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The Water War Myth

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The Carbon Footprint of Barbecue

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Contents Conservation | Vol. 10 No. 3 | July-September 2009

As scientists piece together how climate impacts disease, strange patterns are emerging: mosquito outbreaks can follow drought, shorter migrations make butterflies sick, and more birds (not fewer) can ward off West Nile virus.

Sex Change, page 20

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Deadly cease-fire in Cambodia

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Higher GDP, less ecotourism

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Biofuels drain water supplies

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Deforestation boom and bust

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The case against lead bullets

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Sponge reattachment surgery

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Penguin poop from space

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Carbon footprint of BBQ

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Bee declines overhyped

Lighten Up Cartoons by Pete Mueller

Book Marks Mother Nature’s Dark Side: Maybe we’re not in such good hands Review By Jeffrey Lockwood Plus: Conservation Refugees, Animal Investigators, A Mathematical Nature Walk, and more

From Readers

Think Again Go North and Multiply by Catherine Brahic

On the Fence

People construct fences, sometimes across whole continents, on the poetic assumption that good fences make good neighbors. Unfortunately for wildlife, gated communities are rarely tranquil. By Douglas Fox

Mystery animals pouring across U.S. borders

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Operation Sex Change

Imagine waking up to discover that your mother, your sister, and your friends’ wives are all men. That could be reality for invasive fish if a radical plan to exterminate them takes shape. By Cynthia Mills

Some forests absorb CO2 while others belch it out

Journal Watch

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By Roberta Kwok

Essay Growing in the Dark By Nalini Nadkarni

Is a Warmer World a Sicker World?

The Water War Mirage

What if no one shows up for the fight? By Wendy Barnaby

38 Innovations

Winging It Feather-like spines could reduce vehicles’ fuel consumption

Escape Artist The supremely flexible octopus inspires a new generation of robots

Carbon Gets Stoned Injecting CO2 into subsurface rocks could provide permanent storage

Telltale Stripes Wrapping virtual skins on 3-D models helps track individual tigers

All-purpose Cleaner Algae sop up CO2 from Chinese coal plants

Cover Illustration ©Michael Gibbs Visit us at www.conservationmagazine.org to access the entire Conservation magazine archive, read Journal Watch Online, renew your subscription, and more.

Editors’ Note

your online guide to the best conservation research from over 50 journals 6 conservationmagazine.org

We Do the Legwork So You Don’t Have to

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This Week in Conservation Science

Let’s start with some exciting news: Conservation is the proud winner of the 2009 “Extra Award” issued by the Society of National Association Publications (SNAP). Conservation has been honored in the past with several SNAP accolades (including General Excellence awards in 2007, 2008, and 2009) but this one is particularly special: the Extra Award compares magazines across categories, regardless of size, and rewards publications that are “pushing the edge of the envelope further and taking bold chances to innovate in an everchanging publishing environment.” We believe the award validates one of Conservation’s founding principles: that a small magazine can have big influence if its ideas are powerful and its writing strong. Of course, we can achieve this only if you, our readers, open your minds to the cutting-edge science and ideas that push conservation forward. We’ve always been impressed by your willingness to do so, and we thank you for your passion and support. This issue features a story (Sex Change Operation, page 20) that encapsulates our enterprise. It’s about two unlikely researchers who, despite not having backgrounds in fisheries ecology, have developed a potent (if outlandish) proposal for eradicating invasive fish. The researchers, John Teem and Juan Gutierrez, devised a way to create “transvestite” fish (fish that have male chromosomes but function like females). By implanting these fish in invasive populations, Teem and Gutierrez believe they can skew the sex ratio of these populations until only males remain. The theory is now being tested on invasive European goldfish. If it works, it will be another victory for conservation—and another sign that, in the sometimes bizarre world of conservation science, you have to loosen your inhibitions in order to move ahead. —The Editors

Essay

Growing in the Dark By Nalini Nadkarni

ne way to understand the importance of something in our lives is to recognize that the prevention of contact with it—whether deserved or undeserved—contributes to a sense of punishment. This has occurred over and over in history when people were forcibly removed from their natural surroundings. During the Nazi occupation of Holland, for example, Anne Frank, whose diary made vivid the life of a family forced into hiding for twenty-five months, described the old chestnut tree from the one window in their cramped quarters that was not blacked out. On February 23, 1944, she wrote: “Nearly every morning I go to the attic to blow the stuffy air out of my lungs. From my favorite spot on the floor I look up at the blue sky and the bare chestnut tree, on whose branches little raindrops shine, appearing like silver, and at the seagulls and other birds as they glide on the wind.

As long as this exists, and I live to see it, this sunshine, the cloudless skies, while this lasts I cannot be unhappy.” Prisons are another place where contact with nature is withheld, consciously or not, as punishment. This has always puzzled me, given plants’ association with regeneration and renewal. If we could encourage not only prisoners but also their jailers to value the healing qualities of nature, perhaps the strikingly high recidivism rate— nearly 40 percent in my home state of Washington—would decline. Some prisons do have programs in which prisoners cultivate gardens that supply the prisons with fresh vegetables, which is constructive and healthy. However, interacting with plants in ways that go beyond gardening can secure other intellectual and emotional benefits. Several years ago, I developed a “Moss-in-Prisons” project that brought prisoners together with living, growing things that needed their care. I chose mosses for two reasons. First, I realized

that it was unrealistic to introduce trees within prison walls. But even more important, wild mosses from old-growth forests were in need of help. In recent years, a thriving moss-collecting industry has developed because of demand from florists, who use moss for flower arrangements and for packing bulbs. As of 2005, moss harvesting had an annual economic value of between $6 million and $260 million. The wide range of the estimates illustrates how little is known about the moss harvest trade. Because these plants fill important ecosystem roles and are very slow to regenerate, ecologists were already voicing concern over the expanded harvesting of this “secondary forest product.” Recent studies have shown that moss communities take decades to grow after disturbance, far longer than would allow for sustainable harvest at present removal rates. No protocols exist for growing mosses commercially. To learn how to best cultivate usable moss in sufficient quantities to offset harvest

Conservation Magazine

• Vol. 10 No. 3 | July-September 2009 3

Conservation A Publication of the Society for Conservation Biology

editor

Kathryn Kohm senior editor

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executive editor

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Michael Bean Jennifer Belcher Jamie Rappaport Clark Patrick Daigle Barbara Dean Eric Dinerstein Gustavo Fonseca Jerry F. Franklin Deborah Jensen Peter Kareiva John C. Ogden Mary C. Pearl Ellen Pikitch Michael A. Soukup Steven L. Yaffee

TM denotes the Trade-mark/Official Mark of Alberta Conservation Association, used under license Editorial Office: Conservation magazine, Department of Biology, Box 351800, University of Washington, Seattle, WA 98195USA; Phone: 206-685-4724; Fax: 206-221-7839; email: kkohm@u.washington.edu Subscriptions: An annual subscription for individuals is $30 in the U.S., $36 outside the U.S., and $21 in developing countries. Institutional rates are $75 in the U.S. and $80 outside the U.S., payable in U.S. funds on a U.S. bank. Copyright ©2008 by the Society for Conservation Biology. All rights reserved. No part of this magazine may be reproduced in any form or by any electronic or mechanical means, including information storage and retrieval systems, without the publisher’s written permission. Articles published herein reflect the views of the authors and are not necessarily those of the Society for Conservation Biology or its partners.

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™ from the wild, I needed help from people who have long periods of time available to observe and measure the growing mosses; access to space where flats of plants can be laid out; and most important, fresh eyes and minds to spot innovative solutions. These qualities, I thought, might be shared by many people in prison. The biology of mosses also makes them suitable for novice botanists because mosses possess “poikilohydric” foliage, which means their thin foliage wets and dries rapidly, allowing them to survive drying without damage and resume growth quickly after rewetting. Some mosses that have lain in herbarium drawers for over one hundred years have been revived by simply applying a little water and bringing them into the light. They therefore tend to be resistant to under- or overwatering, increasing the probability of their survival in a prison setting. We started with a straightforward goal: to explore new ways to “farm” moss that would provide an economically viable way to alleviate collecting pressure on the ancient forests of the Pacific Northwest. My students collected a variety of moss samples with a permit from the Olympic National Forest and brought the fragrant sacks of plants to the spare prison yard, where we were surrounded by concrete walls and barbed wire. The prisoners quickly built a small greenhouse with recycled lumber and we were set to go. Each inmate had a notebook and pencil to record his observations. The prisoners quickly learned to identify the four moss species we had collected, using their scientific names (only a few mosses have common names). They devised their own ways to grow them— hanging clumps of moss in mesh bags, for example—and contrived ways to deliver water with medical tubing and hardware clamps. They also learned how (and why) to retrieve randomized subsets of mosses to air-dry for

growth measurements. Each month, my students and I took a set of moss samples to my lab at the Evergreen State College to dry and weigh, for a comparison sample. The results of the project were dramatic in many ways. After eighteen months, we all shared the excitement of knowing which mosses grow fastest (Eurhynchium oreganum and Rhytidiadelphus loreus) and which watering treatment is most effective (misting proved better than droplets). We have since been working with two online nature gift companies to market “sustainably grown moss pots” using the plants the prisoners have propagated. “NatureLink” hangtags accompany each pot to inform the person buying it of the ecological importance of mosses and the need to grow them sustainably. When we finalize negotiations with these companies, we hope that some of the prisoners will pursue this alternative line of employment after their release. Other rewards came from this project, ones I had not foreseen. Nearly all of the inmates (whose names I have changed here) gave me insights into the ways that working with plants had affected them. One of them, Wayne Hunter, joined the horticultural program at the local community college after his release, with a career goal of opening his own plant nursery. “I don’t just want to mow lawns and trim hedges,” he said firmly. “I want to grow real plants.” Another, Jose Juarez, told me he had taken an extra mesh bag of moss from the greenhouse and placed it in the drawer of his bedside night stand. Each morning, he said, he opened the drawer to see if the moss was still alive. “And though it’s been shut up in a dark place for so long, it’s still alive and growing this morning,” he said grinning. And then, more quietly, “Like me.” ❧ From: Between Earth and Sky by Nalini Nadkarni ©University of California Press, 2008

JournalWatch

Your guide to the latest conservation research

©Stefan Ellis/AFP/Getty Images

Cambodia’s Trail of Guns Weapons from the Khmer Rouge now fuel wildlife trade Loucks, C. et al. 2009. Wildlife decline in Cambodia, 1953–2005: Exploring the legacy of armed conflict. Conservation Letters DOI:10.1111/j.1755-263X.2008.00044.x. When armed conflicts erupt, wildlife usually suffers along with people. To better understand exactly how and why this occurs, researchers led by Colby Loucks of the World Wildlife Fund

turned their attention to Cambodia, which suffered devastating violence and upheaval in the decades before Pol Pot’s death in 1998. Since data on the country’s wildlife abundance are scant, the researchers enlisted

an unusual source to chronicle the conflict’s effect: local hunters. Loucks’s team interviewed groups of hunters from eastern Cambodia about the abundances, ranges, and intended uses of 25 species during six political eras, from the early 1950s through 2005. The hunters outlined a substantial decrease in wildlife numbers and diversity, particularly during the war-torn 1970s. Five species, including the Asian elephant and the Siamese crocodile, vanished entirely. Usually, habitat loss would be a prime suspect behind such declines, but the area’s forests remain vibrant. The researchers instead traced the wildlife problems to a shift in livelihood among the villagers. Prior to the unrest, most villagers earned their living from fishing and possessed only rudimentary weapons, which made hunting a difficult proposition. The 1970s saw a huge influx of guns, many of which were given by the brutal Khmer Rouge regime to local hunters, who were then paid to kill wildlife. These kills were traded abroad for more guns and were used to provision the military. Over time, markets for Cambodian antlers, horns, bone, and other wildlife items grew, and commercial hunting became a viable livelihood strategy for many villagers. This hunting culture has proven hard to break, even though local authorities began removing guns from circulation in 2000. The study shows that conflict affects wildlife for years after the fighting ends. The team points out that conservation goals and post-war efforts to build peace and establish the rule of law are complementary. ❧ —Rebecca Kessler

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/i es

Back to Nature People are still flocking to natural areas. Just not in the U.S. Balmford A. et al. 2009. A global perspective on trends in nature-based tourism. PloS Biology. DOI:10.1371/ journal.pbio.1000144.

