Saturday 27 September
2008, San José, Costa
Rica
Salud Orders
Removal Of Chinese Candies From Store
Shelves
"Aguacero,
Granizada y Nube Negra"
Costa Rica's Lottery In
Problems With Unclaimed
Winnings
Chinese Foreign Minister
Meets Costa Rican
Counterpart On Ties
Constitutional Court
Ratifies Land
Expropriations At Las
Baulas park
Ocean Floor Geysers Warm
Flowing Sea Water
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Ocean Floor Geysers Warm
Flowing Sea Water
An international team of
earth scientists report
movement of warmed sea
water through the flat,
Pacific Ocean floor off
Costa Rica. The movement
is greater than that off
midocean volcanic
ridges. The finding
suggests possible marine
life in a part of the
ocean once considered
barren.
With about 71 percent of
the Earth's surface
being ocean, much
remains unknown about
what is under the sea,
its geology, and the
life it supports. A new
finding reported by
American, Canadian and
German earth scientists
suggests a rather
unremarkable area off
the Costa Rican Pacific
coast holds clues to
better understand sea
floor ecosystems.
Carol Stein, professor
of earth and
environmental sciences
at the University of
Illinois at Chicago, is
a member of the research
team that has studied
the region, located
between 50 and 150 miles
offshore and covering an
area the size of
Connecticut. The sea
floor, some two miles
below, is marked by a
collection of about 10
widely separated
outcrops or mounts,
rising from sediment
covering crust made of
extinct volcanic rock
some 20-25 million years
old.
Stein and her colleagues
found that seawater on
this cold ocean floor is
flowing through cracks
and crevices faster and
in greater quantity than
what is typically found
at mid-ocean ridges
formed by rising lava.
Water temperatures,
while not as hot as by
the ridge lava outcrops,
are surprisingly warm as
well.
Finding so much movement
in a bland area of the
ocean was surprising.
"It's like finding Old
Faithful in Illinois,"
said Stein. "When we
went out to try to get a
feel for how much heat
was coming from the
ocean floor and how much
sea water might be
moving through it, we
found that there was
much more heat than we
expected at the
outcrops."
The water gushing from
sea floor protrusions
warms as it moves
through the insulated
volcanic rock and picks
up heat.
"It's relatively warm
and may have some of the
nutrients needed to
support some of the life
forms we see on the sea
floor," said Stein. Her
best guess as to why the
water flows so rapidly
is that it accelerates
off nearby sea mounts
and follows a
well-connected network
of cracks beneath the
sea floor.
The earth scientists
dropped probes from
ships down to the
pitch-dark ocean floor
to collect temperature
and heat-flow data to
form images of what is
happening in this area
of the ocean, with water
flowing down into rock,
heating up and remixing
below the floor
sediment, and then
escaping above the sea
floor.
Only in recent decades
have earth scientists
discovered such life
forms as bacteria, clams
and tubeworm species
living near the hot
water discharges along
the mid-ocean volcanic
ridges. The rather flat
undersea areas which
Stein and her colleagues
studied were thought to
be lifeless, but the
nutrient-enhanced warm
water flows they
discovered suggests this
area too may be capable
of supporting life.
"The sea floor may not
be quite as much of a
desert even as we
thought maybe 20 or 10
years ago, but rather
there may be a lot of
locations similar to
this well-studied area
in terms of the water
flow where there's a lot
more biological
activity," she said.
The earth scientists
hope to do follow-up
studies to add details
to their findings, and
see if they can find
other regions comparable
to the one off Costa
Rica.
"We're only beginning to
really understand the
interplay of the water
flow and the nature of
the ecosystem on the sea
floor," said Stein. "I
think as we move away
from the ridge crests,
understand what's going
in the overall ocean,
we'll have a better
understanding of how
life is distributed and
affects the oceans and
our planet."
The findings were
reported in a letter
printed in Nature
Geoscience's September
2008 issue. Other key
authors of the letter
include Andrew Fisher of
the University of
California, Santa Cruz,
and Robert Harris of
Oregon State University.
The lead author is
Michael Hutnak, now with
the U.S. Geological
Survey.
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