Cod Comeback

Atlantic cod, Gadus morhua. Credit: Hans-Petter Fjeld via Wikimedia Commons.Atlantic cod, Gadus morhua. Credit: Hans-Petter Fjeld via Wikimedia Commons.

The collapse of the northwest Atlantic cod fishery from overfishing in the 1980s and 1990s rewrote our understanding of the fragility of marine ecosystems.

Before the collapse, few expected the removal of cod would have such enormous reverberations on an ecosystem the size of a continental shelf. Nor that it would turn out to be the first-ever documented instance of a trophic cascade—defined as the appearance of conspicuous indirect effects two or more trophic links removed from the primary effect—in a large open-ocean marine ecosystem.

In a 2005 paper in Science, researchers first reported the trophic cascade—the four trophic levels that were ecologically rearranged in the wake of overfishing in the northwest Atlantic: 

  1. Groundfish (cod, et al.)
  2. Pelagic shrimp and snow crabs (plus forage fish)
  3. Zooplankton
  4. Phytoplankton

 Waters off Nova Scotia. Credit: Tango7174 via Wikimedia Commons.Waters off Nova Scotia. Credit: Tango7174 via Wikimedia Commons.

In my book Deep Blue Home I described how that worked:

The cod crash appears to have restructured the food web into something unable to support cod anymore. At the same time cod were being overfished, so were other top groundfish predators, including haddock, hake, pollock, cusk, redfish, plaice, flounder, and skates. Suddenly the cod-dominated ecology of the northwest Atlantic was absent its cod and also any other groundfish who might have swum in to take their place. Small pelagic fish and invertebrate predators, primarily northern snow crab and northern shrimp, once cod prey, were suddenly liberated from their predators. Predictably, their numbers grew, and with them a reciprocal response among their prey—the large herbivorous zooplankton, which declined by 45 percent. Meanwhile phytoplankton increased, presumably because their natural predators, the large herbivorous zooplankton, were declining. Lastly, nitrate concentrations, one of the most important factors limiting marine productivity, decreased as blooms of phytoplankton used them up. The end result was the near mythical rearrangement of an ecosystem, a phenomenon never before observed and scientifically described in a marine environment the size of a continental shelf...The loss of cod triggered an unprecedented four-trophic-level cascade: from crab to zooplankton to phytoplankton to nitrates.


Nova Scotia, the Scotian Shelf to the east. Credit: NASA.Nova Scotia, the Scotian Shelf to the east. Credit: NASA.

Despite a ban on cod fishing since 1993, the ecosystem seemed unable to recover—stymied at least in part by a 900 percent rise in the population of forage fish, the cod's primary prey.

The reason is almost sinister. In the absence of cod, the forage fish—northern sand lance, capelin, and Atlantic herring—became top predators themselves. Their numbers grew hugely, as they fed on the larvae and eggs of struggling cod and haddock—their former predators—a phenomenon known as a predator–prey reversal.   


Puffin with capelin. Credit: Nilfanion via Wikimedia Commons.Puffin with capelin. Credit: Nilfanion via Wikimedia Commons.

And so things seemed stuck. But now a new paper in Nature by some of the same authors as the 2005 Science paper reports interesting—and encouraging—developments on the Scotian Shelf off Nova Scotia:

These erupting forage species, which reached biomass levels 900 percent greater than those prevalent during the pre-collapse years of large benthic predators, are now in decline, having outstripped their zooplankton food supply.


Puffin with capelin. Credit: Nilfanion via Wikimedia Commons.Credit: Nilfanion via Wikimedia Commons.

Recovery (a.k.a. the new ecological rearrangement of fish stocks) is proving as difficult to forecast as collapse. The cod and haddock, though growing in overall numbers, are reaching only half the individual size they used to. And because the haddock are recovering faster, they may ultimately replace cod as the top predators on the Scotian Shelf.

