Using whale songs to image beneath the ocean’s floor

image NOAA

 

From Ars Technica by John Timmier

People tend to think of seismic waves as little more than signals of tectonic events, like an earthquake or lava shifting under a volcano.
But these vibrations are also our best way of getting a clear picture of our planet's internal structure.
By watching how the vibrations' paths shift as they encounter different materials, we can get a picture of where different rock layers meet, where rock becomes molten, and more.

In some cases, we get this picture by waiting for a natural event to produce the seismic waves.
In others, we get impatient and set off explosive charges or use a powerful sound-making device.
Today, Václav Kuna and John Nábėlek of Oregon State University are describing yet another option: waiting for a whale to float by.
Using the songs of passing fin whales, the researchers were able to reconstruct the upper layers of the seafloor off the coast of Oregon.
Quite a song

The song of a fin whale is not exactly the sort of thing you'd typically describe as musical.
It's generally in the area of 20Hz, which sounds more like a series of clicks than a continual sound, and the whales produce it in second-long bursts separated by dozens of seconds.
But they are loud.
A guidance on hearing risks places danger at any level above 80 decibels and the loudest concerts as hitting roughly 120 decibels.
A fin whale's song can be in the neighborhood of 190 decibels (although that's in water, which transmits sound differently from the air), and it typically goes on for hours.

As it turns out, the frequency of whale calls is within the range of a bunch of underwater seismographs that researchers had placed on the ocean floor west of the coast of Oregon.
These seismographs sample for signals 100 times every second, so they can easily pick up the song of a fin whale.

And in fact, the equipment had picked up the songs.
By focusing on the calls themselves, Kuna and Nábėlek could track the whales as they went along singing.

The songs they recorded typically went on for hours, during which time the whales cruised through the area at a rate of between 4 and 10 kilometers an hour.
This meant that the song-filled trips ranged from 15 to 40 kilometers.
During these trips, each individual whale produced anywhere from 200 to 500 individual bursts that could be picked up by the seismographs.

But the whale's songs don't only reach the seismographs by a direct route.
Some of the sound waves get there after bouncing off the ocean's surface or floor—and some of them bounce between the two more than once.
Others hit the ocean floor and then bounce off the different layers of material below it.
All of them reach the instrument at different times within the 40-second window between each individual sonic element of the song.

 

The echoes created by a fin whale are rather complicated.
Kuna and Nábelek

Reconstructing the exact details of which signals arise, and when, is complicated, to put it mildly.
But earth science researchers have a great deal of experience with this sort of thing.
Waves that take certain paths require enough physical space between the whale and the seismometer to undergo all the reflections involved.
So certain elements are cut off when the whale gets closer than 12 kilometers, and another set cut out at 4 kilometers.

By piecing these details together, Kuna and Nábėlek were able to figure out the thickness of the sediment layer, a layer formed by lava flows below that, and more robust volcanic rock below that.
The seismometers were even sensitive enough to register differences in the amount of sediment, which ranged from 400 to 650 meters thick, that had built up.

Overall, the resolution wasn't as good as you'd get with human-triggered sound sources from the surface of the water.
But critically, you don't need an actual boat above the seismograph array to get data.
That's not a huge limitation for a specific study, but there are probably a lot more underwater sensors out there than there are people intentionally making seismic waves for them to pick up.
And fin whales have a global range, so there's likely to be a few around.

There are areas with a complicated topography—meaning lots of lumps on the ocean's floor—where reading whale song probably wouldn't be all that effective.
But the researchers behind this work think they can probably boost the resolution by using a different whale with a higher-frequency song.
They specifically suggest that sperm whales would probably do the trick.

Links :

• DOI: 10.1126/science.abf3962 (About DOIs).
• NYTimes : Whale Songs Could Reveal Deep Secrets Beneath the Oceans
• Gizmodo : How Whale Songs Can Help Us Explore the Ocean

Global salmon farming harming marine life and costing billions in damage

Fish mortality has more than quadrupled, from 3% in 2002 to about 13.5% in 2019, in Scottish salmon farms alone.
Photograph: Robert F Bukaty/AP

From The Guardian by Fiona Harvey

Report says pollution, parasites and fish mortality rates cost an estimated $50bn globally from 2013 to 2019

Salmon farming is wreaking ruin on marine ecosystems, through pollution, parasites and high fish mortality rates which are causing billions of pounds a year in damage, a new assessment of the global salmon farming industry has found.

Taken together, these costs amounted to about $50bn globally from 2013 to 2019, according to a report published on Thursday.

