” to the fungus.

How does the fungus kill? It apparently does not enter systemic circulation, as internal organs are not damaged. All mammals awaken from hibernation occasionally, but Craig Willis of the University of Manitoba has speculated that infected bats have more waking hours, causing them to run out of energy during a period when they neither eat nor drink.

Blehert and his colleagues favor a second explanation: dehydration. Despite the “white nose” name, Blehert says, the most significant infection occurs on the wings. “The wings of a bat have eight times as much skin as the trunk; it’s a massive, very delicate and exposed membrane” with a single layer of epidermis surrounding a thin layer of connective tissue and some muscles and glands. “The fungus selectively invades the wing skin, and destroys everything in its path,” Blehert says.

Beyond their role in flight, bat wings are also needed to regulate temperature, fluids and electrolytes. “The wings may be the Achilles heel that exposes them to such significant infection,” Blehert says.

Indeed, an emerging disease that is devastating amphibians, the chytrid fungus, also affects the skin, and is thought to kill by causing an electrolyte imbalance. “The amphibian’s skin is very important for the balance of water and electrolytes, which has been the basis for our hypothesis about why white nose syndrome is so deadly. There was a paper¹ in 2009 that demonstrated that a superficial chytrid infection causes an ion imbalance in frogs, causing a disruption of the potassium gradient that causes the heart to stop. A superficial fungal infection causes a cardiac arrest! This is a very different concept than getting athlete’s foot and having an itchy foot.”

Stopping the wave of death

As dead bats pile up in caves, what can be done to stop the spread of G. destructans? The first step, trying to slow dispersal, is already under way in affected states, with restrictions on cave entry, and new protocols for disinfecting equipment and people who have a legitimate reason to visit hibernation spots.

The fungus does respond to common anti-fungal agents, according to a 2011 study, which found, unexpectedly, that the meds worked at the low cave temperatures that the fungus prefers. “The challenge is, how could you use pharmaceuticals to manage a disease in free-ranging wildlife?” says Blehert. “They don’t go to the doctor, and they inhabit environments that are likely contaminated with fungus. Say you could treat bats and cure them of the infection. If you can’t remediate their hibernation sites, they will become reinfected when they re-enter the cave.”

The authors of the anti-fungal study did raise the possibility of using meds to decontaminate caves, but this process is not being done, Blehert says. “Going into a cave with a general fungicide would be like dropping a nuclear bomb on a city. Caves are full of bacteria, fungi, invertebrates and vertebrates that may only exist in that unique ecosystem, and getting rid of such an important group of organisms [fungi] could risk significant unintended consequences.”

Willis has proposed using little heaters, since bats seem to fare better in warmer regions of caves, perhaps because that sustains immune function. Small heaters are being tested as bat refuges in some New York State caves, says Lisa Warnecke, a post-doctoral fellow at Manitoba.

Lessons from Europe

G. destructans is an “emerging exotic disease,” and to investigate such diseases, scientists always want to know how the pathogen interacts with hosts in its land of origin, which seems to be Europe:

In 2009, the fungus was found in a greater mouse-eared bat in France²;

ENLARGE

Photo: Gabrielle Graeter, NCWRC

Is this bat unhappy about the tufts of fungus on its muzzle — or the researcher’s big hands?

During the winter of 2009-2010, infected bats were found in 76 of 98 sites in the Czech Republic; and

A 2010 study³ in Europe found a white nose pathogen in 21 of 23 suspected bats that was “100% identical” to the U.S. pathogen.

Although the fungus been found in at least five bat species in Europe, die-offs have not been seen there, suggesting that something is different about how the pathogen, host and environment interact. Pathogens and hosts co-evolve through time in a complex dance:

The pathogen may become milder, improving its own survival (and that of its host);

hosts may evolve immune resistance; and

hosts can change their behavior to reduce exposure to the disease.

In the lab in Manitoba, Willis and Warnecke are studying how long little brown bats are awake during hibernation, whether the fungus is a necessary and sufficient cause of death, and if the North American or European strains of fungus have different effects on the bats. “If both isolates show the same severity for North American bats, that may mean that bats in Europe have co-evolved with the fungus and are resistant to it,” says Warnecke. “On the other hand, if the European isolate does not cause trouble for North American bats, then the fungus in North America is a mutant that has gotten really aggressive.”

Other factors could explain the lack of disease in Europe, says Blehert. “European bats are larger, which may provide them with more of a buffer against a physical insult like a fungal infection.” The little brown bat, the preeminent victim of white nose, weighs about 6 grams – about the weight of two pennies, Blehert says.

European bats also tend to hibernate in small groups. “They don’t have those 100,000-plus hibernacula like we see in the United States. With fewer animals, the disease transmission dynamic is likely to be reduced, with less amplification of the fungus, and lower rates of bat-to-bat transmission.”

