As honeybee colonies in the United States and Europe continue to suffer from a mysterious syndrome called colony collapse disorder (CCD), scientists are scrambling for answers. Another answer arrived this week, with a publication¹ that implicates a widely used insecticide.

CCD endangers many crops, but none more than almonds, which are pollinated by bees in more than a million hives trucked to California during the flowering season. Trucking stresses the bees, and stress is one of several likely contributors to the collapse syndrome.

Indeed, CCD could be several conditions lumped under one name, but here’s the trademark: The bees die away from the hive, obscuring the cause or causes of the collapse.

In the new study, scientists in France glued radio frequency identification tags to bees. Half were fed non-lethal doses of thiamethoxam, a common insecticide, then all the bees were released 1 kilometer from the hive. At the hive, the scientists used a radio-frequency gizmo to count how many flew home.

The tags did not affect the results, says Mickaël Henry, a researcher at the French National Institute for Agricultural Research, in Avignon. “Previous studies have shown that they do not impair movement or behavior of bees, or their time budgets for foraging activity.”

In any case, the control bees also sported tags.

What’s wrong?

How did the insecticide reduce the return rate so significantly? Most likely by causing difficulties with orientation, or locomotor activity, or both, Henry says.

When the experiment was repeated over a distance of just 70 meters, 92 percent of exposed and 98 percent of control bees returned, so both sets of bees were able to fly. The major impairment of exposed bees on the unfamiliar, longer route suggests that the insecticide was most damaging to the ability to learn a new route.

The neonicotinoid insecticides, the category that includes thiamethoxam, trigger nicotinic acetylcholine receptors, which are normally excited by a signal from a neurotransmitter. According to the new study, “Effects of sublethal neonicotinoid exposures in honey bees may include abnormal foraging activity, reduced olfactory memory and learning performance, and possibly impaired orientation.”

These insecticides make bees stupid, in other words.

The experiment was designed to count how many bees failed to return rather than pinpoint the reasons for that failure, Henry stresses. “The next step is to go into deeper detail about the behavior, with time-activity budgets, and looking at their foraging.”

Not the whole story

“This is a nice study, and it does clarify something that a lot of people have pointed to in the disappearance of bees,” says Phil Pellitteri, a faculty associate in entomology at the University of Wisconsin-Madison. “Insecticides have been known to cause bees to get lost, that’s one symptom of collapse. But colony collapse is a complex thing, and you can’t hang it all on one factor.”

Honeybees have long been attacked by viruses, protozoans and mites, Pellitteri says, and pesticides may decrease immunity, thus increasing susceptibility to pathogens. These, combined with the stress of long-distance travel and the scarcity of natural foraging grounds “are the general direction a lot of CCD research is pointing to. It’s a number of things, and their interactions.”

Henry and colleagues fed their data on return rates into a mathematical model, which predicted a perilous slide in colony populations. “The disappearances we observed may cause the colony to reach a population size low enough to be sensitive to other stressors,” he says. “Most bees are exposed to pesticides, and this confirms that exposure can put the colony at risk of collapse; this is the take-home message.”

On March 10, atmospheric chemist “Sherry” Rowland of the University of California-Irvine died in the company of his son and his wife of almost 60 years. Rowland became prominent in the 1970s after warning that common chemicals would destroy ozone 10 kilometers above Earth, exposing life to a shower of harmful radiation.

While exploring how chlorofluorocarbons (CFCs) degrade after being released into the atmosphere, Rowland and graduate student Mario Molina realized the CFCs would float to the upper atmosphere, be cleaved by sunlight, and release chlorine that would destroy ozone through a chain reaction.

(Ozone contain three oxygen atoms; most oxygen molecules contain two oxygens.)

By intercepting cancer-causing UV radiation, ozone in the stratosphere allows life to exist on Earth. Significant damage to this ozone would cause an epidemic of human and animal cancer, and likely damage plants as well.

This alarming prospect was not popular in industries that relied on CFCs, but it sparked a long and largely successful effort to restrict and then ban production of the chemicals.

And although Rowland never retreated from his findings, his calm, charismatic personality helped his cause. Ralph Cicerone, now the president of the National Academy of Sciences, recalls collaborating with Rowland on CFCs. “We talked on the phone nearly every day. I considered Sherry to be my best friend, and over time I learned that many people considered him to be their best friend, too. In the midst of the debates over CFCs, he never exaggerated the dangers, always cited the science, and treated other people with dignity and respect.”

What must a scientist do?

According to the University of California-Irvine’s press service, Rowland knew his results mattered far beyond the lab: “Mario and I realized this was not just a scientific question, but a potentially grave environmental problem involving substantial depletion of the stratospheric ozone layer. Entire biological systems, including humans, would be at danger from ultraviolet rays.”