The current dominance of haddock over cod also raises the question of whether the species makeup of the ecosystem will return to that which prevailed before the collapse. Furthermore, recovery in other over-exploited ecosystems such as the Black Sea, Northern Benguela, the Sea of Japan, and elsewhere has been delayed by jellyfish blooms, the presence of invasive species and by eutrophication, all of which are possible in the system we describe. The widespread body size reductions of benthic [groundfish] fishes documented for other exploited northwest Atlantic systems, if not reversed, could also slow the recovery of the benthic fish complex and adversely affect food web structure. The evolving global climate could alter the ecosystem positively or negatively.


Atlantic cod. Credit: Hans-Petter Fjeld (CC-BY-SA), via Wikimedia Commons.Atlantic cod. Credit: Hans-Petter Fjeld (CC-BY-SA), via Wikimedia Commons.

Still, the takeaway message is hopeful: that even "hopeless" cases may rebound given adequate time and gentle treatment—though they may never return exactly to what they were before.

These uncertainties notwithstanding, the answer to the critical question of whether or not such profound changes in the dynamics of large marine ecosystems are reversible seems to be "yes." This bodes well for other perturbed, formerly cod-dominated systems at latitudes to the north of the eastern Scotian Shelf that have yet to recover. Indeed, subtle signs of cod recovery have been appearing in other sub-arctic northwest Atlantic ecosystems during the past few years. However, the time scales for their recovery are likely to be greater given the lower water temperatures (equates to slower turnover times) and their reduced species richness and, for some, because of the continued exploitation of cod and other large-bodied benthic fish species.

The papers: 

  • Kenneth T. Frank, Brian Petrie, Jonathan A. D. Fisher, and William C. Leggett. Transient dynamics of an altered large marine ecosystem. Nature (2011) DOI:10.1038/nature10285
  • Kenneth T. Frank, Brian Petrie, Jae S. Choi, and William C. Leggett. Trophic Cascades in a Formerly Cod-Dominated Ecosystem. Science (2005: DOI:10.1126/science.1113075

A pig raised by a 4-H member in Tennessee relaxes in its pen.

Until recently, I had never really given 4-H Club a whole lot of thought. This was kind of intentional; I put 4-H in the same category in my mind as books like Old Yeller and Where the Red Fern Grows, in which kids grow to love an animal only to learn that eventually (spoiler alert!) it's going to die. The horror!

But after a trip to the Alameda County Fair, where the kids milling around the 4-H small-animals display area (bunnies galore!) were far less grim than I had imagined, I decided to find out more about the club. The first thing I learned was that it's giant: With 6.5 million members, 4-H is one of the largest youth organizations in the world. In addition to the old standbys of animal husbandry and home economics, the club now offers programs based around science and technology, sports, and a host of other subjects, in cities, suburbs, and rural areas.

But here's the really interesting thing about 4-H: It's full of contradictions. Big Ag has its fingerprints all over the club; among its sponsoring partners, the club lists Monsanto, DuPont, Cargill, John Deere, Philip Morris USA, and Kraft Foods. When you consider the fact that the average age of the American farmer is creeping up toward 60, it makes sense that agribusiness would want to support a program that turns kids on to farming.

And yet, at least when it comes to raising livestock, the values the club teaches are about as far off from industrial agriculture as you can get. The 4-H kids and leaders I talked to all spoke passionately about the importance of raising animals in humane conditions, on a healthy and varied diet. Members are encouraged to spend time with their animals, and they are required to learn about the biology and health of the animals they raise; kids can even participate in animal "bowls," sort of like quiz shows for the animal husbandry set. "In 4-H we try to make kids understand the responsibility that comes with raising an animal," says Stephanie Fontana, a 4-H program representative in Santa Cruz, California. "You're in charge of another being." Imagine that, 4-H agribiz sponsors!