are becoming increasingly less interested in nature has become a familiar lament. But how does it jibe with reports that the popularity of ecotourism and other forms of natural recreation is growing? To unravel this contradiction, a research team led by the University of Cambridge’s Andrew Balmford reviewed visitation records for 280 protected areas in 20 countries. Previous studies on the U.S. and Japan found that nature-based recreation was declining. Balmford’s team found that these countries are the exception, not the rule. Between 1992 and 2006, visits to protected areas increased in 15 of the countries studied. Interestingly, there was a negative correlation between visitation rates and GDP—on a relative basis, natural areas in poor countries receive more visits than those in rich ones. The researchers take these findings as a hopeful sign, arguing that they provide further evidence that nature-based tourism can help promote conservation and protect biodiversity. ❧ —Justin Matlick

The idea that people

Conservation Magazine

©Martin Krasilnikov/iStock.com

A Drink or Drive Issue

The water footprint of biofuels Dominguez-Faus R. et al. 2009. The water footprint of biofuels: A drink or drive issue? Environmental Science & Technology. DOI: 10.1021/es802162x. In the latest blow to biofuels’

green cred, a report in Environmental Science & Technology shows that growing crops for ethanol may take a heavy toll on the water supply. In Nebraska, for instance, it can take 800 gallons of irrigation water to produce the amount of corn necessary to make one gallon of ethanol. Using this as their baseline, the researchers calculated that a typical ethanol-powered vehicle

would effectively guzzle 50 gallons of water for every mile it drives. This consumption level would vary depending on which crops are used and where they are grown; irrigated Iowa corn might require just 23 gallons of water to propel a car one mile, whereas irrigated Texas sorghum would need 115 gallons. Even for ethanol crops requiring little irrigation, water use is still a concern. For starters, the report’s figures don’t include the water needed to process the feedstock into fuel. That adds another few gallons of water per gallon of ethanol, which can add put a strain on water sources. Making matters worse, the cultivation of biofuel crops can also degrade water sources via erosion and agro-chemical runoff. With the federal government mandating big increases in biofuel production, the researchers recommend growing drought-tolerant, high-yield biofuel crops on marginal agricultural lands. Even then, Rice University’s Pedro Alvarez cautions, it will be impossible to entirely mitigate biofuels’ problems. “We cannot expect a major shift in our energy supply, from the oil fields of the Middle East to the farm fields of the Midwest, to occur without some collateral damage,” he says. ❧ —Rebecca Kessler

Process

Liters per Megawatt Hour

Oil refining

80–150

Oil Shale (surface retort)

170–681

NGCC power plant

230–30,300

Coal (IGCC)

~900

Nuclear (closed loop cooling)

~950

Geothermal (closed loop cooling)

1,900–4,200

EOR

~7,600

NGCC (open loop cooling)

28,400–75,700

Nuclear (open loop cooling)

94,600–227,100

Corn ethanol irrigation

2,270,000–8,670,000

Soybean biodiesel irrigation

13,900,000–27,900,000

• Vol. 10 No. 3 | July-September 2009

©Thomas Young/iStock.com

The Forest Giveth and Taketh Away

Old-growth trees absorb carbon, but increasing drought could cause them to belch it out

Lewis S.L. et al. 2009. Increasing carbon storage in intact African tropical forests. Nature 457, 1003–1006. Phillips O.L. et al. 2009. Drought sensitivity of the Amazon rainforest. Science 323, 1344–1347.

for years quietly sequestered carbon, buying the world more time to pursue a globalwarming solution. But how much longer these carbon sponges will chug along remains one of the biggest uncertainties in climate models. Two major studies hammer home the importance of this unanswered question. In Nature, a 33-author team estimates that undisturbed tropical forests have absorbed nearly one-fifth of the carbon dioxide released each year from fossil-fuel burning. They analyzed treegirth measurements collected in the African Congo for over 40 years and

Tropical rainforests have

combined their work with previous data from South America and Asia, yielding a combined 250,000 tree records. Previously, no one had put such a firm number—4.8 billion metric tons—on the total size of the tropical forest carbon dioxide sink. Old-growth trees have stored more carbon by generally growing larger, the authors write. But here’s the rub: A study in Science finds that increasing droughts could stunt tropical forests’ growth. In that case, greenhouse-gas concentrations could shoot up even faster than they are now. The Science paper chronicles how, when one of the worst droughts of the last century hit the Amazon in 2005,

scientists took advantage of the natural experiment. In a normal year, the Amazon forest absorbs about 2 billion metric tons of CO2. In the drought year, dying trees caused the forest to release 3 billion metric tons into the air. That 5-billion-ton net carbon belch is greater than the combined annual emissions of Europe and Japan. Granted, this is only a oneyear example. But models foretell more future dry spells for tropical rain belts. University of Leeds ecologist Simon Lewis, an author on both papers, states that no one knows how well rainforests will bounce back from a bout of drier times. And right now, he says, scientists can’t agree on how long the current tropical forest carbon sink will last–or when it will plateau or even reverse itself. ❧ —Jessica Leber

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©Wojciech Walter/iStock.com

Undocumented Immigrants Millions of unidentified animals are pouring over U.S. borders Smith, K.F. et al. 2009. Reducing the risks of the wildlife trade. Science 324: 594–595. Poor labeling of wildlife imports means that four out of five species entering the United States are improperly identified, according to an analysis in the journal Science. Between 2000 and 2006, researchers found, importers carted 1.5 billion live animals over U.S. borders—a number that corresponds to the purchase of five pets by every person in the U.S. over those years. This incoming tide of animals can facilitate the introduction of foreign species and harmful pathogens into ecosystems. Ninety percent of the imported animals came from wild populations in areas lacking mandatory disease testing, and more than two-thirds came from Southeast Asia, a hotspot for emerging diseases, the study reports.

Conservation Magazine

authors write. But with a third of the crates labeled only by the most general categories—such as “live invertebrates”—the current state of record-keeping makes this all but impossible. ❧ — Jessica Leber

Currently, there is no national strategy, authority, or dedicated funding for oversight of the wildlife trade. Better risk analysis and pre-border screening are desperately needed, the Level of identification given to animal shipments

# Individual live wildlife specimens imported into the U.S. (millions) unknown

250 unknown family 11.9% 7.5%

200known to class genus 11.1%

Class 52%

species 13.6%

order 3.9%

150known to order 100known to family 50known to gneus 0known to species ‘00 ‘01 ‘02 ‘03 ‘04 ‘05 ‘06

It’s anybody’s guess. Only 13.6 percent of animal shipments to the United States from 2000 to 2006 could be identified by species (above left). During that time, 200–250 million animals were imported each year (above right).

• Vol. 10 No. 3 | July-September 2009

Boom Towns Busted Rainforest clearing is not profitable for locals Rodrigues, A.L. et al. 2009. Boom-andbust development patterns across the Amazon deforestation frontier. Science 324:1435–1437.

a lot of tropical deforestation may be wrong, a study in Science shows. Amazon communities that convert their forests to ranches or farms are usually seeking to earn money and better their lives. But a study of 286 municipalities in the poorest regions of Brazil shows that, overall, residents who cleared their local forests were no better off than those who refrained from doing so. In fact, a “boom and bust” cycle follows forest clearing. Communities that cut down their trees initially become more prosperous, as measured by the U.N.’s Human Development Index—an average of life expectancy, literacy, and standard of living. The boom times on the clearing frontiers were fueled by sale of harvested resources and the access brought by new roads. But the improvements were usually only transient, the study found. Before long, the timber was gone and the towns were often left to support a flood of poor migrants who had come during wealthier times. In the end, the “pre-” and “post-” frontier states were pretty much the same. Such results suggest that a more-sustainable development framework would be best, not just for the forest but for locals as well, the team writes. ❧ —Jessica Leber

A basic assumption behind

Bite the Bullet

©Pedro Fernandes

Lead bullets poison the game for everyone Hunt, W.G. et al. 2009. Lead bullet fragments in venison from rifle-killed deer: Potential for human dietary exposure. PLoS ONE 4(4):e5330. DOI: 10.1371/journal.pone.0005330. When human hunters leave a carcass behind, the scavengers who pick it apart often ingest lead bullet fragments. This can cause lead poisoning in condors and other wildlife, spurring some environmental organizations to ask that hunters switch to lead-free bullets. Hunters have largely resisted those requests, but a new research finding may lead some to change their minds. It turns out lead might be a problem not just for wildlife but for humans who eat their kill. To investigate the likelihood of lead poisoning, a research team led by W. Grainger Hunt of the Peregrine Fund had hunters kill 30 white-tailed deer. The animals were subsequently processed into steaks and ground meat. The portions found to contain bullet fragments were then fed to pigs, whose digestive tracts are similar to those of humans. As a control, a separate group of pigs was fed noncontaminated meat. The researchers tested the pigs’ blood-lead levels for several days after the feeding. The control pigs were found to have a daily mean blood-lead concentration of 0.6 micrograms per deciliter, with a peak of 1.2 micrograms per deciliter. Levels were significantly higher in the pigs that consumed the fragments: the blood-lead levels in those pigs peaked reached a mean concentration of roughly 2.3 micrograms per deciliter, with a peak of 3.8 micrograms per deciliter. Similar blood-lead levels could lead to health problems in humans. According to the Peregrine Fund, studies suggest that as little as 2 micrograms per deciliter increases the risk of cardiovascular problems in adults and of cognitive damage in children. ❧ —Justin Matlick

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• Vol. 10 No. 3 | July-September 2009 9

Scat from Space

Penguins tracked down by their “mark” on the ice

Sponge Surgery Researchers propose new way to repair reefs after storms McMurray, S.E., and J.R. Pawlik. 2009. A novel technique for the reattachment of large coral reef sponges. Restoration Ecology 17(2)192-195.

a better fixer-upper for damaged coral reefs. The method could aid local restoration efforts to rehabilitate these ecosystems in the aftermath of hurricanes or harmful human activities. After such e ve n t s , l a r g e sponges often litter the ground and die because they cannot grow back onto the reef. So far, various cements and glues have failed to provide a fix, and as a result, restoration projects have focused on smaller organisms that are easier to patch. Using a new technique involving a “sponge holder,” the team removed and then affixed 20 Caribbean giant barrel sponges at Conch Reef near Key Largo, Florida. Almost two-thirds of the sewed-on specimens survived at least another two to three years, during which four hurricanes passed over the area. Most of the sponges naturally reattached to the reef, something that did not occur in previous surgical attempts. ❧ — Jessica Leber

Scientists have invented

Conservation Magazine

©British Antarctic Survey

Fretwell, P.T. and P.N. Trathan. 2009. Penguins from space: faecal stains reveal the location of emperor penguin colonies. Global Ecology and Biogeography DOI:10.1111/j.14668238.2009.00467.x. Animals often mark their territory with the only thing they’ve got going for them: their poop. Now researchers are using this idea at a whole new level. They are tracking penguin colonies by following their droppings via space satellite, the brown patches blazing against sheets of pure-white ice. Usually, it’s hard keeping track of emperor penguin colonies because the birds rear their young on Antarctica’s harsh sea ice long before the summer thaw. Using Landsat imagery, the researchers analyzed the entire continental coastline for fecal staining, which they describe as a good marker of penguins’ turf. They identified a total of 38 penguin colonies; ten had never been known before, and six More Online had been relocated from previous assessments. See video of Another six colony locations—from old or un- Antarctic penguins at conservationmagazine.org confirmed records—could not be located. This sort of scatological spying is good news for penguins, a species vulnerable to rising global temperatures and melting ice. Previously, scientists regularly monitored only a select few colonies because of difficulties gaining ground access. With the ability to map out penguin movements from afar, scientists will now be able to better track and hopefully conserve this iconic bird. ❧ — Jessica Leber

• Vol. 10 No. 3 | July-September 2009

©Katrina Brown/iStock.com

Much Abuzz about Nothing? Fears of global bee decline may be unfounded Aizen, M.A. and L.D. Harder. 2009. The global stock of domesticated honey bees is growing slower than agricultural demand for pollination. Current Biology 19(11):915-918.

losses in the U.S. and Europe have triggered fears of a worldwide “pollination crisis.” A new study in Current Biology suggests the decline might not be so widespread after all. Bees are needed to pollinate certain crops, and some fear that a global slump in bee numbers could bode ill for the world’s food supply. But when a research team analyzed data from the United Nations, they found that the number of commercial honey-bee colonies worldwide actually increased by about 45 percent from 1961 to 2007. While colony numbers have been dropping in the U.S. and some parts of Europe, other countries have made up for those losses. On the downside, the percentage of crops that require pollination rose from 3.6 to 6.1 between 1961 and 2006. That skyrocketing demand may be straining the world’s bee colonies. Wild and feral bees are likely helping to satisfy the pollination demand for now, but this “service” could be in danger if the spread of agriculture wipes out neighboring habitats. ❧ —Roberta Kwok Reports of bee colony