In the long run, Blehert says, American bats may evolve some resistance. “In general, the population decline in caves and mines comes to about 78 percent, but the bats have not disappeared. We would expect something that gets into population to cause high mortality and a steep drop-off in population. Then, with fewer animals around, disease transmission could moderate.”

Although the regional extinction of the brown bat has been predicted to occur 16 years from now, “our bats may ultimately develop population dynamics more like Europe, with fewer animals and moderated disease transmission and progression,” Blehert says.

Evolution, in other words, could select for animals that, for behavioral or immune reasons, are less susceptible to white-nose.

But letting the situation play out without trying to help the bats, Blehert says, amounts to a high-stakes gamble with one of the wonders of the night sky.

Fish in the Gulf of Mexico: How safe?

The fire and deadly explosion of the Deepwater Horizon drilling rig on April 20, 2010 spewed a gusher of crude oil — about 4.4 million barrels — into the Gulf of Mexico.

The blowout flooded all levels of the Gulf with oil. And that oil, combined with millions of gallons of an oil-degrading chemical, raised questions about the health of Gulf seafood, both shellfish and finfish.

Fishing is major in the Gulf of Mexico, which in 2008 produced 15 percent of total weight of U.S. commercial fishing, and which has more sport fishers than any other American region.

Within two weeks, as a precaution to prevent the sale of contaminated fish, the government began closing parts of the Gulf to commercial fishing.

A report published today in Environmental Health Perspectives reviews the aftermath: How big was the threat? Did the closures harm the fishing industry by giving, in effect, official endorsement to the idea that the fish were contaminated? Were there any gaps in protection?

Not very filthy

The report came to an optimistic conclusion: government-sponsored studies of Gulf fish since the blowout found no significant contamination with heavy, persistent compounds called polycyclic aromatic hydrocarbons. “I don’t know that we have any evidence that the fish were contaminated, ever,” says study first author Julia Gohlke, an assistant professor of environmental health science at the University of Alabama-Birmingham.

PAHs can cause cancer and are often used as a measure of hydrocarbon contamination. According to the new study, “Federal seafood testing results released to date” show PAH levels at roughly 1 percent of the “level of concern” that the Food and Drug Administration established for assessing food safety after the Deepwater blowout.

Other results, she says, have focused on total hydrocarbons derived from oil, rather than PAHs. “My analysis looked at what the government has done,” she says. “There are independent reports of contamination that I tried to include, but they did not measure PAHs, only total petroleum hydrocarbons.”

Large oil spills are so ominous that people can overreact, says Gohlke. “People see an oil spill and fisheries closures and assume everything must be contaminated, and nobody wants to eat anything. There is a misunderstanding of what is considered contamination. There is now a large dataset, at this point, to show there hasn’t been significant hydrocarbon contamination to date.”

Gohlke and colleagues looked at data on the BP blowout, and previous oil spills from around the world, to compare toxicity levels and evaluate the procedures used to close and open fisheries. The project was funded by a grant from the Walton Family Foundation to the Environmental Defense Fund.

Looking at samples taken during and after the blowout, no results suggested that eating fish – whether with shells or fins – would contain elevated levels of PAHs, says Gohlke, who cautions that monitoring should continue for years because buried oil may re-enter the water and contaminate fish.

After the BP spill, fishing was banned in as much as 37 percent of the Exclusive Economic Zone in the Gulf of Mexico, which extends 200 nautical miles from the coast. These bans were precautionary, since they were made in advance of contamination tests, says Gohlke.

Although “safe, not sorry” can be justified, closures can also have unintended consequences, or even backfire, she says. “Part of me thinks the precautionary approach is appropriate, but I don’t know how it has contributed to consumer confidence. Without sufficient risk communication, precautionary closures may create an expectation that the fish is contaminated. The last survey I saw, from February, suggested people were still considering Gulf seafood to be contaminated.”

“I think they make some pretty good recommendations to continue monitoring for PAHs,” says Ron Kendall, director of the Institute of Environmental and Human Health at Texas Tech University. “There is a lot of debate about underwater oil mats that are still floating, and how much oil may still be on the seafloor or in coastal marshes. With hurricane season approaching, we don’t know what kind of remobilizing of suspended oil and the mats will take place.”

To date, Kendall says, the data show that seafood has safe levels of PAHs, but “You’ve got to understand that all this oil is not gone. This story is still unfolding.”

On March 11, a catastrophic earthquake — one of the four largest in the past century — struck in the ocean east of Japan, sending a colossal tsunami against the shore. By March 21, the toll of dead and missing, mainly from the tsunami, was estimated at 22,000.

As Japan confronted what Emperor Akihito called the worst crisis since World War II, we began to hear that the six-reactor complex at the Fukushima Daiichi plant, located directly in the tsunami’s path, had lost electrical power. The emergency generators also failed, apparently due to water damage to them or their fuel supply.

