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

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

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

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

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

And the losers win!

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

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

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

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

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

Photo: Robert Fletcher, Ohlone Preserve Conservation Bank

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

Going down!

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

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

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

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

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

– David J. Tenenbaum

Twelve years on, and another billion people are sharing the planet.

Starting half a century ago, the Green Revolution doubled or tripled production of the major grains, using modern seeds, heavy use of fertilizer and irrigation. The revolution helped India and China to feed themselves and averted widespread starvation.

Today, an estimated billion people go to bed hungry. Hundreds of millions are stunted by poor nutrition. And by 2025 another billion people will want to know what’s for dinner…

What to do?

After World War II, agronomist Norman Borlaug played a role in founding international farm research stations that invented and distributed seeds and technologies to Latin America and Asia, with a focus on the big three crops: rice, wheat and corn (maize).

The green revolution that resulted gave a dramatic boost to farm production. But population continues to rise, and funding for food projects tapered off after the initial gains were realized.

The green revolution averted massive starvation “in some situations, but in others, especially Africa, it failed terribly,” says James Lassoie, a professor of natural resources at Cornell University, and leader of Agriculture Bridge, which attempts to harmonize agriculture with conservation.

Small could be beautiful

As the green-revolution research organizations continue working on high-yield crops, a newer approach to raising food production is emerging that concentrates on methods and technologies that can be built and maintained locally.

For reasons related to economics, environment, and efficient technology transfer, the new projects have steered away from large-scale provision of food, equipment, seeds and fertilizer, and toward social and environmental goals. Many projects work in Africa, where food and population problems are most acute, and with women, who do most of the farming.

Although few would discount the role of high-yield seeds in feeding seven billion, “Economic development needs to support both environmental protection and livelihoods,” Lassoie says. “Technologies are not going to help if they don’t also deal with the social and political dynamics.”

Our look at a few of these projects only offer an educated scanning of the horizon. We neither visited these projects nor possess a crystal ball, and so can neither vouch for their results nor predict the end game. But farmers are smart people who gravitate to things that work — if they fit the local culture, economy and environment.

Enough introductory blather. Let’s take a look!

Progress on one acre in Kenya and Rwanda

Africa’s agriculture is dominated by “small-holders,” people who work an acre or two, mainly with family labor, and are an increasing focus of attention in the effort to feed ourselves.

Services are loans, not gifts, and as is common with micro-lenders, borrowers join small groups that guarantee each loan. One Acre says 99 percent of its loans are repaid.

The fund’s advisors offer farming advice during weekly visits that emphasize profitability as much as productivity. For example, because prices are usually lowest during the harvest, the advisors suggest that farmers hold on to their crops for a few months.

One Acre says its growing and marketing strategies double the average farmer’s income, allowing small-holders to pay school fees and buy land to improve family income and food security. One Acre is reaching 55,000 families in Kenya and Rwanda, and aims to enroll 150,000 families by 2013.

Fish, water and wetland in Uganda

The realization that healthy ecosystems improve water quality and store carbon from the atmosphere has spawned a system called “payment for ecosystem services.” After all, if people downstream are getting clean water or hydroelectric power from a well-forested watershed, that should be worth paying for…

It’s a simple concept that conceals any number of complexities, but these payments do bring in outside money that can support environmental improvements.

In densely populated southwestern Uganda, the organization Nature Harness Initiatives is combining payment for ecosystem services with collaborative management to protect the environment of a wetland in the Kanyabaha-Rushebeya region.

The wetland provides fish for food, bees for honey, and fiber for thatch, mats and baskets, but farming and deforestation by people trying to make a living are causing serious soil erosion, harming the wetland and its many human and non-human residents.

Although baseline data on water quality is short, Nature Harness is convinced that it’s program works, and can be expanded to regions with similar problems.

Growing new farmers in Uganda

In Uganda – and elsewhere — farming is often seen as an occupation best suited to school dropouts and people who cannot afford college. Could interesting the younger generation of Ugandans in growing vegetables reverse this trend?

Through the Project for Developing Innovations in School Cultivation, more than 1,100 children in at least 31 schools have transformed schoolyards into gardens as they learn to grow local crops with traditional and environmentally-minded methods.

Project DISC was inaugurated in 2006 to combat rising food shortages and preserve Uganda’s culinary traditions. By allowing children to experience growing, tasting and cooking fruits and vegetables, it is cultivating a generation that values agriculture and quality, local food.

(The whole setup reminds us of the U.S. urban farming movement.)

The farming lessons includes methods for sustainably growing crops in Uganda’s increasingly hostile climate, as the children learn about raised gardens, drip irrigation and drought-tolerant crops.

Project DISC does face obstacles, such as Uganda’s staggering population growth and declining soil fertility. All the more reason to encourage young Ugandans to see agriculture as a respectable livelihood, rather than a last-resort job.

Community grazing rights in Mongolia

In land-locked Mongolia, 2.7 million people coexist with about 10 times as many horses, cattle, sheep, goats and camels. The people of Mongolia have followed their animals for centuries, living a nomadic life in portable shelters called gers.

This windy, dry and cold land exists at the mercy of the weather; the harsh winter of 2010 killed 20 percent of the country’s livestock. Meanwhile, overgrazing is promoting erosion and making the pastures less productive, while the Gobi Desert encroaches from the South.

It’s a classic case of the “Tragedy of the commons,” the idea that resources owned by all are protected by none.

To avert tragedy, Mongolia is experimenting with “co-management,” a system for making joint decisions about the grasslands to maximize benefits and prevent long-term degradation. In co-management, groups of herders contract with the government to assume the regulation and protection of tracts of land. Contracts are adapted as needed during annual renegotiations.

The result has been a reduction in herd size and an attempt to breed better animals to maximize profits from a resources that is now managed with an eye to community prosperity. Evaluations say the process is raising family incomes by 5 to 10 percent annually, and the idea is catching on elsewhere in Mongolia and Central Asia.

Banking on the harvest in Niger

In many lands with poor people and marginal agriculture, the months before harvest are called the “hunger season.” In Niger, in the dry Sahel region just south of the Sahara Desert, the hunger season has been exacerbated by droughts and locusts.

Niger is second to last in the United Nations Human Development Index.

Micro-lending is catching on as a way to fight poverty, but there’s a twist in Niger: Instead of lending money, the Project for the Promotion of Local Initiative for Development in Aguie lends grain through “soudure” (pre-harvest) banks.

The cooperative buys grain from local farmers, and lends it when needed at 25 percent interest, a fraction of what moneylenders charge.