At the time, scientists were studying the health implications of ozone-bearing smog in the lower atmosphere, but few people knew or cared about “good” ozone in the stratosphere.

The sudden notoriety of CFCs had a certain irony: The chemicals were invented in the 1920s at General Motors, maker of Frigidaire brand refrigerators, as a stable, non-toxic alternative to the ammonia and explosive propane used in air-conditioning and refrigeration.

CFCs later were used to expand plastic foam, clean electronic parts, and propel paint and deodorant in the mushrooming aerosol-spray business.

Antarctic ozone hole, 2011

   

Video: NASA

Chlorine and bromine in the upper atmosphere cause rapid ozone destruction in the super-chilled polar winter. Although the ozone “hole” (blue) is declining with the phase-out of CFCs, it still recurs.

They publish lest we perish!

Rowland’s 1974 study¹ ignited a long squabble over CFC production. Aerosol Age, the spray-can industry’s trade journal, implied that Rowland was a member of the Soviet KGB who wanted to destroy capitalism!

CFCs remained a back-burner issue, however, until the British Antarctic Survey discovered an alarming absence of ozone in 1985. The “Antarctic ozone hole” gave the theoretical worry sudden significance, and as the industry gradually found substitutes for CFCs, the ozone hole stopped expanding.

Today, as we watch the faltering response to global warming, it’s comforting to recall that the ozone threat prompted prompt collective action: The Montreal Protocol, a treaty to restrict CFC production, became effective in 1989 and has since been tightened after further alarm over ozone destruction, and 196 nations — essentially all of them — have signed the original Protocol. Production of ozone-depleting substances has fallen by more than 95 percent.

“CFCs were extremely useful compounds and their use was pervasive,” says Rudy Baum, editor in chief of C&EN (Chemical and Engineering News). “Although manufacturers maintained that there would be dire consequences if the use of CFCs were restricted or banned, it became clear pretty quickly that alternatives could be found in most cases.”

And yet ozone is still a problem, as shown by a 40 percent drop in Arctic ozone in the winter of 2010-2011. Continuing destruction is blamed on the stability of CFCs and the fact that the replacements, while less damaging, still destroy ozone. “Ozone can be thought of as a patient in remission, but it’s too early to declare recovery,” said Susan Solomon of the University of Colorado.

Not bounded by the lab walls

Nonetheless, the Montreal protocols are considered an epochal case of planetary preventive medicine, and Rowland, Molina and Paul Crutzen, who also worked on CFCs, were awarded the 1995 Nobel Prize for Chemistry.

But for 10 or 15 years, Rowland had played the role of maverick — speaking outside the laboratory about the importance of what he had found inside it. It’s not a comfortable role for many scientists; many find it safer to stay in the lab and let others figure out what to do with their results.

Jonathan Fink, vice-president of research at Portland State University, says “The culture of science is pretty deep in terms of how we are trained. Most science grad students are taught to focus on being the best at something, rather than thinking about the application of what they do to society.”

All along, Rowland explained the science and gently reminded us of our stake in an intact ozone layer. He continued to study atmospheric chemistry, mentor younger scientists, and show by example how scientists could speak responsibly about what their results mean for the rest of us.

Somehow, Rowland managed to fight his battles without making enemies, at least outside the industries that had inadvertently begun calamitous destruction of ozone.

Why do scientists like Rowland speak out? “Because they’re scientists and scientists are addicted to facts and what facts tell them,” says Baum. “I knew Sherry Rowland pretty well — I was the West Coast correspondent for C&EN from 1991 to 2004 … he was a gracious, dignified, reserved individual, certainly not a rabble-rouser. But he knew that his science was solid and that it told him that humans were doing something that would have catastrophic consequences if they didn’t stop. So he spoke out. Simple as that.”

A new disaster unfolds

Even before the Montreal Protocol was signed, climate scientists were starting to warn that carbon dioxide in the atmosphere would enhance the greenhouse effect and trigger global warming. In testimony to the U.S. Senate in the torrid summer of 1988, NASA climatologist James Hansen linked rising temperatures to rising levels of greenhouse gases from fossil fuels.

The debate over global warming and climate change had begun, and going public put Hansen in much the same position as Rowland had occupied 15 years before. Via email, Hansen credited Rowland and atmospheric scientist Don Hunten as “role models… . They showed that it was possible to do first-rate science and also uphold our responsibility to make clear the implications of our research for society.”

Rowland redux?

Until then, Hansen had been a well-regarded but faintly visible NASA expert in planetary atmospheres. He had studied Venus, where an atmosphere choked with carbon dioxide produces a “runaway greenhouse effect” that raises the surface temperature to 460° C.

After making news in 1988, Hansen retreated from the public discussion of warming, but in the early 2000s, as temperatures continued to rise, he began to speak up again. In 2005, after the Bush White House tried to muzzle him, he went public with a vengeance.