©Dandanos/Dreamstime.com

Trial by Fire

The Carbon Footprint of Barbecue Johnson, E. 2009. Charcoal versus LPG grilling: A carbon-footprint comparison. Environmental Impact Assessment Review DOI:10.1016/j.eiar.2009.02.004.

kg CO2

Who says science is no picnic? To assess the carbon footprint of barbecues, Eric Johnson rounded up eight volunteer grillers (including himself ) and held the equivalent of 50 cookouts. The researchers used both gas and charcoal grills and kept tabs on their fuel usage, the length of time they grilled, and the amount of food they cooked. Johnson, of Atlantic Consulting in Gattikon, Switzerland, then included those numbers into a life-cycle analysis of each grill type. In the end, charcoal turned out to have a far-higher carbon footprint than gas. The researchers concluded that charcoal grilling sessions 1200 typically carry a footprint of 6.7 100 charcoal kilograms—roughly the same as 800 driving a car 35 kilometers. Gas 600 grilling, by contrast, produces just 2.3 kilograms of CO2 per 400 gas session. 200 One key reason for the 0 disparity: producing charcoal is 25 50 100 150 grilling sessions a carbon-intensive proposition that involves harvesting wood and heating it to 300 to 500 degrees Celsius. Also, charcoal grillers typically use the same amount of fuel, no matter what they’re cooking, while it’s easier to vary the fuel output of gas grills. ❧ —Justin Matlick

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• Vol. 10 No. 3 | July-September 2009 11

n the late 1990s, a set of alarming maps created a stir in the scientific community. Based on predictions by a team of Dutch and Australian researchers and initially published in the journal Environmental Health Perspectives, the maps charted how global warming could increase the risk of malaria in seemingly unlikely locales: northern countries such as Poland, the Netherlands, and Russia. Over the next several years, versions of the maps continued to appear in journals and at scientific meetings as researchers raised the disquieting possibility that climate change could trigger an expansion of disease. An article in Scientific American reprinted one iteration of the maps and declared that “by the end of the 21st century, ongoing warming will have enlarged the zone of potential malaria transmission from an area containing 45 percent of the world’s population to an area containing about 60 percent.” Statements like these added to the popular perception that a warmer world will automatically be a sicker one. But what if this isn’t true, or is only partially true? Kevin Lafferty, an ecologist at the U.S. Geological Survey, is among a handful of scientists now raising these questions and rethinking conventional wisdom. Lafferty recently published a controversial article in the journal Ecology suggesting that, while climate change may shift the ranges of certain diseases, it won’t necessarily increase the total amount of territory they affect. (1) And Sarah Randolph, a parasite ecologist at the University of Oxford, has reviewed recent disease outbreaks—some of which have been attributed to global warming—and concluded that human actions and other factors may have played a larger role than climate. Lafferty’s and Randolph’s opinions have stirred intense debate. While there are credible arguments on both sides, the overriding point is that some scientists are beginning to see the ecology of disease as far too complicated to support simple declarations about the impact of global warming. It turns out that disease ecology is made up of a multitude of moving parts, ranging from precipitation patterns to animal migrations, that constantly shift and adjust in relation to each other. And when climate changes, the end result may be an increase in disease—or not.

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As scientists piece together how climate impacts disease, strange patterns are emerging: mosquito outbreaks can follow drought, shorter migrations can make butterflies sick, and more birds (not fewer) can ward off West Nile virus.

Warmer World Is a

Sicker World?

ÂŠRobybret/Dreamstime.com

By Roberta Kwok

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Nature vs. Nurture When tick-borne encephalitis spread throughout the Baltics, was the culprit climate change or the fall of the Soviet Union? Sarah Randolph has spent more than 30 years studying vector-borne diseases (diseases transmitted to hosts by insects and other animals). She’s also a maverick who has devoted the latest chapter in her career to digging beneath what she calls “seductive mindsets.” As she wrote in a response to Lafferty’s Ecology article, one of these mindsets is that recent disease outbreaks are caused by climate change, “adding fuel to the fire of predicted impending doom.” (2) Take tick-borne encephalitis (TBE), a nasty viral disease that can cause inflammation of the brain. Beginning in the 1980s and 1990s, a rise in temperature appeared to correspond with a TBE surge in several European countries, where thousands of people were stricken with headaches, fever, and other unpleasant symptoms. In Sweden, some scientists suggested that warming had triggered the rise in TBE cases and that future climate change would exacerbate the scourge. Randolph decided to conduct her own investigation. In a 2007 study, her team examined county-level TBE trends in the Baltic countries of Estonia, Latvia, and Lithuania; they found patterns that couldn’t be explained solely by climate. While temperatures rose in 1989 across the Baltics, TBE cases in individual counties began spiking anytime between 1990 and 1998. To investigate further, Randolph’s team studied the region’s social and economic history. After the Baltics broke from Soviet rule in the early 1990s, unemployment rates—and poverty—surged. Poorer people were less likely to be vaccinated, the researchers found, and more likely to forage for food in tick-filled forests. This suggested to Randolph that, contrary to popular assumptions, the disease surge probably had far more to do with human actions than planetary changes.

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The TBE case isn’t unique. “In the last two decades,” Randolph argues, “there’s practically no examples where a vector-borne disease can be pinned on climate change.” Of course, Randolph is only one player in a contentious debate, and other scientists say they have found links between climate and diseases such as malaria, dengue, and cholera. Just because disease is influenced by a myriad of factors doesn’t mean we should ignore climate, warns Richard Ostfeld of the Cary Institute of Ecosystem Studies. “To me, that’s kind of like saying because we know that obesity is also a risk factor for heart disease, we don’t need to worry about smoking,” he says.

Dry and High Why did mosquito populations surge after drought dried up their habitat? the disease puzzle, some of the most complicated variables revolve around the mosquito. Notorious for transmitting malaria, West Nile virus, and other pathogens, mosquitos are expected to develop faster at higher temperatures, raising concerns that global warming could spur disease outbreaks. But as researchers like Jonathan Chase unravel how mosquitos respond to key climate conditions, they’re reaching surprising new conclusions. An ecologist at Washington University in St. Louis, Chase didn’t set out to discover anything about mosquitos. He wanted to know how droughts affected biodiversity, so his team built artificial wetlands by filling outdoor tanks with dirt and water. To simulate different wetland drying patterns, they left some tanks full yearround, while others were drained annually. A third type of tank was drained only once in three years, mimicking wetlands that generally retain water but go dry during a drought.

As researchers piece together

You might think periodic droughts would diminish mosquito populations by drying up habitat. But the number of mosquitos in the third group of tanks skyrocketed to more than 20 times the amount in the other tanks. Chase thought back to figure out what might have happened. He knew that, since those tanks usually held water, they housed mosquito predators and competitors that were poorly suited to dry conditions. When the “drought” killed many of them off, mosquitos likely seized the opportunity to multiply. With their fast breeding times, Chase reasoned, mosquitos could quickly recolonize the area before their predators rebounded, resulting in the population boom. To see whether the idea held up in nature, Chase turned to data from a survey of Pennsylvania wetlands. Sure enough, ponds that dried out only during a drought showed a spike in mosquito larvae the following year. The results confirmed what Chase had suspected—the drought had opened a “giant habitat for a small window of time,” he says, allowing mosquitos to flourish. Chase’s team took the research a step further to see how this might affect the spread of disease. They analyzed data on human West Nile virus cases in the United States between 2002 and 2004, comparing the trends to changes in precipitation. In the western United States, the number of cases increased after dry years, as expected. But in the eastern part of the country, the pattern was the opposite: outbreaks happened after rainy years. The variation might arise from a difference in mosquito species, says Chase. Mosquitos that spread the virus in the western United States tend to dwell in wetlands and thus would benefit if a drought wiped out fellow inhabitants. But mosquito species on the other side of the country prefer to breed in puddles and waterfilled containers, so they could take advantage of higher rainfall. Chase’s mosquito findings illustrate how much scientists still have to learn before they can accurately forecast the effects of climate change on disease. “You have these simple no-

tions that one factor will work in one way,” says Andrew Read, an infectious-disease researcher at Pennsylvania State University who was not involved in Chase’s work. “But in the context of community ecology and food chains, anything can happen.”

Photo courtesy of Sonia Altizer, University of Georgia

Canceled Flights Do long migrations keep butterflies healthy? It has long been feared that climate change will

enable disease to run rampant through animal populations. A warming world could alter the borders of suitable habitats, leading migratory species to new territory and exposing them to diseases they haven’t encountered before. But scientists are only beginning to get their arms around the mechanisms that might allow disease to weaken some populations while others emerge unscathed. Karen Oberhauser, an ecologist at the University of Minnesota, has been pursuing answers to questions about how climate change might

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Remote Diagnosis Satellite data can suggest when and where epidemics will strike next

In December 1997, large numbers of cattle, goats, and sheep began dying in the Garissa district of northeastern Kenya. A month later, people started dying, too. It was, at the time, the biggest recorded outbreak of Rift Valley fever in East Africa. Some 100,000 stock animals succumbed, and about 90,000 people were infected—hundreds fatally—in five countries. In December 2007, the same thing happened. Or rather, it started to happen but was stopped in its tracks. The difference was that the second time around there was ample warning. In September, researchers at the Goddard Space Flight Center in Greenbelt, Maryland—part of NASA, the U.S. space agency—told authorities in Kenya that they had a problem. They told them again in October. And again in November. By the time the epidemic emerged, the Kenyan health ministry had dispatched teams to the area to distribute mosquito nets and urge village leaders and religious authorities to stop people from slaughtering and eating animals. Though the outbreak still killed 300 people in Kenya, Somalia, and Tanzania, it could have been a lot worse. According to Kenneth Linthicum of the

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U.S. Department of Agriculture, the number of deaths would probably have been more than twice as high without the warning. The warning itself was possible because of a model of how disease spreads that Dr. Linthicum helped design. And the data plugged into that model came from satellites. What the researchers at Goddard had noticed at the time of the first outbreak was that in the months preceding it, surface temperatures in the equatorial part of the Indian Ocean had risen by half a degree. These higher temperatures brought heavy and sustained rains, cloud cover, and warmer air to much of the Horn of Africa. Mosquitos multiplied wildly—and lived long enough for the virus that causes the fever to develop to the point where it is easily transmissible. In September 2007, the researchers saw the same thing happening in the ocean and suspected the same consequences would follow. Attempts to foresee epidemics such as these have traditionally relied on fieldwork on the ground. This is often slow and expensive. Crunching data from satellites is much-less costly. Satellites transmit

Photo courtesy of NASA

copious information on temperatures, precipitation, vegetation cover— and the health, moisture content, and chlorophyll production of plants. As David Rogers, an expert in ecology and disease at Oxford University, observes, this is an enormously useful combination of variables. His research has linked levels of photosynthesis, detected from satellites, to the size of a vein in the wings of West African tsetse flies. This vein measurement indicates the health and size of fly populations— and suggests the likelihood of epidemics of sleeping sickness, a tsetseborne parasitic disease that kills tens of thousands of Africans a year. That means satellite data can be used to predict epidemics without having to collect any flies on the ground. And it is not only Africa that is benefiting. Satellite research indicates a “significant risk” that dengue fever, malaria, and Rift Valley fever will enter Europe, according to Renaud Lancelot, head of the EDEN project, a group of laboratories and public-health agencies in 24 European and African countries. Indeed, chikungunya, a mosquitoborne virus endemic to tropical Africa and Asia, has already arrived in Albania and Italy. A harbinger of things to come, perhaps? ❧ ©The Economist Newspaper Limited, London (May 21, 2009)

affect the monarch butterfly. Today, eastern North American monarchs can log up to 5,200 kilometers on their annual trips to forests in Mexico. But in a 2003 study, Oberhauser found that global warming might make these forests too wet for monarchs. Instead of flying to Mexico, she says, the butterflies might take a shorter migration route to the Gulf Coast of the United States. On the face of it, shorter migration flights might not seem alarming. But Sonia Altizer, a former student of Oberhauser’s who is now at the University of Georgia, has been finding surprisingly strong links between the length of monarch migrations and the prevalence of disease. Altizer examined nearly 15,000 monarchs to determine which were infected with the parasite Ophryocystis elektroscirrha, which can cause wing deformities and shorten life spans. Among monarchs that travel long routes to Mexico, less than 8 percent of the butterflies were heavily infected. But for western North American monarchs that take shorter flights to California, the numbers went up to about one-third. And in a Florida population that didn’t migrate at all, more than 70 percent were stricken. Altizer’s team speculated that migration might weed out infected butterflies, which wouldn’t survive strenuous trips. To investigate, they attached monarchs to the end of a butterfly “treadmill”—a horizontal rod that could spin around a pivot—and let them fly in circles. The researchers found that infected butterflies stopped an average of 14 percent sooner and traveled 10 percent slower than uninfected butterflies. If monarchs start wintering in Texas instead of Mexico, the population might accumulate more diseased butterflies, says Altizer. Shorter or stalled migrations might pose a threat to other migratory species as well. For instance, reindeer and fall armyworm moths may also shake off parasites through seasonal migrations, either by ridding themselves of sick individuals or leaving contaminated sites. Climate change could even create year-round habitat that encourages migratory species to stay put, Altizer says, strengthening the foothold of infectious diseases.