At the Alameda County Fair, I met Kendyl Schultze, a 17-year-old high school senior from San Ramon, California, who has been raising animals with 4-H for nine years. Watch Kendyl talk about her 4-H experience in this video made by my fellow MoJo editor Jen Quraishi:

After hanging out with Kendyl, I wanted to know more. What's it like to get an animal ready for fair time? Is 4-H actually inspiring kids to be farmers? So I decided to make friends with a few more 4-Hers. Over the next few months, I'll be blogging about kids who walk their pigs in Oakland, a family that raises heritage turkeys through a partnership with Slow Food, and a pair of twins who are trying to save their family's ranch with chickens that started out as a 4-H project. Know a cool 4-H member I should talk to? Let me know in the comments.

It took the Obama administration almost two years to issue a new scientific integrity plan, a government-wide policy to ensure that decisions are based on science, not politics, and to allow scientists to do their jobs without fear of intimidation. The administration promised the plan would go a long way toward "restoring scientific integrity to government decision making" after the Bush years, during which scientists were silenced and their work was ignored or heavily edited.

When the Office of Science and Technology Policy finally issued the plan last December a year and a half overdue, it was really more of a framework that set a minimum government-wide standard and then directed individual agencies to write their own policies. On Friday afternoon—the last day before the deadline—the Environmental Protection Agency issued its plan.

The draft plan aims to "enhance scientific integrity throughout EPA." Its intent is to make sure both that scientists and engineers within the agency are operating with integrity and following ethics rules, but also to ensure that they are able to operate "free from political influence"—i.e., they're not being forced to do things because of some manager or a political appointee. The plan is open for public comment through September 6.

The watchdog group Public Employees for Environmental Responsibility (PEER), though, called the standards "pathetically weak" in a press release on Monday. The group, which often represents government employees tangled up in exactly this type of problem, say the rules don't do enough to prohibit political interference with science, promote transparency or ensure that whistleblowers are protected within the agency.

"EPA has put forward by far the weakest scientific integrity rules of any agency. In many ways, it is a big step backward," said PEER Executive Director Jeff Ruch in the release. "Under EPA's plan to protect scientific integrity, only its scientists can be punished for misconduct as there are no firm rules against managers manipulating or masking technical work and no mechanism to enforce rules if they existed."

The group was also critical of the policy that the Department of Interior issued last year.

We Won!

Good news: The Society of Environmental Journalists just announced the winners of its 10th Annual Awards for Reporting on the Environment—and we won! Mother Jones took first place in the large market beat reporting category for our coverage of the 2010 BP oil spill. Here's what the judges had to say:

An impressive devotion of resources to cover a major story. The journalists wove intriguing narratives into their stories, which reflected both a depth of knowledge and aggressive reporting. In the best journalistic tradition, they did not take ‘no’ from authorities, but pursued the stories and the human face of the disaster. A very nimble response to the story of the year, with smarts to weave together existing, related work that greatly broadens our understanding of the full threat posed by the BP spill. The Mother Jones team gave us the basic science we need to know, along with vivid reporting on the emotions of people who live in the Louisiana communities affected by the BP spill – all of it combined to give the public a comprehensive picture of one of the worst environmental disasters of our times.

Kudos to our crack BP spill reporting team: Josh Harkinson, Mac McClelland, Kate Sheppard, and Julia Whitty. Huzzah!

Philips' new LED bulb casts white light, even though it's yellow.

Last week there were lightbulbs in the air at Mother Jones. Reporter Tim Murphy had no sooner penned his piece on Rep. Michele Bachmann's weird conspiracy theories about compact fluorescent legislation than a big package arrived on my desk. I opened it, and there, unfortunately nestled between two hunks of Styrofoam (have I mentioned how annoyed I get when companies send me "green" swag swaddled in unnecessary packaging?) was Philips' brand new LED warm white bulb. According to its package, the 12.5-watt LED acts exactly like a 60-watt incandescent bulb—with the addition of a few cool tricks: It lasts 15 years and will save me $142.50 in electricity costs over its lifetime. On Slate, Farhad Manjoo recently raved about LED bulbs. I thought: Sign me up!