As we focus on the nuclear disaster at Fukushima, we emphasize that as of now, the tsunami itself is the far larger human tragedy. But like the tsunami itself, the nuclear disaster may portend further problems in other places, and is likely to affect a trend toward greater use of nuclear power around the world.

Not cool

Immediately, the arrow of trouble aimed at the most ominous type of nuclear accident: loss of cooling. Fission — splitting of radioactive elements that powers nuclear reactors — can stop when reactor operators flip a switch to insert control rods to absorb neutrons. This stops the chain reaction — the divison of uranium atoms that releases neutrons that split other atoms and generate heat — which is the whole point of building nuclear reactors to boil water and drive turbines.

But once the fission reactions cease, decay heat continues to be released from the unstable atoms that remain after fission, and it is this heat that must be removed by a cooling system after shutdown.

Past accidents have shown that decay heat can build up in seconds; and significant damage to the fuel and potentially reactor equipment can occur within minutes. The danger of such a “meltdown” is a major reason why nuclear designers and engineers focus so much effort on cooling the reactor core.

In the beginning, there was Three Mile Island

Japan, target of the only two atomic bombs used in war, is hardly the first nation to confront a “loss of coolant” emergency at a reactor. That happened on March 28, 1979, in the United States, where Pennsylvania’s Three Mile Island (TMI) reactor #2 began a partial melt-down.

Much later, the Nuclear Regulatory Commission concluded that the accident “was caused by a combination of personnel error, design deficiencies, and component failures.” As hundreds of alarms buzzed in the control room, operators, lacking a direct measurement of the water level inside the reactor, made a bad situation worse, the reactor went at least partly dry, and a large percentage of the fuel melted.

It’s safe to say the public reaction verged on panic as a bubble of explosive hydrogen built up inside the plant and evacuations were ordered.

The slow, dangerous removal of fuel revealed massive heating and damage inside the reactor. According to the book, “TMI 25 Years Later”¹: “A large portion of the core melted and flowed into the lower vessel. Most of the core experienced temperatures of at least 1727° C, with certain parts reaching 2527°C.”

At these temperatures, the essential containment vessel can weaken and fail.

TMI, the above book concluded, neared a complete a meltdown. “No one can say for sure, but some experts say that had the accident continued for another 20 to 45 minutes, the [reactor] vessel would have heated up and the metal would have lost its strength, leading to a rupture,” preventing further cooling and allowing superheated fuel to melt through the reactor vessel and enter – and likely exit — the reactor building.

From there, it’s impossible to speculate how widely the radiation would have spread, the authors wrote, but this is what is called the China Syndrome — a runaway load of reactor fuel melting its way down into the earth. Oddly, “China Syndrome” – the movie — was released 12 days before the TMI meltdown.

TMI #2 has since undergone a major cleanup. Intact and damaged fuel has been moved to storage at Idaho National Engineering Laboratory. Reactor #1 is operating normally, and final removal of the destroyed #2 awaits the decommissioning of its companion.

According to the Nuclear Regulatory Commission: “Estimates are that the average dose to about 2 million people in the area was only about 1 millirem. To put this into context, exposure from a chest X-ray is about 6 millirem.”

Nevertheless, the alarm over TMI sent the U.S. nuclear industry into a tailspin.

 

The meltdown of TMI was the death knell for growth in American nuclear industry — the spate of plants licensed during the 1980s had all been planned or under construction by 1979. Rollover to see a comparison of present dependence on nuclear energy.

Graph 1: U.S. Nuclear Regulatory Commission. Graph 2: International Atomic Energy Association

Chernobyl – the unmitigated disaster

The Lord Voldemort of nuclear accidents started on April 26, 1986, when Chernobyl reactor #4 exploded, burned and melted down in a spectacular fire that spewed an estimated 50 tons of radioactive fuel over a swath of Eastern Europe. Unlike TMI (and the imperiled Japanese reactors) Chernobyl had no vessel to contain its fuel, and a giant fire – consuming the estimated 800 tons of graphite used to slow neutrons in the reactor — burned for more than a week as brave crews tried to damp it with sand, boron and lead.

Chernobyl was located in a part of the Soviet Union that is now in Ukraine.

The meltdown produced some of the worst radiation injuries in history, and hundreds of thousands were force-evacuated from an “exclusion zone” — roughly 30 kilometers in radius — around the smoking, radioactive hulk of #4.

Within months, the cooling reactor was hastily wrapped in a giant concrete “sarcophagus” (stone coffin) to contain further radiation. But the sarcophagus is leaking, says Leon West, a professor of mechanical engineering at the University of Arkansas, who has 40 years of experience in nuclear physics, radiation protection and nuclear engineering. “Chernobyl is still open and is still a threat to the local environment.”
“Construction has already begun on the New Safe Confinement,” says photographer Michael Foster Rothbart, who lived 12 miles from the exclusion zone between 2007 and 2009, “and although it keeps falling behind schedule, target finish date is 2013.”