By the middle of 2010, about 168 soudure banks, managed by over 50,000 women, were storing enough millet – a local staple grain — to feed 350,000 people for at least a month. That storehouse helped villagers survive the hunger season (see #38) during the spike in global food prices in 2008.

Beating hillside erosion in Yunnan, China

After a devastating flood in 1998 in Southwest China (blamed largely on deforestation of steep slopes), a new reforestation project focused on planting trees that generate income. (Reforestation projects can drive farmers and herders from their land by planting trees that may offer long-term environmental advantages but do not provide income to local people.)

The World Agroforestry Center has sponsored a different approach to reforestation on a 42-square-kilometer watershed in Yunnan Province. The project began with a collaborative design process that focused on using trees for food, forage or other purposes.

Walnut trees provide edible nuts. Beneath the trees, medicinal herbs are planted as a cash crop. Women may spend four hours a day collecting firewood, but new fermentation devices transform pig dung into biogas for cooking.

Although the project is said to be working on the small scale, and is producing enough income so parents can send kinds to school, these techniques will only provide a meaningful benefit once they are applied more broadly.

WFARM-TV in Benin

Rice, a staple crop and food through much of southern Asia and tropical Africa, is usually grown on small farms. To stimulate and propagate farmer creativity, Africa Rice develops short videos with significant input from local farmers, and distributes them across the rice-growing region.

Farmers are inherently interested in the ideas of other farmers, and seeing their innovations legitimizes farmer experiments and leads to further improvements.

The 10- to 20-minute videos cover such topics as preparing land, transplanting seedlings, managing weeds and harvesting the rice. AfricaRice distributes the videos through farmer associations; the farmers line up the video equipment and stage the screenings, which are often held outdoors.

By 2009, 11 videos were available to communities in Africa; some have been translated into more than 30 African languages and/or been transcribed for radio broadcast.

– David J. Tenenbaum

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

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

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

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

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

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

Not so obvious after all

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

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

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

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

Well done

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

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

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

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

What are the practical implications?

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

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

Good news for conservation

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

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

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

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

– David J. Tenenbaum

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

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

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

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

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

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

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

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

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

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

Cool news for your atmosphere

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

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

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

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

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

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

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

– David J. Tenenbaum

With fanfare that even snared some attention outside scientific circles, the 10-year Census of Marine Life came to a conclusion Oct. 1. The headlines and self-congratulation were deserved: our “ocean planet” is predominantly covered with salt water, and the Census had strength in numbers: 2,700 scientists from more than 80 nations spent $650 million exploring life in salt water. Working in 25 groups, the scientists sifted and collated old data and performed new studies on 540 field expeditions.

The Census also crafted the ground-breaking Ocean Biogeographic Information System. This public database contains 30 million records on more than 100,000 marine species, derived from new studies and about 800 existing databases that were harmonized for easy digital access (or so we’re told; we confess we’ve not looked up our favorite lobster in the database).

Kiwa hirsuta, Ifremer, A. Fifis, 2006

South of Easter Island in the Pacific, Census explorers discovered the yeti crab, which became the first member of a new biological family, Kiwida (Kiwa was the mythological Polynesian goddess of shellfish). The yeti crab supposedly resembles the abominable snowman, the “yeti.”

The effort was monumental, but necessary, considering that roughly 71 percent of our planet is covered by ocean. For reasons of remoteness, expense, logistics and physics, ocean science is difficult and expensive, and as a result, we know a lot less about life in the oceans than on land.

And even on land, scientists cannot agree on the total number of multicellular species, let alone count the bacteria and other one-celled critters.

The effort to explore salty sections of the planet that began in 2000 has already boosted the number of known marine species from 230,000 to 250,000. About 5,000 more candidate species await analysis in jars and freezers around the world.

What is the big picture?

Educated guesstimates suggest that the oceans may hold 1 million multicellular species – four times the number that’s been cataloged. In total, since 2000, an average of 1650 new marine species have been named each year — proof that the age of biological discovery continues. That number includes about 150 species of fish.

Courtesy Patricia Miloslavich

Half of fish biodiversity in the Caribbean is located near venerable marine science stations (circled). “Very few samples come from the huge, deep-sea basin in the middle,” says Census scientist Patricia Miloslavich. “If you go to places where you have never been, you will find new species.”

Our view of marine biodiversity suffers from sampling bias – we find more species near scientific stations, and that is one error Census projects are trying to correct, says Patricia Miloslavich of Simon Bolivar University in Venezuela. Miloslavich, a co-senior scientist for the census and head of its Caribbean project, says biodiversity data for the Caribbean, “did not show the location of biodiversity so much as the location of marine scientific institutions. There are little hot spots around … the places where most research been carried out in the last 50 to 80 years.”

Because South America extends so far north and south, and fronts two major oceans, it posed a good test for the notion that biodiversity would peak in the tropics and taper off toward the poles. Miloslavich says Census data from South America refuted that conventional wisdom.

Near South America, at 40° to 50° south latitude, biodiversity is much higher in the Pacific than the Atlantic, probably due to the many biological niches in Chile’s convoluted coastline. Scientists traditionally expect to find more biodiversity in the tropics.

In the tropics, the expected high biodiversity did appear in the Pacific and the Atlantic, Miloslavich says. But the Pacific also showed a biodiversity hotspot between 40° to 50° south latitude. “The Chilean fjords are a very irregular coast, with a lot of biodiversity,” Miloslavich says, “but at the same latitude on the Atlantic side, off Argentina, biodiversity was low.”

No way can we summarize this huge effort to catalog and measure ocean life. Instead, we’ll encourage you to browse for yourself while we focus on new data about:

Canada’s coldest realm

The Census of Marine Life studied Canada’s Atlantic, Pacific and Arctic coasts, which by themselves account for 16 percent of the globe’s coasts, says Philippe Archambault, first author of the report on Canada’s “three oceans”.

The Census attempted to negate sampling bias, which had suggested that the Atlantic was more diverse than the enormous Arctic coast, which stretches more than 160,000 kilometers.

Colossendeis colossea, Mylène Bourque, Benthic Ecology Laboratory, Institut des sciences de la mer, Rimouski, Quebec.

This large sea spider, from the Canadian Arctic, feeds on corals and other organisms by sucking their contents through his enormous mouth, or proboscis, located at lower right. Although the sea spider has a small body, its vital organs, including gonads, are housed in its elegant legs.