Fish mortality has more than quadrupled, from 3% in 2002 to about 13.5% in 2019, in Scottish salmon farms alone.
About a fifth of these deaths are recorded as being due to sea lice infestations, but about two thirds are unaccounted for so the real mortality owing to sea lice – which feed on salmon skin and mucus, effectively eating the fish alive – could be much higher.

Scotland is one of the biggest producers of farmed salmon in the world, with the industry worth an estimated £2bn a year to the Scottish economy.
But the costs in environmental terms alone were reckoned to be £1.4bn from 2013 to 2019, by Just Economics, which carried out the research for the report, entitled Dead Loss, for the Changing Markets Foundation campaigning organisation.

The sheer quantity of wild fish used in salmon farms is also a growing concern.
About a fifth of the world’s annual wild fish catch, amounting to about 18m tonnes of wild fish a year, is used to make fishmeal and fish oil, of which about 70% goes to fish farms.
This is causing problems for fishers in developing countries, who are seeing their stocks depleted in order to feed western consumption of farmed fish, according to the report.

Key species such as sardines in west Africa are now heavily overfished for this purpose, and this situation is likely to deteriorate further as fish farmers plan substantial expansion in the coming years.
Scotland alone plans to double its farming capacity by 2030, while Norway expects a fivefold increase by 2050, according to the report.

 

Salmon farmers could use oils from algae as a source of Omega 3 for their farmed fish, to replace fish oil from wild fish, but few do so, according to the report.
Natasha Hurley, campaigns manager at the Changing Markets Foundation, told the Guardian: “Moving away from using wild caught fish in food would make salmon farming more sustainable, as it is having a huge impact on wild fish.”

She said consumers were often unaware of what they were buying, as fish is poorly labelled in UK supermarkets and its farmed origin is often not obvious.
She called on governments to tighten the rules on licensing fish farms, to enforce lower stocking density on farms, and to improve labelling.

The report also examined the salmon farming industry in Canada, Norway and Chile, the other biggest global producers.
It found that of the costs associated with fish farming, about 60% were borne by the producers, especially in the form of fish mortality and the cost of treating sea lice, but about 40% of the costs were borne by wider society, for instance in pollution, loss of fish populations and the impacts on the climate crisis.

Mowi, a Norwegian company, produces a fifth of the world’s farmed Atlantic salmon, and is named in the report as showing 50m premature fish deaths from 2010 to 2019, at a cost of about $1.7bn.
A spokesperson for the company said: “We are pleased that the report finds that, when considering the full range of benefits and impacts, the business of salmon farming demonstrates overall positive benefit.
We agree that there are opportunities for continued improvements for our business.
The inclusion of small amounts of fish meal and oil in our salmon’s diet is certified sustainable by third parties and integral to a salmon’s health and welfare.”

A spokesperson for the Scottish Salmon Producers Organisation said: “Farmed salmon has a great environmental story to tell – it has the lowest carbon footprint of any main livestock protein, it is a nutritious and healthy food and, as the UN and other international experts have acknowledged, aquaculture provides one of the best solutions to feeding the world’s burgeoning population in the years to come.
It is a shame that the authors have chosen to ignore these undeniable benefits when publicising this report.”

Links :

• The Scotsman : Supermarkets suspend trading with salmon farm amid investigation 
• Food Navigator : Report reveals hidden cost of salmon farming
• BBC : Is there a problem with salmon farming?
• MarineBiology : Review: The environmental and economic impacts of salmon aquaculture
  

Scientists accidentally discover strange creatures under a half mile of ice

photograph : Dr Huw Griffiths /BAS

From Wired by Matt Simon

Researchers only drilled through an Antarctic ice shelf to sample sediment.
Instead, they found animals that weren't supposed to be there.

Bivouacked in the middle of the Filchner-Ronne Ice Shelf—a five-hour flight from the nearest Antarctic station—nothing comes easy.
Even though it was the southern summer, geologist James Smith of the British Antarctic Survey endured nearly three months of freezing temperatures, sleeping in a tent, and eating dehydrated food.
The science itself was a hassle: To study the history of the floating shelf, he needed seafloor sediment, which was locked under a half mile of ice.

To get to it, Smith and his colleagues had to melt 20 tons of snow to create 20,000 liters of hot water, which they then pumped through a pipe lowered down a borehole.
It took them 20 hours to melt through the ice inch by inch, finally piercing through the shelf.

Next, they lowered an instrument to collect the sediment, along with a GoPro camera.
But the collector came back empty.
They tried once more.
Still empty.
Again, nothing comes easy here: Each round trip of the instrument took an hour.