Japan: Facing Three Mile Island or Chernobyl?

By March 21, 10 days after the tsunami, the owners of the Fukushima power plant reported that it had reconnected electric power to all six reactors. The disaster seems headed toward resolution, says Jeff Geuther, who manages a research reactor at Kansas State University. “My understanding is that the fuel [in the three recently operating reactors and the three spent-fuel pools at other reactors] is all under water. The radiation dose has been falling at the plant, an indication that water level has increased in the spent fuel pools.”

Although it’s not clear how much fuel has melted, Geuther says, “It’s fairly clear that the cladding [a thin sheathing on the fuel rods], at a minimum, had some damage. Iodine and cesium have been detected offsite; these are fission products that would be typically be trapped inside the cladding.”

By March 23, the utility reported that the lights were on in the control room of reactor #3, but work had not yet begun on monitoring equipment and reactor cooling pumps in the three reactors that were operating before the quake. By March 24, smoke was rising from several reactors, three plant employees were being treated for radiation exposure, and the zone of concern about radiation in drinking water had been expanded. The local populace remains under evacuation.

Near-term progress in stabilizing the Fukushima plant will be measured by

A near miss?

Two positive factors helped what looks like a near-miss at Fukushima. First, those reactors (unlike Chernobyl) had thick steel containment vessels, which, despite some reports of damage, seemed to hold up reasonably well.

Second, also unlike Chernobyl, Fukushima used water, not combustible graphite, to slow neutrons.

On the other hand, Fukushima faced systemic difficulties due to the precipitating natural disasters: After the epochal earthquake-towering tsunami sequence shut the reactors down, the electric grid died, killing the emergency cooling pumps.

Then the emergency diesel generators failed, and without cooling, the reactors quickly overheated. But with roads out and the nation tending to survivors and victims of the tsunami, the nuclear emergency festered for days, through a series of explosions, fires, bursts of radiation, and evacuations of plant workers.

At one point, just 50 workers were on hand to deal with multiple emergencies at several reactors and pools of spent fuel. The desperation was on display when helicopters tried to dump buckets of water into the fuel pools and fire trucks sprayed cooling water through explosion-blasted walls.

How many broken reactors?

Despite early fears that Fukushima was mimicking Chernobyl, it seems rather to be headed toward the less malignant TMI precedent, says West. “A big leak [like Fukushima] is not like the open-air nuclear bonfire of Chernobyl that spewed radioactive materials into the upper atmosphere. The extent of the release of radiation and the continuing difficulties with cooling of reactors and spent fuel has clearly put the Daiichi site at the TMI stage.”

As radioactive particles cross the Pacific on the jet streams, “California, Oregon, and Washington should start reporting measurable traces of radioactive materials in air samples,” says West, “but for the United States, this should be more like a Chinese test of a nuclear weapon and of no health consequence.”

Radiation has already been detected on milk and green vegetables near the reactor, and now in drinking water in Tokyo. “The Japanese will need to monitor and control agriculture products to minimize the risk to public health,” says West. “This will be similar to efforts in the United States during the 1950′s, when the U.S. was detonating nuclear weapons in Nevada,” and farmers were prohibited from selling milk for four days afterwards.

Japanese meltdowns, American reverbs

As Japan evacuated neighbors from the Fukushima plant, the U.S. Nuclear Regulatory Commission (NRC) advised American citizens in Japan to move at least 50 miles away. That’s much further than specified American evacuation plans, notes Vicki Bier, a professor of industrial engineering at the University of Wisconsin-Madison. “If the NRC is concerned up to 50 miles in Japan, that certainly calls into question emergency planning here, which is limited to 10 miles.”

On March 16, California Senators Barbara Boxer and Dianne Feinstein asked the NRC to review safety at two California plants located near earthquake faults. “Roughly 424,000 live within 50 miles of the Diablo Canyon and 7.4 million live within 50 miles of San Onofre Nuclear Generating Station,” the senators wrote.

And on Mar. 22, the Nuclear Regulatory Commission agreed to accelerate a safety review at Indian Point, a pair of reactors 30 miles from Manhattan.

Japan: How prepared, in reality?

How did such severe nuclear troubles arise in Japan, where “tsunami” was coined, and which is the world’s leader in earthquake engineering and disaster preparedness?

For starters, the tsunami was much bigger than expected. But we’ve also learned from the Associated Press (on March 24) that Japanese preparations focused on natural disasters.

Was the nuclear emergency made worse because six reactors were at one location? As we saw, radiation vented from one reactor caused the flight of workers trying to tame other reactors. But multiple siting had “always been considered to be a really good idea,” says West. “You have a collection of focused professionals with lots of resources [for example, to fight fires], so if one reactor has difficulties, you could take those excess resources and focus on that situation. … This is the first situation, where [multiple sitings] appears to need to be reexamined.”