On the Arctic coast, biodiversity counts covering just 53 square meters (“the size of three Canadian kitchens!” Archambault says) revealed 1,200 species (mainly animals longer than 1 millimeter). In comparison, studies of 170 square meters of the shorter Atlantic coast showed 1,300 species. We offered the conventional wisdom, that the Arctic is biologically boring. “This was not the case when we put out a similar sampling effort,” Archambault says.

The planetary warming that is melting the Arctic ice is already affecting sea life, Archambault adds. In areas that were normally covered with ice for most of the year, the summer melt allows a brief pulse of sunlight that energizes plants, starting a simple food chain in which animals graze the plants and drop to the sea floor, to be eaten by predators. But when the water remains ice-free for more time, Archambault says, small crustaceans called copepods in the water eat the grazers before they can reach the sea floor. “So you now have copepod feces going to the sea floor, and you don’t have the same animals living down below.”

Photo: Casey Debenham, University of Alaska Fairbanks

These subarctic sunflowers live in the shallow waters of Prince William Sound, Alaska; part of an Arctic that now seems unexpectedly rich in biodiversity.

The studies organized by the Census are documenting today’s conditions in the Arctic, so we can understand what happens as the climate changes. “The Arctic is almost the last pristine area on the planet,” Archambault says. “When the ice melts, there will be more shipping, more potential for oil spills, and yet we don’t have baseline information” to help track the anticipated changes. (This video shows biological exploration in the Arctic.)

The Canadian studies highlighted how biology is hobbled by a shortage of taxonomists — experts who can distinguish one species from another. “We are losing taxonomic expertise in Canada, and everywhere,” says Archambault. “We have much more technology for counting species, but this can only help us know how many species are there, it won’t tell us what they are doing.” He notes that the Census of Marine Life had to send 25 samples of polychaete worms, a common sea-bed resident, to Mexico for analysis, and one turned out to be an unknown species. “We cannot do this identification in Canada anymore,” says Archambault. “Taxonomy is not sexy enough!”

A lot of biology is at stake in the frozen realm, Archambault says, yet we don’t even know what’s living there. “Each time we send in equipment, in the Arctic, in the Pacific or the Atlantic, there is a big chance of finding something new.”

Tracking fish

Migrations always fascinate biologists, whether it’s the monarch butterfly winging thousands of miles between central Mexico and the American Midwest, or the Arctic tern, flying a round-trip of about 9,000 miles from the South Atlantic to Norway.

Whales migrate, turtles migrate, and so do fish like the salmon. Because tracking migrations, especially for smaller critters, is difficult, one Census project has laid strings of underwater microphones across rivers, straits and the continental shelf along British Columbia.

The strings can be used to track fish or other animals that carry tiny noisemakers.

On the continental shelf, receivers spaced 800 meters apart can detect 90 percent of the fish swimming past, says Jim Bolger, executive director of POST, the Pacific Ocean Shelf Tracking project. Because the network can identify individual animals, remote-control migration tracking becomes possible once the noisemakers are in place.

Scientists who use the network “are not only looking at where they go and how fast they traveling, but are identifying bottlenecks for survival, where fish fail to show up,” says Bolger, who also directs the Vancouver Aquarium. Such information can abet management measures designed to make life easier for many types of marine creatures.

2004 photo, POST

Acoustic units prepare for a swim in the Strait of Georgia, British Columbia, to prove that these arrays of microphones can track animals bearing distinctive noisemakers.

Salmon in the Northwest have been a focus of concern for many years — as their spawning rivers are dammed, fewer are returning to the ocean to mature. Fish tagging can be used to track salmon, if you can find the fish later on, but POST works much quicker, Bolger says. “We don’t have to wait four or five years to see how they survive; we can measure survival almost in real time.”

Bolger says salmon swim complex routes. A POST study of four salmon species in British Columbia found major variations in swimming speed and route.

A second study of young salmon in British Columbia linked survival to the timing of migration: young salmon that hit the ocean when plankton were blooming had 150 percent to 300 percent better survival.

This type of data could help conservation groups and hatcheries trying to restore salmon, but . “There is no one-size-fits-all strategy,” Bolger says. “Even within the same species, on the same river, we have tremendous complexity in how they swim and where they go. Some go north, others to the south. This could be a survival strategy; they don’t send all their progeny in one direction.”

Photo: POST

The new noisemakers are so small they can even be placed inside young salmon, before they start their migration down rivers and into the ocean.

Information from the acoustic array can also be melded with data on genetics and physiology, Bolger says. “We can see whether fish with high levels of stress hormone behave differently than those with low levels. Scientists can examine the blood chemistry and genetics when the tag is implanted,” and then correlate the data with their subsequent movement.

The magic of microbes

Perhaps the biggest single question about ocean life concerns microbes — bacteria, their primitive relatives called Archaea, and other single-celled organisms such as protists and ameba. Species are difficult to define in bacteria and Archaea, which is why scientists use “taxa” instead, but the numbers are daunting: the oceans could contain tens of millions of taxa, and the exploration has just begun.

“Small” does not mean insignificant: the approximately 10²⁹ microbes in the sea weigh one trillion (1,000,000,000,000) tons, and comprise an estimated 90 percent of life in the ocean, by weight. Not only are microbes critical to the food chain, but they also engineer many of the basic chemical reactions that move fundamental elements like carbon and nitrogen through the oceans.

Global Seafloor Biomass

Photo: Chih-Lin Wei and Gilbert T. Rowe

By measuring carbon, scientists estimated biomass, including creatures from bacteria to plants and the biggest animals, at the seafloor. Generally, the tropics seafloor is low in biomass compared to temperate and polar regions.

Scientists long ago gave up trying to distinguish microbes by growing them in culture, and now count them with genetic techniques nick-named “molecular bar-coding.” These methods evaluate similarities and difference in a specific section of the genes, then use the data to build an evolutionary tree. Bar-coding applies to all life, and is widely used to assess evolutionary relationships in higher organisms as well as bacteria.

Ten years ago, scientists using molecular bar-coding concluded that a single liter of ocean water might contain 3,000 types of microbe, says Mitch Sogin, of the Marine Biological Laboratory in Woods Hole, Massachusetts, and a leader of the International Census of Marine Microbes, “But what blew the doors off that estimate was a very deep molecular sampling effort in 2005 … which revealed that the number is at least an order of magnitude higher.”

Today, it’s estimated that a liter of seawater may have 30,000 to 40,000 types of microbes, Sogin says, “so if we take all 1,200 samples [from the microbial wing of the ocean census], we very conservatively estimate that they contain one-half million kinds of microbes.”

