The Blog

Sea Otters Fight Climate Change

We’ve hit the big time, getting mocked in the Onion!

Researchers at the University of California, Santa Cruz, found that kelp forests were able to absorb 12 times more carbon dioxide in the presence of sea otters, a result of the aquatic mammals preying on kelp-eating sea urchins. What do you think?

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Sea Otters Strike a Blow for the Environment?

From National Geographic, a short well-done article on our recent sea otter – carbon pub.

When hungry sea otters whack spiky urchins against rocks on their chests, the mammals may also be striking a blow against global warming.

By preying on urchins—which themselves devour greenhouse gas-absorbing kelp forests—the sea otters encourage the plants to flourish.

The result? An otter-assisted kelp forest “can absorb as much as 12 times the amount of CO2 [carbon dioxide] from the atmosphere than if it were subject to ravenous sea urchins,” according to the study, published Friday in the journal Frontiers of Ecology and the Environment.

Based on a new analysis of 40 years of data on both otters and Pacific kelp forests off Alaska and Canada, the study concludes that “otters ‘undoubtedly have a strong influence’ on the cycle of CO2 storage,” if only in their local environments.

So are sea otters the new global warming “warriors,” as some headlines have it?

Not exactly, said Jeffrey Dukes of the Purdue Climate Change Research Center in Indiana.

The otter-induced increase in CO2 absorption is “relatively inconsequential in terms of the big picture of climate change,” said Dukes, who wasn’t part of the study. But, he added, it’s “an interesting study identifying how dramatically a predator can alter the cycling of carbon in an ecosystem.”

Study co-author Chris Wilmers, a biologist at the University of California, Santa Cruz, agreed that the offset is “unlikely to have a big effect on global warming” worldwide.

But while otters alone can’t do the job, such seemingly incremental, natural advantages may become ever more important as we look for ways to blunt climate change’s impacts, according to study co-author James Estes, also of UC Santa Cruz.

“The general phenom in which the interactions between species are linked to the carbon cycle,” he said, “is going to be very important.”

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The ghost cat: Mountain lion slips across Highway 17 regularly

From the Santa Cruz Sentinel/San Jose Mercury News, a nice article on 16m’s penchant for crossing roads.  Not sure where they got the name Atlas from, but so it goes.  By the way, that large scare he has in the photo above on his rump – we think he got hit and dragged by a car on hwy 17, but he survived and is doing well now.

But what sets this mountain lion apart is the expanse of his territory. Atlas, at he is sometimes known, roams the mountains on either side of Highway 17, crossing the busy road regularly to reinforce his domain. He is distinguishing himself not only by the risks he assumes, but by surviving them.

“What he’s basically done is set up a home range that has Highway 17 as a line right down the middle of it,” said Chris Wilmers, who heads UCSC’s Santa Cruz Puma Project, which has tagged and tracked nearly 40 lions throughout the Santa Cruz Mountains.

Read the full Sentinel article here.

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Predators, Prey and Lyme Disease

From the NY Times, a great article on our recent PNAS paper showing a possibly important role of predators in the emergence of Lyme disease.  Be sure to read the comments section.  Taal does a brilliant job of answering a number of tough questions about the study.

Deer ticks are aptly named, in a sense; a Northeastern deer can carry over 1,000 of these ticks on its body. But as far as humans are concerned, the ticks might be more relevantly called mouse ticks. That’s because white-footed mice and other small mammals, not deer, are now known by scientists to be major carriers of Lyme disease.

Lyme disease is spreading in the Northeast and the Midwest, and according to the national Centers for Disease Control, the number of annual cases over the past decade has been increasing. However, no one is quite sure why. In a new study published in the Proceedings of the National Academy of Sciences, researchers tried to figure out what is driving the proliferation of Lyme disease in human populations by studying populations patterns in animals that interact with ticks. Their study suggests that large predators like coyotes and foxes that aren’t typically associated with Lyme disease transmission may have a big impact on the spread of the disease.

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More coastal salmon spawning helps grizzlies and fisheries

From Conservation Magazine, a short article on our recent PLoS Biology article:

Letting more salmon escape fisheries along the coast could boost both grizzly bear populations and fishery yields, according to a new study in PLoS Biology.

Fishery managers already let a certain number of salmon slip away so those fish can spawn. But it’s not clear which “escapement” level is best for the fisheries and the ecosystem. Grizzly bears eat salmon and often leave the remains of their meals by streams, providing nutrients for plants and animals. And the number of spawning fish also affects fishery yields down the line.

Researchers tackled the problem by modelling the effects of different escapement levels for four coastal sockeye salmon stocks and two inland stocks in Alaska and British Columbia, Canada. In the coastal systems, leaving more salmon to spawn would increase bear density by 8 to 44 percent. Fishery yields would jump as well — “an apparent win-win situation,” the authors write.

Read the full article here.

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‘Smart Collar’ in the Works to Manage Wildlife Better

From the NY Times an article on our NSF funded collaring technology.  There’s some nice quotes from Terrie on her recent trip to Colorado.

The collars, in development in academia and intended for commercial production in the next few years, use a combination of global positioning technology and accelerometers for measuring an animal’s metabolic inner life in leaping, running or sleeping. From the safari parks of Africa to urbanized zones on the edge of wildlands across the American West — places where widespread interest in the devices has already been voiced, scientists said — the mysteries of the wild might never be the same.