Early reports point to a critical design failure at Fukushima, says Bier, an expert on risk assessment at nuclear plants. “They were designing for earthquake and tsunami, but not for this level of damage; you’ve got to give engineers some criteria; they can’t design for anything. They could have designed for what did happen, but they apparently decided it was too unlikely.”

Design: Where are the goalposts?

A specific weakness concerned the emergency diesel generators needed to run the pumps, which apparently were swamped by the tsunami, says Bier. “There is a lot we won’t know for months, but there is reasonable speculation about things that could be done differently at modest cost. You can’t prepare for every eventuality, but probably it would have been possible to get better protection for the diesels in a bunker or on higher ground.”

The systematic disruption and near chaos interfered with tasks like avoiding melt-downs in the pools holding spent fuel, which lack the containment usually found on reactors. As Fukushima proved, accidents can be made worse as effects are compounded: the real-life scenario included a combination of a Japan-record earthquake, massive tsunami damage, regional blackouts and radiation releases.

“The surrounding area was so damaged by earthquake and tsunami that it impeded the emergency response,” says Bier. “We have seen stories about people within the evacuation zone who could not evacuate because the roads are impassable or buildings have collapsed, and they were not sending in rescue teams because the radiation was too high. Certainly it was not anticipated that the damage would be this severe, or the radiation would be too severe to evacuate.”

 

Photo: Japan Red Cross Society

Thousands of Japanese have been evacuated from around the Fukushima Daiichi reactors; masks retard the spread of disease in close quarters. Few experts expect the need for a permanent exclusion zone, like the one in Chernobyl, around Fukushima.

Fukushima: End game

Will the six reactors at Fukushima Daiichi be dismantled, like TMI #2, or wind up inside a Chernobyl-style concrete coffin?

The three reactors that got emergency cooling with sea water are likely finished due to corrosion, not to mention possible explosion damage. “Salt water is a killer,” says Robert Rosner, professor of astronomy, astrophysics and physics at the University of Chicago. Rosner expects these reactors to be taken apart and trucked to long-term storage.

Although the age of the reactors – about 40 years – militates against spending large sums on refurbishment and updating, Japan now faces an electricity shortage, so Rosner expects one or two of the plants to return to service, at least for a while.

West, however, suggests that at least one reactor may wind up encased in concrete. “If I were an engineering manager, I would be looking at the possibility of stabilizing it to deal with all the issues” and then build an outer containment to isolate the reactor but allow service visits.

Credibility at stake

Assessing the long-term impact of Fukushima requires us to look at the technology’s unique place in the popular eye. Whether the nuclear industry likes it or not, nuclear carries plenty of emotional baggage. Nuclear physics produced the mushroom clouds over Hiroshima and Nagasaki long before it was used to make electricity. And because ionizing radiation is invisible, it’s a case where what you don’t know can hurt you.

Nuclear energy also arouses fear because power-plant neighbors cannot control it, says Nathan Hultman, an assistant professor of public policy at the University of Maryland. “A lot of research has looked at why people view risks differently, and both dread and the degree of control in nuclear are nerves that are touched very strongly. We feel safer driving cars than in an airplane, even though statistically, airplanes are much safer, because we feel in control in a car.”

 

Photos: TMI, Cherobyl:Wanrouter.

While TMI today shows the scars of its accident (reactor #2 on left melted down in 1979), Chernobyl’s gravesite (rollover) evokes a much bleaker history and deeper wounds. The thrown-together concrete enclosure may need to be replaced – a hazardous, expensive task.

The Japanese nuclear industry also faces credibility problems, Hultman notes.

“Small nuclear accidents were covered up,” says Hultman. “Often the initial reaction was ‘Everything is just fine, the situation is normal,’ then it came out there was a deeper problem. Now we are in a situation where very bad things are happening, and people are not sure what to believe.”

Hultman adds that these issues are a likely fixture in the coming debate over nuclear power. “Nuclear is not the only way to boil water to generate electricity,” he says, and the discussion of energy sources must be broader than that. “Rather than say, ‘We must have nuclear,’ we need to talk about alternatives as well.”

The Fukushima debacle could further polarize a nuclear debate that was altered by both TMI and Chernobyl, says Hultman. “There is almost a religious division. People who believe it’s good think it will be the answer to all our problems, and people who don’t like it, really really don’t like it.”

An omen for the future?

The Fukushima disaster carries striking ironies. Japan was the only country at the receiving end of atomic bombs, and studies of survivors at Hiroshima and Nagasaki have been the basis for understanding the health effects of low-level radiation.