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Musk ox on Nunivak Island/U.S. Fish and Wildlife Service

Parasites Lost and Found Why do warmer Arctic summers give musk oxen nosebleeds?

are changing, so are the organisms that play a key role in disease ecology: parasites. Often carried by insects or other animals to their hosts, parasites are the infectious agents behind many human and wildlife diseases. And as climate change begins to alter the life cycles and biodiversity of these organisms, scientists say, it could have a powerful impact on disease patterns. Susan Kutz, a wildlife parasitologist at the University of Calgary, began studying one Arctic parasitic worm in 1994. The worm penetrates the feet of slugs, using them as a growth chamber until the slugs are eaten by musk oxen. The worms then take up residence inside the musk oxen’s lungs, causing nosebleeds, weakening the

As climate and animal movements

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animals, and making them vulnerable to predators such as grizzly bears. To investigate how climate change might affect the parasite’s life cycle, Kutz spent two summers on the Arctic tundra, tracking the worm’s growth. She calculated that a couple of decades ago, the tundra would have been too cold for the worm to develop in one summer. But around 1990, rising temperatures probably allowed the parasite to grow faster, shortening its development time from two years to one. This finding suggests that small changes in temperature can trigger large jumps in parasite life cycles, says Kutz. Since the faster growth rate would have allowed more worms to survive to maturity and infect the musk oxen, she speculates, it might explain why musk oxen numbers declined in a 1994 survey—although there aren’t enough data to say for sure. The parasite equation is complicated by the fact that, in addition to allowing some parasites to develop faster, climate change could drive others to extinction. Those that can’t handle warmer conditions might try to find new hosts to the north or let existing hosts carry them to cooler

regions, Kutz suggests. Once they reach new habitat, they will face competition from other parasite species. If they can’t win the struggle for animal hosts, she says, they may run out of places to go. Parasites could also be in trouble if their hosts become endangered or extinct, the USGS’s Kevin Lafferty says. Biodiversity is expected to decline with climate change, and the disappearance of one animal species could threaten multiple parasite species. “Listen, you don’t want to be a parasite of a polar bear or a penguin,” he says. As outlined in a recent article in Proceedings of the Royal Society B, one possibility is that the disappearance of certain parasites could simply allow remaining parasites to spread. And parasites that lose mammal hosts to extinction might just switch to a different host species—possibly humans. (3) But Lafferty cautions that it’s far too early to leap into crisis mode. Instead of adding to the slew of doom-and-gloom climate predictions, he believes it’s first necessary to withhold judgment and construct a more-complete portrait of disease ecology. It’s a daunting task, but it’s also within reach. Ecologists already have the tools to study intricate systems, Lafferty suggests, and that could allow them to disentangle the contributions of various factors, including climate, to disease. Until this happens, predictions of climate-driven disease spread are likely to be insufficient and incomplete. “The outcome is important enough,” Lafferty says, “that we should get it right.”

sity. In other words: If there’s a large number of species to choose from, a disease-carrying bug could miss its target and bite a species that isn’t susceptible. Some recent studies have affirmed this. A team led by Brian Allan at Washington University in St. Louis found that West Nile virus infection was more common in areas with low bird diversity, areas which also tend to harbor the species most likely to transmit the virus. In another study, researchers removed small mammals from plots in Panama and observed higher hantavirus infection rates among remaining host species. But the disease buffer could vary depending on which species are lost or gained. In some lowdiversity communities, animals that transmit a particular disease may have already dropped out, says Peter Hudson, an ecologist at Pennsylvania State University. Alternatively, the presence of certain species could help spread the disease. If some species are a particularly good disease buffer, it could be tempting to try to add more of them to ecosystems. But that’s probably infeasible, says Richard Ostfeld of the Cary Institute of Ecosystem Studies. Opossums are known to reduce Lyme disease risk, he says, “but are we going to go out and air-drop opossums into suburban neighborhoods? I don’t think so.” ❧ Roberta Kwok is a freelance writer based in Foster City, California. Literature Cited: 1. Lafferty, K.D. 2009. The ecology of climate change and infectious diseases. Ecology 90(4):888–900. 2. Randolph, S.E. 2009. Perspectives on climate change impacts on infectious diseases. Ecology 90(4):927–931.

Strength in Numbers Can biodiversity thwart the spread of disease? to believe biodiversity could act as a powerful repellent to infectious disease. “Biodiversity gives insects a choice of what to bite,” says Andy Dobson, an infectious disease ecologist at Princeton UniverSome scientists are starting

3. Dunn, R.R. et al. 2009. The sixth mass coextinction: Are most endangered species parasites and mutualists? Proceedings of the Royal Society B DOI:10.1098/ rspb.2009.0413. Further Reading: Pascual, M. and M.J. Bouma. 2009. Do rising temperatures matter? Ecology 90(4):906–912. Ostfeld, R.S. 2009. Climate change and the distribution and intensity of infectious diseases. Ecology 90(4):903–905.

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Feature

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peration sex change by cynthia mills • illustration by ken orvidas

Imagine waking up to discover

have a bizarre solution to an intractable probthat your mother, your sister, lem: They want to eradicate invasive and your friends’ wives are all fish populations from the inside out by men. That could be reality for using transvestite fish. In all fairness, “transvestite” isn’t invasive fish if a radical plan to their term of choice. They call these fish exterminate them takes shape. intersex. In some cases, they might look like normal females, but they have the chromosomes of a male. Teem and Gutierrez believe that if they can dupe normal fish into mating with these gender-bent fish, they can kick off a chromosomal cascade, skewing the entire population until it consists entirely of males—effectively wiping it out. It’s the kind of bizarre idea that brings to mind the old Kinks hit “Lola”—or even a bit of twisted science fiction. But Teem and Gutierrez might just be on to something. And while right now it’s only a plan on paper, it may quite possibly be the best plan we’ve got. John Teem and Juan Gutierrez

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The Science of Sex Change Scientists have come up with a plan to eradicate invasive fish using “transvestite” fish—fish that begin life with male chromosomes and then transform into females.

XY 1st estrogen application

Step 1. Researchers expose an unsuspecting male fish (or an egg) to estrogen. This triggers a reaction that leaves the male’s chromosomes intact but changes the fish into a female capable of mating and laying eggs.

Step 2. This XY “she-male” is mated with a regular XY male. Their progeny include some unusual offspring: males bearing two Y chromosomes.

genotype screening

2nd estrogen application

Above schematic adapted from: Cotton, S. and C. Wedekind. 2007. Control of introduced species using Trojan sex chromosomes. Trends in Ecology and Evolution 22(9):441-443. Photo ©Elfphoto/Dreamstime.com

genotype screening

The earth is plagued everywhere with invasive

species, but it would not be a stretch to say that fish are among the most intransigent of all. From Nile perch that have crowded out or eaten nearly all the cichlids in Africa’s Lake Victoria to Asian carp that have taken over whole sections of the Mississippi River, invasive fish have wreaked havoc on ecosystems and economies worldwide. But researchers can’t find a way to eliminate these ecological scourges. Around the world, fisheries biologists have spent years hunting for a remedy that can zero in on a single species and, like a surgical air strike, eradicate it with-

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Step 3. Researchers identify these so-called “supermales,” then expose them to a round of estrogen. The result is another bizarre mutant: a fish that has two male chromosomes yet breeds like a female. Step 4. When these YY females are introduced into invasive fish populations, they mate with normal XY males. Because they both have male chromosomes, it is impossible for them to create females. Over time, this skews the population’s gender ratio until only males remain.

out collateral damage. To date, however, they have come up with only blunt tools—such as poisoning the water with rotenone. Ostensibly organic because it comes from tropical plants, rotenone is nonetheless lethal; a lake treated with the chemical is effectively purged of all life, including fish, crustaceans, and insects. The few other tactics biologists have pursued— including fish bounties and genetically modified fish that produce sterile offspring—also have severe limitations. As the quest for the holy grail of invasive species eradication rolls onward, Teem and Gutierrez might have a leg up on the scientific

of their offspring in much the same way that humans do: with an X and a Y chromosome. A fish becomes female if she is given two X chromosomes, one from each parent. Males receive a father’s Y chromosome to go with the mother’s X chromosome. Thus, the male parent, as with humans, determines the sex of the offspring. But unlike humans, fish can change genTo understand Teem and Gutierrez’s idea, you have to go back to the early 1990s, when re- der during development and even later in life. searchers in the U.K. were mysteriously discov- Female hormones in water can turn fish geering vast numbers of what they politely termed netically programmed to be male (XY fish) into “gender-ambiguous” fish. They were neither completely functional females—females that completely male nor completely female. In can lay eggs that then grow into healthy fish. Healthy fish, but not a healthy populasome cases, these fish were functionally female but started out life—genetically speaking—as tion. Here’s the rub: If a genetically male fish lays eggs, she/he will males. In search of an theoretically donate an explanation, scientists disUnlike humans, fish X to half the eggs and a covered a new and insidiY to the other half. She/ ous type of pollution. can change gender during he will mate with a male These pollutants development and even later who will also theoretiwere streaming not out cally donate an X or a Y of our factories but out in life. Female hormones in to each half of the eggs. of our bathrooms. And the toxins were not so water can turn fish genetically The potential result will be a generation that is much conventional poisons as pharmaceuticals. programmed to be male into one-quarter normal XX females, one-half normal Millions of women take completely functional females XY males, and one-quarbirth control pills and ter YY males (otherwise hormone replacement therapy. Hormones not absorbed into their known as “supermales”). In other words, three bodies are excreted in urine and filter down of every four fish born would be male. With each passing generation, more fethrough the sewage system, eventually ending up in rivers and other bodies of water. All it males would be squeezed out until one day the takes are tiny doses—on the order of parts per population would consist almost entirely of lonely males with little more to do than gaze at billion—to affect a fish’s gender. In the years since hormone pollution each other and wonder what went wrong. As Nagler pondered the problem, he came was first discovered, it has become clear that it is confined neither to the U.K. nor to fish. to a chilling conclusion: cleaning up the polResearchers have turned up cases around the lution could wipe out the population. In other world, from alligators in the U.S. to eels in words, the pollution would not only distort France. Even in pristine areas of the U.S. Pa- the fish population, it would also make the fish cific Northwest, University of Idaho researcher dependent on it. Once a population’s gender James Nagler sampled endangered salmon and mix had been skewed toward males, the only found gender-ambiguous fish. Reporting in the way to produce females would be via continued journal Environmental Health Perspectives, he hormone pollution: the population would need found that, of 100 fish (50 female, 50 male), the human hormones to transform males to 80 percent of the females carried chromosomes females. Without the outside hormones, there would be no way for the fish to reproduce. that appeared to be male. How could this happen? The answer starts The pollution would become the salmon’s only with basic biology. Salmon determine the sex lifeline to survival. establishment. Neither has the standard fisheries biologist’s résumé. In fact, in neither one’s background is there a shred of evidence that he would end up concerned with fish at all, much less transvestite fish. But science is like that; often it takes someone with a fresh, even naïve perspective to see past conventional wisdom.

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became Teem’s solution. The problem Nagler had foreseen was all about chromosomes. When Teem read Nagler’s paper, he’d just taken a job in the Division of Aquaculture at the Florida Department of Agriculture. His duties included devising solutions to invasive fish problems. He had no background in fisheries or even fish—but he did know about chromosomes. And he could recognize a solution when he saw one. Teem speaks with the carefully measured tones of an impeccably trained scientist. As a graduate student at Brandeis University, he specialized in the molecular biology of yeast. Over the years, his career has taken a number of circuitous turns, including a stint studying cystic fibrosis and an assistant professorship at Florida State University. By 2004, his family had tired of moving and Teem needed a job that would allow him to stay put in Florida. “[W]hat that meant for me was doing something related either to the environment or agriculture,” Teem says. Which is what he got, in spades, working for the Florida Department of Agriculture. Teem’s job focuses mainly on regulations and management, but it does allow him to ponder ideas for research. “Being a molecular biologist . . . I was looking for ways to apply genetic solutions.” And here he found the mother lode. Teem wondered whether it might be possible to create female fish with two Y chromosomes in a lab and then introduce them into invasive populations. If these “transvestite” fish could woo the others, they could breed them out of existence by turning the entire population male. Nagler’s conundrum, however,

but turning an entire population of fish into males is not only possible, we do it every day—at fish farms. Fish farms make money off the pounds of filets they produce, and male fish are often bigger than females. So the farms try to produce as many males as possible. To accomplish this, they can simply dip the eggs into water spiked with female hormones, or they can fuss with the genetics. Tilapia fish farms can even buy patented supermales and superfemales: YY fish that, when mated with other fish, can produce only sons.

