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lite.cnn.com - on gopher - inofficial
ARTICLE VIEW:
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Scientists make surprise discovery of life in the seafloor’s
‘underworld’
By Ashley Strickland, CNN
Updated:
3:43 PM EDT, Wed October 16, 2024
Source: CNN
Scientists have uncovered communities of animals such as tube worms and
snails living in volcanic caves beneath the seafloor, revealing a
previously unknown but thriving ecosystem.
Researchers made the astonishing discovery during a 30-day expedition
aboard the Schmidt Ocean Institute’s research vessel “Falkor
(too)” to explore an undersea volcano off Central America that’s
part of the .
A volcanically active ridge, the extensive rise occurs where two meet
on the floor of the Pacific Ocean. Located along the ridge are , or
openings in the seafloor where seawater and hot magma from beneath
Earth’s crust come together to create a type of underwater hot
spring.
A variety of sea life clusters around the vents, which belch out
elements that help bacteria, mussels, tube worms and other animals
survive at extreme ocean depths. The vent ecosystem has been studied
in-depth, but areas beneath the vents have largely remained out of
reach.
Using the remotely operated vehicle SuBastian, researchers exposed
parts of the subseafloor and uncovered a surprise: caves connected to
the vents teeming with giant tube worms, some reaching up to 1.6 feet
(0.5 meter) long, and other animals. The revelation suggests
connectivity between the seafloor and subseafloor ecosystems, allowing
life to thrive in unexpected places above and below the ocean floor.
While the team first observed the subseafloor ecosystem in the summer
of 2023, the research describing the environment and its animals
published Tuesday in the journal .
“We want to understand how animals travel and how they disperse, so
we looked for the first time into the subsurface,” said study
coauthor Dr. Sabine Gollner, marine biologist and senior scientist at
the Royal Netherlands Institute for Sea Research, in a video the
Schmidt Ocean Institute released. “Animals are able to live beneath
hydrothermal vents, and that, to me, is mind-blowing.”
‘Underworld’ of the seafloor
Scientists have long been intrigued by the animal life that clusters
around hydrothermal vents and have studied these unique ecosystems for
the past 50 years.
The shifting of Earth’s tectonic plates gives rise to new
hydrothermal vents over time, and foundational seafloor animals such as
tube worms have been known to colonize these new vents in the span of a
few years.
based on samples from fluid released by the hydrothermal vents, some
research has also suggested. And tube worms were observed living
several centimeters deep within the cracks of the seafloor near vents,
but the study team wasn’t sure how tiny tube worm larvae, less than
0.04 inch (1 millimeter) in length, would be able to swim against the
current to settle and grow in these spaces, Gollner said. Tube worms
are immobile creatures that settle and grow in one place without
moving, like barnacles.
“That is why we hypothesized that tubeworm larvae can travel in
cracks below the ground with the warm vent fluid to colonize the
surface vents from below,” Gollner said in an email.
The research expedition, helmed by lead study author Dr. Monika Bright,
professor and head of the department of limnology and bio-oceanography
at the University of Vienna, designed an experiment involving the
placement of mesh boxes on the seafloor 8,251 feet (2,515 meters) below
the ocean’s surface to collect samples from cracks in Earth’s
crust.
But it was more difficult than expected, Gollner said. Direct evidence
of animal life beneath the seafloor would require more heavy lifting
— literally.
“We kind of needed to be creative and apply basically a new
method,” Gollner said. “Flipping around the rocks opened our view
into the underworld of hydrothermal vents.”
The team used the SuBastian robotic explorer to drill small holes into
rocks on the seafloor and lift them up. The ROV’s arm flipped over a
small chunk of the volcanic crust, revealing cavities below the
hydrothermal vents filled with water at a balmy 75 degrees Fahrenheit
(24 degrees Celsius) — as well as tube worms in both larvae and adult
form, mobile animals such as snails, and bacteria.
Sunlight can’t penetrate the depths of the ocean floor to help
organisms convert elements into oxygen and sugar through
photosynthesis. Instead of sunlight, chemosynthetic bacteria use
chemical reactions to produce sugars that other animals clustered
around the vents use to live.
“Our understanding of animal life at deep-sea hydrothermal vents has
greatly expanded with this discovery,” Bright said in a statement.
“Two dynamic vent habitats exist. Vent animals above and below the
surface thrive together in unison, depending on vent fluid from below
and oxygen in the seawater from above.”
Uncovering life in this previously unknown subhabitat suggests there
may be many more organisms than scientists have documented within the
ocean’s depths or along its floor, said Alex Rogers, marine biologist
and science director for . Rogers was not involved in the new study.
It’s also likely that these subterranean ecosystems remain once the
vents become inactive over time, so they could form new habitats for
other species, he said.
“The paper adds to our understanding of vent ecosystems, how
populations of vent organisms are maintained and just how much life
exists at these systems,” Rogers said.
Protecting a subterranean world
Next, the team wants to determine whether life exists beneath all
deep-sea hydrothermal vents as well as how far the caves extend
horizontally and vertically, Gollner said.
“The discovery of animal life beneath the surface of the Earth’s
crust raises questions concerning the extent of these ecosystems, which
is larger than what can be seen on the seafloor surface,” the authors
wrote in the scientific report. “The study of the subseafloor
biosphere for animal life has just begun.”
But extreme care must be taken when studying these fragile ecosystems.
For the study, the researchers only lifted six small squares of the
seafloor measuring about 20 by 20 inches (50 by 50 centimeters) to make
as little disturbance as possible.
The team worries that lifting larger pieces or any form of major
drilling, such as deep-sea mining, could change the route of
hydrothermal vents and redirect them to be expelled at other locations,
causing the animal life that clusters around the vents to die, Gollner
said.
“With this understanding, we also know that we not only need to
protect what we see on the surface, but also we should protect what is
living below, because it is one important component of this
ecosystem,” Bright said.
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