Historically, the Fukushima disaster occurred as nuclear was gaining so much traction as a low-carbon solution to global warming that some prominent environmentalists had begun to talk nuclear. “This is going to have a big effect on the rebound toward nuclear,” says West, who adds, “We just can’t burn our forests — and coal is an old forest — forever,” due to global warming.

Even technological disasters that loom large in the short run may eventually be seen as lessons, West says. “The crash of a major aircraft … does not mean that air travel should end, it means we need to tighten up our design.”

Rosner, however, suggests that nuclear, with its potential for widespread, long-term contamination, needs to live by different rules. “When you are engineering something where the consequences, if something goes wrong, are devastating, even though the probability is very small, you need to engineer to avoid the devastation. We’ve known how to do that for 50 years, but it was always just a bit too expensive on the front end, so the decision was made: The probability is so low, we are not going to worry about it.”

Japan, a world leader in earthquake engineering, has been paralyzed by a series of giant waves that followed one of the most violent earthquakes in a century.

Although the magnitude 9.0 quake on Mar. 11, 2011, apparently did not collapse high-rise buildings, the ensuing tsunamis flattened vast areas along the northeast coast. The death toll is swelling steadily as bodies wash in on the surf, and citizens and Japan’s Self Defense Forces scour a landscape turned upside down by inconceivably powerful waves.

The news recalls the estimated 250,000 people who perished, mainly on the Indonesian island of Sumatra, in the 2004 “Christmas tsunami” that followed a huge, offshore quake. (Both Japan and Indonesia are volcanic lands in the Ring of Fire, which partly surrounds the Pacific Ocean in a giant series of subduction zones and volcanoes.)

Shortly after Japan stopped shaking at 2:46 pm local time on Friday, March 11, we began hearing about troubles at a series of nuclear plants. After the reactors automatically shut down during the quake, emergency systems for removing heat still being generated in the reactors were routinely switched on.

But because the electric grid was down and the standby generators were damaged — perhaps by seawater — the emergency cooling failed. By Tuesday, March 15, three reactors had exploded, a fourth was burning, radioactive material was airborne, reactor workers were being evacuated, electricity was growing short in Tokyo, and the crucial containment vessels were under severe threat if not already breached.

With the first nuclear meltdowns since Chernobyl, in 1986, under way, global stock markets were crashing.

What causes tsunamis?

As Japan licks its wounds, The Why Files wants to know what causes tsunamis. How do they travel across the ocean? How they have impacted coastal people through history? Can we reduce our vulnerability to nature at its most cataclysmic?

Graphic: Anthony Liekens

Movement of the sea floor translates into waves at the surface.

Tsunamis — once slangily called tidal waves — are extremely powerful waves caused by large undersea disturbances. (“Tsunami” derives from Japanese for “harbor wave,” reflecting the fact that harbors can concentrate their energy. True tidal waves are the slow oscillations that drive ocean tides in response to solar and lunar gravity.)

Although landslides and volcanoes cause some tsunamis, probably 95 percent result from underwater earthquakes that contain a strong vertical motion. Such quakes often occur where one of Earth’s tectonic plates dives, or “subducts,” beneath another.

Like the Sunda trench near Sumatra, the subduction zone in the Japan trench is notorious for large earthquakes, says Timothy Masterlark, an associate professor of geological science at the University of Alabama. Although the timing is always uncertain, he says, “The history was known, big earthquakes were known, and even though the people and government went to great lengths to prepare, at some level … there is simply nothing they can do.”

Lessons from Sumatra

Masterlark, who has studied the giant, 2004 earthquake and tsunami in Sumatra, says the magnitude 9.0 earthquake in Japan likely broke a fault stretching at a shallow angle from the sea floor roughly 150 kilometers beneath Japan, along a trench several hundred kilometers in length.

We asked Masterlark how, if the slip was mainly horizontal, the rocks had enough vertical movement to cause a tsunami. “In Sumatra, we found a shallow slip created some vertical movement because the rock at the surface was softer, so the fault became more vertical, which changed the slip from mostly horizontal to mostly vertical.”

To imagine how vertical movement of the seafloor causes a tsunami, imagine making waves by throwing a stone in a pond. Even though earthquakes disturb the bottom of the water, the analogy works: just as a larger stone, thrown faster, makes a larger wave, the size of the tsunami depends on extent and speed of the ocean-floor movement.

The tsunami is usually most intense close to the earthquake: as waves spread from the epicenter in a typical arc-shaped pattern, their energy also spreads out.

Spread out, but still powerful

One factor that distinguishes tsunamis from more familiar waves is their extreme wavelength. On the open ocean, the peaks of waves may be 300 kilometers apart, and they may travel at 500 to 600 miles per hour. Even though they can keep pace with a jetliner, you wouldn’t see a tsunami from the cockpit of a jet. A killer tsunami may be only 2 feet tall in mid-ocean — far too small to be noticed from an airplane or even a ship, yet it can carry huge amounts of energy across the Pacific.

