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

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

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

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

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

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

Don’t fence me out!

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

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

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

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

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

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

What’s the beef about carp?

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

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

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

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

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

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

Can we keep carp from the greatest lakes?

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

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

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

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

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

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

Muscling in on the mussels

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

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

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

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

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

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

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

Buying time, but could time be on our side?

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

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

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

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

The seas’ most sought-after fish are swimming between a rock and a hard place: the fisherman’s net and an encroaching mass of suffocating water.

A recent study has uncovered a new dose of bad news for ocean fish and the fishing industry. Areas of the deep ocean with little dissolved oxygen, called dead zones, are expanding and, thus, shrinking many fishes’ watery homes.

One driving force behind the predicament is none other than that pesky climate problem.

“Climate change is actually working in tandem with overexploitation of the animals to push these populations into a real dangerous place in terms of population collapse,” said Eric Prince, a fisheries biologist with the National Oceanic and Atmospheric Administration’s Southeast Fisheries Science Center and co-author of the study.

For example, Prince and his colleagues calculated that the Atlantic blue marlin, an economically valuable fish that was a focus of their study, has lost about 15 percent of its habitat from expanding dead zones since 1960. Dwindling habitat threatens not only the lives of fishes, but also the sustainability of the already ailing fishing industry.

Breathing room

Like their above-water brethren, fish need oxygen, which is dissolved in the water. Big, predatory fish, such as the blue marlin, need more dissolved oxygen than most, because they require lots of energy to grow and survive. Without sufficient oxygen, they’ll suffocate.

The level of oxygen in the water thus partly delineates fish habitat boundaries. Dead zones often draw these borders.

As climate change causes open ocean dead zones to balloon, fish habitat deflates.

Diagram modified from one originally published in Deep Sea Research Part I: Oceanographic Research Papers, Vol 57, Issue 4, Lothar Stramma, Sunke Schmidtko, Lisa A. Levin, & Gregory C. Johnson. Ocean oxygen minima expansions and their biological impacts, 587-595, Copyright Elsevier (2010).

Technically known as oxygen minimum zones, dead zones are actually a natural occurrence. Found at depths of between 200 and 1000 meters, they are caused partly by seawater circulation and partly by the decomposition of organic matter, namely deceased sea critters that sink from surface waters.

As aerobic bacteria nosh on the organic matter, they use up the oxygen in the water. Eventually, hypoxia happens—the water becomes so depleted of oxygen that many creatures can’t survive.

Since deep-sea dead zones are insulated from the ocean’s surface, where the water borrows oxygen from the atmosphere, they can only reload with oxygen if currents make a long-distance delivery, according to Sunke Schmidtko, an oceanographer at the University of East Anglia, the other co-author of the study.

Deep-sea dead zones are different from their coastal cousins like the one in the Gulf of Mexico. Coastal dead zones form due to a buildup of agricultural fertilizer that rivers, such as the Mississippi, collect and then flush out to sea, causing abnormal blooms of plant life.

De-fizzing the ocean

But climate change is turning what Mother Nature does normally into a big problem. As the air is getting hotter, so is the water, and warmer water can hold less oxygen than colder water.

This is similar to what happens to a soft drink on a hot day. After sitting in the heat and sun, the fizz fizzles, and you are left with a flat, carbon dioxide-depleted beverage.

Also, warmer surface waters are less likely to sink to the ocean’s lower layers, because warm water is lighter than the colder water below, Schmidtko explained. In other words, as the oxygen-rich surface layers heat up, they could have a harder time delivering oxygen to the deeper ocean.

Schmidtko clarified that oceanographers are still trying to determine how exactly climate change is affecting the ocean, but with their knowledge of how water works, these represent their current speculations.

The rock below

With less oxygen to go around, oxygen minimum zones are swelling and intruding on many fishes’ living zones.

For example, marlins often dive deep to feed, sometimes as far down as 800 meters. However, in the eastern Atlantic’s growing dead zone, which is already one of the largest in the world, Prince found that marlins can’t dive as deep as their west-side counterparts.

“They need to go where the food is and where they can breathe,” he said.

With less breathing room below, the floor of their habitat rises, and they are pinned to the surface layers. With nowhere to go but up, marlins become squished into tighter, testier quarters with other predatory fish and their prey. They also find it harder to dodge a waiting fishing hook or net.

“Concentrating them makes it much easier for overexploitation by [humans],” said Prince.

The increasing concentration of animals at the top could also lead to a boost in the amount of sinking organic matter, which would further worsen the oxygen shortage below.

Softening the hard place above

As a prized catch, Atlantic blue marlins are already victims of overharvesting. In fact, their populations have dropped 60-64 percent over the past three fish generations (14-18 years).