Why? Journalist Mark Hertsgaard, who has written extensively about global warming and repeatedly interviewed Hansen, says he “thinks like a scientist, believes if you find the information, and present it properly, the truth should carry the day. I think he came out of hibernation in 2005 only because he felt he had to. He looked around and saw that the information alone was not carrying the day.”

Hansen’s regular emails combine climate facts with political opinions for a broad audience. For example, a recent commentary argued that “Scientists attempt to communicate, but are flummoxed by the ability of the profiteers to manipulate democracies. The scientific method (objective analysis of all facts) is pitted against the talk-show method (selective citation of anecdotal bits supporting a predetermined position).”

On Aug. 29, 2011, Hansen was arrested at the White House with hundreds of others protesting the Keystone XL tar-sand oil pipeline. Tapping such a vast reservoir of carbon, Hansen believes, will bring us that much closer to a “tipping point” on greenhouse warming. “Now we’ve got the spectacle of one of the world’s foremost climate scientists getting arrested and urging others to get arrested,” says Hertsgaard. “This is way beyond speaking out.”

Hertsgaard, a native of Minnesota, says it’s “very hard for [Iowa native] Jim Hansen the person to speak out.” In the Midwest, Hertsgaard says, “it is just not seemly to draw attention to yourself or bring up a topic that is likely to discomfort others. … but it’s not corny to talk without irony about the importance of doing the right thing.”

The scientific culture

A fully indoctrinated scientist is chary of talking much beyond the lab, Hertsgaard says. “Many scientists very much frown on taking the public agitator role, and that’s another tribute to Hansen’s courage. He was prepared not only to take brickbats from the Exxon-Mobil front groups, but to endure the judgment of his own peers, who said ‘That’s not what scientists do.’ He remembers that he’s not just a scientist, he’s a human being too.”

Despite the successful example of the Montreal Protocol, the global warming problem is vastly harder to solve, says Baum of C&E News. “The scale of fossil fuel use is several orders of magnitude larger …. Humans consume between 80 million and 90 million barrels of petroleum every day, and that represents only about a third of the fossil fuel that is consumed.”

Finally, while the specter of cancer caused by increased UV radiation is unsettling, “people actually like the warmer conditions, at least for now,” Baum wrote. “We didn’t have a winter in Washington, D.C., this year … and people loved it.”

So will the environmental victory over CFCs that started with Rowland and Molina be mirrored by serious action over global warming? Maybe not, says Spencer Weart, a long-time chronicler of warming. Comparing the ozone battle to the fight over global warming “is like comparing a single battle to a world war. Ozone depletion (once the ozone hole was detected) was clearly an urgent problem, with a straightforward solution. But with global warming, it’s hard for people to worry much about something that seems remote in space and time — isn’t it just a problem for polar bears and our grandchildren?”

Slowing warming “will require wholesale changes in our entire world economy,” Weart says. “And that must begin with government regulation of the fossil fuels industry, the largest concentration of economic power the world has ever seen. The pushback has been fierce, beginning with industries that suspected their profits would be restricted, and extending to people who fear governmental threats to their freedom.”

Rowland was once libeled as a Soviet spy, but “Scientists who have put themselves into politics like Jim Hansen … have been subject to ad hominem attacks: crude vilification and direct threats far beyond anything that Rowland experienced.”

Hansen and his colleagues, says Weart, “have persisted nevertheless. For the logic of their scientific understanding forbids them from keeping silent about the dangers they foresee.”

Should an artificial waterway in Chicago be closed to block two highly destructive fish from entering Lake Michigan and then the other four Great Lakes?

On Feb. 27, the Supreme Court said ‘no’ when it declined to revisit an appeal by the State of Michigan, which wanted to compel closure of the Chicago Ship and Sanitary Canal. The canal, created to drain stormwater and wastewater from Chicago, could allow silver and bighead carp from the nearby Des Plaines River to enter Lake Michigan.

Since the two carp, native to Asia, escaped from fish ponds in the South in the 1970s, they have occupied much of the Mississippi River system, and have become extremely abundant in rivers near the Canal. Biologists, state agencies and the Great Lakes Commission warn that once the fish reach Lake Michigan, they will likely spread through the five lakes, then into the St. Lawrence River.

The Great Lakes hold almost 20 percent of the world’s fresh water and border eight states and two Canadian Provinces. Given the silver carp’s fearful jumping habits, and the potential for both species to steal food from the mouths of sport fish, the invasion could threaten recreational boating and commercial, sport and tribal fishing that gross $16.4 billion per year.¹

Although the Great Lakes already house at least 180 invasive species, ecologists warn about irreparable harm from Asian carp. They say prevention is cheaper and easier than eradication — which may be a practical impossibility.

Originally, the watersheds of the Great Lakes and Mississippi River were separate. The two were united by the Chicago Sanitary and Ship Canal, which drains stormwater and treated wastewater into the Mississippi River system.