All that kinetic energy can hide in waves we can barely see because long-wavelength waves are extremely deep, and the massive amount of water moving beneath the surface contains enormous energy.

In deep water, boats can ride the worst tsunamis without noticing them; but when they reach shallow water and “run aground,” these waves become dangerous.

Like all waves, tsunamis slow when the lower part of the wave encounters the upward-sloping ocean floor. But while the front of the wave slows, the wave behind is still moving faster, causing a giant pile-up at the front, and the kinetic energy that was spread through the ocean depth concentrates in a towering wave at the surface.

Wild waves

It is these surface waves — which can be 10 meters high or taller as they cross the beach — that cause the utter destruction of tsunamis. Like all waves, tsunamis have both a rising and a falling motion, says Masterlark. “Depending on where you are with respect to the earthquake, you may first see a wall of water, or the opposite, the sea retreating.” In 2005, during a research cruise to Sumatra, “We were told that the tourists had heard that the ocean was retreating, and saw this as a great holiday, ‘Let’s walk on the seashore,” and this wall of water came in and killed them. This was a great warning, when they saw the water retreat, they should have headed away from the shore.”

Tsunamis have other quirks. They can be spaced as much as one hour apart, so subsequent waves can kill those who return to help victims of earlier waves.

In 1998, Harry Yeh, a civil engineering professor now at the University of Oregon, told us that tsunamis can have decidedly unconventional behavior. In one case, he said, a tsunami destroyed houses in a cove without damaging a house on an unprotected headland: “It’s the exact opposite of what a storm wave would do.”

A warning

Modified from original image by NASA

Location of foreshocks, aftershocks and the March 11 Japan earthquake (M 9.0). Circle size represents quake magnitude. Dotted lines = foreshocks; solid lines = aftershocks

The Pacific Tsunami Warning Center, established in Hawaii in the wake of the deadly 1946 tsunami, is a nexus in the global warning network. Since almost all tsunamis originate in earthquakes, the warning centers rely on data from seismographs, many of them located on the unstable ring of fire.

Tsunami warnings are now triggered automatically, says Masterlark, based on measurements of earth movement. “Seismographs are excellent because in seconds they can tell that a quake of some magnitude, big enough to trigger a tsunami, has occurred. This information can automatically trigger a warning in seconds.”

In tsunamis, seconds saved can translate into lives saved.

Researchers are working to use global positioning system (GPS) data to refine size estimates, Masterlark adds, to give “a more refined view of the potential risk, but this takes a little longer and is still in a research mode.”

Further confirmation of the size of the wave may come from special purpose ocean buoys, if they are in the right place, Masterlark says. “But they only work once the tsunami has already arrived, so they can only confirm or help refine the warning.”

Tricks of the tsunami trade

In terms of generating tsunamis, not all underwater earthquakes are created equal, says Andrew Newman, assistant professor of earth and atmospheric sciences at Georgia Tech. “A few times a decade, we have what we call ‘tsunami earthquakes’ that create a tsunami that’s much larger than would be expected for the magnitude of the earthquake,” largely due to a shallow rupture. “Usually a magnitude 7.8 earthquake would create a tsunami that might rise only 20 centimeters to 1 meter [when it reaches land], but one in Sumatra last year created a 17-meter tsunami.”

These large tsunamis come from a smaller break in the ocean floor, and so contain relatively little energy and do not travel well across the ocean, Newman says. But they also offer less warning because local people do not feel the massive shaking associated with a major tsunami.

Newman and colleagues have developed software to detect the peculiar signature of the tsunami earthquake, and are now running it on a research basis. “We get an earthquake or tsunami warning within four or five minutes, our algorithm starts processing, and a few minutes after that, the system sends email to the Pacific Tsunami Warning Center and the U.S.G.S. [Geological Survey],” Newman says.

Although the Japanese had little time between the earthquake and the tsunami, Newman says the national warning system did work. “In some ways, you have to look at real success in Japan. They have developed a substantial tsunami warning system, and it worked in as quickly as three minutes. People did evacuate, for the large part. Much of the video you see is from helicopters, or people watching from two or three stories up in buildings. There is only so much you can do with these events; this is a massive force.”

But the rising casualty counts highlights the deadly role of proximity to the quake, says Masterlark. “The very sad part is that because the quake was so close to the coast, they had very little warning; the time between the earthquake and the tsunami was minutes.”

More distant regions had adequate warning, Masterlark adds. “We had several hours before the wave reached Hawaii, and so were prepared. But Japan, unfortunately, even if you knew it was coming, you had only minutes, and that’s not enough time for many people to get to higher ground.”