But the growing dead zones can actually fool scientists and fishermen into thinking fish populations are doing just fine, since more fish are squeezed into a smaller area. Thus, to ensure the dead zone-fishing vise does not become their demise, Prince said scientists must more carefully monitor fish populations, as well as the expansion of the dead zones.

While fish stock assessments are starting to incorporate this information, Prince warned the pace needs to quicken.

And if the Earth is to continue warming, as most scientists predict, Schmidtko added that humans should chill out on fishing.

After all, we will never be capable of “ventilating the ocean,” he said.

Fish in the Gulf of Mexico: How safe?

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

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

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

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

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

Not very filthy

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

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

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

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

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

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

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

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

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

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

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?

The endocrine system is a marvel of subtlety and complexity. Through the life of the animal (human or otherwise), waves of hormones control reproduction, development, behavior, even other hormones. What happens when this natural system gets bollixed up?

We’ve known for decades that endocrine disruptors sourced in pesticides and plastics can operate at the parts-per-billion level. Disruptors in common body-care products ranging from birth-control pills to shampoo are washing down toilets and drains, then causing deformations in the animals that live downstream.

In 2006, for example, David Norris of the University of Colorado caged fathead minnows in the outflow from Boulder’s wastewater treatment plant. Within seven days, adult males were “feminized,” showing female anatomy and behavior.

Water leaving the treatment plant contained a regular toiletful of hormonally active crud, including ethinylestradiol, a chemical used in most contraceptives, and natural estrogens made and excreted by people. Other endocrine disruptors in the water included two common plastic compounds, bisphenyl A and phthalates. Detergents and pesticides had contributed (is that the right word?) a further group of endocrine suspects called nonylphenols.

Diagram courtesy Renewable Water Resources

Hormones run amok

To compare their ability to trigger the estrogen receptor on cells, estrogen disruptors are measured in units called estradiol equivalents per liter. In 2006, Boulder Creek contained 30 to 40 units, most of it artificial, Norris says.

A few trillionths of a gram in a liter of water may not sound like much, Norris realizes. “At first, people thought, ‘That’s such a small quantity, it can’t be meaningful,’ but biological systems can see it and respond to it. In lab studies, as little as 1 estradiol unit is enough to feminize a fish, so there was plenty of stuff there.”

All the estrogens, artificial and natural, work through same receptor, he says, “so the effects are additive. Even if any single one is not high enough, they add up.”

Ending the endocrine monster?

After the 2006 study (and for reasons unrelated to hormone disruption), Boulder’s treatment plant was upgraded. The newly installed “activated sludge process” transfers most of the estrogen disruptors from the liquid to the solid material, called sludge or biosolid, that remains after treatment.

“Bacteria are eating the estrogen disruptors to some extent, but the vast majority of the chemicals that come into the sewage are trapped in the biosolids,” says Norris. “It’s not a mechanism that was planned to deal with these chemicals at these concentrations, but the procedures are pretty efficient at getting the endocrine disruptors out of the water.”

For the study he just presented at the Endocrine Society, Norris repeated his 2006 study, and found no feminization in fish after 28 days, even among fish that lived in pure treated wastewater.

That finding accords with tests performed at the Wisconsin State Laboratory of Hygiene, says Jocelyn Hemming, a research environmental toxicologist at the lab. “Activated sludge really helps a lot,” she says. In tests using both ultra-sensitive chemical analysis and living cells, “there was definitely good removal of endocrine disruptors, although it wasn’t complete at all facilities.”

The activated sludge process did transfer some unwanted hormone to the sludge, but Hemming says the bacteria likely ate some of the troublesome compounds. “I think there is a pretty good chance of destruction from the microbial community in the activated sludge; it would not all go into the solids.”

In Boulder, the chemists are not ready to release the numbers, but “preliminary chemistry shows that the levels of endocrine disruptors in the effluent have gone way down,” Norris says. “When you are dealing with nanograms per liter [parts per trillion, by weight], you have to be really careful.”

Most of the endocrine disruptors in the Boulder sewer system are artificial, Norris says, coming from plastics, solvents and drugs. About 5 percent comes from birth control pills, and about 10 percent is natural, human estrogen.

– David J. Tenenbaum

Many individuals engage in what social psychologists call “third-party punishment.” We may enforce social codes, even laws, related to marriage, sex, sexuality, vice and property. A classic example is a good Samaritan who ignores personal risk to chase a purse-snatcher.

Third-party punishment is so common that evolutionary psychologists suspect that it has genetic roots. Because punishment takes effort and can spark retaliation, it can only have evolved if it benefits the punisher: it can help the punisher reproduce (a direct benefit), or help the community survive (an indirect benefit).