This may sound far-fetched,

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Teem set out to calculate how to apply this scheme outside the confines of a fish farm by fiddling with an Excel spreadsheet. But he found that he didn’t have the math skills to do all the calculations. Enter Juan Gutierrez. Gutierrez, who worked for an IT company in the same building as the Florida Department of Agriculture, walked into the coffee lounge one day and met Teem. New to the U.S., Gutierrez had left his native Colombia under duress; his business installing remote sensing systems for oil and mining sites had meant traveling through rebel territory, and dodging bullets and paying bribes wasn’t good for his bottom line. So he abandoned that career and taught himself software programming in order to become a good candidate for immigration. Soon, he found himself in Florida. Gutierrez is a sort of mathematical savant. Once in Florida, he entered graduate school while still working full-time for the IT company. His graduate work included mathematically linking brain imaging to unrelated data such as genome sequences. Not satisfied with two fulltime jobs, he also created a few websites. One, Literatronica, generated a new writing genre, hyperfiction, where novels can be rearranged to fit the preferences of the reader. So when, in the coffee lounge, with little else in common to talk about, Teem told him about his idea and the problems he was having in making it work, Gutierrez said, “I could do that.” “This kind of surprised me,” Teem recalls. “He said he’d get back to me. I just sort of brushed it off, thinking, that’s not going to happen.” But Gutierrez did get back to him. And he proved mathematically that not only would creating transvestite fish work, but that you could make a population go extinct by introducing every year or so just over three transvestite fish for every 100 members of the population you wanted to eradicate. It would take years, but that small percentage could make an invasive species population disappear completely—with no possible rescue, no escape. Teem and Gutierrez hammered out the details of this model for two years. Gutierrez was in graduate school and working at the IT

Climate Change

Sex Change

Percentage of Males

Talk about a glass ceiling. As global warming causes water temperatures to rise, it could cause females to disappear from some fish populations. In a small number of fish species, gender is determined by water temperature instead of genetics. In other words, the embryos develop male or female reproductive organs depending on which will be most advantageous at a given temperature. And, according to a paper in PLoS One, rising temperatures cause most of these embryos to turn male, creating a gender imbalance that could drive a population toward extinction. (1) Conducted by Natalia Ospina-Álvarez and Francesc Piferrer-Circuns of Spain’s Institut de Ciències del Mar, the study looked at the roughly 40 species whose genders are temperature-determined. The researchers found that, on average, a temperature increase of 1.5 degrees Celsius would silverside fish (Menidia menidia) 100 shift the ratio of males to females catfish (Hoplosternum littorale) from 1:1 to 2:1, while a 4-degree 75 increase would push the ratio to 3:1. blackbelly limia (Limia melanogaster) 50 At least one species, the Argentinian silverside Odontesthes desert topminnow (Poeciliopsis lucida) 25 bonariensis, is already undergoing a gender shift, and a 1.5-degree rise 0 10 15 20 25 30 35 could push the population’s percentage of males from 50 percent to Temperature (oC) roughly 73 percent. That could pose a threat to the fish’s survival, since fish communities need a substantial pool of egg-bearing females in order to reproduce at a sustainable rate. —Justin Matlick

1. Ospina-Álvarez, N. and F. Piferrer. 2008. Temperature-dependent sex determination in fish revisited: Prevalence, a single sex ratio response pattern, and possible effects of climate change. PLoS One 3(7):1-11. Photo: Argentinian silverside, Odontesthes bonariensis by Sara Sverlij

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system could then augment populations instead of extirpating them. Teem and Gutierrez’s scheme is still very much

a work in progress, and perhaps the biggest critic is Teem himself. Some invasive species populations are huge. Producing the necessary numbers of transvestite fish would take industrial-level production and considerable up-front capital investments. In addition, some species require individual hormone injections, making treatment much more expensive and difficult to handle than simply dipping eggs into hormone-spiked water. Successful eradication can be done only with species that use X and Y chromosomes for sex determination. This limits the tool to perhaps one-third of species in total—in fact, there are numerous species where the sexdetermination system remains unknown. But Nagler and other fisheries biologists are intrigued, albeit cautious, about the idea. As Nagler puts it, transvestite fish make for great reading, but he needs to see the scheme applied in a real-world setting to be convinced it could work. Teem’s idea also assumes wild fish won’t resist being seduced by transvestites. If the altered fish are not attractive or not viable, the whole system fails. In other words, these transvestite fish might look good from a distance, but up close you might be able to see the stubble. Then again, stubble or no, some fish may just be willing to risk it all for a walk on the wild side. ❧ Trained as a veterinarian, Cynthia Mills has been writing about animal and wildlife issues for over ten years. Recently she turned from clinical practice to field work, looking at the impact of biodiversity on human diseases in wildlife. Her writing has been included in the Best American Science and Nature Writing anthology. Literature Cited 1. Gutierrez, J.B. and J.L.Teem. 2006. A model describing the effect of sex-reversed YY fish in an established wild population: The use of a Trojan Y chromosome to cause extinction of an introduced exotic species. Journal of Theoretical Biology 241:333–341. 2. Cotton, S. and C. Wedekind. 2007. Control of introduced species using Trojan sex chromosomes. Trends in Ecology and Evolution 22(9):441-443.

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company; Teem’s job description did not include working out the details of ideas perceived as quite this wild. As Gutierrez puts it, “We had no money, no time, no support, and we were not part of the scientific establishment. To date, we still conduct our research meetings Sundays at 7 a.m.” In 2006 they published a paper in the Journal of Theoretical Biology. (1) The idea got traction. The journal Nature even published a news article announcing it. Although Teem could not convince his own agency to fund a demonstration project in Florida, his concept did find a home half a world away, with a scientist at the University of Lausanne, Switzerland. Claus Wedekind, an evolutionary biologist, had been studying an odd imbalance in the sex ratio of European graylings. In researching the possible causes and consequences, he came across Teem and Gutierrez’s paper. It had nothing to do with the graylings, but he was captivated. He enlisted graduate student Samuel Cotton to take up the idea. “First we wrote a short piece just to tell others that this is a brilliant idea,” he said, “and then we started to develop it further.”(2) Wedekind decided to try to make his own YY fish. He chose the common goldfish, a species that has become an ecological scourge throughout Europe. When people set pets free into previously fishless ponds, the goldfish decimate native populations of frogs and salamanders that have never had to deal with piscine predators before. In just two years, Wedekind has produced female goldfish with X and Y chromosomes. It was not a trivial task, however, and many of the treated fish died. Nonetheless, he now has a healthy colony of survivors. Once they reach sexual maturity, which can take two years, he will breed them. If all goes well, some of them will be YY super males. Besides using this technique to eliminate invasive fish, Wedekind also had the idea that he could use it to provide a boost to populations of endangered fish. In a mirror image of the Teem-Gutierrez Trojan sex chromosome, Wedekind believes it may be possible to produce super females that could produce more females than males. Since females are normally the limiting factor in population growth, the

Feature

People construct fences, sometimes across whole continents足, on the poetic assumption that good fences make good neighbors. Unfortunately, for wildlife, gated communities are rarely tranquil. Douglas Fox reports

On The Fence

A three-meter fence, anchored by sections of railroad track driven like stakes into the ground, cuts across South Africa’s Eastern Cape Province. On one side sits Addo Park, a thriving slice of wilderness containing the largest elephant population in the region. These beasts, with their rare tuskless females, represent a gem of biodiversity unique among Africa’s elephants. Just meters away on the other side of the fence stands row upon row of orange trees sagging heavily with fruit. This fence might as well separate an oil refinery from a raging brush fire—such is the notorious appetite of elephants for citrus that they would long since have raided those orchards. Only the fence, packing 8,000 volts of gentle persuasion, has protected those trees. By keeping citrus trees alive, this fence has also kept the elephants alive. It was conflict with farmers and trains which nearly extinguished Addo’s elephants 80 years ago. The construction of the fence between 1931 and 1954 saved these pachyderms from farmers’ guns and from themselves. Since 1931, the population has grown from 11 animals to over 400. “Good fences make good neighbors,” goes the Robert Frost poem—and this African parable seems to confirm it. But within this quiet gated community called Addo Elephant Park lurk the beginnings of a crisis. Confinement created an ecological echo chamber which transformed the mix of species, the topography of the land, and even the fundamental nature of elephant society. Elephant-on-elephant homicide has soared in recent years, and the fat pads on these beasts’ rumps have deflated. The slow-moving crisis threatens to turn these keystone herbivores into malnourished paupers. It’s just one example of how well-intended fences can exert unintended effects. The world over, such fences exist on a massive scale. At 5,320 kilometers, Australia’s dingo fence represents one of the longest engineered structures in human history—five times as long as the U.S.-Mexican border fence and roughly equal to the Great Wall of China. These fences even show up from space. Satellites orbiting 700 kilometers above the earth’s surface can spot the edges of Addo Park, where thicket meets 28

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orchard, and Australia’s rabbit fence cuts a rulerstraight line for 300 kilometers between greencheckered farmland and brown savannah. Expansion of human populations is even spawning fences in regions that were traditionally free of fences. In Kenya, desperate, drought-plagued farmers have moved into parks and felled trees—forcing the government to consider building protective fences around Mount Kenya, the Mau forest, the Aberdare range, and other reserves that were long connected by tracts of open land which linked their individual ups and downs, their population booms and crashes, into a collective equilibrium. These fences stand as the ultimate response to irreconcilable conflicts. They transform the physiology of landscapes. They block not only the movement of cattle, diseases, and invasive species, but also the dispersal of plants, the flow of genes, and the millennia-old migrations of animals. We humans have changed our world in many ways, but among the most-profound of those changes stand our fences.

In Addo, the artificial effects of fencing were long mistaken for the facts of nature. Park brochures extolled the gem of genetic diversity preserved inside Addo’s boundaries—136 out of 140 adult female elephants here carried no tusks, distinguishing this rare herd from any other on Earth. But as scientists reconstructed the history of Addo’s elephants, that image of diversity began to unravel. Anna Whitehouse, a graduate student of Graham Kerley at the Nelson Mandela Metropolitan University in Port Elizabeth, analyzed over 8,500 historical photographs of Addo’s elephants dating from 1931. She identified each elephant based on its pattern of eye wrinkles and ear tears, noted which calves hung beside which mothers, and constructed a universal family tree including every elephant that had lived in Addo for the past 70 years. Her exercise revealed a classic case of inbreeding. As recently as the early 1930s, half of all females carried tusks. But since then, the frequency of tusked females has plummeted exponentially, to 3 percent in 2000. Without a single male immigrant in 70 years, every

One famous incident, 20 years after the fence went up, left 50,000 sun-baked carcasses scattered across the Kalahari elephant born in Addo since 1954 descended from a single male, and this real-world Papa Smurf scenario almost certainly enriched recessive genes which stalled tusk development. A supposed hallmark of diversity was unmasked as a symptom of this herd’s inbreeding and genetic isolation—its confinement, for better or worse, within a fence. Whitehouse’s 70-year pedigree also revealed another surprising fact. Overall elephant mortality dropped after the fence’s construction—as expected—but males began dying at a much-higher rate than females. Kerley and Whitehouse noticed that males were living 10 to 20 years less than females. Closer investigation of park records revealed what no one had seen before: 70 to 90 percent of male deaths over the past seven de-

cades resulted from fights—healthy bulls found gored through the neck by the tusks of another elephant. Nowhere else in Africa were elephants known to fight to the death so often. Kerley and Whitehouse now view those fights-to-the-death as a consequence of Addo’s confinement. Male elephants normally disperse from family groups once they mature. This dilutes face-to-face competition for mating females. But not in Addo. Infrasonic mating calls can travel 20 kilometers—and fences prevent males from wandering beyond that range. A single female making a mating call can attract every male in the park. Ironically, even as the fence made life riskier for adult males, it made life safer for young calves—and this fueled another problem: runaway population growth. In natural settings, Conservation Magazine