There are reasons to suspect that the actual number may be much higher, Sogin says, but even using this definition, “Every time we look at a new sample, we identify new taxa, and yet we have only sampled 1,200 liters, which is 1 in 10 ¹⁸ parts of the total ocean.”

when bacteria make rock

Loihi Seamount, courtesy Katrina Edwards

An iron-processing bacteria (bean-shaped object) forming iron-oxide needles.

Unfortunately, molecular bar-coding does not show what newfound microbes are eating, or how they affect their surroundings. At Loihi Seamount, a submarine volcano near Hawaii, marine census scientists have explored microbial iron-mongers. Katrina Edwards, a professor of marine and environmental biology at the University of Southern California, says, “At Loihi, we could dig our heels in to study a particular class of microbes that we think are pretty ubiquitous at the seafloor.”

These bacteria “play a very large role in iron oxidation and the deposition of enormous quantities of iron oxide,” which eventually becomes rock, Edwards says. “If we can understand how these rocks are formed in the modern world, and can understand the physiology, genome and ecology of the bacteria, we can interpret” old rocks found in other locations.

Microbes: Why so many?

Linda Amaral-Zettler, a microbial ecologist and program manager for the International Census of Marine Microbes, has a question: “Why are there so many different kinds of microbes living in this environment, that at first blush, seems uniform?”

One answer comes from the billions of years of every that have produced so many life patterns and genetics. But another answer, she says, may be “that there are a lot more niches or places to live than we have appreciated. Somehow these organisms are sensing these micro-habitats and are able to survive despite the competition.”

Photo: Enric Sala

Coral reefs serve as the perfect haven for co-habitation between microbes and sharks!

Microbes can be extremely specialized, and scientists have found that the most common microbes living on one species of sponge are not among the most common on another sponge, says Amaral-Zettler, who works at the Marine Biological Laboratory in Massachusetts. “Animals, plants and other multicellular organisms are likely to be havens for microbes, and we have barely sampled them. Essentially any surface that is out in the ocean can be colonized.”

Even trash?

Apparently. “All the signs say that even garbage is something the microbes are taking advantage of; likely they are degrading it and using it for an energy source,” says Amaral-Zettler, who is starting to examine microbes on plastic in the sea in collaboration with the Sea Education Association.

Here’s another question: Why are most of the microbial taxa discovered by the Census so rare? Having a few dominant species and plenty of rare ones is often characteristic “of an environment that is impacted in some way” Amaral-Zettler says, “but it seems to be a repeating pattern in the sea; we see it everywhere we look. We are struggling to understand the ecological consequences of having so many rare microbial species.”

Photo: Karen Gowlett-Holmes

Plant or animal? The leafy seadragon confuses predators by mimicking drifting seaweed.

This business of the “rare biosphere” fascinates Sogin, a specialist in microbial evolution, who suggests that the many rare species:

Should we worry?

If there is an uncountable diversity of microbes in the sea, should we ignore the conventional cavil about biodiversity — that too many species will go extinct? Why worry if the sea has more microbes than we can count?

Not so fast, says Sogin, who warns that we are changing the sea in ways that could harm microbes and boomerang back to harm us.

It’s not just that all multicellular organisms evolved from single-celled creatures, Sogin says. Life can survive happily without people, but life relies on microbes. “During 80 percent of the history of life, microbes transformed the planet into something that was habitable by multicellular organisms. They created an environment we can live in. This process continues, because so many microbes in the ocean carry out processes that are essential to our survival.”

People, after all, are dumping garbage, sewage and fertilizer into the ocean, warming it with greenhouse gases, and as the ocean absorbs our carbon dioxide, it becomes more acidic.

Since we don’t understand how the ocean works, we cannot predict the consequences of a major change in the environment.

However, Sogin says, “We know from lab work in microbiology that tremendous shifts can occur in population structures and lead to an imbalance and then a further change in environmental conditions. What will happen with continued ocean acidification or a dramatic shift in seawater temperature? We are going to have a disruption of the microbial community. Is that good or bad? We don’t know.”

Photo: Tim Lindenbaum

American coots take wing at Thompson Lake at the Nature Conservancy’s Emiquon Preserve along the Illinois River in Lewiston, Ill.

In part I, The Why Files described the growing evidence that rivers around the world are under attack by overuse, overfishing, pollution, damming, diversion and invasive species.

Amid growing concerns about a shortage of freshwater, the damage shows up in terms of declining biodiversity and widespread ecosystem damage.

On Oct. 8, 2010, Newsweek magazine summed up what it called a “global freshwater crisis”:

As rivers are dried, dammed, polluted and fished to within an inch of their ives, environmental needs, inevitably, take second place to human water requirements. Wetlands — essential to flood control, fish and birds—are drained or diked off. Dams store water but prevent fish from spawning and inundate floodplains. Dams and levees channelize and regulate rivers so barges can travel, blocking the natural oscillation of water levels and destroying wetlands. And some water diversions are so huge that they prevent rivers from reaching the sea.

It’s a spiral of decline. Pollution, demand for freshwater and over-fertilization injure rivers, which in turns harms groundwater and freshwater on the surface. Environmental damage reduces our long-term supply of fish and freshwater, and over-use of water and related resources boomerangs back to cause environmental harm.

The use and abuse of water is all about cycles, and actions taken to help the environment can help freshwater resources, and vice versa.

Photo: Mountain Visions/NOAA

In southwest Idaho, 2,100 volunteers have helped restore rivers and wetlands to benefit migrating salmon.

Light at the end of the (water) tunnel?

As The Why Files looked around at proposals to reduce damage to rivers, we noticed that many projects are trying to bring nature back to rivers and watersheds.

Faced with a succession of floods, a few American towns have headed for higher ground. In the late 1970s, for example, Soldier’s Grove, Wis., abandoned its riverside site after repeated flooding. In May, 2010, nearby Gays Mills, also on the Kickapoo River, received a $4.4 million grant to do the same, and construction of housing and businesses has begun on higher ground.

Dams are a major source of environmental trouble on rivers, and their removal is becoming an accepted restoration tactic. Although we could not find an international number, the conservation group American Rivers says more than 600 dams have been removed in the United States during the past 50 years.

Most removed dams are small, so each removal affects only a few miles of the river. However, in 2011, a 210-foot high dam will be yanked out of the Elwha River in Washington State.

