Biggest Dam Removal in History on Washington’s Elwha River
The biggest dam removal project in history began Sept. 17 on Washington's Elwha River. American Rivers, the national leader in restoring rivers through dam removal, applauded the effort which will revitalize salmon runs and deliver significant cultural, economic and recreation benefits to the Lower Elwha Klallam tribe and surrounding communities.
"This is one of the most significant river restoration efforts the world has ever seen," said Bob Irvin, president of American Rivers. "We will witness a river coming back to life, with great benefits for people and the environment. The lessons we learn on the Elwha will inform and inspire other river restoration efforts around the country."
The demolition of the two Elwha River dams was the culmination of a three-year process. Actor and American Rivers board member Tom Skerritt emceed the ceremony at Elwha Dam, which included Lower Elwha Klallam Tribal Chairwoman Frances Charles, Governor Christine Gregoire, Secretary of the Interior Ken Salazar, Senators Patty Murray and Maria Cantwell, and Rep. Norm Dicks.
American Rivers has dubbed 2011 'The Year of the River' because the U.S. will reach the significant milestone of 1,000 dams removed nationwide. Dams can provide useful services, but should be removed when they have outlived their usefulness, are unsafe or when their costs outweigh their benefits.
The Elwha River flows from the heart of Olympic National Park to the Strait of Juan de Fuca in Puget Sound. Dam removal and river restoration on the Elwha will bring hundreds of millions of dollars of economic benefits to the community, from restored fisheries to recreation and tourism. Dismantling Elwha Dam and Glines Canyon Dam will allow the river to flow freely for the first time in 100 years, restoring more than 70 miles of salmon and steelhead habitat. Fish populations are expected to grow from the current 3,000 to more than 300,000 a year, benefiting the entire web of life, from black bears to eagles to orca whales.
At 210 feet tall, Glines Canyon Dam will be the tallest dam ever removed.
The Elwha River restoration effort is the result of decades of work by the Lower Elwha Klallam Tribe, American Rivers and many other conservation partners. American Rivers has advocated for dam removal on the Elwha for more than 25 years, from intervening in the dam relicensing proceedings to supporting the 1992 legislation authorizing dam removal, to helping secure $50 million in federal economic stimulus funding for the project.
"All of us care about clean water, and about the rivers where we fish, swim and paddle," said Irvin. "American Rivers is committed to protecting and restoring the Elwha and all of our nation's rivers for future generations. Rivers connect us."
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American Rivers is the nation’s leading voice fighting for clean water and healthy rivers. For almost 40 years we have protected and restored rivers, scoring victories for communities, fish and wildlife, and future generations. American Rivers has offices in Washington, DC and nationwide, and more than 100,000 supporters and volunteers. Visit www.americanrivers.org, www.facebook.com/americanrivers and www.twitter.com/americanrivers.
The ghoulishly named ogre-faced spider can "hear" with its legs and use that ability to catch insects flying behind it, the study published in Current Biology Thursday concluded.
"Spiders are sensitive to airborne sound," Cornell professor emeritus Dr. Charles Walcott, who was not involved with the study, told the Cornell Chronicle. "That's the big message really."
The net-casting, ogre-faced spider (Deinopis spinosa) has a unique hunting strategy, as study coauthor Cornell University postdoctoral researcher Jay Stafstrom explained in a video.
They hunt only at night using a special kind of web: an A-shaped frame made from non-sticky silk that supports a fuzzy rectangle that they hold with their front forelegs and use to trap prey.
They do this in two ways. In a maneuver called a "forward strike," they pounce down on prey moving beneath them on the ground. This is enabled by their large eyes — the biggest of any spider. These eyes give them 2,000 times the night vision that we have, Science explained.
But the spiders can also perform a move called the "backward strike," Stafstrom explained, in which they reach their legs behind them and catch insects flying through the air.
"So here comes a flying bug and somehow the spider gets information on the sound direction and its distance. The spiders time the 200-millisecond leap if the fly is within its capture zone – much like an over-the-shoulder catch. The spider gets its prey. They're accurate," coauthor Ronald Hoy, the D & D Joslovitz Merksamer Professor in the Department of Neurobiology and Behavior in the College of Arts and Sciences, told the Cornell Chronicle.
What the researchers wanted to understand was how the spiders could tell what was moving behind them when they have no ears.
It isn't a question of peripheral vision. In a 2016 study, the same team blindfolded the spiders and sent them out to hunt, Science explained. This prevented the spiders from making their forward strikes, but they were still able to catch prey using the backwards strike. The researchers thought the spiders were "hearing" their prey with the sensors on the tips of their legs. All spiders have these sensors, but scientists had previously thought they were only able to detect vibrations through surfaces, not sounds in the air.
To test how well the ogre-faced spiders could actually hear, the researchers conducted a two-part experiment.
First, they inserted electrodes into removed spider legs and into the brains of intact spiders. They put the spiders and the legs into a vibration-proof booth and played sounds from two meters (approximately 6.5 feet) away. The spiders and the legs responded to sounds from 100 hertz to 10,000 hertz.
Next, they played the five sounds that had triggered the biggest response to 25 spiders in the wild and 51 spiders in the lab. More than half the spiders did the "backward strike" move when they heard sounds that have a lower frequency similar to insect wing beats. When the higher frequency sounds were played, the spiders did not move. This suggests the higher frequencies may mimic the sounds of predators like birds.
University of Cincinnati spider behavioral ecologist George Uetz told Science that the results were a "surprise" that indicated science has much to learn about spiders as a whole. Because all spiders have these receptors on their legs, it is possible that all spiders can hear. This theory was first put forward by Walcott 60 years ago, but was dismissed at the time, according to the Cornell Chronicle. But studies of other spiders have turned up further evidence since. A 2016 study found that a kind of jumping spider can pick up sonic vibrations in the air.
"We don't know diddly about spiders," Uetz told Science. "They are much more complex than people ever thought they were."
Learning more provides scientists with an opportunity to study their sensory abilities in order to improve technology like bio-sensors, directional microphones and visual processing algorithms, Stafstrom told CNN.
"The point is any understudied, underappreciated group has fascinating lives, even a yucky spider, and we can learn something from it," he told CNN.
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