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Elephant-on-elephant homicide has soared in recent years, and the fat pads on these beasts’ rumps have deflated. The slow-moving crisis threatens to turn these keystone herbivores into malnourished paupers calves often succumb during thirsty marches from one water hole to another in hot years. But by making it impossible for animals to stray more than 20 kilometers from water, the fence reduced this sort of mortality—and neutered a key mechanism of population control. Biologists in Addo have documented the effects of overpopulation. Elephants have grazed some plants, such as succulents, into oblivion. The diversity of plants has lessened, and numbers of thicket-grazing bushbuck and grysbok have declined. Plant diversity has declined even in parts of Addo where elephants remain fenced out—because some plants depend on elephant dung to disperse seeds and on elephant grazing to provide openings for germination and growth. Overgrazing has impacted the ability of this landscape to retain nutrients. Topographic surveys now show a decrease in so-called “runon” areas, which gather leaf litter and other nutrients transported by wind and water. Ele30

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phant gorging, in other words, has triggered a slow bleed of biome-sustaining nutrients from the landscape. Kerley naturally wondered whether these ecological repercussions have reverberated back to the elephants themselves. His student, Christelle de Klerk, decided to find out. De Klerk pried apart cantaloupe-sized nuggets of elephant dung to assess their fiber and protein content. She found that the beasts in Addo now consume woodier, lower-quality vegetation than do elephants in other parks. This fibrous, colon-blowing diet has taken a toll on the elephants’ bodies. When de Klerk measured the protrusion of hip and shoulder bones beneath the hides of Addo’s elephants, she found them skinnier than elephants in five other parks. That physical wasting will eventually squelch the production of healthy calves—but not before these Humvees of the animal kingdom have mowed the vegetation down to a

putting green. “Fencing was very successful in conserving elephants,” concludes Kerley. “But there are deeper issues which most people don’t pay attention to.” Biologists managing Addo are working to address those issues. In 2003 they imported four male elephants—a move which injected fresh genetic capital, leading to the birth of several females with tusks. Exporting bulls from Addo could reduce the problem of love polygons and pachydermicide, although it raises the question: Where to move these males? And as biologists prepare to open additional parts of Addo Park to elephants, they’re already debating whether to provide permanent water in those areas. Limiting water could spare areas far from water holes the full brunt of elephant herbivory—providing a refuge for succulent plants. It could also provide a gentle brake on elephant numbers, as thirst drops a few hapless calves from the herd. One thing is certain: In the case of Addo, a confined population is no longer a natural one. Far from walling off the problem or ending human intervention, the construction of fences guarantees it into perpetuity.

Addo’s small size provided a perfect ecological Petri dish for untangling the subtle effects of fencing. But similar problems probably occur around the world—even if local conditions don’t allow biologists to see them, says Simon Thirgood, a mammologist at the Macaulay Land Use Research Institute in Aberdeen, Scotland. “These effects of fencing,” he says, “must be quite widespread.” A recent survey of 23 large mammal migrations, from pronghorn and bison in North America to zebra and wildebeest in Africa to reindeer and Mongolian gazelle in Eurasia, found that six of these migrations have fizzled out—while most others declined in number. “Migratory ungulates are in a pretty poor state, and fencing is part of the problem,” says Thirgood, who helped in that analysis. In Botswana, a web of fences erected to halt transmission of foot-and-mouth disease from wildlife to cattle has decimated migrating wildebeest. One 250-kilometer barrier, the Kuke fence, prevented wildebeest from ventur-

ing north toward the waters and grasses of the Okavango Delta. One famous incident, 20 years after the fence went up, left 50,000 sun-baked carcasses scattered across the Kalahari—hapless animals which the Kuke fence prevented from reaching edible forage during a drought. Wildebeest numbers—once well over half a million— have fallen 90 percent since the 1960s, and much of that implosion resulted from blocked migration routes. The Kuke story reflects a fundamental mismatch between fences—built as immobile infrastructure at thousands of dollars per kilometer—and the evolving face of natural landscapes. Long-distance migrations fluctuate over years, decades, and centuries, pulled in unpredictable directions by changes in rainfall, fire, and forage. “Mobility is the key for a lot of species,” says Keith Lindsay, a U.K.-based biologist who surveyed the impacts of the Kuke fence in the 1980s. “The way they survive in a dry place is to be able to move around.” Even rivers can shift routes in these arid landscapes; biologists who work in southern Africa speak of rivers migrating 15 kilometers in a decade. The dingo fence in southeastern Australia has seen similar die-offs in dry years—of kangaroos. But it also produced more subtle effects. Populations of small native marsupials have plummeted on the dingo-free side of the fence but remained more stable on northern, dingopopulated side. Biologists now see the decline in native species as a knock-on effect of dingo suppression. By excluding dingoes, the fence allowed smaller invasive predators such as cats and foxes to increase—permitting them to devour small marsupials into oblivion. The fence also led to increased kangaroo numbers—another blow to small marsupials, since kangaroos devour tall grasses which provide small marsupials with cover. One even finds complications hidden within success stories. Wildlife managers have re-established wild dogs in a dozen or so fenced reserves across South Africa. But the biologists who carried out this project must take an active role in genetic management of the species by periodically transferring dogs from one reserve to another. Fencing remains a “last resort” for saving species, concludes biologist Matt Hayward, who Conservation Magazine

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manages native species reintroductions for the Australian Wildlife Conservancy in Wentworth. “Working out ways to reduce the impact of those fences is going to be a key element of biodiversity conservation for the next couple of decades.” Perhaps Frost was right when he wrote in his famous poem: Before I built a wall I’d ask to know What I was walling in or walling out, And to whom I was like to give offense. It’s time that we rethink our fences—how they’re built, what they’ll keep in or out, and how to turn them into appropriately selective barriers. A fence that keeps in cattle needn’t necessarily block the flow of pronghorn, bears, wild horses, or their genes. Inexpensive radio-frequency ID (RFID) tags implanted in cattle might one day electrify fence wires as soon as a marked bovine steps near. Pronghorn, deer, and moose could duck under or step over the same fence, undeterred. Even without evoking smart fences or RFID technology, we can already render barriers species-selective. Simply adjusting the spacing of wires on a fence can suffice. Placing the top wire no higher than 42 inches above the ground and the bottom wire no lower than 16 inches (with barbed wire reserved for only the middle wire) allows pronghorn to pass over or under the fence while keeping less-nimble cattle contained. From Wyoming to Colorado to Arizona, conservation groups are already working to restore the permeability of the landscape and reanimate migration corridors which gushed with seasonal pronghorn traffic for thousands of years before the arrival of suburbs and ranches. Among the rust-red dunes of South Australia, biologists who fenced in populations of native bettongs, bilbies, and bandicoots to protect them from feral cats and foxes are now experimenting with a logical next step. Biologists with a company called Arid Recovery are building into these fences species-specific portals based on the animals’ different burrowing habits and crawling or hopping gaits. These allow small marsupials (but not predators) to exit—thereby enabling native animals to dis32

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perse as populations within protected areas reach holding capacity—without humans having to do the job themselves. Biological approaches to species-specific barriers have also shown promise. Efforts to establish a pack of African wild dogs in Botswana’s Northern Tuli Game Reserve are hindered by the dogs’ tendency to wander into adjacent areas, where preying on cattle is likely to get them shot. But researchers with the Botswana Predator Conservation Trust have used scent markers—derived from the urine of other dog packs—to lay down invisible barriers, which the dogs won’t cross. The team is working to identify specific chemicals in the dogs’ urine that could be mass-produced in order to scale up these bio barriers. If the approach is found to apply to other large predators, one could easily imagine a reserve in which various species are bio-fenced into overlapping but distinct areas of land—each according to its ecological needs. Biologists have also discovered that the mere sound of bee hives repels elephants. Hive sounds broadcast over loudspeakers—or real hives positioned at gaps in fences—could deter elephants while allowing other species to pass through. In Tanzania and Kenya, cash for maintaining fences is scarce—but the availability of land provides another solution: Thirgood has found that soft-edged buffer zones around parks work just as well as fences—keeping elephants from crops and poachers from elephants. Making fences more malleable could render them amenable to landscapes where rainfall and riverbeds shift across years and decades. Fences in which individual segments can be lowered and raised already exist; a network of such adjustable fences could provide the first step in that direction. Wildlife managers could also shift scent-based or bee-based bio-fences from year to year. “Something there is that doesn’t love a wall, that wants it down,” wrote Frost 95 years ago. The reality of suburbs in North America and citrus orchards in southern Africa won’t allow us to raze all our fences, but at the very least we can reinvent them. ❧ Douglas Fox is a freelance writer based in San Francisco. He has written for New Scientist, Natural History, and Discover.

Feature

The Water War Mirage By Wendy Barnaby

What if no one shows up for the fight?

written a book about biological warfare and the publishers were keen for me to write another. “How about one on water wars?” they asked. It seemed a good idea. The 1990s had seen cataclysmic forecasts, such as former World Bank vice-president Ismail Serageldin’s often-quoted 1995 prophecy that, although “the wars of this century were fought over oil, the wars of the next century will be fought over water.” This and similar warnings entered the zeitgeist. Tony Allan, a social scientist at King’s College London and the School of Oriental and African Studies (SOAS) in London, summarized the not-so-subtle argument as “if you run out of water you reach for a Kalashnikov or summon the air strike.” I had no difficulty finding sources to back up this argument, and I set about writing chapters on the Jordan, the Nile and the Tigris– Euphrates river systems. My chapter choice relied on what seemed a perfectly reasonable assumption: that water scarcity was governed by the presence or absence of flowing water. Allan had made the same assumption a few decades earlier when he set out to study the water situation in Libya. By the mid-1980s, water stress in North Africa and the Middle East had worsened; but Allan A few years ago, I had just

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began to question his assumptions when he found no sign of the widely predicted water wars. Instead, the burgeoning populations of the Middle Eastern economies had no apparent difficulties in meeting their food and water needs. Allan had been forced to grapple with a situation in which people who are short of water do not necessarily fight over it.

Invisible Water Allan’s earlier thinking about water wars began

to change after meeting the late Gideon Fishelson, an agricultural economist at Tel Aviv University, Israel. Fishelson argued that it is foolish for Israel, a water-short country, to grow and then export products such as oranges and avocados, which require a lot of water to cultivate. Fishelson’s work prompted Allan to realize that water “embedded” in traded products could be important in explaining the absence of conflict over water in the region. As a global average, people typically drink one cubic meter of water each per year, and use 100 cubic meters per year for washing and cleaning. Each of us also accounts for 1,000 cubic meters per year to grow the food we eat. In temperate climates, the water needed to produce this food is generally taken for granted. In arid regions, Allan described how people depend on irrigation and imported food to fulfill these needs. Imported food, in particular, saves on the water required to cultivate crops. The relationship of food trade to water sustainability is often not obvious, and often remains invisible: no political leader will gain any popularity by acknowledging that their country makes up the water budget only by importing food. Allan saw through this to document how the water budgets of the Middle East were accounted for without conflict. Allan wrote about embedded water for a few years without it exciting any comment. Then, on a dark Monday afternoon in November 1992, during a routine SOAS seminar, somebody used the term “virtual” water to describe the same concept. Allan realized this attention-grabbing word, in vogue with the computer-literate younger generation, would 34

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catch on better than his own term. And he was right: “From there on it flew,” he says. Allan’s work explained how, as poor countries diversify their economies, they turn away from agriculture and create wealth from industries that use less water. As a country becomes richer, it may require more water overall to sustain its booming population, but it can afford to import food to make up the shortfall. Areas seemingly desperate for water arrive at sustainable solutions thanks to the import of food, reducing the demand for water and giving an invisible boost to domestic supplies. Political leaders can threaten hostile action if their visible water supplies are threatened (a potentially useful political bluff ), while not needing to wage war thanks to the benefits of trade.