 

video : Dr Huw Griffiths, BAS

see NewScientist tweet

Later that night in his tent, Smith watched the footage, and recognized a rather glaring problem.
The video shows a descent through 3,000 feet of blue-green ice, which suddenly terminates, opening up into dark seawater.
The camera coasts another 1,600 feet until the seafloor finally comes into view—mostly light-colored sediment, which Smith was after, but also something dark.
That dark thing turned out to be a rock, which the camera hits with a thud, tumbling face-down into the sediment.
The camera quickly rights itself and scans the rock, revealing something the geologists hadn’t been after at all.
In fact, it was something highly improbable: life.

photo : Dr Huw Griffiths, BAS

“It’s like, bloody hell!” Smith says.
“It's just one big boulder in the middle of a relatively flat seafloor.
It’s not as if the seafloor is littered with these things.” Just his luck to drill in the only wrong place.

Wrong place for collecting seafloor muck, but the absolute right place for a one-in-a-million shot at finding life in an environment that scientists didn’t reckon could support much of it.
Smith is no biologist, but his colleague, Huw Griffiths of the British Antarctic Survey, is.
When Griffiths watched the footage back in the UK, he noticed a kind of film on the rock, likely a layer of bacteria known as a microbial mat.
An alien-like sponge and other stalked animals dangled from the rock, while stouter, cylindrical sponges hugged the surface.
The rock was also lined with wispy filaments, perhaps a component of the bacterial mats, or perhaps a peculiar animal known as a hydroid.

The rock Smith had accidentally discovered is 160 miles from daylight—that is, the nearest edge of the shelf, where ice ends and the open ocean begins.
It’s hundreds of miles from the nearest location that might be a source of food—a spot that would have enough sunlight to fuel an ecosystem, and be in the right position relative to the rock for known currents to supply these creatures with sustenance.

 
Not to tell life its business, but it’s got no right being here.
“It's not the most exciting-looking rock—if you don't know where it is,” says Griffiths, lead author of a new study published in the journal Frontiers in Marine Science.
Since you now do know, then it means your jaw may be somewhere near the floor right about now.

We can say for certain that these animals are living in total darkness, which is fine—plenty of deep-sea critters do the same.
But animals that live sessile (read: stuck in place) existences on the deep sea floor must rely on a fairly steady supply of food in the form of “marine snow.”

Every living thing swimming in the water column above must one day die, and when they do, they sink to the depths.
As the corpses descend and decompose, other creatures pick at them and fling off particles, tiny morsels that accumulate even on the deepest of seafloors.
(When a whale dies and sinks, by the way, it’s epically known as a “whale fall.”)

This works in most parts around Antarctica, where the waters are incredibly productive.
Tiny critters known as plankton feed all kinds of fish, which feed large marine mammals like seals.
All this activity produces detritus—and dead animals—that one day become marine snow.

But the Antarctic critters on this particular rock don’t live under a bustling water column.
They live under a half-mile of solid ice.
And they can’t roam away from their rock in search of food.
“The worst thing in a place where there's not much food, and it's very sporadic, is to be something that's glued to the spot,” says Griffiths.
So how on Earth could they be getting sustenance?

At bottom left, you can see stalked animals.
Top right are sponges.
picture  : Dr Huw Griffiths, BAS

The researchers think it’s likely that the drift of this marine snow has been flipped on its side, so that the food source is moving horizontally instead of vertically.
Looking at charts of currents near the drill site, the researchers determined that there are productive regions between 390 and 930 miles away.
It may not be much, but it’s possible that enough organic material is riding these currents hundreds of miles to feed these creatures.
That’s an extraordinary distance, given that in the deepest part of the ocean, the Challenger Deep near Guam, marine snow produced at the surface has to fall 7 miles down to reach the seafloor.
To reach the animals on this Antarctic rock, food would have to travel as much as 133 times that distance—and it would have to do so by floating sideways.

Given what scientists know about currents around Antarctica, this isn’t particularly far-fetched, says Rich Mooi, curator of invertebrate zoology and geology at the California Academy of Sciences, who has studied Antarctic sea life but wasn’t involved in this new work.
As seawater cools in the region, it grows more dense.
“It sinks to the sea bottom and pushes water outward, radiating outward from the Antarctic,” says Mooi.
“And these currents are actually the germ of many—if not almost all of—the current systems on the planet.”

As that water pushes outward, something has to fill the void.
“There's going to be some inflow to replace that,” Mooi adds.
“And that inflow, even over hundreds of kilometers, is going to carry organic matter.”

For our lifeforms stuck on that boulder, this would bring food.
The currents could also bring new animals to add to the population on the rock.

