Earthweek: A Diary of the Planet (May 17, 2013)

Wayward Giant
A gray whale that was sighted off the coast of Namibia in early May was the first-ever appearance of the marine mammal south of the equator.  The species had been extinct in the Atlantic since the 18th century and has been mainly confined to the North Pacific.  A seperate one was sighted in the Mediterranean in May 2010.  Experts say this could suggest the leviathan is recovering from the disastrous whaling hunts that ended in the 20th century, or it could mean changing climate is disrupting its feeding habits.  Another possibility is that the increasing population could be allowing it to regain some of its ancient migratory routes.  Gray whales grow up to 45feet in length and undertake the longest known migration of any mammal.  They complete a round tip of over 18,000 miles between their summer feeding grounds in the high Arctic and winter breeding area off the coast of Mexico.
Citrus Greening
A nutrient-draining bacterial disease is devastating Flordia's citrus trees, posing a major threat to the state's economy and to the international trade in oranges, lemons, limes and citrus juices.  Since it was discovered in 2005, this strain of "citrus greening" disease has rapidly spread from the south of the state to its northern border and beyond.  Transmitted by the Asian citrus psylid, a minuscule fly that spreads the bacteria when it feeds on the foliage of trees, citrus greening is so named for its greening effect on infected fruit.  Starving the tree of nutrients, the illness causes fruit to become bitter and drop from the tree before it is ripe.  Though the disease affects all citrus fruits, including grapefruit and lemons, Flordia oranges have been most severly affected.
Jellyfish Boom
Overfishing of the world's oceans is the leading cause of an unprecedented jellyfish population boom, a new study claims.  Published in the Bulletin of Marine Science, the report argues that the unrestricted fishing of small open-water fish, such as sardines and herring, has reduced the number of creatures that jellyfish complete with for plankton and other forms of food.  By thinning out these hunting rivals, many of which also feed on jellyfish eggs, the unregulated fishing has eliminated the main checks on explosive jellyfish population growth.  Over the past decade, that growth has been apparent, with jellyfish showing up in bodies of water where theyhad never before been a problem, such as the Sea of Japan and the Mediterranean Sea.  There, they have clogged fishing nets and driven swimmers onto dry land.
Earthquakes
Iran was struck with the third deadly earthquake within a month's time when a 6.0 magnitude temblor killed a child and injured 20 others.  The latest quake struck a remote mountainous region in the south of the country, where officials said 70 villages suffered severe damage.
*  Earth movements were also felt in northwestern Libya and the Philippine province of Negros Occidental.
Tropical Cyclones
Bangladesh and Myanmar were spared a major catastrophe when Cyclone Mahasen weakened over the Bay of Bengal before arriving.  Thousands of shacks along the coast of Bangladesh were destroyed, and officials reported at least six fatalities.
*   Tropical Storm Jamala emerged briefly in the central Indian Ocean while Alvin formed off Mexico.
Volcanoes
Activity at Mexico's Popocatepetl volcano intensified, prompting officials to raise the alert level as lava bombs were tossed more than a half-mile from the crater.  The country's National Disaster Prevention Center said ash fell on communities as far away as 15 miles from the towering volcano.  Steam and vapor also blew toward Mexico City, which is located about 35 miles northwest of Popocatepetl.  There have been several moderate blasts from "Popo" in recent years, with some forcing the government to evacuate as many as 75,000 people at a time.
*   Lava has begun flowing from southwestern Alaska's Pavlof and Cleveland volcanoes.  Both have been put on alert status and could pose ash risks to trans-Pacific aviation should they produce explosive eruptions
Cicada Snack Alert
Animal health experts are warning people living along the East Coast of the United States not to let their pets eat too many of the billions of cicadas that are emerging across the region.  Every 17 years at this time, like clockwork, Brood II cicadas crawl out of the ground from North Carolina to New England.  "As tempting as bugs may be, the outer skeleton of the cicada contains a tough material called chitin that is problem-atic when eaten in large quantities," cautioned Brian Collins, of the Cornell University Hospital for Animals.  He said that chitin is also found in lobster shells, and eating too much could cause cats and dogs to experience vomiting or constipation, which would require a visit to the vet.