Don’t fence me out!

Although three electric “fences” across the canal have apparently managed to block the fish from entering Lake Michigan, many scientists view the barriers as stopgaps at best, and Asian carp DNA has been found several times beyond the fences.

While that DNA suggests that the carp are already in Lake Michigan, the fish have not been found there. Still, ecologists, accustomed to studying the disastrous aftermath of invasives on land and in water, would love to protect the Great Lakes from the carp by closing the canal. That would also protect the Mississippi River from invasion from the Lakes.

“The Asian carp situation is analogous to medicine, where an ounce of prevention is worth a pound of cure,” says Jake Vander Zanden, a professor of zoology at University of Wisconsin-Madison, and an expert on freshwater invasive species. “It makes so much more sense to keep them out, rather that let them in and deal with the consequences forever.”

The shipping industry, reliant on these waterways, wants to keep the Chicago waterways open, said Mark Biel, chairman of UnLock Our Jobs by email. “Nobody wants to see the Asian carp get into the Great Lakes… This is, however, a manageable issue that requires a long-term, comprehensive plan, and separation is simply not a solution. Given the size, scope and complexity of separating the two bodies of water, it’s clear that the costs would be enormous and the timeline — if it’s possible at all — would do nothing to address the immediate threat of Asian carp.”

Invasions can be expensive. The Environmental Protection Agency figured that just the invasives delivered in ballast water cut commercial fish landings by 13 percent to 33 percent in the U.S. Great Lakes, at an annual cost of $200 million. The estimate did not cover Canada’s part of the lakes, or species that arrived by other means.

What’s the problem with carp? What can be done to prevent their entry into the Great Lakes and beyond? Are invasive species always so damaging to ecosystems?

What’s the beef about carp?

Asian carp are heavy-bodied fish native to Asia that have occupied large parts of the Mississippi River watershed, where their rapid reproduction, voracious feeding (up to two or three times their body weight in plant and animal plankton per day), and made-for-home-video jumps are making life miserable for native fish and fishing people alike. The two carp considered most threatening to the Great Lakes — silver and bighead — originated in Southern fish ponds, where they were placed as natural vacuum cleaners to suck plankton from dirty ponds.

Since at least 1980, when the escape of the silver and bighead was detected, that voracious appetite was transformed from selling point to sticking point.

You might observe — correctly — that species have been moving since life began. It’s true that invasions are an old story, but it’s only half the story: the process has been force-fed by commerce and technology. “This is a natural process; it was once a trickle, but the rate at which it happens now is so devastating,” says Vander Zanden. “With globalization, trade, travel, things are moving so fast, it’s a fundamentally different process, and the implications are huge.”

It’s impossible to predict exactly how well Asian carp would fare in the Great Lakes; their abundance will depend on temperature, food supply, the emergence of diseases and predators, and factors that we can’t predict. But the lakes have a wide variety of habitats, and inevitably some would be conducive to the invaders.

The fundamental reason why invasive species reach nuisance levels resides in the predators, diseases or competitors they leave behind in their homeland. In the new habitat, the traveling species often gets an unfair advantage, enabling it to grow to astonishing abundance and crowd out native species.

Asian carp provide a perfect example of the process. They were deliberately imported to work on Southern fish ponds, and their ability to outcompete native fish for food and habitat “has led to the widespread establishment of Asian carp in the Mississippi River, impacting the natural balance of the aquatic ecosystem,”².

Can we keep carp from the greatest lakes?

On January 31, 2012, the Great Lakes Commission, an international body charged with maintaining the environmental and economic vitality of Earth’s largest lakes, issued a report describing three options for physically separating the two giant drainages to block invasions in both directions. The report was greeted by a number of officials from the region, including Michigan Senator Debbie Stabenow and Chicago mayor Rahm Emanuel.

The Obama Administration opposes closure of the Chicago canal, and in February it proposed to spend $51.5 million on Asian carp research. The money will buy more trapping and netting, to assess whether the fish have reached Lake Michigan, research on fish trapping with chemical attractants, and noisemakers to scare carp from entrances to the lake.

The focus on Chicago is misleading, according to Biel, who notes that the Great Lakes and Mississippi River Interbasin Study, from the Army Corps of Engineers, found “18 aquatic pathways throughout the region (not just Chicago alone) by which the Asian carp could get into the Great Lakes. The existence of these other pathways, which cannot simply be closed, demonstrates the importance of a regional solution to control Asian carp populations. That’s why we have to expand our sights beyond Chicago to determine a comprehensive control plan that implements measures in all of the pathways… .”

