Posts Tagged ‘oceanography’
“We can only sense that in the deep and turbulent recesses of the sea are hidden mysteries far greater than any we have solved.”*…
A new study finds that the vast majority of the deep sea floor remains undocumented. Nell Greenfieldboyce report…
Bizarre creatures like vampire squid and blobfish make their home in the dark, cold, depths of the deep sea, but most of this watery realm remains a complete mystery.
That’s because humans have seen less than 0.001% of the globe’s deep seafloor, according to a new study.
In fact, the area of the deep seafloor that’s been directly visualized is roughly equivalent to the state of Rhode Island, researchers report in the journal Science Advances.
Maps created with tools like sonar can show the shape of the seafloor, but it’s much harder to send cameras down beyond 200 meters, or more than 656 feet, where sunlight begins to fade rapidly and the waters turn cold and dark. This is the region of the ocean that’s considered “deep.”
“The fact of the matter is, when you’re down there with a remotely operated vehicle or other sort of deep-submergence vehicle, you can only see a very tiny bit of the deep sea floor at any one time,” says Katy Croff Bell of the nonprofit Ocean Discovery League, who led this new research…
… To try to get a better accounting of the total area of the deep seafloor that’s been observed so far, she and her colleagues created a database of all known efforts. They found records of more than 43,000 trips down, starting in 1958, with everything from robotic vehicles to human-driven subs to simple landers that didn’t move around.
It turns out that most of the exploratory expeditions occurred within 200 nautical miles of the United States, Japan, and New Zealand. Those three countries, along with France and Germany, led nearly all of the efforts.
As a result, scientists really haven’t seen a very representative sample of what’s going on around the globe…
… Bell says we don’t know what habitats might yet be discovered — and that even though the deep ocean might be out of sight and out of mind for most people, the currents down there bring oxygen and key nutrients up towards the surface.
“All of these things are connected, and impact us in so many different ways,” she says.
What little has been explored beneath the deep ocean suggests that it can have dramatically different ecosystems that support very different kinds of living things. Already, in the ocean, explorers have seen hot hydrothermal vents, alkaline vents, and cold seeps.
“But given how little we’ve seen and how biased it is, we can’t really give you a global map of all the habitats of the deep sea, because we just haven’t been to all of them,” she says.
Past explorations to the deep have revealed completely unexpected forms of life. For example, in the 1970’s, researchers discovered microbes at hydrothermal vents that did not depend at all on the sun and photosynthesis, and instead got their energy from chemical reactions.
“That was completely revolutionary and completely rewrote all the science books,” she says.
Geologist and deep sea expert Jeffrey Karson of Syracuse University, who wasn’t part of this research team, says this is the first time he’s ever seen a well-documented number that really encapsulates what’s been seen of the deep ocean floor so far.
He would have assumed the area seen by humanity was less than 1% of the total, he says, but was still surprised the faction would be “such a tiny number.”
“We’re spending a lot of money to try to understand other planets, maybe planets outside of our solar system. And yet right here on our own planet, we know so little of what’s going on in this area that covers about two-thirds of our planet,” says Karson. “Almost every time we go there, we learn something new and exciting, and many of our discoveries on the seafloor have been serendipitous. So, you know, we’re feeling our way in the dark, literally, there.”..
We’re asleep to the deep: “Humans still haven’t seen 99.999% of the deep seafloor,” from @ngreenfieldboyce.bsky.social and @npr.org.
* Rachel Carson, The Sea Around Us (1951)
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As we dive deep, we might spare a thought for Robert S. Dietz; he died on this date in 1995. A marine geologist, geophysicist, and oceanographer with the United States Coast and Geodetic Survey, he developed (in 1961) a theory of seafloor spreading (a term he coined), in which new crustal material continually upwells from the Earth’s depths along the mid-ocean ridges and spreads outward at a rate of several inches per year.
“Purple, formalized, iridescent, gelatinous”*…
Doug Muir on one of Nature’s more striking creations…
There’s been a a certain amount of negativity floating around lately. So, let’s talk about a toxic, venomous freak of nature and the parasite that afflicts it.
Biology warning, this gets slightly squicky.Let’s start with the toxic, venomous freak of nature: the Portuguese man-o’-war…
… So it’s a jellyfish. Except it isn’t really: it’s several jellyfish, smooshed together. And here’s where the “freak of nature” part kicks in.
