Earthweek: A Diary of the Planet (March 22, 2013)

Deep Discovery
The deepest place in the ocean is home to an unlikely abundance of microbial life, according to a new study.  A Danish-led team of marine microbiologists looked at sediment samples collected by a robot from the bottom of the Mariana Trench and found evidence of bountiful bacterial activity.  The Mariana Trench, an undersea canyon in the western Pacific, is not a place one would expect to be teeming with life.  Microbes living at the bottom of the underwater fissure survive in near freezing tempereatures, with no sunlight, and in crushing pressures.  The discovery suggests that many of the world's deepest and darkest oceanic canyons might be hot spots of microbial life.
Manatee Deaths
A new wave of manatee deaths has struck Florda following a string of fatalities among the marine mammals due to red tide algae blooms along the state's southwestern beaches.  But marine biologists say they don't know exactly what's killing the manatees along the eastern coast since there have not ben any reports of red tide there, and the weather hasn't been cold enough to account for the deaths.   Nearly 200 manatees have died due to red tide along Florida's Gulf Coast so far this year.  While lacking physical evidence to prove it, wildlife experts believe the deaths in eastern Florida are due to different types of algae blooms that have killed off vast amounts of sea grass the manatees typically feed on.  That may have caused the lumbering sea animals to instead ingest large amounts of macroalgae, which sent them into fatal toxic shock.  The east coast algae blooms were due to storm runoff that flushed fertilizers and other manmade nutrients into waterways.
Reindeer Cull
Thousands of reindeer have been slaughtered on a remote British island where the animals were introduced a century ago from a herd in Norway.  Reindeerhave become an increasing threat to native wildlife on South Georgia, which is located in the far South Atlantic, near Antarctica.  A team of 16 hunters corralled many of the targeted 3,500 animals into pens on South Georgia.  Others in remote areas were shot with rifles.  About 1,500 remaining reindeer will be targeted in a final cull next year.  A few dozen reindeer were brought to South Georgia by whalers in the early 20th century to be used as a reliable source of food in the remote region.  But their population has since exploded, with the hoofed animals stomping through the ground nests of native birds.
Monarchs in Peril
The third straight year of decline for the North American monarch butterfly population has brought the number of the orange-and-black insects to the lowest levels ever reliably measured.  Six of the past seven years have also seen numbers decline, bringing the population to only one-fifteenth of what it was in 1997.   Scientists say it is no longer possible to attribute the decline to just yearly or seasonal events that have always affected the species.  The World WildlifeFund is one of the groups that sponsored the butterfly cenus.  It says climate change and agricultural practices are to blame.  One of the biggest factors is the use of pesticides that kill off the monarch's main food source of milkweed.  Logging in the butterfly's wintering home in the forests of western Mexico was once considered the main threat to the species.  But it has been virtually halted in recent years by conservation efforts.
Tropical Cyclone
An area of disturbed weather spinning off Australia's Cape York Peninsula briefly developed into Tropical Storm Tim.  The disturbance remained over the Coral Sea, well off the Queensland coast and the adjacent Great Barrier Reef.
Earthquakes
The strongest tremor to jolt Auckland, New Zealand, in six years left some sidewalks cracked but othrerwise caused no significant damage. 
* Earth movements were also felt in southwestern New Zealand, China's Yunnan province and in Istanbul and other areas of the southern Black Sea region.
Evolution on the Fly
Natural selection during the age of motorized transportation has caused at least one species of bird to evolve with shorter wings that help it avoid being struck by passing vehicles.  Researcher Charles Brown of the University of Tulsa has collected dead swallows that became roadkill over the past 30 years.  Swallows are known to build nests on concrete bridges of major highways, making them prone to becoming traffic fatalities.  Brown has measured the wings of such dead birds in relation to those snagged in nets.  Writing in the journal Current Biology, Brown says he found the wings of vehiclle-killed birds grew longer over the study period, while the general population of the birds grew shortere wings.  It's believed that the shorter wings allow birds to make sharp turns more quickly, and escape being hit by vehicles.