Philip Moy is a senior scientist at the Aquatic Sciences Center at UW-Madison who previously worked on the issue for the Corps of Engineers. “Electric barriers buy us time, and we need to do two things,” Moy says. “We should look into additional barrier technologies that can be added to augment the electrical approach… . We need to look pretty hard at the Great Lake Commission report suggesting that the lake and river can be re-separated. It would cost a lot of money, a century of infrastructure has built up there, but what’s the logic of waiting another 10 years to get started on a project that can take a generation to complete?”

The “mid-system separation alternative” proposed by the Great Lakes Commission was estimated to cost $3.26 to $4.27 billion. The latest federal appropriation for monitoring and research related to Asian carp will bring the three-year cost for controlling Asian carp in the area to $156.5 million.

Separation, Biel wrote, “would effectively end waterborne commerce through the Chicago Area Waterway System. The Great Lakes Commission report mischaracterizes how vessels could move containers around the Chicago rail gridlock, giving the impression that there would be a way to facilitate both separation and continued cargo movement.”

Muscling in on the mussels

There are good reasons why zebra and quagga mussels are often mentioned in discussions about invasives in the Great Lakes. Since the zebra entered the lakes in ballast water used to stabilize ships a couple of decades ago, it has clogged water intakes at power plants and water utilities.

Along with a later arrival, the quagga mussel, the zebra has eaten enough plankton to change the ecology of the lakes, and the zebra is now spreading to smaller lakes and rivers.

To prevent further hitchhikers in ballast water, ships now must replace their ballast water in the ocean with salt water, which carries organisms that are unlikely to survive in the freshwater lakes. “Every ship coming in is inspected by the Coast Guard before it reaches the Great Lakes,” Moy says, “and we haven’t discovered another ballast-related species since 2006. In the lakes, there is a growing spirit of cooperation between the companies that operate ships and the states.”

p. 74, “Aquatic invasive species in the Rio Bravo/Laguna Madre Ecological Region”

Salt-water invaders are carried in ballast water and through the pet and fishery trades.

Species invasions also plague smaller lakes, which explains the growing push to prevent the movement of invasive fish, mollusks and plants, by requiring boaters to clean and dry their boats and trailers as they leave a lake.

In Wisconsin, at least, that effort seems to be succeeding, even though not every boater complies, Moy says. “Some people say, ‘If this guy didn’t do it, it’s not the end of the world if I don’t also,’ but it usually takes multiple introductions over time to establish a population. If we reduce the number of introductions per year, we reduce the potential for establishment. Every person makes a difference.”

Buying time, but could time be on our side?

As ecologists pursue the science of invasives, what to do about the carp now knocking on the door of the Great Lakes? Biel, of the shipping industry, says, “Despite the uptick in hysteria on this issue, Asian carp populations in Illinois haven’t actually moved up river in six years. That said, we fully support funding the existing electric control barriers because their effectiveness has been demonstrated over and over again.”

Despite “substantial strides” in controlling Asian carp in Illinois and Indiana, including a third electric barrier and physical barriers along the Des Plaines River and the Illinois and Michigan Canal, “there’s simply not enough being done by other Great Lakes states,” Biel says. “Continued calls for lock closure remain a higher priority for our neighbors and other like-minded groups than actually implementing tactics for prevention.”

During the years it would take to seal the Chicago waterways, control technology may improve, says Moy, who points to fresh ideas from the U.S. Geological Survey. Instead of using the pesticide rotenone as a “big hammer” to kill all fish, he says, the Survey is testing a coating for rotenone that would make a deadly fish feed. Once sprinkled in the water, carp and other filter feeders would eat the feed, but only Asian carp have the enzyme that can dissolve the coating to release the rotenone. “It’s much more specific; an elegant application that takes advantage of the fish’s feeding behavior and internal physiology, using an existing, certified” chemical agent, Moy says.

There are benefits to working several angles at once, Moy adds. “These invasions are not inevitable. We can reduce the rate of invasions and the number of introductions per year, and that reduces the likelihood of establishment, and each year we delay introduction to a lake gives research time to come up with a solution.”

In hot, dry places, water recycling has joined water conservation as a weapon against water shortages. After being treated at a sewage plant, wastewater is increasingly used for irrigation, industrial purposes, restoring groundwater, and after further purification, for drinking.

Photo: gingerpig2000

He thinks it’s pure water, but could this thirsty hiker be guzzling recycled filtered, treated, oxidized, and disinfected, sewage water?  Could that be safe?

About 0.1 percent of the municipal wastewater treated in the United States is reused for potable (drinking) water, according to a new National Research Council report. That may sound trivial, but “reclaimed water can account for the majority of the drinking water supply in some areas,” the report said.

In general, those areas have taken every reasonable measure to clamp down on water waste before embarking on the more dicey path of reuse. Drinking water is a small part of the growing movement toward reuse; far more common is the recycling of water for irrigating farms and landscapes, recharging groundwater, and for cooling generators and other industrial equipment.