I mean, yeah, strictly speaking nature has no freaks; every species that exists, belongs; everything is a product of evolution and Life’s Rich Pageant, yadda yadda. But the Portuguese man-o’-war — Physalia physalis, for you biologists — is honestly kinda freaky. Because Physalia is a colonial organism.
What this means: a single Portuguese man-o’-war is composed of four or five separate animals. (We’re not actually sure how many.) One animal is the balloon-sail-thingy on top; another is the stinging tentacles; another is the digestive system; another is the gonads. And they’re completely distinct organisms.
How this happens: when a Physalia egg is fertilized, it starts dividing, like every other fertilized egg. But pretty quickly it breaks apart into two and then more distinct embryos — genetically identical, but physically separate. And those embryos develop into completely different creatures. Then, later in development, those creatures re-attach to form a single Frankenstein organism. The various parts have their own nervous systems, which don’t seem to connect.
Here’s an analogy: imagine that before birth, you are identical twins. But instead of growing into two babies, one twin grows into a bodiless head, the other into a headless body. Then just before birth they stick together, but they don’t actually merge back into one. No, going forward you are a bodiless head glued on top of a headless body, ever after. It’s kind of like that.
Now, colonial animals aren’t unknown in nature. But most of them are either dinky (Volvox, don’t ask) or they’re big, but it’s basically cut-and-pasting the same creatures over and over. So, some corals are colonial, but all this means is that the individual polyps have grown into each other to produce a sort of living carpet interlaced through their stony skeleton. But the man-o’-war is a respectably large animal — they can grow as big as a large house cat — and so are its colonial components. And the components are extremely specialized: the float-animal part of it looks and acts nothing like the tentacle-animal part.
Physalia is by far the largest complex colonial animal. And — this bit is odd — it doesn’t have any relatives. It’s the only genus in its family. Put another way, within the jellyfish it has no siblings and only a few very distant cousins. (One of which is the ridiculous creature known as the Flying Spaghetti Monster Jellyfish, but never mind that now.) It’s a very successful organism! There are millions and millions of them, found all over the world in tropical and subtropical oceans. So you would expect to see speciation, different relatives — big ones, little ones, a bunch of variations on a theme. More on this shortly.
But meanwhile, the whole “colonial animal” thing looks like evolution’s first attempt to figure out, you know, organs. I mean, the first multicellular animals were probably sponges, and sponges don’t actually have organs. But more complex animals have distinct and differentiated organs, modules of specialized tissue performing particular functions, because those turn out to be super useful. Physalia and other colonial animals look like a beta-test platform for this new “organ” technology. Most of the animal kingdom moved on to “oh wait, why don’t we just have one single creature that grows the different modules inside it”, but a few colonial animals stuck with Plan A and made it work.
Okay, so that’s the “freak of nature” part. What about the “toxic and venomous”?…
Read on to be astounded: “Occasional Paper: Four Hidden Species of Portuguese man-o’-war,” from the always-illuminating @crookedtimber, via Ingrid Burrington‘s exquisite newsletter, Perfect Sentences.
* “The purple, formalized, iridescent, gelatinous bladder of a Portuguese man-of-war was floating close beside the boat. It turned on its side and then righted itself. It floated cheerfully as a bubble with its long deadly purple filaments trailing a yard behind in the water.” – Ernest Hemingway, The Old Man and the Sea
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As we tangle with tentacles, we might spare a thought for Columbus Iselin; he died on this date in 1971. An oceanographer, he taught at both Harvard and MIT, and was a long-time Director of the Woods Hole Oceanographic Institution, which grew materially in both scope and impact under his leadership.
His own work included both the invention of the bathythermograph and other deep-sea instruments responsible for saving ships during World War II and foundational scholarship on the oceanography of the Gulf Stream… where, of course, one can find the Portuguese man-of-war.
“No water, no life. No blue, no green.”*…
Between AD 1275 and 1300, the Anasazi, a civilization that had thrived in the canyonlands of the Four Corners area of the American Southwest for a thousand years, simply vanished, abandoning their urban centers, their irrigated lands, their sacred enclosures. Their descendants, the Hopi and Zuni, tell of a time of drought, the end of the rains. Without food in the desert, one can live for a fortnight; without water, perhaps a day. The collapse of the Anasazi occurred in a single generation.