Disarming the dam! River liberation

River engineering and ecosystem alteration are a fact of life on the Mississippi River and its major tributaries, where levees hem rivers into narrow channels. Although most of the Mississippi floodplain in Wisconsin and Minnesota is in nature refuges, half of the river’s floodplain has been drained and diked in Iowa and Illinois. And according to Richard Sparks, director of research at the National Great Rivers Research and Education Center, 90 percent of the floodplain has been drained and leveed in the state of Mississippi.

Above St. Louis, the U.S. Army Corps of Engineers owns dams spaced about 20 miles apart, which it uses to control water level, essentially creating a barge canal on the iconic river.

Dams and levees have sundered the river from its floodplain, which served as a home of plant and animal biodiversity and a relief valve during spring floods. Because the Mississippi carries a heavy load of sediment, that stable water level has left a thick layer of muck in sloughs along the river.

If the water level can resume its normal undulation—rising in spring and falling in fall – the yucky-mucky can be restored to wetlands inhabited by the plants and native animals that evolved to live in that varying habitat.

Restoring these wetlands is the goal of an agreement that the Corps has negotiated with fish and wildlife agencies. The Corps is adjusting dam operation so the water level falls during summer, allowing native plants to recolonize shorelines, to the benefit of migratory waterfowl and other animals. “By adjusting the control, they are having biologically measurable effects,” says Sparks, “although it does cost a little more because the Corps has to dredge areas where sediment accumulates.”

The water level may fluctuate by just half a foot near Minneapolis, and up to three feet near St. Louis, but even this smidgeon of variation is allowing hundreds of acres of wetlands to return to some of the “reaches” between dams, Sparks says. “Sediment along the shoreline can dry out and compact during summer, so when it’s reflooded, there’s less sediment to be resuspended; it’s a cumulative effect.”

Leavening the levee! Wetland watershed

The catastrophic Mississippi River flood of 1993 — when broken levees flooded millions of acres — caused a rethinking of the role of levees in the river and its major tributaries. Still revered as essential protection for cities and farms, levees are also recognized for making floods taller and more dangerous.

Photos: NASA

Satellite view of the meeting of the Mississippi, Missouri and Illinois rivers above St. Louis, Missouri. Top: 1991 (an average year); bottom: the flood of 1993. Billions of dollars worth of development has since been built in areas that were flooded in 1993.

Because levees also divide rivers from their floodplains, some conservation groups want to convert floodplain farms back to wetlands. On the Illinois River alone, conservation organizations have bought out three agricultural levee districts, Sparks says. The goal is to reconnect these areas to the river, “and attempt to recreate a water regime that mimics a more natural flood pulse.”

At Emiquon Preserve, thousands of acres of corn and soybean are being turned into wetland, upland prairie and forest by the Nature Conservancy. Between them, the Conservancy and the U.S. Fish and Wildlife Service own about 14,000 acres on this part of the Illinois River, says Doug Blodgett, director of river conservation at the Illinois Conservancy.

Instead of removing the levee, the Conservancy has recreated wetlands by shutting down pumps that once dried the farmland behind it.

Removing the levee would expose the wetland to the disturbed hydrology of the watershed, where the water level naturally fell in summer and, as in the Mississippi, fostered plant growth and soil consolidation. Low water in late summer is no longer reliable, Blodgett says, “Because we have destroyed the upland wetlands, changed prairies into row crops, channelized streams, put in parking lots and roofs, and so the river no longer behaves naturally.”

The water flow has been so altered, Blodgett says, that some land along the Illinois is “nearly devoid of plants, especially submerged aquatics.” Simply removing the levees today “would nearly wipe out the plant community that we are trying to restore.”

Once the Army Corps builds gates in the levee, however, they will be opened when the river is behaving normally. “That would let critters move back and forth, so the plants and wildlife can return to the river,” Blodgett says.

Bald eagle over the Emiquon Preserve by Jane Ward

Restoring the natural wet-and-dry cycle to the floodplain benefits the native plants and animals that evolved to live there. for example, mussels are among the most endangered species in North America, and Blodgett notes that “The Illinois River had the most productive mussel beds in North America, and that was due to the backwaters like Emiquon.”

Emiquon is already seeing a surge in rare pumpkinseed sunfish, spotted gar, horned grebe, and American white pelican. The threatened red-spotted sunfish was recently introduced, and the Conservancy and its partners plan to rear starhead topminnow, weed shiner, emerald shiner, and iron color shiner. (We don’t know much about these fish, but don’t they have gleaming monikers?)

Attitudes about floods, levees and rivers are changing, says Sparks, who has spent decades studying big Midwestern rivers. “Today, there is a better understanding on the part of the public, decision makers and conservation organizations, of what a floodplain river is. This pulsing is normal, and flooding up to certain point is good. When you said ‘flood’ 25 years ago, the immediate reaction was, ‘How do we stop it?’”

Loving the locks! Fish rodeo in the Southeast!

Dams on the Pacific Northwest are infamous for blocking the upstream spawning journeys of salmon, but the problem is widespread. Along the Gulf of Mexico, for example, the Jim Woodruff Lock and Dam on the Apalachicola River has blocked the threatened gulf sturgeon and the Alabama shad, a prolific, base-of-the-food-chain fish.

Photo credit: Steve Herrington, The Nature Conservancy

Drink up! Researchers implant a transmitter in the stomach of an Alabama shad at Woodruff Lock and Dam. These trackers show that the Southeast’s sole fish rodeo is working.

The Alabama shad, which used to occur as north as far north as Illinois, is “taking a nosedive nationwide, barreling toward official listing as threatened or endangered,” says Steve Herrington, Nature Conservancy’s project manager for the Woodruff Dam project. The inability to reach spawning grounds is a major cause of decline.

Dynamiting the dams would be unpopular and expensive, but when conservationists in the Southeast looked to help the shad, their found solution in the lock itself. “Could we move fish like we move boats?” Herrington says.

After all, when spawning time approaches, the fish naturally swim upstream — until they slam into the dam. Would it be possible to corral those fish into the lock, lift them to Lake Seminole, and allow them to continue their upstream spawning journey?

Adapting techniques previously used to help American shad migration in Maine, Pennsylvania and South Carolina, a broad group of conservation agencies, scientists and conservationists, and the Army Corps of Engineers, devised a plan to open the lock to migrating fish.

The fish rodeo occurs twice a day during spring, the spawning season.

Photo credit: Shawn Young

Fish rodeo ahead! A water pump creates a fake waterfall that attracts fish into the lock at Jim Woodruff Lock and Dam, which impounds Lake Seminole on the Georgia-Florida border.