Sources of War Israel ran out of water in the 1950s: it has not

since then produced enough water to meet all of its needs, including food production. Jordan has been in the same situation since the 1960s, Egypt since the 1970s. Although it is true that these countries have fought wars with each other, they have not fought over water. Instead they all import grain. As Allan points out, more “virtual” water flows into the Middle East each year embedded in grain than flows down the Nile to Egyptian farmers. Perhaps the most often quoted example of a water war is the situation in the West Bank between Palestinians and Israel. But as Mark Zeitoun, senior lecturer in development studies at the University of East Anglia in Norwich, U.K., has explained, contrary to what both the mass media and some academic literature say on the subject, while there is conflict and tension—as well as cooperation—there is no “water war” here either. Ten million people now live between the Jordan River and the Mediterranean Sea. If they were to be self-sufficient in food, they would need ten billion cubic meters of water per year. As it is, they have only about one-third of that: enough to grow 15–20 percent of their food. They import the rest in the form of food. When it comes to water for domestic and industrial

use, the rainfall and geology of the West Bank the 1960 Indus Waters Treaty, arbitrated by alone should provide enough water for the the World Bank, has more than once helped to population there: Ramallah has a higher annual defuse tensions over water. average rainfall than Berlin. But today, water for even these needs is scarce. Oil and Water Don’t Mix Power struggles and politics have led to overt and institutionalized conflict over water— Yet the myth of water wars persists. Climate but no armed conflict, as there is over borders change, we are told, will cause water shortand statehood. Instead, Palestinian and Israeli ages. The Intergovernmental Panel on Climate water professionals interact on a Joint Water Change estimates that up to 2 billion people Committee, established by the Oslo-II Accords may be at risk from increasing water stress by in 1995. It is not an equal partnership: Israel the 2050s, and that this number could rise to has de facto veto power on the committee. 3.2 billion by the 2080s. But they continue to meet, and issue official Water management will need to adapt. expressions of cooperation, even in the face But the mechanisms of trade, international of military action. Ineqagreements, and ecouitable access to water nomic development resources is a result of that currently ease the broader conflict and water shortages will power dynamics: it does persist. Researchers, there were no formal not itself cause war. such as Aaron Wolf The Nile Basin Ini- declarations of war over water at Oregon State Unitiative, launched in 1999 versity, Corvallis, and and encompassing nine Nils Petter Gleditsch nations, is another example of the way in which at the International Peace Research Institute wider geopolitical and economic factors help in Oslo, point out that predictions of armed to balance water allocation. Historically, vast conflict come from the media and from popular, differences in the political clout of nations non–peer-reviewed work. across which, or along which, a river flows have There is something other than water for resulted in unequal water division. Under the which shortages, or even the perceived threat 1959 Nile Waters Agreement between Egypt of future shortages, does cause war—oil. But and Sudan, Egypt has had rights to 87 percent the strategic significance of oil is immeasurably of the Nile’s water, with Sudan having rights to higher than that of water. Serious interruptions the rest. Ethiopia, whose highlands supply 86 of oil supplies would stop highly developed percent of Nile water, does not even figure in economies in their tracks. Oil is necessary for a the agreement: continuing conflicts weakened developed economy, and a developed economy the agreement to a point where Ethiopia has provides for all the needs of its citizens, includbeen unable to press a claim. But Egypt’s de- ing water. People in developed economies do sire to consolidate its economic development not die of thirst. necessitates that it now come to better terms My encounter with Allan’s work killed my with its neighbors, improving prospects for book. I offered to revise its thesis, but my publocal trade. So Egypt is willing to engage in the lishers pointed out that predicting an absence multilateral initiative to cooperate more on mat- of war over water would not sell. ❧ ters such as hydroelectric power development, power-sharing cooperatives, river regulation, Wendy Barnaby is editor of People & Science, the and water-resources management. Likewise, although India and Pakistan magazine published by the British Science Association have fought three wars and frequently find Reprinted by permission from Macmillan Publishers themselves in eyeball-to-eyeball confrontation, Ltd: Nature 458:282-283. 2009.

In five decades,

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Lighten Up

Humor is just another defense against the universe. — Mel Brooks

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Innovations

Winging It Feather-like spines could reduce vehicles’ fuel consumption

be an odd sight. But it’s not beyond the realm of imagination for a group of engineers at the University of Genoa, Italy, who say that fibers designed to imitate bird feathers could one day improve the efficiency of trucks, ships, and small unmanned planes. The project began when the team came across research on the brown skua (Catharacta antarctica), an Antarctic bird. Photographs of the birds showed short, fluffy feathers popping up from its wings, and scientists suggested these feathers might improve the aerodynamics of flight. To investigate further, the team ran computer simulations of a cylinder featuring spines that mimicked feather shafts. It turned out the spines weakened nearby air vortices, which would normally create drag, and boosted pressure behind the cylinder, pushing it forward. With the right set of spine properties, drag could be reduced by 15 percent, the team reported in the Journal of Fluid Mechanics. The results suggest that, if added to vehicles that move in air or water, feather-like structures might lower the vehicles’ fuel consumption—and thus their carbon footprint, says lead author Julien Favier. Large planes could present challenges, cautions Favier, since they fly in turbulent conditions and at high altitudes, where ice can form on the wings. For its next test, the team hopes to add feather-mimicking spines to a plastic wing, then test it in a wind tunnel. ❧ —Roberta Kwok

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A truck with a furry coating might

Escape Artist

The supremely flexible octopus inspires a new generation of robots A one-meter-long octopus can squeeze its body through a hole just two

centimeters wide. What’s more, its arms can stretch to twice their original length and can alternate between being soft and rigid, depending on the task at hand. Now, scientists are developing a robot that mimics this unique dexterity, with hopes it will help them extract samples from some of the oceans’ hardest places to reach. The rigid robots currently used for ocean research are too clunky to navigate through small spaces, and they pose a threat to coral and other undersea structures. The new robot, under develop- More Online ment by a research team led by Cecilia Laschi of Italy’s Scuola Watch octopus acrobatics Superiore Sant’Anna, would be a soft-bodied alternative that conservationmagazine.org could reach into tiny cracks and crevices, grab objects, and bring them back to the lab for analysis. The robot could also be equipped to take close-up photos of reefs. The researchers have successfully tested a system that mimics an octopus arm’s movements. Now, they are working to recreate the unique arrangement of muscles in those arms and to develop a system that allows all eight legs to work in unison. ❧ —Judy Wexler Conservation Magazine

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Carbon Gets Stoned

Injecting CO2 into subsurface rocks could provide permanent storage Even if scientists find a way to soak up atmospheric CO2, there remains the problem of where to put the gas once it’s captured. Some researchers have proposed storing it underground, but there’s always the chance it could leak out and wreak havoc. Now, two geochemists have come up with an alternative that they say is permanent, safe, and comparatively cheap: turn the CO2 into rock. The idea rests on a naturally occurring reaction between CO2 and peridotite, the most common type of rock in the earth’s subsurface mantle. When the rock and gas come into contact, they form travertine, limestone, and other carbonite minerals, locking the CO2 away in a nearly permanent form. Peter Kelemen and Jürg Matter of Columbia University propose capturing CO2 from industrial facilities before it is emitted into the

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atmosphere, and then injecting the gas into peridotite deposits near the earth’s surface. Their work has been focused on deposits in Oman, which they believe could be coaxed to consume upwards of 4 billion tons of CO2 each year. That’s about 10 percent of the human population’s annual carbon emissions. Kelemen hopes to have a pilot project up and running within three or four years. If it works, scaled-up facilities could then be built in Oman or elsewhere: New Caledonia, Papua New Guinea, and Albania also have big peridotite deposits. Yet Kelemen cautions that, while such facilities could slow global warming, they would exact their own environmental price by disrupting landscapes. “Large-scale solutions to CO2 increase…are themselves going to be large-scale industrial projects,” he says. “There’s really no way around that.” ❧ —Rebecca Kessler

Telltale Stripes Wrapping virtual skins on 3-D models helps track individual tigers Most tigers have over 100 stripes, aligned in a unique pattern that can be as intricate—and as hard to identify—as human fingerprints. So it seems sensible that, in search of a better way to monitor tigers and the criminals who poach them, scientists have turned to technology normally used by police. To keep track of Asian tiger populations, researchers now rely on a network of hidden cameras spread across miles of jungle. When one camera snaps a tiger photo, it kicks off a painstaking process in which researchers try to match that image with photos shot elsewhere. A research team led by Lex Hiby of Conservation Research Ltd. has developed software that can dramatically reduce this workload. Based on the facial-recognition technology law enforcers use to pick criminals out of a crowd, the computer program electronically “pins” pictures of tigers or tiger skins on a 3-D virtual cat. The program then uses the animal’s stripe pattern to match that image with others on file. Hiby hopes this will not only speed up census efforts but also help in the fight against poaching. When authorities seize a poached tiger skin, for instance, they could use an image of that skin to figure out which tiger was killed and where that tiger lived. ❧ —Judy Wexler

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All-purpose Cleaner Algae sop up CO2 from Chinese coal plants a greenhouse filled with transparent pipes appears to belong on the set of a particularly slimy episode of Star Trek. But this is not a science-fiction horror story, it is one of humankind’s most ambitious attempts to recruit algae in the fight against climate change. Developed by a groundbreaking Chinese firm, ENN, the greenhouse takes carbon captured from industrial plants, then uses it to breed microalgae. China is the world’s biggest emitter of greenhouse gases, largely because it relies on coal for 70 percent of its power. Almost none of the carbon dioxide is captured, partly because there is no profitable use for it. Algae may be the answer—the organism can absorb carbon far more quickly than trees can. ENN scientists are testing microalgae to clean up the back end of a unique process to extract and use coal. First, coal is gasified. Then, the carbon dioxide is extracted and “fed” to algae, which can then be used to make biofuel, fertilizer, or animal feed. The company plans to scale up the trial to a 100-hectare site over the next three years. If the process proves commercially feasible, coal plants around the world could one day be flanked by carbon-cleaning algae greenhouses or ponds. “The biology has been proven in the lab,” said Zhu Zhenqi, a senior advisor on the project. “The challenge now is an engineering one: we need to increase production and reduce cost. If we can solve this challenge, we can deal with carbon.” ❧ — Jonathan Watts

The garish gunk coursing through

Book Marks

“Medea” by Eugène Ferdinand Victor Delacroix (1862)

Mother Nature’s Dark Side Maybe we’re not in such good hands • Review by Jeffrey Lockwood The Medea Hypothesis is simple and provocative: Life is self-destructive. Alluding to Medea, the mythic Greek villainess who killed her children, Ward inverts James Lovelock’s famous Gaia hypothesis. Earth is not a stable, self-regulating organism where life begets favorable conditions for furthering itself, Ward claims. It is instead a place where living organisms

The thesis of Peter Ward’s

foster major extinctions that will culminate in planetary biocide. To flesh out his grim vision, Ward makes the case that plant growth will continue to rapidly erode silicate rock. In turn, this rock will eventually absorb so much CO2 in the course of forming limestone that life will become impossible. But is

Ward’s biogeochemical dirge any more plausible than Lovelock’s ecological kumbaya? The conceptual backbone of Ward’s thesis is that Darwinian competition makes life a lethal process as each species struggles to consume as much and as fast as possible in outcompeting its neighbors. The evidence of this exclusively murderous tendency, however, is unconvincing. After all, life has persisted for 4 billion years—hardly indicative of a biosphere that’s hell-bent on killing itself. On the other hand, Ward provides intriguing accounts of how organisms might have played a role in mass extinctions. Runaway biotic processes triggered by geological events are the modus operandi. For example, the “greenhouse extinctions” were started by volcanos spewing carbon dioxide, allowing particular bacteria to flourish and release hydrogen sulfide, which snuffed out other living organisms. But an accomplice can’t take the whole rap—geological processes conspired with life. Moreover, life recovered between these episodes, and Ward doesn’t explain how that occurred if evolution is self-destructive. Ward’s case for life’s ultimate extinction via CO2 depletion relies on mathematical models. These are valuable tools, but a billion-year forecast is borderline absurd. In fact, the model that predicted the end of plant life in 100 million years was revised a decade later to yield an estimate of one billion years. Tweak another parameter, and the estimate might be 5 billion years (by which time our sun is kaput, anyway). Ward’s arguments are fascinating but fraught with inconsistencies. For

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example, he contends that the Gaia hypothesis is not testable—but then provides evidence that supposedly refutes it. It seems that the Medea hypothesis is necessary—but not sufficient—to explain global ecology. Arguing whether Ward’s or Lovelock’s hypothesis is right is like the fruitless debate of nature versus nurture. The real question is: Under what conditions are biological systems Gaian or Medean? And if life is globally selfdestructive over the long haul, what are we supposed to do? Ward criticizes environmentalism and environmental philosophy (although he muddles these enterprises and creates an outdated straw man). He dismisses going “back to nature” and advocates various technologies (e.g., limited airline travel by jet) to solve the contemporary excesses of CO2, but he offers little to stave off future shortages. As I see it, if we solve the current problem, then humans score a point for Gaia and have a billion years to work on Medea’s hypothetical depletion. Despite the book’s shortcomings, Ward provides a vital intellectual service. His Medea hypothesis counters the lopsided Gaian view of Mother Earth in perpetual balance, which still holds sway among much of the public, even though it’s no longer a mainstay among ecologists. However, while the Gaia-versus-Medea ecological smackdown makes for good reading, it is ultimately a false dilemma. I believe a third option is the most sensible. Let’s call it the Janus hypothesis; perhaps the two-faced Roman is the best characterization of the nature of Nature. ❧ The Medea Hypothesis: Is Life on Earth Ultimately Self-Destructive? By Peter Ward, Princeton University Press, 2009.