The drought in the American Southwest has now entered its twenty-third year– and as Wade Davis explains in an excerpt from his book River Notes: Drought and the Twilight of the American West, the historic drought of the last couple of decades is threatening the Colorado River (on which 40 million Americans and 5.5 million acres of agriculture depend) and raising that specter again…
… We are today in the third decade of a drought that, despite heavy snowpacks in California and parts of the mountain west, remains unrelenting.
Over the last century, the river’s flow has averaged roughly 15 million acre-feet a year, far less than the 17.5 million acre-feet that planners anticipated when water rights were apportioned to the seven states of the basin — Wyoming, Colorado, Utah, New Mexico, Nevada, Arizona, and California — in 1922. In that year, the population of Arizona was roughly 350,000, that of Nevada a mere 80,000. Between 2000 and 2022, the flow of the river dropped to an average of 12 million acre-feet; over the last three years the annual flow has been but 10 million acre-feet. Even as the volume of water coming down the Colorado has dramatically declined, the seven states of the basin continue to clamor for allotments based on flawed assessments established nearly a century ago, exerting rights to consume what the river cannot provide.
As a result, during a drought of historic severity, water consumption has consistently surpassed the total natural flow of the river; altogether since 2000, water use has out-stripped supply by 33.6-million acre-feet (an acre-foot is 325,851 gallons). To meet demand, water has been diverted from the major reservoirs. Lake Mead, last full in 1983, is today down to 28 percent of capacity, 1,040 feet above sea level, the lowest it has been since the floodgates closed in the 1930s. If the reservoir drops below 950 feet, the Hoover Dam will no longer generate hydroelectric power. At 895 feet, the reservoir becomes a deadpool; water can no longer pass through the dam. The river downstream ceases to exist.
The situation at Lake Powell is equally grim. Its capacity is now down to 22 percent. In February 2023, the reservoir dropped to 3,522 feet above sea level, the lowest since the Glen Canyon Dam became operational in 1963. Should the water level drop another 32 feet, which can readily occur in a year, it will no longer be possible to generate electricity that today powers and cools the homes and businesses of 4.5 million citizens. A power outage in Phoenix, coinciding with a two-day heat wave, could result in half the population — 800,000 or more — seeking emergency care in hospitals set up to handle but 3,000 patients. An estimated 12,800 would die. At 3,370 feet, Lake Powell will reach deadpool. The Glen Canyon Dam will be but a concrete plug. Water will cease to flow, cutting off the drinking supply of well over 25 million Americans, including most of those living in Phoenix, Las Vegas, Tucson, and much of the Los Angeles basin.
…ordinary American families are already experiencing shortages that would have been unthinkable in 2006. For decades, the Arizona city of Scottsdale has provided the Rio Verde Foothills, a community of two thousand homes, with access to its municipal water supply, sourced from the Colorado. On January 1, 2023, this supply was cut, a decision made by a city facing its own crisis, leaving the people of Rio Verde no option but to buy water by the truckload at prices that tripled overnight. Those who dug wells discovered that, after years of drought, the water table had fallen by hundreds of feet. Residents have turned to using paper plates and urinating outside, even while coping with monthly water bills as costly as their mortgage payments.
Cities such as Las Vegas have implemented strict conservation measures, banning ornamental grass, limiting water deliveries to golf courses, reducing the size of swimming pools, using recycled water whenever possible. Yet despite these efforts, Las Vegas still uses twice as much water as the average US consumption. Hedging its bets, the city is building a three-mile-long tunnel that will come up at the bottom of Lake Mead, a $1.4-billion drain to ensure that if the reservoir ever runs dry, Las Vegas will get the last drop.
In the end, what Las Vegas and other cities do hardly matters, for the elephant in the room remains agriculture. Fully 80 percent of the water drawn from the Colorado goes to irrigating some 5.5 million acres, most of which is used to grow alfalfa and grass to feed cattle, and not only in the United States. Alfalfa grown in Arizona is exported by the ton to fatten cattle in Asia and the Middle East…
Water, water– not a drop to drink? “The Climate Crisis Could Mean the Twilight of the American West,” from @authorwadedavis in @RollingStone. Eminently worth reading in full.
