“Massive acoustic trauma.” It sounds like an ’80s metal band, but according to scientists at the Technical University of Catalonia in Spain, it’s what happens to squid and other cephalopods when they are exposed to sounds similar to boat noise. After exposing 87 cephalopods to low-volume, low-frequency noises for two hours, the researchers found damaged nerves, lesions, and other trauma in the creatures’ hearing organs. There are some holes in the team’s methods (see below), but if the findings hold, squid will be added to the long list of marine animals (including whales, dolphins, and crustaceans) endangered by human-made noise in the oceans.
Whales and the U.S. Navy have tangled repeatedly over the past years over charges that the Navy’s sonar exercises disorient or injure whales and other marine mammals. Now, whales in the Pacific appear to have a new champion: the National Oceanic and Atmospheric Administration, which is considering limiting the Navy’s sonar tests in certain marine mammal “hot spots.”
The announcement was made in a letter (pdf) from NOAA head Jane Lubchenco to the White House Council on Environmental Quality. NOAA also called for development of a system for estimating the “comprehensive sound budget for the oceans,” which could help reduce human sources of noise — vessel traffic, sonar and construction activities — that degrade the environment in which sound-sensitive species communicate [Los Angeles Times].
While NOAA’s new investigations into limiting the Navy’s sonar use is good news for whales, it may take years before new rules are issued. And until then, fights will rage on in courts. Back in 2008, a 5-4 vote in the U.S. Supreme Court allowed the Navy to conduct sonar tests in the Pacific Ocean, despite environmental groups fighting to stop the tests. But that wasn’t the end of litigation over this issue. Last week a consortium of environmental groups sued the Navy in U.S. District Court to stop a sonar project on the other side of the country, in the Atlantic Ocean waters off Florida.
The proposed Undersea Warfare Training Center would cover 500 square nautical miles in an area ideally close to two Navy bases, one in Georgia and another in Florida. However, the range would lie just outside the shallow waters where right whales give birth and nurse their calves each year from mid-November to mid-April [Los Angeles Times]. Right whales are an endangered species numbering only about 350, researchers believe.
Bats and dolphins are two of the most celebrated users of echolocation, employing high-frequency sounds to locate prey, find their way, or to communicate. Now a new set of findings in Current Biology show that not only do the two different kinds of mammals use the same method, they also evolved nearly the exact same molecular means for hearing at high frequencies.
That second part was a surprise, study author Stephen Rossiter says: “It’s common on a morphological scale but it’s assumed not to occur at a DNA level because there are so many different ways to arrive at the same solution” [BBC News]. That is, while it’s quite common for different species to separately evolve similar features—like the tusks of elephants and walruses—it’s quite unlikely that natural selection working in separate species would settle an essentially identical gene and protein for growing tusks, hearing high-frequency sounds, or anything else. Or so the thinking went.
Wind power may prove to be a promising source of clean energy, but it can also be deadly to bats. Not only can the animals be sliced by the blades of wind turbines, but the sudden drop in air pressure around the turbines can also cause bats’ lungs to explode. An electromagnetic field emitted near the turbines, however, may help bats steer clear of them, according to a new study published in the Public Library of Science One.
Bat casualties near wind turbines have proven to be significant: In 2004, over the course of six weeks, roughly 1,764 and 2,900 bats were killed at two wind farms in Pennsylvania and West Virginia, respectively [LiveScience]. If wind power continues to become increasingly prevalent, so too might the turbines become a growing threat to bat populations. “Given the growing number of wind turbines worldwide, this is going to be an increasing problem, no question about that,” said [co-author] Paul Racey [LiveScience].
Bats may have a clever way of catching prey, but it turns out the tiger moth has some tricks of its own to avoid becoming a bat’s next meal. According to a study published in Science, the tiger moth disrupts the sound waves the bat uses home in on prey by emitting its own ultrasound blasts.
Researchers knew that the tiger moth emitted ultrasound waves, but they weren’t sure why. Previous studies indicated the moth’s sounds might serve to startle the bats, or warn them that the insects were unpalatable. The new research, however, tested both of these theories. The scientists had so-called big brown bats hunt tiger moths in a chamber fitted with ultrasonic recording equipment and high-speed infrared video. If the moth sound is used to startle bats, then in the chamber the bats should be disrupted on first attack, then learn to ignore the ultrasonic click, the team figured. That didn’t happen. If the moths’ clicks are warnings that the insects taste bad, then the bats should hear the click, bite the moth—and never do so again whenever they hear the sound. That didn’t happen either [National Geographic News].
A French nuclear submarine has joined the search for the “black box” of Air France Flight 447, which disappeared over the Atlantic last week with all of its 228 passengers. The “black box” is actually an orange cylinder — about 13 pounds of metal wrapped around a stack of memory chips and designed to withstand the force of being slammed high-speed into a brick wall. Actually a pair of devices — the flight data recorder and a voice and audio recorder — the equipment records virtually everything about how an airplane is working [CNN].
Aviation experts hope that the black box, if it can be located on the seafloor, will provide an explanation for what went wrong on the flight, which vanished so mysteriously. On board the French sub, the Emeraude, crewmen called “golden ears” were straining to pick up in their headsets the acoustic pings aircraft black boxes are supposed to transmit for 30 days under water. Nothing is better equipped for such faint sounds than an attack submarine with sophisticated sonar gear for detecting vessels deep in the ocean, naval officers said [Times Online].