The key is an artificial waterfall — a fancy term for a stream of water. “These are natural cues, and this bit of splashing seems effective,” Herrington says.

A stream just below the lock attracts the fish, then the lock opens, and a second stream lures the fish further inside. After the lower door closes, the lock fills, and within about an hour, the upper door opens, releasing a new cargo of Alabama shad and gulf sturgeon into Lake Seminole, and then into two rivers that supply the lake.

After five years, the collaboration has proven that it can move fish, says Herrington. “The fish we tag are moving 100 miles, through good habitat, until they bang into the next dam” on the Flint River.

Data from the Georgia Department of Natural Resources provides “strong circumstantial evidence” that the effort is also bolstering populations of the shad and the sturgeon, Herrington adds. “They are almost certainly spawning in the Flint River due to the fish passage.”

The Why Files had to mutter that the fish rodeo sounded too good (and too cheap!) to be true, but Herrington reminded us that the fish are just doing their thing. “If you have acres and acres of good spawning habitat, which we do, then all the things we know about fish biology say this is what we would expect to see.”

Aside from buying a pump and some PVC pipe from a bigbox retailer, the only cost is to open and close the lock, Herrington says. “We are trying to be really simple; we want to keep cost down to nothing.”

Crushing concrete! Reviving an urban river

During the 1960s, Milwaukee’s Kinnickinnic River was converted to a concrete ditch, useful for flushing rainwater quickly into Lake Michigan, but with no biological value. The concrete ditch, intended for flood control, further reduced the watershed’s porosity and prevented surface water from entering the groundwater.

Courtesy Milwaukee Metropolitan Sewerage District

Milwaukee’s concrete-clogged Menomenee River is scheduled for restoration in spring, 2011. Roll mouse over image to see computer image of this location after restoration.

Impervious watersheds are closely linked to a variety of river deficits, says Thomas Chapman, an engineer with the Milwaukee Metropolitan Sewerage District (MMSD). “There are studies galore that show that the minute a watershed starts getting over just 10 percent impervious, the impacts are seen, and at 25 percent, it’s a significant impairment,” says Chapman. “Most of our urban areas already have that.”

The combination of fast runoff and slow infiltration starves groundwater and washes pollutants and abnormally warm water into Lake Michigan. Meanwhile, the concrete “river” quickly parches between rainfalls.

The sewerage district also needs to reduce runoff because storms overwhelm its treatment plants, which accept both stormwater and sewage in 10 percent of its service area, and a few times each year untreated sewage can flow into Lake Michigan during heavy storms.

Ideally, Chapman says, restoring natural processes should reduce runoff into the lake, slow the storm surge, and allow incoming wastewater to be treated.

The desire to slow runoff, speed infiltration, improve esthetics and recreation and allow natural processes to clean river water have motivated the MMSD to fund a return to more natural conditions along the Kinnickinnic and Menomenee Rivers in Milwaukee.

Contractors have started obliterating the first 1,000 feet of concrete on the Kinnickinnic, says Chapman, and 84 homes are being purchased for recycling and removal. Eventually, MMSD will remove about three miles of concrete along each river, to create a 200-foot wide stream corridor — essentially a park with esthetic and biological value. “These are paved stream with no aquatic life, with garages lined up to the edge of the concrete,” Chapman says. “They are drainage ditches, kids would float through in heavy storms, and there were some tragedies.”

Milwaukee has good experience busting concrete. In 1997, the city removed the North Avenue dam on the Milwaukee river, Chapman says. “I’ve had people tell me fly fishing along the Milwaukee river is gorgeous. Who would have thought that we would get tourist dollars because we removed a dam? You lose the perception that 1,000 feet away is a high-density urban area…”

Getting organized! Australia responds to long drought

Photo: Irene Dowdy/MDBA

A long drought in Australia has sparked interest in smarter water management.

In Australia, the driest continent, the water problem is all about shortage. But after a decade-long drought, the continent-nation has learned something about water management. In fact, when they are pressed for an example of enlightened water management, water experts often cite Southeast Australia’s Murray-Darling river basin, home to one-third of the country’s agriculture, two million people, and the only two major rivers.

Faced with a long drought and caught between thirsty cities, parched farms and drying wetlands, the basin could be the stage for a water war. Instead, it is the site of advanced water-allocation by the Murray Darling Basin Authority.

The crisis has been put to good use, says Bradley Udall, a specialist in western U.S. water resources at the University of Colorado. “Frequently a water crisis brings out some very novel, innovative solutions that prior to the crisis was politically unthinkable. All sorts of interesting opportunities arise, because lots of people want to do the right thing, and are freed from political constraints.”

The authority favors transparency and provides online access to the current storage situation in itsreservoirs.

Because surface- and ground-water are both over allocated, the authority is producing a new plan, with plenty of public input, to align demand with supply.

Like a hanging in the morning, the 10-year drought, with the accompanying wildfires and economic dislocations, have concentrated minds in Australia, Udall says. “Changes have gone on in politics, policies, infrastructure, conservation, agriculture and the economy, they have all kinds of solutions on the table that prior to the drought would have gone nowhere.”

The language used to discuss water reflects the changes, Udall says. “They use the term ‘water security’ over and over, and they use ‘security’ the way we use ‘national security.’ It’s a reflection of how seriously they take their water problems.”

As Udall indicates, nothing could be more dangerous than taking freshwater for granted. How will the rest of the planet respond to the growing freshwater shortages?

Photo: Oct. 7, 2010, friedrich glorian

With red sludge still visible, women survey the damage in Hungary. Eight died when a dike burst at a factory that processed ore into alumina, a raw material for aluminum.

Have you seen the photos of aluminum sludge surging through villages in Hungary, heading for the Danube River? With eight people dead, and new cracks appearing in the wall containing a pond-ful of alkaline sludge, we’re left to hope that the toxic crud is defanged by dilution before it does too much damage to the mighty Danube.

Still, the spill got us to thinking about the plight of the world’s rivers. Rivers are our foremost source of freshwater, used for drinking, industry and agriculture. Their wetlands and floodplains clarify water, temper floods, and provide an irreplaceable habitat for countless plants and critters, many of which are the major source of protein for hundreds of millions of people.

But a new study in the journal Nature shows that the globe’s rivers are being lambasted by pollution and invasive species. Heavy burdens of artificial fertilizer have created dead zones at the mouth of hundreds of rivers. Rivers are being over-fished, channeled into barge canals, and drained for irrigation, industry and drinking water.

