Earthweek: a diary of the planet
Arctic mystery
NASA scientists flying over a remote stretch of the Canadian Arctic spotted a phenomenon that they’d never seen before and are struggling to explain. Images taken April 14 during an Operation IceBridge flyover of the Beaufort Sea, northwest of the Mackenzie River Delta, revealed mysterious rings around small holes in the relatively thin sea ice. One scientist suggested the rings might have been formed as seals came up for air through the holes, creating small waves that wash outward and freeze. Others believe they formed as currents flowing out of the Mackenzie River interacted with the sea-bed and gushed up through the holes in the surface ice.
Arboreal ‘heartbeat’
Researchers say they have found evidence of a kind of “heartbeat” in trees that causes them to change shape in a regular rhythm that is much shorter than a day- night cycle. András
Zlinszky and colleague Anders Barfod at Aarhus University in Denmark scanned 21 species of trees in windless and lightless conditions and found seesaw oscillations in branches that were most pronounced in magnolia trees. Branches move up and down an average of 0.6 inch during cycles that are 2 to 6 hours in duration. The pair say the pulses likely are evidence that trees have a “heartbeat” in which they actively squeeze water upward from their roots.
Fish competition
Damage to fishing nets caused by dolphins
is increasing across the Mediterranean as overfishing forces the marine mammals to compete more with humans for seafood. Damage to the typically small-scale fishing businesses is now costing thousands, or even tens of thousands, of dollars per year, according to researchers at the University of Exeter in England. Acoustic “pingers” used in an attempt to deter dolphins haven’t worked, and perhaps acted as “dinner bells” that actually attracted the ocean animals in some cases, the researchers found.
Suicide bombers
The first new species of “exploding ants” since 1935 has been discovered in the remote rainforests of Borneo, Thailand and Malaysia. The insects give their lives in selfless acts that produce a burst of toxic yellow goo to kill invaders. “When threatened by other insects, minor workers can actively rupture their body wall,” said lead researcher Alice Laciny of the Natural History Museum in Vienna, Austria. “Apart from leading to the ants’ imminent death, the ‘explosion’ releases a sticky, toxic liquid … to either kill or hold off the enemy.”
Historic eruption
Japan’s Mount Io erupted for the first time in 250 years, prompting officials on each side of the border between Miyazaki and Kagoshima prefectures to warn of flying rocks and pyroclastic flows. Io, which erupted twice in less than a week, is one of the craters in the Mount Kirishima group of volcanoes. Nearby Mount Shinmoe erupted violently for the first time in about seven years on March 9.
Tropical cyclone
The Indian Ocean island of Réunion was raked by hurricane- force winds as Tropical Cyclone Fakir skirted the French overseas territory.
Earthquakes
Dozens of people were injured in southeastern Turkey when a magnitude 5.2 earthquake caused damage to buildings in Adiyaman province. Earth movements also were felt in western Nicaragua, southeastern Michigan and a wide area of Southern California.