Although the roots of human third-party punishment may have nothing to do with evolution, evolutionary psychologists often assume that its major benefit is indirect: I promote social stability by chasing a purse-snatcher. In stable society, I can have more children. Hence in evolutionary terms, chasing a purse-snatcher has indirect benefits.

Courtesy Gerry Allen

Colorful cleaners: A pair of blue-streaked wrasses ( Labroides dimidiatus ) clean Achanthurus mata.

But in a study published this week, researchers found that third-party punishment directly benefits the punisher, at least when said punisher is a “cleaner” fish. Cleaner fish eat parasites housed on larger fish, called “clients.” The relationship is classic symbiosis: the cleaner gets food, while the client stays healthy.

In the blue-streaked wrasse Labroides dimidiatus under study, males and females clean in pairs. Occasionally, a female cleaner switches from eating parasites to the more delectable mucus, a sticky goo that protects the client from infection.

(We sure swear to skirt slimy, sophomoric silliness and subsequently stick to the science.)

Your cheatin’ heart

Behavioral ecologists call this “cheating” because it breaks the symbiosis and harms the client.

Redouan Bshary of the University of Neuchatel in Switzerland studies the wrasse in the Red Sea. He says a client typically swims into a “cleaning station” for about 20 seconds, where a male and female wrasse eat parasites from its exterior. When the female cheats, the client tends to get annoyed and swim to another cleaning station – unless the male wrasse darts at the female to keep her in line. That’s third-party punishment.

Courtesy Richard Smith

A blue-streaked wrasse cleans a member of the genus Amblyglyphidodon

To test the situation in the lab, first author Nichola Raihani, a post-doctoral fellow at the London Zoological Society, smeared a Plexiglas plate with prawn meal or the less palatable fish flakes. When the females ate the prawn goop, the lab-keepers removed the plate and both fish confronted the sad sight of an empty menu.

When males responded aggressively to female cheating, the females were less likely to cheat again, reinforcing the notion that punishment would sustain the symbiosis and get him more food.

Is punishment beautiful?

Even though males were not directly harmed by the cheating, they directly benefited from the punishment, the authors wrote. “The establishment of self-serving third-party punishment in response to personal losses may be a key step toward third-party punishment without current involvement, as in humans.”

Scientists have observed punishment among other animals, says Katherine Cronin, a post-doctoral psychology research fellow who studies cooperation among monkeys at the University of Wisconsin-Madison. “Dominant rhesus monkeys might lash out at subordinates who didn’t properly alert them to food,” Cronin wrote us, “and female cowbirds (a species that lays eggs in other birds’ nests to be reared by hosts) may seek out and destroy the eggs of hosts who have previously destroyed cowbird eggs in a surprisingly mafia-like fashion.”

Nonetheless, Cronin says, “careful, experimental demonstration of punishment in animals has been rare and requires creative experimental designs like the one employed by Raihani and colleagues.” Cronin notes that cleaner fish are cooperative. “The strongest examples of punishment might not come from the most cognitively complex animals, but rather from the ones that rely most heavily on cooperation to survive.”

Photo: futureshape

The “good behavior” encouraged by this sign from the London (UK) police department may help the group and produce indirect benefits to the good-behaver. But in some cases, watching the behavior of others may also benefit the individual…

Sexual politics, fish-style

Exactly how does the male cleaner benefit from chasing misbehaving females? In most cases, we’d assume that keeping the food source (the client) around would constitute an evolutionary advantage because better-fed males can have more baby fishies, but we must remember that blue streaked wrasses are hermaphrodites. They begin reproducing as females, but females that grow large enough can turn into males.

Males can control this conversion, and avoid having another competitor for food, females and territory, by acting aggressively toward females, Bshary says. “If you remove the male, within two days, the female will show male behavior, and within a month, can release sperm that can fertilize eggs.”

And thus a male has an incentive to control the largest female in his harem, Bshary adds. “Typically the male tries to control her through aggression so she will not change sex. This is likely to be the main reason why the male responds aggressively to the female.”

What’s the human impact?

Whether the benefit is retaining food, a mate, or both, the study could shed light on puzzling human behaviors, says Raihani. “Until now, most studies on third party punishment have tended to assume it stems from a group-level benefit.”

A group-level evolutionary explanation for a crime-fighting good Samaritan would say that living in a crime-free society enables all people, including the Samaritan, to have more children. An individual-level explanation might suggest that the crime-fighting hero could gain social status, and therefore have a better choice of mates.

In the fish study, Raihani says, “We are trying to emphasize that you can get what looks like group-level behavior that evolves by individual selection.”

One final note, in case you thought the study is “just about fish.” The females are not the only fish who cheat, Raihani says. “Males cheat slightly more than females in this pair cleaning interaction, but females never punish males, because they are so much smaller.

So the males can have their cake and eat it too.”

Sound familiar?

David J. Tenenbaum