So I switched the new bulb into my desk lamp. For the past few days, it's been casting a nice whitish glow over my desk. Still, I probably won't be retrofitting my house with LEDs anytime soon, for one big reason: Models like the one Philips sent me retail for a prohibitive $45, compared to $1.50 for a CFL bulb. The price difference doesn't quite correlate with lifespan: CFLs last about one-third as along as LEDs. And while we all know older CFL bulbs were flickering, headache-inducing disasters, most newer models are actually pretty comparable to incandescents in light quality. So is the LED really worth the hefty initial investment?

First off, it's worth pointing out that both CFLs and LEDs are dramatically more energy efficient than old-fashioned incandescent bulbs, by about 75 percent and 90 percent, respectively. The main reason that LED bulbs cost so much more than CFLs is that they rely on more complicated (and therefore more expensive) technology. The light-emitting source in a CFL is a small amount of gas that, when stimulated with electricity, illuminates. LED bulbs, on the other hand, contain semiconductors, which give off light through movement of electrons when a current passes through. "Think of an LED like a small electrical appliance," says Celia Lehrman, deputy home editor at Consumer Reports.

Aside from their long lifespan, LEDs have a few noteworthy advantages over CFLs. While CFLs can take as long as three minutes after being turned on to reach their full brightness, LEDs brighten immediately. LEDs work much better with dimmers than CFLs. Another big LED plus: Unlike CFL bulbs, they don't contain mercury. Although few LED-bulb-specific recycling programs exist (Philips spokeswoman Sylvie Casanova says LED bulbs are "like small appliances" and therefore have to be recycled like any other e-waste) their long lifetime will give manufacturers a head start on creating recycling programs.

Lehrman expects Consumer Reports to release its report on CFL bulbs in September. Till then, if you're in the market for an LED bulb, says Lehrman, make sure you know what you're looking for. While incandescent and CFL bulbs' brightness is generally measured in watts, LEDs are measured in lumens: An 800-lumen bulb is roughly equivalent to a 60-watt incandescent. Another important label to look for is color temperature or light color, measured in Kelvin. My freebie bulb has a color temperature of 2,700, which means it emits a warm white light. With higher temperatures come different colors: 3,000 would look more like the bright, white light emitted from a halogen bulb, and 4,000 and higher would look bluish.

If you're not willing to shell out for an LED bulb yet, Lehrman says the price is likely drop down the line, and a few LED manufacturers are planning to offer rebates. Till that happens, I'll probably stick to CFLs and continue to phase out my electricity gobbling old incandescents. Sorry Michele Bachmann! 


Precipitation, elevation, and even cloud-cover affect tree ring growth, but now there's another factor for scientists to consider: sheep. A new (ewe?) study out of Norway shows that the number of livestock in an area affect tree rings more than temperature.

The study compared 206 birch trees growing in Norway for 9 years at three different levels of sheep density: no sheep, 25 sheep per square kilometer, and 80 sheep per square kilometer. Researchers found that the more sheep around, the slimmer the tree rings. Trees that grew up in a sheep-less environment had rings three times wider than the trees that grew up around the most sheep.

This isn't to say that all tree ring data used to estimate past climatic conditions is invalid, but it is another element to factor in. Study lead author James Speed said, "Our study highlights that other factors interact with climate to affect tree rings, and that to increase the accuracy of the tree ring record to estimate past climatic conditions, you need to take into account the history of wild and domestic herbivores. The good news is that past densities of herbivores can be estimated from historic records, and from the fossilised remains of spores from fungi that live on dung."

So, basically, next step: study shrooms that grew on sheep poop centuries ago. Sounds exciting. Until then, the sheep study will likely give fuel to those who maintain that tree ring data are not a reliable indicator of climatic history, despite the fact that scientists also use things like coral records and ice cores to estimate past temperature changes. As Mother Jones has reported in the past, sometimes the controversy has come from very particular tree ring data sets calculated in scientifically unsound ways. If nothing else, this study involving sheep has uncovered a way to make tree ring data more accurate. Whether climate skeptics will see this as a positive or a negative is up for debate.