“What you end up with is a diary for the animal, a 24-hour diary that says he spent this much time sleeping, and we know from the GPS where that was,” said Terrie Williams, a professor of biology at the University of California, Santa Cruz, and one of three co-investigators on the project. “Then he woke up and went for a walk over here. He caught something over here. He ate something and we know what it was because the signatures we get for a deer kill vs. a rabbit kill are very different.”

Read the full article here.

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Luring mountain lions to learn to live amongst them

From Crosscurrents on NPR, I love this radio piece about our puma project.  Pay close attention to my toothbrush quote!

Although they live all around us, encounters with lions are unusual because there just aren’t a lot of them and each lion has a large territory. In the Bay Area, males use about 200 square miles and females about 50. People are increasingly hiking and biking in mountain lion country, yet attacks remain exceedingly rare – although media hype may make it seem otherwise.

WILMERS: With over 30 million people in California and thousands of lions, there’s only been six lethal attacks in the entire history of the state. So basically that means there’s a very, very, very small probability of ever getting attacked, and if you do, of dying. You’re much more likely to die from getting struck by lightning or from impaling yourself on your toothbrush than you are from a mountain lion.

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Let Them Run

From Conservation Magazine, a nice little article on our recent paper in Conservation Letters calling for a small number of fully protected salmon runs.

Ask not what a park can do for spawning salmon. Ask what robust salmon runs could do for the park – and for coastal fishing communities.

That’s the provocative idea behind a “radical” proposal being floated by a group of conservation biologists. Limiting fishing for some pink and chum salmon bound for spawning streams in British Columbia parks could reinvigorate ecosystems that thrive on the annual infusion of millions of fish carcasses. And, in the long run, protecting the runs could produce economic benefits by making ecosystems more productive and resilient to change.

“Although managers safeguard protected areas for migratory species, little consideration has been given to how migratory species might benefit parks,” a team led by Chris Darimont of the University of California, Santa Cruz, and the Raincoast Conservation Foundation in Canada write in Conservation Letters. Case in point: Headwaters streams in coastal parks in British Columbia once saw huge annual runs of Pacific salmon. Many of the spawned-out fish died, producing a “fertilizer effect” that pumped a vast pulse of nutrients into surrounding ecosystems. “The breakdown of salmon carcasses…  ultimately can affect communities of riparian plants, terrestrial and freshwater invertebrates, resident fish, and songbirds,” the authors note. These days, however, commercial and recreational fishers kill up to 90% of the fish before they can spawn, blocking the transfer of nutrients.

To restore at least part of that pulse, the authors propose limiting catches of pink and chum salmon(Oncorhynchus gorbuscha and keta), which have still have large runs but low commercial value. While Chinook salmon sold for $1.23 a pound in 2002, for instance, pink and chum sold for just 6 to 16 cents a pound. “We believe that a focus on pink and chum… provides opportunity to implement our ideas without severe economic consequences.”

The authors concede that “some might deem our idea politically unachievable,” but add that their “aim is to inform and inspire decision-makers with a plan that not only favors biodiversity but also one that ultimately might yield economic and management benefits. Our goal is to inoculate the literature with a provocative idea to stimulate discussion.”

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Top 100 Stories of 2009

Discover magazine listed our PNAS article as #30 on its list of top 100 science stories of 2009.

Humans are powerful agents of evolutionary change: Wild animals and plants that are hunted or harvested evolve three times as quickly as they would naturally, according to a study from the University of California at Santa Cruz. In our quest to bag the biggest and the best, we introduce selective pressures that favor less desirable creatures, such as those with smaller bodies or less majestic horns. Hunting also gives a competitive advantage to animals that have babies when they are younger, before they become tempting targets for humans.

A team led by biologist Chris Darimont combed through data on dozens of species—predominantly fish but also bighorn sheep, caribou, marine invertebrates, and two plants. (“Hunters also want the biggest ginseng,” Darimont says.) Animals that are routinely subject to pursuit are, on average, 20 percent smaller and reproduce at a 25 percent younger age than what would be expected without human influence, the researchers determined. Predation is not the only way that people affect populations. Creatures that are exposed to environmental influences like pollution also experience accelerated evolution, although the effect is less dramatic.

The resulting changes have ripple effects, Darimont notes. Smaller and earlier breeders often produce fewer offspring, for instance. “Size really matters,” he says. “If a harvested animal keeps shrinking, it may no longer be prey to its predator. The whole food web can be altered.”

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Human-Driven Evolution

From Science Friday on NPR, Chris Darimont discusses our recent PNAS paper on human-driven evolution.  Listen to the full radio spot here.

Can humans angling for the prize-winning fish shift the course of evolution? Research published this week in the Proceedings of the National Academy of Sciences says that predation by humans through hunting, fishing, and gathering has had significant influences on the rate of evolutionary change in a wide variety of species. Traits such as body size and first reproductive age shift significantly in species that are ‘harvested,’ the authors say.

“Fishing regulations often prescribe the taking of larger fish, and the same often applies to hunting regulations,” said Chris Darimont, one of the authors of the study. “Hunters are instructed not to take smaller animals or those with smaller horns. This is counter to patterns of natural predation, and now we’re seeing the consequences of this management.” Darimont and colleagues found that human predation accelerated the rate of observable trait changes in a species by 300 percent above the pace observed within purely natural systems, and 50 percent above that of systems subject to other human influences, such as pollution,. We’ll talk with Darimont about the team’s findings.

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