Photo: Sarah Ruth

Basic tsunami safety

Public education and quick personal action remain the only ways to reduce the tsunami death toll:

1. Be on guard for strong earthquakes, which can spark a tsunami. If you feel one near the water, run inland.

2. Heed the warnings, and stay tuned to emergency radio stations.

3. Never go down to the beach to watch for tsunamis — they move much faster than you can run. People die doing this.

4. Most structures in the danger zone provide no protection. However, the upper stories of tall, reinforced concrete hotels can provide refuge if you have no time to move inland or to higher ground.

5. A tsunami is a series of waves. Don’t go near the water until you hear the all-clear from emergency authorities.

Following fatal footsteps?

Seismologists are loathe to predict earthquakes, but in the past decade or two, they have recognized that earthquakes occur in series along major faults in Turkey and Sumatra, as big quakes place extra stress on the adjacent fault. In Sumatra, a violent series of quakes began in 2004 with a magnitude 9.1, a magnitude 8.7 in 2005, a magnitude 7.6 in 2009, and a magnitude 7.7 in 2010.

The large quake in 2005 did not cause a major tsunami, but its timing, just three months after the Dec. 26 monster, suggests a compelling reason to focus intensively on the earthquake zone in the Japan trench, says Masterlark. “I am not trying to be alarmist, but I’m trying to look at where earthquakes have occurred along nearby faults to identify faults at risk. We’ll bring in numerical modeling and try to predict this as fast as possible. Time is of the essence, as we saw in Sumatra.”

When Deepwater Horizon blew up and melted down in April, the wound it tore in the Earth’s crust released a gusher of crude oil, estimated at 4.2 million barrels, into the Gulf of Mexico.

The massive microbial munching of methane during the BP spill may be the only good news from the Deepwater Horizon disaster.

The blowout also released about 160,000 tons of methane. If you counted molecules in BP’s blowout, methane (CH₄), the simple hydrocarbon that fuels stoves, furnaces and electric generators, was the single most abundant one.

But a report published in today’s Science shows that BP’s methane was totally devoured by microbes in the Gulf of Mexico, leaving less than .01 percent of the methane to enter the atmosphere. “We measured the sea-to-air flux of methane and found it was completely negligible,” says first author John Kessler, an assistant professor of oceanography at Texas A&M University.

Within four months of the April 20, 2010, blowout, a population explosion among methane-eating bacteria native to the Gulf decomposed virtually all of the methane, mainly in deep water, says Kessler.

Study author John Kessler extracts a water sample from a device that detects changes in water conductivity and temperature with depth.
NOAA Pisces.

The study offered three lines of evidence that bacteria were “eating” the released methane:

• Methane levels in the Gulf fell up to 10,000 times between June and October.
• Methane-munching microorganisms became extremely abundant downstream of the blowout. “Over the summer, the methane degraders were higher than we have ever seen at any other place in the world,” says Kessler.
• Dissolved oxygen in the water dropped as methane and oxygen reacted to form carbon dioxide and water, Kessler says. “Once we summed up all the lost oxygen in the area of the methane plume, we saw that it could only be explained by a complete [microbial] consumption of this methane.”

Although oxygen depletion is already a concern in the Gulf’s “Dead Zone,” the average loss was only 3 percent, Kessler says.

In a previous study, ethane and propane, two other natural gases that BP also released, decomposed even faster than methane, and were no higher than background levels by early fall. In both studies, Kessler collaborated with David Valentine of the University of California at Santa Barbara.

Cool news for your atmosphere

In the short term, spilled methane is less environmentally dangerous than crude oil, but it can pose a global warming problem in the long term, since a molecule of methane stores much more heat than a molecule of carbon dioxide.
Methane seeps are frequently found at ocean floors, where methane from decomposition enters the ocean. And unfathomable quantities of frozen methane are stored beneath the seabed.

So inquiring minds want to know: If and when this methane enters the ocean, could it reach the atmosphere and accelerate global warming?

Pisces, a research ship of the National Oceanic and Atmospheric Administration, was a floating laboratory to study Deepwater Horizon's aftershocks.
Photo: John D. Kessler/TAMU

The giant Deepwater spill contained too little methane to affect atmospheric levels, says Kessler, “but it does simulate a very energetic release from a seep or a methane hydrate, and so we were interested in using it as an analog for understanding how a massive submarine release of methane might behave.”

Although the microbes-eat-methane story provides a rare bright spot in BP’s ecological disaster, it’s not clear what would happen in shallow water, and in places lacking natural methane and a ready supply of methane eaters.

“The Gulf of Mexico has many natural methane seeps,” says Kessler, “that probably account for why Gulf waters are populated with these microorganisms, which are ready to degrade methane once there is a massive restocking of their ‘buffet.’ How this may play out at another place, without the natural seeps, I’m not sure.”

Within four months, bacteria had spawned enough offspring to devour essentially all of the added methane in the Gulf. “But if the bacteria are at lower abundance, would this take five months or two years? We don’t know.”

– David J. Tenenbaum