The winners: Acropora corals. Credit: Albert Kok at Wikimedia Commons. The winners: Acropora corals. Credit: Albert Kok at Wikimedia Commons.

After 14 years of tracking coral colonies at Sesoko Island, Okinawa, Japan, through two coral bleaching episodes—1998 and 2001—the big coral winners and losers on the reef have been announced...

  • The winners: Porites, faviids, and Acropora colonies
  • The losers: pocilloporids

Except it's not that simple, the authors of a new study warn. Since 14 years is hardly the long long run.


The losers: Pocillopora corals. Credit: Mila Zinkova at Wikimedia Commons.The losers: Pocillopora corals. Credit: Mila Zinkova at Wikimedia Commons.


In a new paper in the current issue of MEPS we get a sense of what happens in the short long term aftermath of a big coral bleaching event. 

Background: Coral bleaching occurs when water temperatures rise, stressing the coral animals enough to expel their symbiotic partners—the zooxanthellae. These single-celled plants give corals their beautiful colors and help feed them through photosynthesis. In some plant-animal partnerships, the zooxanthellae entirely feed their corals, making those species more vulnerable to bleaching.

In the past 30 years, rising sea surface temperatures have stressed and bleached corals worldwide.  Yet few researchers have looked at what recovery looks like over time—whether the species of corals that fare better in the short term also fare better in the long term.


A partially bleached faviid coral. Credit: Nhobgood at Wikimedia Commons. A partially bleached faviid coral. Credit: Nhobgood at Wikimedia Commons.


At Sesoko Island, the researchers found that although species richness recovered after 10 years, the composition of coral species on the reef had changed. The pocilloporids were nearly completely gone. Among their other findings:

  • Short-term winners were generally heat-tolerant encrusting and massive corals, like Porites, faviids, and small (<5 cm/2 in) Acropora colonies. 
  • Ten years after the thermal disturbance the community was still structurally different from the original community, consisting of a combination of survivors that were either:
  1. Tolerant to stress

  2. Surviving as fragments that experienced rapid regrowth

  3. Regionally persistent colonies that recruited locally


Credit: R. van Woesik, et al. MEPS. DOI:10.3354/meps09203.Credit: R. van Woesik, et al. MEPS. DOI:10.3354/meps09203.


The last point is interesting because it means that having healthy reef neighbors enabled some species to recover—thanks to seeding from nearby islands. 

Yet even the short long term winners may not survive the long long term. The authors close with these strongly cautionary words: 

The present study suggests that as the oceans warm even further, the coral assemblages will change. Reefs may soon essentially only support heat-tolerant coral species. The narrowing of genetic diversity within communities is likely to impact other dependent species such as fishes and crustaceans, especially if important reef-building branched corals, such as Acropora, Stylophora, Pocillopora, and Porites cylindrica, become rare on account of their inherent sensitivity to thermal stress. Bleaching may also become punctuated over the next several decades. In the short term, the remnant yet hardy populations may show some resistance to the higher water temperatures, and bleaching may be reduced for a decade or more if Acropora and pocilloporids are removed from local reefs. However, reduced bleaching may give false hope because once the inevitable temperature threshold of the remnant communities is surpassed, widespread coral mortality will follow. Given that even the hardiest coral genera have their limits, global temperature increases will eventually lead to an exponential rate of local, regional and global reduction of coral species. To what extent this reduction of coral species will occur will depend on how rapidly and by how much the ocean temperatures increase, which depends on the fossil-fuel-emission pathway that humans choose.


Coral recovery underway on a reef. Credit: Bruno de Giusti at Wikimedia Commons. Coral recovery underway on a reef. Credit: Bruno de Giusti at Wikimedia Commons.

