New Sea
Otter Scourge Found
July 01, 2004, Adapted by Megan Mansell
Williams and Kathleen M. Wong,
California Academy of Sciences
Southern sea
otters are dying from diseases carried by opossums as well as cats. The
discovery, part of an ongoing study of sea otter mortality, may help
scientists figure out how to stem the marine mammal's alarming decline.
Last year was particularly rough on Southern California otters. In April
2003, sixty-two washed ashore dead, beating the one-month record of 42
deaths set the year before.
Wildlife
veterinarian Melissa Miller of the Univeristy of California, Davis,
determined each animal's cause of death. She found 11 were infected with
Sarcocystis neurona, a parasite spread through opossum feces. Previously,
Miller and colleagues had found otters dying of Toxoplasma gondii, a
parasite found in cat feces. Both organisms attack the brain and nervous
system.
Miller says the
otter likely caught Sarcocystis neurona by eating contaminated shellfish.
Runoff after rainstorms can carry infected feces into the ocean. The
opossum parasite may be particularly lethal to sea otters because it is
unfamiliar; opossums were introduced to California from Virginia in the
1900s.
Alaskan Earthquake Touches Yellow Geysers
An earthquake
that rocked Alaska replumbed geysers as far away as Yellowstone National
Park. The magnitude 7.9 quake, centered in Alaska's Denali National Park
in November 2002, sparked a flurry of smaller earthquakes and erratic
geyser behavior at Yellowstone, nearly 2, 000 miles away. The seismic
rumbles set off eruptions in some geysers and quieted others.
This is the
first time such a distant quake has been observed to cause major changes
at geothermal hot spots, report park geologist Hank Heasler and colleagues
in the journal Geology. The seismic ripples changed water pressures
in the conduits beneath the geysers, causing some pipes to clog and others
to gush. These pressure changes triggered nearly 1, 000 small
earthquakes at Yellowstone within a week of the Denali shaker.
Of the 22
geysers observed during that time, eight showed changes in their eruption
behavior, but most resumed their usual behavior in the days and months
after the quake.
Antarctic Snow Casts Doubt on a Coming Ice
Age
Forget what you
saw in the movie The Day After Tomorrow - a new ice age isn't
dawning anytime soon. Currently, Earth in the midst of a warming period
that began about 12, 000 years ago.
Because the
three warming periods preceding this one lasted only about 10, 000 years,
some have speculated that another ice age is long overdue. But according
to a new study published in the journal Nature, Earth might be only midway
through its current temperature phase.
After five
years of drilling, scientists with the European Project for the Ice Coring
were able to obtain Antarctic snow layers 10, 000 feet deep. The cores
contain a record of climate conditions dating back 740, 000 years. By
analyzing the hydrogen in the ice cores, the scientists determined that a
warm period that peaked 430, 000 years ago endured for a whopping 28, 000
years. Climate data from that time is particularly relevant because
Earth's orbital position, which influences the amount of sunlight it
receives, was very similar to today's.
Only the Strongest New
Galaxies Survive
The Milky Way
is orbited by a dozen smaller galaxies - far fewer than current theories
would predict. Now a new computer simulation run by Andrey Kravtsov and
colleagues at the University of Chicago may explain why.
According to
conventional theories, slow-moving dark matter, which makes up a good
portion of the universe, slowly aggregates into clumps. Overtime, these
clumps grow large enough to contain the normal matter needed to make stars
and then galaxies. Kravtsov' team ran simulations of the formation of our
galaxy in slow motion using small time increments.
This
fine-grained analysis revealed that as gravity exerts its pull, the
largest dark matter clusters actually pull mass away from the smaller
ones, limiting their growth and shutting down star formation in these
wimpy clumps. As a result, the number of orbiting galaxies in
Kravsov's model matches what actually exists. The team reposts its results
in the The Astrophysical Journal.
Saturn's Moon Phoebe Unmasked
The Cassini
space robe has obtained the closest look yet at Saturn's strange moon
Phoebe. Images of the moon's battle-scarred surface should help
astronomers pin down the rock satellite's origins.
A joint project
on its way to a four-year orbit around Saturn. Images sent back over the
weekend reveal deep craters, thin fissures, and chains of pits on Phoebe's
surface, probably caused by many cosmic collisions. NASA scientists
suspect that ice-rich Phoebe, which circles Saturn in the opposite
direction of its 31 sister moons, formed in the outer solar system and was
captured by Saturn early on.
Continuing data
analysis of the Cassini images should reveal more in the coming weeks. The
last time a craft was in the neighborhood was in 1981, when Voyager 2
passed within 1.4 million miles of the moon.
Source.
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