* Sylvia Earle
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As we dowse, we might spare a thought for Bjørn Helland-Hansen; he died on this date in 1957. A pioneering oceanographer, his studies of the physical structure and dynamics of the oceans and their interactions with the atmosphere were instrumental in transforming oceanography from a science that was mainly descriptive to one based on the principles of physics and chemistry.
“Sharks. I never saw that coming.”*…
While many land-based predators (like wolves) avoid cities, scientists tracking sharks in Florida’s Biscayne Bay found the fish spent just as much time near Miami as away from it. Warren Cornwall explains…
Certain kinds of wildlife are notorious for thriving in urban settings. Think rats, rock pigeons and even the occasional coyote. Now, Florida scientists have added another creature to the list: sharks.
While many large predators show little appetite for city living, an intriguing project tracking the movements of sharks as fearsome as hammerheads revealed the fish are unexpectedly tolerant of life up close to the 6 million humans of greater Miami.
“We were surprised to find that the sharks we tracked spent so much time near the lights and sounds of the busy city, often close to shore, no matter the time of day,” said Neil Hammerschlag, director of the University of Miami’s Shark Research and Conservation Program.
Ecologists group animals into two main categories when it comes to their tolerance for human development. Some, like raccoons or rats, have figured out how to capitalize on the trash we make and the nooks and crannies we build. They are “urban exploiters.” Then there are the animals like mountain lions, lynxes and wolves that generally give human infrastructure a wide berth, often abandoning habitat where roads or buildings encroach. These are the “urban avoiders.”
As that list suggests, on land, big, toothy predators generally keep their distance from the din of the city. But less is known about their aquatic counterparts. So, a group of researchers set out to see if the sharks of Miami’s Biscayne Bay might shed some light on the matter…
“The new wildlife in town: Sharks,” from @WarrenCornwall in @AnthropoceneMag.
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As we hug the shore, we might send deep birthday greetings to Robert Ballard; he was born on this date in 1942. An oceanographer, explorer, retired naval officer, and professor, he noted for his work in underwater archaeology: maritime archaeology and archaeology of shipwrecks. He is probably best known for his discoveries of the wrecks of the RMS Titanic in 1985, the battleship Bismarck in 1989, the aircraft carrier USS Yorktown in 1998, and the wreck of John F. Kennedy’s PT-109 in 2002. But he believes that his most important discovery was the existence of hydrothermal vents.
“The future belongs to those who give the next generation reason for hope”*…
After this post, your correspondent is heading into his customary Holiday Hiatus; regular service will resume in early 2021. In the meantime, a piece to ponder…
“Civilizations with long nows look after things better,” says Brian Eno. “In those places you feel a very strong but flexible structure which is built to absorb shocks and in fact incorporate them.”undefined You can imagine how such a process could evolve—all civilizations suffer shocks; only the ones that absorb the shocks survive. That still doesn’t explain the mechanism.
In recent years a few scientists (such as R. V. O’Neill and C. S. Holling) have been probing the same issue in ecological systems: how do they manage change, how do they absorb and incorporate shocks? The answer appears to lie in the relationship between components in a system that have different change-rates and different scales of size. Instead of breaking under stress like something brittle, these systems yield as if they were soft. Some parts respond quickly to the shock, allowing slower parts to ignore the shock and maintain their steady duties of system continuity.
Consider the differently paced components to be layers. Each layer is functionally different from the others and operates somewhat independently, but each layer influences and responds to the layers closest to it in a way that makes the whole system resilient.
From the fastest layers to the slowest layers in the system, the relationship can be described as follows:
All durable dynamic systems have this sort of structure. It is what makes them adaptable and robust…
Stewart Brand (@stewartbrand) unpacks a concept that he popularized in his remarkable book How Buildings Learn and that animates the work of The Long Now Foundation, which he co-founded– pace layers, which provide many-leveled corrective, stabilizing feedback throughout the system. It is in the contradictions between these layers that civilization finds its surest health: “Pace Layering: How Complex Systems Learn and Keep Learning.” Do click through and read in full…
* Pierre Teilhard de Chardin
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As we take the long view, we might recall that it was on this date in 1872 that HMS Challenger set sail from Portsmouth. Modified for scientific exploration, its activities over the next four years, known as The Challenger Expedition, laid the foundation for the entire academic and research discipline of oceanography.
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