The paper:

  • van Woesik R, Sakai K, Ganase A, Loya Y (2011) Revisiting the winners and the losers a decade after coral bleaching. Mar Ecol Prog Ser 434:67-76. DOI:10.3354/meps09203.

This post courtesy BBC Earth. For more wildlife news, find BBC Earth on Facebook and Posterous.

Never one to shy away from getting hands on with the animal kingdoms greatest hunters, "Deadly 60" presenter Steve Backshall gets to grips with the heavy-bodied king of the squeeze.

The strongman of the snake world, a boa constrictor is capable of exerting 6 to 12 lbs per square inch of pressure, and literally squeezes the life out of its prey, as Steve found when he tested this... on himself!

Not a situation many of us would like to find ourselves in. Here's how to behave around the big guns.

• Back off: If you come across a snake, especially a big one, give it a wide berth. They're shy and would rather be left alone.

• An angry snake is a dangerous snake: don't poke or harass them, you could be asking for trouble.

• Leave it to the experts: Dealing with snakes is a tricky business. Steve is an expert herpetologist, and is used to handling snakes.

• Help at hand: Never handle big constricting snakes alone. Steve had a number of strong men at hand to remove the snake if he got too hot under the collar.

• Remain calm: Director Nikki ensured no one startled the snake as it may cause it to tighten its grip further.

• Medical help: When attempting to handle a big snake like this, director Nikki ensured that the team consisted of first aiders, and local snake experts.

A study financed by plastics manufacturer Procter & Gamble has found that biodegradable plastics emit methane faster than other kinds of trash. The study was carried out by researchers from North Carolina State University and published in the journal Environmental Science & Technology.

Researchers focused on one type of biodegradable plastic called PHBO, which is one of a few plastics Procter & Gamble is developing under the trade name Nodax. The study found that PHBO emits more methane than food waste or newspaper in landfills and, because it degrades much faster than newspaper, will emit that methane in a matter of years rather than decades. Some landfills are able to capture and use methane, but the EPA estimates that two-thirds of landfills do not have methane collection capabilities.

"If we want to maximize the environmental benefit of biodegradable products in landfills," study co-author Morton Barlaz told Science Daily, "we need to both expand methane collection at landfills and design these products to degrade more slowly, in contrast to FTC guidance." The FTC policy Barlaz is referring to requires that any product labeled as "biodegradeable" to "completely break down and return to nature, i.e., decompose into elements found in nature, within a reasonably short period of time after customary disposal." 

While Barlaz emphasized that biodegradable plastics are not necessarily more friendly to the environment and should decompose more slowly, the study's lead author, doctoral student James Levis, has said that the study should not be taken to imply that regular plastics (which can take centuries to decompose) are better than biodegradable plastics: only that when considering a plastic, one should think of the entire life-cycle, including where it ends up and how long it stays there.

The Department of Interior gave Shell the green light to begin drilling in the Arctic on Thursday, though the move is expected to prompt a legal challenge.

Enviros were hoping that the administration would take a more cautious approach to drilling there, given the disaster in the Gulf last year and the overwhelming evidence that a spill in the Arctic would be really, really bad. But with the conditional approval of the DOI's Bureau of Ocean Energy Management, Regulation and Enforcement (BOEMRE), Shell will be allowed to drill four shallow-water wells starting in July 2012.

Reuters has more on the approval for Shell:


While this is a step forward in Shell's push to tap the Arctic's vast oil and gas reserves, the oil giant still has a long way to go before it can begin carrying out its ambitious drilling plans.
The conditional approval of the exploration plan is contingent upon Shell receiving permits from other government agencies, including the Environmental Protection Agency and the U.S. Fish and Wildlife Service.

Earthjustice and other environmental groups say they are assessing their options for responding to the decision, which could include a legal challenge to the permit. So while Shell is closer to drilling, it's not quite a done deal yet.