New Scientist - USA (2022-01-22)

20 | New Scientist | 22 January 2022

Marine life

THE largest colony of fish nests

ever seen has been found under

an ice shelf near Antarctica.

Autun Purser at the Alfred

Wegener Institute in Germany

and his colleagues came across

the breeding ground in the Weddell

Sea by chance when they went

on a six-week expedition to the

polar region in February 2021.

They were on board RV

Polarstern, a massive polar

exploration ship designed to

navigate freezing waters by

breaking through ice cover. Purser’s

job was to trail a camera behind

the ship to image the sea floor.

The researchers were doing

a routine analysis of the seabed

when they stumbled on thousands

of nests made by Jonah’s icefish

(Neopagetopsis ionah), a type of

small ray-finned fish that is typically

found in the Southern Ocean.

The nests (pictured) look like blue

circles on the sea floor and are each

about 15 centimetres deep. The

researchers then spent the next four

days documenting the colony. They

estimate that it contains more than

60 million nests and covers at least

240 square kilometres. Each of the

nests had one adult fish and about

1500 to 2000 eggs, equating to

around 100 billion across all nests

(Current Biology, doi.org/hcqb).

While researchers have observed

this species before, they have only

been seen in small colonies. “An

assemblage on this scale is just

mind-blowing,” says Katrin Linse

at the British Antarctic Survey.

Purser’s team has left cameras

on the sea floor near the active nests

to try to capture footage of the eggs

hatching. Jason Arunn Murugesu

Vast icefish breeding ground

discovered in frigid waters

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News In brief

STAR-forming regions that

surround our solar system have

been mapped for the first time.

These regions appear to lie on

a deformed surface 1000 light

years across, called the Local

Bubble. The bubble’s interior,

which is where the solar system

is found, is mostly empty space.

But its shell is made of cold gas

and dust that was left over from

exploding stars. New stars are

now forming from this material.

We have known about the

existence of the Local Bubble – and

about the star-forming regions

nearest to the solar system – for

decades. But Catherine Zucker

at Harvard University and her

colleagues have now made a clear

connection between the two.

They did so using data from

the European Space Agency’s

Gaia satellite, which maps the

positions, distances and motions

Space

of stars with high precision.

This allowed them to construct

a three-dimensional map of the

different star-forming regions.

The map also used Gaia’s motion

data to chart how the Local Bubble

has evolved over time and created

the star-forming regions (Nature,

doi.org/hcrg).

When some stars reach the end

of their life, they trigger a powerful

explosion called a supernova.

Our Local Bubble appears to have

formed when several supernova

shock waves swept gas and dust

through space, forming the

bubble’s dense shell.

With time, the material in the

shell began to form a series of

molecular clouds, or stellar

nurseries, which are the

birthplaces of new stars.

“This result argues strongly

for the case that star formation

triggered by expanding shells is

probably more important than

we thought before,” says Martin

Krause at the University of

Hertfordshire, UK. Alex Wilkins

Giant bubble around

solar system charted

ORGANIC compounds – those

containing carbon atoms – found

all over Mars were produced by

water interacting with volcanic

rocks, according to the analysis

of a Martian meteorite.

Andrew Steele, who is at the

Carnegie Institution for Science

in Washington DC, and his team

examined a Martian meteorite,

known as Allan Hills 84001, that

contains organics, which can also

Mars

be produced by life. The rock was

ejected from the surface of Mars

by a collision and later landed on

Earth. They found that its organics

were formed by water filtering

through tiny cracks and pores

in the rock and interacting with

the minerals there.

The team found signs of two

processes known as carbonisation

and serpentinisation. Each occurs

when water interacts with rock.

This results in hydrogen and

carbon dioxide that react to

create organic molecules

(Science, doi.org/hc2p).

However, even though the

organics in Mars rocks seem to be

created abiotically – without the

help of life – those compounds

could still be important in the

hunt for life on Mars. “Abiotic

chemistry gives you a background,

and life picks and chooses what it

needs from that and concentrates

those up, so to find life you look

for higher concentrations of those

background abiotic levels,” says

NA Steele. Leah Crane

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Organics in martian

rock not made by life