But recycling for potable water is a growing trend in the Middle East, Australia, California and Florida. Miami-Dade County, Florida is about 80 percent through a project at a sewage plant that will use microfiltration, reverse osmosis, advanced oxidation and ultraviolet disinfection to disinfect partially treated wastewater. Each day, 21 million gallons of water “whose quality will be near that of distilled water” will be piped from a moat at the Miami Metrozoo. From there, the water will percolate into the ground to recharge groundwater.

The interest in reuse coincides with a need to update potable water-treatment plants, to the tune of $200 to $300-billion over the next 20 to 25 years.

In 2002, Florida was recycling the most wastewater, followed by California, Texas and Arizona.

The 2004 Guidelines for Water Reuse from the Environmental Protection Agency (EPA) estimated total U.S. water reuse at 1.7 billion gallons per day, with a growth rate of 15 percent per year.

But that’s just an estimate; the comprehensive Research Council report could not find solid numbers on current water recycling in the United States. “In 30 years we have not made a concerted effort in the United States to even figure out how much water we are reusing,” says Anders Andren, a professor of environmental chemistry and technology at the University of Wisconsin-Madison, and director of its Sea Grant Institute.

Globally, the estimate on total (not just potable) water reuse was 5.5 billion gallons per day.

Drink in the irony

If you’re gagging at the idea of guzzling highly treated wastewater, you may already be doing so, courtesy of “de-facto reuse.” The treated effluent discharged by wastewater plants often winds up in rivers, streams and lakes, and can easily enter intakes at downstream water utilities.

“Nobody has tried to figure out where we are in the United States by doing a quantitative survey of de facto reuse,” says Andren, meaning an unknown number of water utilities are delivering drinking water containing an unknown amount of treated wastewater.

If drinking water meets federal water-purity standards, it’s safe, but the issue of de facto reuse does merit further study. “This is the kind of thing every water system ought to be looking at, where the source water is coming from, and what is its quality,” says Henry Anderson, adjunct professor of population health science at the University of Wisconsin-Madison. In most cases, he says, the quality of the intake water is already a factor in deciding how to treat potable water.

On a per-capita basis, Israel, Singapore and Australia are leaders in water reuse. In every case, the local culture, economy, environment and demand for water affect how water is treated and used.

Here, we’ll concentrate on drinking water — the most demanding aspect of water reuse. Because it’s not legal to connect a drinking-water system directly to a sewage plant outfall in the United States, the treated effluent must reside in groundwater, surface water or a container for a while before it is piped to the water-treatment plant.

This delay provides a second layer of protection called “environmental attenuation,” says Anderson, who helped write the recent Research Council report. “The concern of the committee is that no system works with 100 percent efficiency all the time. If you are using a membrane to treat wastewater and it tears … we want multiple layers of protection.”

During attenuation, the treated wastewater can be mixed with surface water or groundwater, and then the water will go through the complete process for treating potable water, Anderson says.

How clean is safe?

Science and technology play dual roles in the adoption of water recycling. Improving water purification technology is offering an increasing number of choices. But technology costs money, and drinking water that comes from ground- or surface water is almost always cheaper than reclaimed drinking water.

But science is also able to detect an increasing number of contaminants in drinking water, and at ever-lower doses. In recent years, this analytical equipment has raised worries about hormones and pharmaceuticals in wastewater that have added to traditional worries about pathogens.

However, these highly accurate chemical-detection methods can raise spurious warnings, says Andren, an expert in water purification techniques. “Analytical capacities are such now that you can find literally everything, but they may pose no health hazard at those concentrations. It’s getting to the point that we can detect a thousand molecules in a liter of water, but this does not necessarily mean there’s anything wrong with the water.”

How it’s done

Water treatment plants come in two varieties. Some treat sewage, and others treat drinking water. In essence, water recycling creates a loose connection between these two plants, although federal law requires that treated wastewater be mixed and stored before it enters a plant treating potable water.

Both types of water plant already use multiple steps for treating water, but recycling has entailed an increase in the amount and intensity of treatment.

The specific treatment methods depend on the nature of the incoming water stream, which could come from sewage treatment plants, street runoff or industry. “The incoming streams can vary so much, in composition, type, quality and quantity,” he says.

Technologies must be chosen to deal with the situation, says Andren. “In certain instances, the main problem is getting rid of salt, in others it’s getting rid of bacteria, or pharmaceuticals, or organic chemicals or metals. It depends on the source water.”

Many challenges

Even though per-capita use in the United States is declining, recycling makes a lot of sense in water-short regions, says Andren. In the United States, “about 12 billion gallons a day [of 32 billion gallons treated per day] is shot into estuaries and oceans. In areas with generally high populations we are shooting away this water and will never have our hands on it again. If just a part of that could be reused, that would be good.”

But due to cost, recycling will only interest places with significant water shortages, Andren says. “We can do a great job at a cost, we can do anything at a cost.”

