January 24, 2007
WANDERLUST
-- DEEP-SEA FAUNA UNDER ANTARCTIC ICE
SHELF
Under the former
Larsen ice shelf
east of the Antarctic Peninsula,
deep-sea sea
cucumbers and stalked feather stars were ubiquitously found in shallow
waters.
These animals usually inhabit far greater water depths.
The main aim of the
current
Polarstern expedition to Antarctica
is the
investigation of marine ecosystems under the former Larsen ice shelf.
This
"white spot" with regard to biodiversity research gave rise to the
following questions: What kind of life actually existed under the
former
floating ice shelf which was up to several hundreds of meters thick?
What are
the prospects for the future after the collapse of the ice shelf?
Obviously,
prosperous life did not exist in the area where the Larsen B ice shelf
broke
off three years ago. This is surprising since Antarctica's
seafloor communities are known for their rich assemblages of sessile
sponges,
cnidarians and moss animals. Instead, underwater video footage and
catches of
towed sampling gear revealed the dominance of typical deep-sea animals
and
corresponding life forms.
Here, sea cucumbers
and stalked
feather stars are the main representatives. These deep-sea inhabitants
belong
to a group called echinoderms. Until now, stalked feather stars have
only been
found sporadically and then only below 800-meter water depths in this
sector of
Antarctica. But
locally in the Larsen B
region, they occurred rather frequently at depths of merely 200-meter.
"During my nine expeditions to Antarctica,
the only time I have seen the two most abundant species of sea
cucumbers was
below the far bigger Filchner-Ronne ice shelf further south." This
second
encounter brought back chief scientist Julian Gutt's memories of his
first trip
to Antarctica and
his Ph.D. thesis 21 years
ago. Preliminary results show that a unique macrofauna exists in
conjunction
with the ice shelf. The sea cucumber Elpidia is probably the most
prominent
deep-sea animal but is also known to occur in shallow Arctic waters.
Maybe this
is the reason why this animal is aptly named glacialis (icy) especially
with
regard to our confirmatory findings on the opposite pole – Antarctica.
This species, its
bigger
"sister" Scotoplanes globosa and other relatives according to their
feeding mode are referred to as grazers. Myriads of single-celled algae
that
sink down to the seafloor are literally grazed by herds of sea
cucumbers. The
oceanographer Enrique Isla is excited about further processing the
collected
data back in the Marine Sciences Institute (ICM) in Barcelona.
"Our measurements of
environmental parameters of the sediment and the water column will
contribute
to answer the question, why there are such similarities between habitat
use of
the deep-sea and below the former ice shelf." Scientists on this
expedition will meet again in autumn in Barcelona
to work on a synthesis of various results combining the different
aspects of
ecosystem components. This workshop will be hosted by the ICM and is
supported
by the Census of Antarctic Marine Life (CAML). Marine ecologist Julian
Gutt is
looking to the future: "The minute we have a better understanding of
how
ecosystems under the ice shelf work we might dare to put forward
prognoses how
biodiversity on the seafloor changes with respect to ongoing
atmospheric
warming".
##
Contact:
Dr.
Angelika Dummermuth
Alfred
Wegener Institute for Polar
and Marine Research
49-471-483-11742
Angelika.Dummermuth@awi.de
This text derived from:
http://www.awi-bremerhaven.de/index-e.html
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