The remote drill site

picture : Dr Huw Griffiths, BAS

 

Links :

• BAS : Discovery of life beneath Antarctica’s ice shelves
• The Guardian : Researchers rethink life in a cold climate after Antarctic find
• New Scientist : Life found beneath Antarctic ice sheet 'shouldn't be there'
• CNN : Antarctic sponges discovered under the ice shelf perplex scientists
  

Behold all 42 maps from Jules Verne’s extraordinary voyages, the author’s 54-volume collection of “Geographical Fictions”

From OpenCulture

Jules Verne’s tales of adventure take his characters around the world, through the deepest seas, even into the center of the Earth—on journeys, that is, difficult or impossible in the 19th century.
Verne himself, however, spent most his life in France, writing of places he had not seen.
In one apocryphal story, the young Jules Verne is caught trying to sneak aboard a ship bound for the Indies and promises his father he will henceforth travel “only in his imagination.”

Whether or not he made such a vow, he seemed to keep it, though the idea that he never traveled at all is a “tiresome canard,” writes Terry Harpold in an essay titled “Verne’s Cartographies.”

Verne’s famed novels Twenty Leagues Under the Sea, Journey to the Center of the Earth, and Around the World in Eighty Days constitute only a fraction of the 54-volume Voyages Extraordinaires, a collection of fiction conceived on the basis of a science we might not think of as a rich field for material.

“Of the 80 novels and other short stories he published,” geographer Lionel Dupuy writes, “62 make up the corpus of Extraordinary Voyages (Voyages Extraordinaires).
These books, in which imagination played a vital role, were termed ‘geographical novels,’ a category the author himself used for them.”

Verne would also use the term “scientific novel,” but he made it clear which science he meant:

I always had a passion for studying geography, as others did for history or historical research.
I really believe that it is my passion for maps and great explorers around the world that led me to write the first of my long series of geographical novels.

As a geographical novelist, and member of the Geographical Society from 1865 to 1898, it was only fitting that Verne include as many maps as he could in his quest, as he put it, “to depict the Earth, and not just the Earth, but the universe, for I have sometimes carried my readers far away from the Earth in my novels.”

To that end, “thirty of the novels” in the first edition of Voyages Extraordinaires” published by Pierre-Jules Hetzel, “include one or more engraved maps,” Harpold points out.
“There are forty-two such engravings in all.” View them here.

“These images and design elements are nuanced, graceful, and evocative; drafted and engraved by some of the finest artists of the time,” Harpold writes.
“They represent the pinnacle of late nineteenth-century popular-scientific cartography.” They also represent the author of geographical fictions who, as both a scientist and artist, refused to let either form of thinking take over the text, combining myth and poetry with observation and measurement.
As Dupuy puts it, “in Extraordinary Voyages, the passage from reality to imagination and back is encouraged by the emergence of a ‘marvelous’ that we can call ‘geographical.’”

In one sense, we might think of most kinds of fiction as geographical, in that they describe places we have never seen.
This is particularly so in fictions that include maps of their imagined territories, such as those of William Faulkner, J.R.R.
Tolkien, Robert Louis Stevenson, and so on.
We might look to Jules Verne as their towering forbear.
“Several of the maps appearing in the Hetzel Voyages were drafted under Verne’s close supervision or were based on his sketches or designs.
Maps in three of the novels (20,000 Leagues[top], Hatteras [further up], Three Russians) were drafted by Verne himself, whose talents in this regard were appreciable,” writes Harpold.

Verne’s maps mix real and fictional place names and are “always ambiguous and semiotically unstable objects.”

They appear almost as admissions of the mythmaking that goes into the science of geography and the act of exploration.

Near the end of his life, maps became more real to Verne than the world outside.

As he grew too weary even to leave the neighborhood, he wrote to Alexandre Dumas fils, “If I have maintained a taste for work… , nothing remains of my youth.

I live in the heart of my province and never budge from it, even to go to Paris.

I travel only by maps.” See all of Verne’s maps from the Hetzel edition of Extraordinary Voyages, such as those for Around the World in Eighty Days (above) and Five Weeks in a Balloon (below), here.

 

Links :

• Jules Verne’s Most Famous Books Were Part of a 54-Volume Masterpiece, Featuring 4,000 Illustrations: See Them Online
• An Atlas of Literary Maps Created by Great Authors: J.R.R Tolkien’s Middle Earth, Robert Louis Stevenson’s Treasure Island & More
• William Faulkner Draws Maps of Yoknapatawpha County, the Fictional Home of His Great Novels
• GeoGarage blog : Jules Verne's most famous books were part ...  / Where is Point Nemo? 

Weymouth. 'Sovereign' trials (1964)

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America's Cup Yacht Race: Rhode Island (1964)