Conservation Magazine

Conservation Refugees The HundredYear Conflict between Global Conservation and Native Peoples By Mark Dowie MIT Press, 2009

Yosemite, one of the oldest and most-famous national parks in the U.S., was made into a wilderness area only after the extermination of native people who for centuries had lived in its valley. Conservation Refugees documents their plight along with the stories of peoples from Thailand, Africa, and India. The fiery Mark Dowie, who has for years documented the conflict between conservationists and indigenous peoples, argues that for environmentalists to be truly successful, they must recognize the interests of and work with those whom they’ve long oppressed. ❧

A New Conservation Politics Power, Organization Building, and Effectiveness By David Johns Wiley-Blackwell 2009

David Johns is a lawyer and political scientist who sees conservation through these two powerful lenses, and his new book looks at how those fighting to protect biodiversity can learn from other powerful movements in history—from the abolition of slavery to the antiapartheid movement. ❧

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Galapagos at the Crossroads Pirates, Biologists, Tourists, and Creationists Battle for Darwin’s Cradle of Evolution By Carol Ann Bassett, National Geographic, 2009

If we fail to protect the biodiversity of the Galapagos, humanity will have lost its last chance to live in harmony with nature; we might as well go live on the moon. So argues one naturalist in Carol Ann Bassett’s account of the precarious state of this famous archipelago. The book is a modern portrait of the islands, and its author examines who has what at stake as tourists, fishermen, and immigrants all exact their toll on the fragile ecosystem. ❧

Witness to Extinction How We Failed to Save the Yangtze River Dolphin By Samuel Turvey Oxford Press 2009

Turvey’s book does not just lament the loss of another species. It’s an engaging story that melds natural history with a retelling of the author’s personal involvement in doomed efforts to save the Chinese bottlenose dolphin. Witness to Extinction explains how international ambivalence, delays, uncertainty, and lack of will all led to the loss of this charismatic cetacean. ❧

Book Marks Paradise Found Nature in America at the Time of Discovery By Steve Nicholls University of Chicago Press, 2009

In the 1500s, a fisherman off the coast of Newfoundland reported that cod populations there were so dense they occasionally impeded the progress of ships. His account, and thousands of others, form the basis for Paradise Found—a book that retells the European conquest of North America from a natural-history perspective. Author Steve Nicholls has painstakingly reviewed primary documents and modern science in this account. His new book is an indulgence for history and ecology buffs alike. ❧

Macaw reference samples in the U.S. Fish and Wildlife Service’s forensics lab. Scientists use this collection to identify victims of illegal wildlife trade. Photo courtesy of Laurel Neme

A Mathematical Nature Walk By John A. Adam Princeton University Press 2009

Animal Investigators How the World’s First Wildlife Forensics Lab Is Solving Crimes and Saving Endangered Species By Laurel Neme Scribner 2009

Criminal investigators typically have their hands full just trying to pin down a suspect. For forensic scientists tracking illegal wildlife trade, the challenge is not only finding the guilty party but also determining the identity of the victim—who could be one of 30,000 species. Animal Investigators goes behind the scenes of the only wildlife forensics lab in the U.S. as its scientists and agents crack three cases—one involving headless walruses, one looking into the trade of gallbladders from black bears, and one tracing secret shipments of feathered headdresses from the Amazon to the U.S. ❧

For those of you who’ve wondered how far away a cloud is, how close a storm is, or how high a tree is, consider purchasing John Adam’s book as your next field guide. A Mathematical Nature Walk asks—and answers, using mostly pre-calculus or arithmetic—these and 93 other questions about the natural world. The book is a catalogue of playful inquiries and their mathematical solutions. ❧

Reviews by Judy Wexler Conservation Magazine

• Vol. 10 No. 3 | July-September 2009 45

From Readers

The Value of Preservation

From an Old-School Hunter-gatherer

The title of your feature article “Taming the Blue Frontier” (April-June 2009) sounds a bit like “Manifest Destiny.” As one of those old hunter-gatherers who fish the sea, I hope you’ll permit me a few remarks before you outlaw my language. Much of the rationale for offshore aquaculture is the same as was used to promote expansion of the U.S. fishing fleet in the 1970s: increase the world food supply, reduce trade deficit, and create jobs. But just like the fisheries development that preceded it, hightech aquaculture is about making money by depreciating natural and social capital and entering it into accounts as profit. A World Bank report released in October 2008 expresses concern about the way countries artificially inflate their GNPs by depleting natural capital. This cooking of the books is supported by the belief that exploitive technology will substitute for declining resources, but that is an article of faith that belongs in a religious text rather than a magazine called Conservation. ❧ Paul Molyneaux Commercial Fisherman 2007 Guggenheim Fellow, Author of Swimming in Circles: Aquaculture and the End of Wild Oceans 46

Conservation Magazine

Jim Robbins’s article “Between the Devil and the Deep Blue Sea” (AprilJune 2009) does a disservice to the Everglades and to conservation. His portrayal of the potential effects of sealevel rise on the region and the potential “waste” of money on Everglades restoration is flawed for several reasons. First, the “Everglades” are much more than Everglades National Park, which occupies the southern portion of the region. Robbins cites the most-recent assessment of the restoration effort by the National Research Council; he might have noticed that this publication begins with an extensive description of the extent and resources of what is called the “Everglades ecosystem.” This ecosystem is defined as the region of sawgrass and marl prairie wetlands south of Lake Okeechobee and is about double the size of just the national park. The Comprehensive Everglades Restoration Plan, which is currently expected to cost approximately $11 billion (not the $15 billion cited in the article), addresses the entire Everglades ecosystem, including Lake Okeechobee and its watershed—the estuaries of the St. Lucie Canal and Caloosahatchee River, Biscayne Bay,

• Vol. 10 No. 3 | July-September 2009

and Florida Bay. Indeed, in order to restore habitats within the park and to develop ecological resiliency within the park, most of the money will actually be spent on restoring much of the land north of the park, creating a resilient system that stretches north many miles past the park’s boundaries. Robbins’s description of the restoration plan is misleading and undermines support for this crucial conservation effort by implying that the money is dedicated solely to preserving the park. Second, Robbins’ article underreports the many uncertainties concerning both the extent of sea-level rise and

the capacity of the system to buffer or resist change. Because of these substantial uncertainties, it makes sense to act as quickly as possible to restore the entire system (up to and including the Lake Okeechobee watershed), if only because a restored system stretching over this large area provides the best insurance that suitable habitat will

continue to exist within the Everglades system and that species therefore will be able to adapt to changing conditions over the next century. Given the large and numerous uncertainties in many aspects of sea-level rise and ecosystem responses to it, most ecologists—and the scientists of the NRC committee— are convinced that there should be no delay in implementing the plan, although they have carefully considered the threats of sea-level rise and climate change. A failure to go ahead as quickly as possible with the restoration almost certainly dooms to extinction many species and the whole communities on which they depend. The restoration may at some point in the future be compromised by sea-level rise, and part of the park may indeed be lost, but restoration of the Everglades ecosystem will give those species and communities a fighting chance to survive. It would be a great shame if misinformation about the Everglades and

the nature of the restoration plan led conservationists to fail to support the restoration effort. ❧ Joan G. Ehrenfeld, PhD Professor, Rutgers University Member, National Research Council Committee on Independent Scientific Review of the Everglades Restoration Plan New Brunswick, New Jersey

Working with What We Have

David Malakoff ’s article on biofuels (April-June 2009) seems to assume, like many other articles on the subject, that every driver will have his own car and will continue to drive alone. It also emphasizes that breakthroughs in new technology are necessary. Neither of these assumptions need be true. There is a lot that can be done now to save energy and moderate global warming with existing technology.

Getting more people into a car would reduce the cost of roads as well as reduce air pollution, congestion, and waistlines. Try putting a tax on the first car in the family (higher if fuel-inefficient), a higher tax on the second, and a still-higher tax on the third. About 25 years ago, the E.P.A. proposed that employers of 100 or more people would have to reduce the numbers of cars coming to their site. It was vetoed when Newt Gingrich took control of the House of Representatives. But it can be tried again. The idea is to devise a carrot-stick approach that makes it expensive to drive alone in a car. We can also look to other countries for inspiration. Switzerland does very well while using only one-third as much energy per capita as Americans do. ❧ Albert Matlack Adjunct Professor, Chemistry & Biochemistry, University of Delaware Hockessin, Delaware

The Galápagos Exploring Darwin’s Tapestry John Hess After describing the islands’ origins and the complex of physical forces that make the Galápagos so remarkable, Hess then focuses on the animals most encountered by visitors. A photo essay for each of these species provides an intimate look at their physical and behavioral adaptations. 208 pages, 188 color illustrations, $49.95

The Mississippi A Visual Biography Quinta Scott Photographer Quinta Scott has documented the progression of the Mississippi River from its source to the Gulf of Mexico, with hundreds of stopping points along the way. Scott explains how we have changed each site depicted, how we try to manage it, and the wildlife that occupies it. Available in November, 352 pages, 200 color illustrations, $75.00

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Think Again Go North and Multiply by Catherine Brahic

“Teeming with life” may not

Catherine Brahic is the online environment reporter for New Scientist. Prior to joining New Scientist, she wrote about the environment, biomedical sciences, and science policy for The Economist, Science, The Scientist, and SciDev.net. Reprinted by permission of New Scientist magazine

be the description that springs to mind when thinking of the Arctic Ocean, but that could soon change as global warming removes the region’s icy lid. A study of what the Arctic looked like just before dinosaurs were wiped off the planet has provided a glimpse of what could be to come within decades.(1) Alan Kemp, of the U.K. National Oceanography Center in Southampton, and colleagues used powerful microscopes to inspect cores of mud extracted from the bottom of the Arctic Ocean. They found successive layers of tiny algae called diatoms. The pattern of the layers and the distribution of the diatoms provides strong evidence that the Arctic was free of ice during the summer and, contrary to recent studies, frequently covered in ice during the winter. Ice-free summers and icy winters are precisely what glaciologists fear could happen in the Arctic within decades. Over the past few years, wind patterns, and warm temperatures have been gradually thinning Arctic sea ice, making it less and less likely to survive the summer. Some believe the Arctic could be ice-free during the summer as soon as 2030. The researchers say that the sheer number of diatoms locked in the mud suggests that when the dinosaurs roamed the earth, the Arctic Ocean was biologically very rich during the summer, on a par with the most productive regions of the Southern Ocean today. Since dia-

toms are at the very bottom of the food chain, waters rich in diatoms can support a lot of larger life forms as well. “On the basis of our findings, we can say that it is likely that a future Arctic Ocean free of summer sea ice will also be highly productive,” says Kemp. Arctic fauna today is limited by the region’s harsh conditions. The ocean is home to very few species of fish—such as the Arctic cod—which in turn support seals, whales, and polar bears. While more diatoms during the summer does not mean that larger animals will spontaneously appear in the Arctic over the coming decades, it could give species currently living further south an incentive to move into the region by providing them with food. The mostlikely scenario is one in which larger species migrate to the Arctic in the summer to feed on the enriched summer food chain, then move back south during the dark winters. “The outcome would depend on organisms at all levels of the food chain moving in to exploit this potential,” says Kemp. “What is unpredictable is what species from elsewhere may migrate in to fill the new ecological niches.” A study of fossils and fossilized feces carried out around Devon Island in the Canadian Arctic suggested last year that the regions may once have been home to a rich gathering of larger fish and possibly even sharks during the late Cretaceous. (2) Presumably, these animals would have been supported by Kemp’s diatoms. ❧

1. Davies,A., A.E.S. Kemp and J.Pike. 2009. Late Cretaceous seasonal ocean variability from the Arctic. Nature DOI:10.1038/ nature08141. 2. Chin, K. et al. 2009.Life in a temperate polar sea: A unique taphonomic window on the structure of a late Cretaceous arctic marine ecosystem. Proceedings of the Royal Society B, DOI:10.1098/rspb.2008.0801.

Conservation Magazine

• Vol. 10 No. 3 | July-September 2009

Sentinels of Water Quality The Xerces Society works to protect freshwater mussels. Freshwater mussels are among the most imperiled animals in North America. Native fish and mussels are intimately linked; fish help mussels move into new habitats and mussels filter water as they feed, thereby purifying streams. Mussels are long lived and sensitive to environmental changes, and thus are excellent indicators of water quality. The decline of freshwater mussels has been well studied in eastern North America. In order to better understand the extent of the decline in the West, the Xerces Society is preparing a status review of western species. If you have any records of freshwater mussel occurrences west of the Rockies, please contact us at mussels @ xerces.org.

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