Ramping up reuse depends on introducing new technology, but that is a natural outgrowth of the steady introduction of sophisticated ways to clean wastewater and drinking water.

Andren, who reviewed the recent National Research Council report, says, “One of the major recommendations is that we basically have the treatment technology, and the approach to assess the hazards through risk assessment. Now we have to formalize that and work together on federal guidelines on how to start using more reclaimed water in daily life.”

Although a water shortage is not healthy, recycling, even if it increases supply, must still overcome the obvious “ecch” factor. “A lot of people ask, ‘If you have effluent from a sewage plant, and it goes through treatment, would you drink that?’” Anders says. “Absolutely, the technology is there, it’s being done all over the world. Our treatment technology and our ability to determine the quality of the water are such that it can be absolutely safe; it can be better than what you presently get out of the tap.”

Iraq resents American drones that monitor outside the U.S. embassy in Baghdad. Iran is delighted to capture a high-tech U.S. drone. And the United States plans more drone purchases even amid slowing growth of the military budget.

As remote-control airplanes get cheaper and better, drones seem to be everywhere:

And it turns out that drones are ideal for watching wildlife: rabbits, sea lions, gulls and a range of elusive or inaccessible species.

Counting the mini-bunnies

Researchers in Idaho have used drones to track the pygmy rabbit, a hand-size mammal that eats sagebrush. The rabbit, a “species of concern” in Idaho, is already extinct in neighboring Washington State.

Pygmy rabbits are reclusive, spending much of their time inside burrows, says Jennifer Forbey, an assistant professor of biology at Boise State University. Forbey, along with Janet Rachlow at the University of Idaho, the U.S. Geological Survey, and Washington State University, is using used military drones called Ravens to explore how habitat factors like cover, forage quality and temperature affect rabbit populations.

The Ravens are small, and able to carry only one of these instruments at a time:

The drone can cover the entire two-kilometer square site in about three hours, but its gadgetry sees neither rabbits nor their burrows. Because the drone noise would scare the rabbits back into their burrows, the plane does not work when the bunnies are likely to be active.

To find the animals, Forbey says, “We have to walk for days and days, to identify where the rabbits are. We hike around, looking for fresh fecal pellets, fresh digging, fresh clipping on plants.”

But the data on forage quality, combined with tried-and true shoe-leather counting, shows that the rabbits are discriminating eaters. “They are specialized to sagebrush, but not all [sagebrush] plants are created equal, some types are more palatable, and also provide better cover for them,” Forbey says.

It’s possible that in winter drones could get a better picture of rabbit activity by looking for tracks in the snow.

To actually see rabbits from the air without frightening them, Forbey suggests a back-to-the-future approach — perhaps lighter than air craft.

“We are trying to develop some other platforms, maybe blimps, that could stay static over burrows to get infra-red video of rabbits without making noise.”

Although airborne surveys have begun, they are a help but not a panacea, says Forbey. “Not much is known about pygmy rabbits. They are cryptic. You have to spend the time walking the habitat.”

Gulls in Spain

Black-headed gulls nest in large colonies, and like many colonial birds, monitoring from the ground is difficult, and viewing from conventional aircraft can be expensive and confusing.

Pick up a battery-powered, radio-controlled model airplane, and the picture changes, says Francesc Sarda, at the Center for Forestry Technology of Catalunya, in Spain. When the drone flies over at an altitude of 30 to 40 meters, “The gulls hear it, but they don’t identify it as predator, don’t know what kind of element it is, and so they do not care about it.”

In a 2010 study,¹ Sarda equipped the plane with a still camera, pointing straight down. A video camera in the “cockpit” broadcast a live feed to a laptop on the ground, where the “pilot” operated controls.

The plane is “easy to fly, many people do it for hobby,” says Sarda, and it’s affordable — at just 1,400 Euros for the plane and the equipment. Depending on wind, the plane can stay aloft for 15 to 20 minutes, but batteries are cheap, and easily replaced before the next flight.

Water birds often nest in dense colonies, and can be difficult to study. Those that nest on cliffs can be observed from the side. On flat land, wildlife biologists may have to walk through the colony, but “If there are thousands of birds, it’s very difficult to count,” Sarda says.

Encounters with human counters can also annoy the birds, he adds. “In our case, they will fly away, even if there are chicks or eggs on the nest. You have to be very careful.”

The drone sidesteps this problem, he says. “You can do your count, and repeat your sampling” after a week or a month, to assess changes.

Laws about low-level flight are much less stringent in Spain than in the United States, Sarda says, and the system is “very cheap, compared with manned aircraft. You can use it yourself, whenever you want.”

