Abundance of life discovered beneath an Antarctic ice shelf

Date:
December 20, 2021
Source:
British Antarctic Survey
Summary:
Far beneath the ice shelves of the Antarctic, there is more marine
life than expected.



FULL STORY ==========================================================================
Far beneath the ice shelves of the Antarctic, there is more marine life
than expected, finds a recent study in the journal Current Biology,
published this week (20 December 2021).


========================================================================== Despite occupying nearly 1.6 million km2, ice shelves are amongst the
least known environments on Earth. Life has been seen in these perpetual
dark, cold and still habitats on camera but has rarely been collected.

Using hot water, a team of researchers from the Alfred Wegener Institute
(AWI), Helmholtz Centre for Polar and Marine Research, Germany, drilled
two holes, through nearly 200 metres of the Ekstro"m Ice Shelf near
Neumayer Station III in the South Eastern Weddell Sea in 2018. The
environment is harsh and extremely cold (minus 2.2 degrees centigrade).

The fragments of life on the seabed collected were extraordinary and
completely unexpected. Despite being several kilometres from the open sea,
the biodiversity of the specimens they collected was extremely rich. In
fact, richer than many open water samples found on the continental shelf
where there is light and food sources.

The team discovered an incredible 77 species - including sabre shaped
bryozoans (moss animals) such as Melicerita obliquaand serpulid worms
such as Paralaeospira sicula , more than previously known about from
this entire environment.

Lead author Dr David Barnes, a marine biologist at British Antarctic
Survey, says: "This discovery of so much life living in these extreme conditions is a complete surprise and reminds us how Antarctic marine
life is so unique and special. It's amazing that we found evidence of
so many animal types, most feed on micro-algae (phytoplankton) yet no
plants or algae can live in this environment. So the big question is
how do these animals survive and flourish here?" The team concludes
there must be enough algae carried under the ice shelf from open water to
fuel a strong food web. Microscopy of samples showed that, surprisingly,
annual growth of four of the species was comparable with similar animals
in open marine Antarctic shelf habitats.

Co-author Dr Gerhard Kuhn (AWI), who coordinated the drilling project,
says: "Another surprise was to find out how long life has existed
here. Carbon dating of dead fragments of these seafloor animals varied
from current to 5800 years.

So, despite living 3-9 km from the nearest open water, an oasis of
life may have existed continuously for nearly 6000 years under the ice
shelf. Only samples from the sea floor beneath the floating ice shelf
will tell us stories from its past history." Current theories on what
life could survive under ice shelves suggest that all life becomes less abundant as you move further away from open water and sunlight. Past
studies have found some small mobile scavengers and predators, such as
fish, worms, jellyfish or krill, in these habitats. But filter feeding organisms -- which depend on a supply of food from above -- were expected
to be amongst the first to disappear further under the ice.

The team also notes that with climate change and the collapse of these
ice shelves, time is running out to study and protect these ecosystems.

========================================================================== Story Source: Materials provided by British_Antarctic_Survey. Note:
Content may be edited for style and length.


========================================================================== Journal Reference:
1. David K.A. Barnes, Gerhard Kuhn, Claus-Dieter Hillenbrand, Raphael
Gromig, Nikola Koglin, Boris K. Biskaborn, Betina A.V. Frinault,
Johann P. Klages, Julian Gutt. Richness, growth, and persistence
of life under an Antarctic ice shelf. Current Biology, 2021; 31
(24): R1566 DOI: 10.1016/j.cub.2021.11.015 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/12/211220120032.htm

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