Graphic: Barry Carlsen, copyright University of Wisconsin Board of Regents

A new analysis of 23 threats to global water security and biodiversity shows many regions with a high cumulative level of threats.

When the study¹ assessed river health in terms of pollution, biological change, watershed disturbance and water resource development, rivers carrying 65 percent of the total amount of water that rivers bring to the ocean “is moderately to severely threatened on a global basis,” says study co-author Peter McIntyre, a professor of zoology and freshwater expert at the University of Wisconsin-Madison.

Dam difficult

Both human water supplies and the natural world are endangered, McIntyre says. “One-quarter of the world’s vertebrate species live in fresh waters, and hundreds of thousands of plants and animals are at risk because they live in places where threats are high.” In total, biodiversity is more threatened in freshwater than it is in saltwater or on land, McIntyre says; ominous declines are being seen in fish, turtles, mussels and plants.

Lest “biodiversity” sound frivolous, estimates suggest that the value of “ecosystem services” like clean air and clean water exceeds the global economic output. The necessity of clean water is obvious, but we are also utterly reliant on plants, above and below water, to convert carbon dioxide into oxygen.

And these ecosystem services are best served by stable ecosystems.

Managing freshwater is a delicate balancing act, and some experts anticipate that tightening supplies will lead to disputes or even water wars later in the century. The U.S. government says if current trends continue, “by 2025, one-third of all humans will face severe and chronic water shortages,” with the first and worst problems appearing in Africa and the Middle East.

Already, the Colorado River in the United States, and the Yellow River in China, are so thoroughly exploited that they scarcely reach the ocean. Low flows and massive pollution plague rivers in China, India, the Middle East and Africa.

Nile denial

Photo: Bionet

The Nile River supplies virtually all water in Egypt (notice how fields cluster along the river?) and major portions in Uganda, Sudan and Ethiopia. The Nile is polluted by sewage and agricultural chemicals, and is failing to supply growing populations along its dry lower stretches with enough water for a good standard of living. With a watershed that includes parts of 11 nations, disputes over the Nile’s water could devolve into war.

Water security vs. environment: Inevitable tension?

Although pollution, invasive species and overfishing play major roles in declining freshwater biodiversity, dams and associated water diversions are a fundamental part of the tension between environment and river development.

Dams are built to store and divert water, supply hydroelectric power and prevent floods. Dams, and the locks that allow ships to traverse them, remain a keystone of river management in Western Europe and the United States, which is home to an estimated 75,000 dams.

While dam construction is largely over in Europe and North America (where some dams are even being removed), the 20th century was epic for dam building, says Bradley Udall, director of the Western Water Assessment at the University of Colorado. Udall notes that the volume of water stored behind dams has risen 350 times since 1900, to 5,000 cubic kilometers.

At the same time, Udall notes, due to such alterations as damming, draining, levees and development, “We have destroyed one-half of wetlands worldwide, which are very important for all kinds of ecological services, including water purification.” (Watch 23,000-plus large dams spread across the world.)

Chinese (river) checkers

Dam building is booming in developing countries, as an answer to floods and shortages of water and electricity. China’s Three Gorges Dam was essentially completed in 2008, after more than 1 million people were moved away from a new lake that is expected to cover 400 square miles. With a planned electrical output equal to more than 20 large nuclear plants (about 10 times greater than Niagara Falls), Three Gorges was also intended to halt disastrous flooding on the Yangtze River.

The series of dams that China is building or planning along the Yangtze and its tributaries will generate even more electricity than Three Gorges.

Yangtze River in When, China

Photo: Doris Antony

The river, shows intense pollution and human habitation in a city of about 9 million.

Dams can raise issues in any location. As Three Gorges proved, they displace riverside villages and cities and drown archeological sites. As is happening at the Glen Canyon dam in the United States, reservoirs can fill with silt, losing storage capacity and causing erosion as downstream areas are deprived of their normal silt supplies.

Dams also divert money that could be used for other purposes.

Granted, dams are a critical source of usable water, but they can also be a scourge of native plants and animals. “There is definitely a tension between human infrastructure and biodiversity conservation,” says Laurence Smith, a professor of geography at the University of California at Los Angeles, and author of a new book on environmental trends².

China is embarked on the largest water project in history, a 50-year program to move water from the Yangtze toward population centers in the drier north. Designed to move 50 cubic kilometers per year, the project aims to reduce sandstorms and water shortages while bolstering sinking aquifers in North China.

U.S. Fish and Wildlife Service

Rivers in the North, like Alaska’s Koyukuk, are far less impacted by pollution, diversion and damming.

Failing fish

Courtesy Peter B. McIntyre

A man fishes at Igamba Falls, on the Malagarasi River, Tanzania, site of a proposed hydroelectric dam. Fish are a major source of protein — and dams are a major cause of fish declines.

Altering rivers with dams enacts fundamental changes in ecosystems, says Smith. “A lot of the most biologically diverse riverine environments are seasonally flooded wetlands and flood plains. Biodiversity is not found in a big reservoir behind a dam… It is more the episodic flooding [of natural rivers] that gives this diverse habitat.”

Dams block the migration of important fish species, including the salmon, which is vanishing along the Atlantic and Pacific coasts of the United States, where dams block the upstream spawning journey.

That problem is widespread, says McIntyre. “In the tropics, species like big catfish, and the family known as the tetras, are very intensively fished. You have regions where people depend on these migratory fish, and if you put in a dam to stop the migration — rivers are aquatic highways — you profoundly change the system. There’s a real concern that if fisheries collapse, hundreds of millions of people worldwide who get a majority of their protein from freshwater fish could go hungry.”

In the central United States, massive dams and engineering projects on rivers like the Illinois, Missouri, Mississippi, Tennessee, Wisconsin and Ohio have also been blamed for ecosystem destruction.

For example, locks and dams north of St. Louis on the Mississippi stabilize the water level so large barges can traverse the river. But that stability, combined with extensive levees on the banks, has eliminated vast wetlands that once bordered the river. When the river no longer surges in the spring and subsides in the fall, remaining flat land along the river turns to muck that can no longer support native plants and animals.

Photo: Jason Sturner

Massive engineering projects along the upper Mississippi River have essentially changed the river into a barge canal.

Biodiversity black hole

One reason to foster biodiversity in rivers and watersheds is this: Biological systems with many interacting species tend to be more stable, and people, like other animals, have adapted to a fairly stable environment. “In experiments with bacteria, if you strip away species, you eventually hit a point where the basic properties change,” says zoologist Peter McIntyre. “It can be on a plateau of high function for a while, but there is a threshold, and we can’t predict where it occurs, things start to fall apart.”