See the sea lion

Sea lions and the fishing industry are squaring off in the Gulf of Alaska, where a rapid population decline of Stellar sea lions has been blamed on a scarcity of the fish they eat. But studying these fearsome and elusive creatures is difficult and data are sketchy, says Greg Walker, who manages the unmanned aircraft program at the University of Alaska. “The sea lion is an endangered species, and it’s affecting the fishery, but the science behind it is pretty spotty. The sea lions that have been monitored are healthy, not starving.”

Fishing restrictions are costly to the industry, and Walker observes that boats are catching more fish in the same amount of time, which suggests no scarcity of prey. “Their technology is no better than it was five years ago, and if they are catching more fish, maybe there are more fish” in the Gulf, he says.

Currently, sea lions are counted by looking at “haulouts,” rocky locations along the shore where these mammals mate and give birth, but the Aleutian Islands are hardly an ideal place to fly, Walker says. Airports can be hundreds of miles apart, and weather predictions cannot accurately say if clouds will block the view, wasting time and money.

Last June, Walker and his colleagues launched a drone from a fishing boat standing offshore. After a 12-mile flight, the drone flew over the colony, without causing obvious disturbance, and obtained video and photos clearly showing the sea lions.

Ironically, the same restrictions on fishing that were enacted to protect the sea lion have made fishing boats scarce. “We started working with a fishing cooperative; would fly off their boat while they were fishing, since they were going to be in the area anyway,” says Walker. “But closing the fishery has meant fewer fishing boats in the area,” and the lack of convenient launch pads could raise the price of drone-based monitoring.

If cost can be contained, larger surveys are possible, Walker says. “We will try to survey more of the island coastline, not just the historic haulouts. We want to know, is this a real population decline, or are they just in another part of the habitat? If you are always looking at the same street address, when someone moves down the street,” you may think they are dead, he notes. “Maybe a more consistent survey would find more of the sea lions.”

Eventually, if he can round up a bigger drone, Walker would like to use synthetic aperture radar, which can see through clouds, and could sidestep, finally, the cloud problem. But he also hopes the drones can fly at 500 feet, beneath many clouds. Flying that low is dangerous for manned aircraft, but that concern does not apply to disposable drones.

Having proved the concept of drone-powered surveillance of the sea lions, Walker and associates are planning to begin a three-week campaign in March.

Stop us from droning on!

Drones have a broad range of advantages compared to other ways of studying the environment. We’ve already mentioned how they can get access to awkward locations without bugging the animals.

Flying low and slow, drones can also identify and measure invasive weeds or many other types of ecological dislocation.

H. Franklin Percival, program leader for unmanned airplane research at the University of Florida, says safety is a critical motivation for using drones. “Low-level manned aircraft is the leading cause of workplace mortality for wildlife biologists. Wildlife biologists do this kind of thing all the time, studying salmon nesting, alligators in Florida, seals in Alaska, there’s a lot of low-level stuff.”

In 2010, a pilot and two biologists died in a helicopter crash while studying salmon nesting on the Selway River in Idaho. “That drives the interest [in drones] now,” says Percival. Before nesting, salmon fan away sand and gravel on the river bottom, “and we can see these from the air.”

FAA blues

In the United States, a major limitation on scientific use of drones comes from the Federal Aviation Administration, which is, rightly, worried about collisions between piloted planes and drones. Currently, the FAA requires that the pilot or a spotter be a licensed pilot, and limits a drone’s range and altitude to avoid danger. Those restrictions raise both the cost and bureaucratic rigmarole, and ecologists and the unmanned airplane industry are hoping for a change.

On Feb. 6, the Senate sent legislation to the President requiring FAA action on the issue within three years, USA Today reports.

If the concern is safety, new, more relaxed standards seem most appropriate to drones that fly short distances at low altitude.

If the FAA redrafts regulations to maintain safety while allowing more civilian use of drones, Forbey of Boise State expects ecologists to be lining up for unmanned aircraft. “This integration of technology with ecology and conservation is really exciting. I think what these planes provide is a spatial level that you can’t get from satellite, and can’t get from being on the ground. Both in terms of the area they can cover, and the type of data they offer, they fill a gap.”

Let a thousand drones bloom

Robot planes and the associated technology of cameras, communications and GPS-based recording of location are moving ahead even as the FAA promulgates regulations. At the University of Florida, Percival, who has directed the development of five generations of a robot plane called Nova, says drones should be designed according to the scientific goal. “What are the data required? Can it deliver that kind of data, and can you do the appropriate statistics to give reliable information? The airplane should be built around your question.”

As drones with ever more sophisticated sensors return a growing quantity of data, Percival favors automating data-processing to spit out reliable data that can be manipulated statistically. “To estimate the number of nesting birds in a pelican colony, we want to differentiate the components in the imagery with a computer as opposed to some guy’s eyeballs.”

Photos show a lot, but they do not automatically reflect reality, Percival says. “Just because we can see well does not mean the numbers are as precise, as accurate, as we’d like.”

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