The classic analogy, McIntyre says, “is popping rivets on the wing of an airplane; you pop one too many, and boom! down you go. In the global river context, we are rolling the dice, we know we are losing species. The rates of extirpation and extinction are highest in freshwater; and that is where we are seeing the worst human impacts.”

Scientists who are looking more broadly at the health of river ecosystems are hampered by a lack of information. “There are no global data sets” that would support an exact measurement on the biological health of rivers around the world, says Carmen Revenga, a freshwater scientist at the Nature Conservancy.

Still, new evaluations of biodiversity are delineating the difficulties. Revenga says a recent assessment listed 253 endemic species of freshwater fish in the Mediterranean — meaning they are found nowhere else — and 56 percent of them are threatened with extinction. Another survey found severe declines among 40 percent of the 300 species of freshwater turtles, she adds. “Nobody would have guessed it was that bad.”

The inevitable tension between environment and human water use is growing more intense in dry places such as Africa and Australia, with heavy population pressure and intense land usage.

When farms, people or industry get thirsty, “Freshwater biodiversity has not tended to play role in discussions about water security,” Revenga says. “Usually there is a lot of focus on providing water that is secure and safe. Irrigation took precedence at first, and now cities take precedence, but the ecosystem hardly gets included.”

The sad, dry Aral Sea

Photo: Gilad Rom

The Aral Sea in Central Asia dried up after the rivers that fed it were diverted to irrigate vast cotton farms.

And that leaves less water for ecological purposes, Revenga adds. “When we calculate the amount of runoff in a basin, we assume we can tap all the water that’s available” for human uses. “The conservation and environmental community has not interacted with the water supply community, and the environment is almost forgotten.”

Mono Lake in California, whose water was diverted to Los Angeles in the 1940s, is one example showing that cities and farms have come first in American water management. According to the Mono Lake Committee:

In recent decades, California has been pressured to allot some water to environmental purposes, part of a gradual rebalancing of water use in the dry, densely populated American Southwest.

We’ll explore evidence of progress in water management in the next Why Files, but note that cities like New York rely on watershed protection to ensure a clean, adequate water supply. “It’s a very good strategy to protect upland forest, and reduce siltation and runoff into streams, but a lot of projects don’t look at biodiversity in the river,” Revenga says. Watershed protection is rare, and in any case the ecological benefits are secondary to the need to provide clean water to cities, she adds.

Climate change

As more people look to rivers to supply more water, there’s one final factor to consider: the climate. Brad Udall of the University of Colorado, an expert on the waters of the West, told us that climate change is not just about temperature. “You could make a compelling argument that it’s about changes to water cycles; changes in the quantity, quality and timing, almost all of which are detrimental” to freshwater supplies.

In general, Udall says, studies of ancient climate show that “wet areas get wetter and dry areas get drier.” In the Colorado River basin, where climate change has been intensely studied, “we can expect a 10 percent to 20 percent reduction in runoff by 2050.”

Photo: Laslovarga

Hoover Dam and its reservoir Lake Mead are major factors in Western water management, but at what environmental cost?

Because so many rivers in the American West are fed by melting snow, warmer winters already have a major impact, Udall says, with the earlier spring causing earlier runoff in the rivers. Studies project that the floods could happen as much as 60 days earlier in the spring, “and we are already seeing 20-day advances, especially in lower-level snow-dominated systems, like in the Pacific Northwest.”

At the same time, river flow is likely to diminish earlier in the late summer, and the water will also be warmer, Udall says, which poses problems for life. “Many critters in the water are stressed in high temperature, which also carries less dissolved oxygen.”

Dry conditions in late summer also contribute to a longer wildfire season in the West.

Climate change may be even more catastrophic where drinking water comes from rivers sourced in melting glaciers, Udall warns. Large cities like Bogotá and Lima in South America, “could go from having a glacier upstream one day to not having it the next. The United States does not have that problem, but in the Andes, there is potential for very harsh consequences.”

The Ganges: A river or a sewer?

Photo: Daniel Bachhuber

Worshippers leave heaps of offerings alongside the Ganges river in Varanasi. It’s easy enough to hose away the dregs into the river, but that just adds more pollution to the “Mother Ganges.” Says Science Daily, the Ganges “contains untreated sewage, cremated remains, chemicals and disease-causing microbes. … Cows wade in the river. People wash their laundry in it and drink from it. … The Ganges River is a major source of disease.”
If this can happen to a sacred river…

Summary judgment

Rivers collect runoff from their watersheds, and therefore carry messages about conditions from most of the land on our planet. As the authors of the recent Nature study found, trying to assess the health of rivers around the world is not for the data-shy. Differences in economy, history, geography and culture all affect how we view rivers, and how we decide whether to use, alter or preserve them.

Photo: Steve Dewey, Utah State University, Bugwood.org

Purple loosestrife is striking, but it invades wetlands near rivers, reducing biodiversity, destroying habitat for native species, and reducing the ability to filter water.

But most “decisions” that affect rivers, like allowing them to be polluted with chemicals, topsoil or fertilizer, or building a dam to store water for the dry season, are made not with rivers in mind, but with another goal, like growing more food or getting people something to drink.

“You don’t miss your water ’til your well runs dry,” pertains to rivers as well as groundwater, says Peter McIntyre, one author of the recent global river survey. “In the industrialized world, we go home at night, turn on the faucet and get beautiful, clear water, it’s safe to drink and bathe; it poses no risk to us and our kids. Mass investments in engineering and infrastructure have granted us this water security.”

As developing countries, where people struggle to find water for faucets, farms and factories, embark on the dam-building that was so crucial to European and American water supplies, saying “don’t do what we did” seems hypocritical at best and repugnant at worst.

And yet experience shows that dams can damage or destroy plants and animals in rivers and their floodplains. We’ll concede that questions about biodiversity, the environment and the long term seldom interest people who are hungry or thirsty. But they may still be worth asking. Will a proposed dam harm an essential fishery? Will it produce benefits over the long term, or will it silt up in a decade because trees have been stripped from its watershed?

There are lessons to be learned from the water-management experience in Europe and North America, and one of the most significant one is to expect a continual tension between human water use and biodiversity. “I am not pretending there is an easy answer,” McIntyre says, “or that I should have the right to dictate to that person whether they build a dam or not.”

Coming Oct. 28: Part II : The Why Files will discuss some river-management ideas for balancing human and environmental needs.