Intro

Our planet is full of beautiful places but it's also full of wonderfully weird places. And we here at SciShow have made a lot of episodes about Earth's bizarre places in the past. And now we've put together some of our favorites explaining the planet's weirdest lakes. Now, Earth's lakes are great. Many of them are beautiful places to relax and enjoy nature and these bodies of water are a big reason why we have a planet so full of nature in the first place. In fact, every body of water on Earth seems to be teaming with life. Except for in one place. Here's how that happened.

'The Only Water on Earth Without Life'

Wherever there's water on Earth, there's a pretty good chance that you'll find life. Like, even in the driest parts of the Atacama desert in South America, single celled organisms live in rocks that extract water from the air. And in Japanese hotsprings there are microbes that survive in acidity on par with battery acid. So in almost any water that would be deadly to you or me, there's probably something that calls it home. But there are a few places full of water that appear to be completely inhospitable to life. Some super acidic, super salty, and super hot pools in Ethiopia's Dallol Geothermal Field. And so far these pools are the only wet places anyone has found on Earth that don't host life. The Dallol Geothermal Field is at the top of a volcanic crater filled with salt, and it's a pretty dreadful place to try and live. It's got toxic gases coming out of cracks in the ground at temperatures above the boiling point of pure water and ridiculously acidic brines. So these pools aren't exactly jacuzzis, but some scientists who study extremophiles, or organisms that live in extreme environments, wondered if anything was possibly alive in there. After all, they'd found a lot of single-celled archaea in nearby areas, including the land around the water where conditions aren't as extreme but they aren't exactly homey either.

So between 2016 and 2018 an international team of researchers collected 200 water samples from multiple locations in the area to hunt for life. They took water from the steaming hot, extremely acidic ponds at the top of the Dallal dome as well as from the nearby black and yellow lakes which were not as hot or acidic but were super salty. And these samples were completely devoid of any native life. The only signs of life scientists detected were bacteria that appeared to have come from humans or the lab equipment. And there were others that might have blown in on dust carried by the wind. There was not a single native organism or any evidence that these foreign cells could actually survive the conditions in the Dallal pools. And there are some pretty good reasons why nothing would want to live there.

For one, there's the temperature. The temperatures in these pools range from 40 to 108 degrees Celsius. And when temperatures get too high, molecules that cells need to function, like proteins, start to lose their shape. And if they're the wrong shape they can't do their jobs. Which is kind of bad since they're basically involved in every part of keeping cells up and running. And under really extreme temperatures, proteins, and even DNA, will just break down altogether. And that's not the only problem in these pools either.

On top of the heat, they're extremely acidic. When acids are dissolved in water, they produce hydrogen ions, which are just plain old protons. And those ions are eager to chemically react with proteins. Which, again, messes with a cell's ability to function. So high temperature and acidity are a pretty deadly combination. But, to top it all off, these pools are also extremely salty.

Now, living organisms need some salt in their lives but too much quickly turns deadly. If the concentration of salt in water outside a cell is higher than what's on the inside, water will rush out of the cell to try to balance everything out and the cell will shrivel up like a raisin. So, that's bad to begin with, but certain salty solutions are extra deadly. Some salt ions, like magnesium, are what's called chaotroipic. Because they cause chaos. They break hydrogen bonds between water molecules which can lead to the breakdown of the complex molecules that organisms need to live and function.

And in case that's not bad enough, these ions also interact with water molecules in a way that prevents cells from being able to use that water in important chemical reactions. So these ponds are not welcoming to living things, but it's still kind of surprising that there's nothing living there. Because as deadly as these conditions are, around the planet there are certain extremophiles that can deal with some of these ridiculous challenges.

For example, thermophiles have extra hearty proteins with extra bonds built in that help them hold their shape. Some of them also have special proteins to repair molecules that have been damaged by heat.

And then there are the so-called acidophiles, which are either really good at pumping protons out of their cells or have special compounds to keep protons out entirely.

And, there are halophiles which have evolved to tolerate extreme salinity. For example, some of them build up a bunch of Potassium ions or other compounds on the inside to balance out extreme salinity on the outside.

So there are single-celled organisms that can handle extreme environments and there's even life that can handle more than one of these deadly conditions at a time. But the Dallal pools seem to be especially deadly and no one knows exactly why, but there are a few ideas.

It may be that its conditions are on the extreme end of extreme. Like, the salinity in the black and yellow lakes is over 50 percent, meaning that the lake is half salt. For comparison, the ocean's salinity is about 3.5 percent. These lakes also have high concentrations of those chaotropic salts like magnesium chloride and calcium chloride that make salty solutions especially deadly. And to make matters worse, there's the one-two punch of extreme salinity and acidity. Scientists aren't sure what, exactly, is so deadly about that combination, but even with so many extremophiles in the world, no one has yet found any organism that can tolerate both high salinity and high acidity. Which is what you've got in these pools.

So scientists may one day find some other wet part of Earth that's too extreme to harbor life, or maybe future tests will find something that can survive in these seemingly inhospitable pools. But either way, research like this helps scientists understand what it takes for life as we know it to survive. Which can be a great starting point when it comes to looking for life beyond Earth.

Transition

which can be a great starting point when it comes to looking for life beyond Earth.

So, you're not exactly gonna put on your sunglasses and dip your toes in that lake, but, as hostile as it seems, it's a pretty extreme case, like a perfect storm of deadliness. Because, on the other hand, some places that sound purely toxic are actually great for life. Olivia's got more on that.

Weird Places: The Jacuzzi of Despair
OLIVIA: You can find a lot of weird things when you dive deep into the ocean--bioluminescent fish, microbes in 86 million-year-old clay, or a priceless blue diamond necklace casually chucked from a research boat. But one thing you might not expect to find at the bottom of the ocean is a lake.

In the Gulf of Mexico, there's a lake so deadly that anything that goes for a swim gets pickled, yet there's a thriving ecosystem literally living on the edge, which might give astrobiologists a hint on how life could thrive on other worlds. Its name? The Jacuzzi of Despair.

A kilometer below the ocean surface, not too far off the coast of Louisiana, this underwater lake was discovered back in 2013 using the remotely operated vehicle called Hercules. The "jacuzzi," or sometimes "hot tub," moniker is because it's warmer than the nearby 4 degrees Celsius ocean water. During return visits in 2015, researchers recorded temperatures from 7.8 up to 19 degrees.

This underwater lake, and others like it around the world, are scientifically known as brine pools. Brine pools form over millions of years. To make our Jacuzzi, a proto Gulf of Mexico got closed off from the rest of the ocean during the Jurassic Period, some 165 million years ago. Over time, the water evaporated, leaving salts and other minerals behind. Then, that salt bed got buried under layers of sediment and, eventually, was submerged underwater again. Under all the weight of the sediment and ocean water, the salt bed deformed and shifted around. Scientists call this movement salt tectonics. Cracks in the sediment allowed water to creep downward, dissolving the salt to form a super concentrated

brine. In the Jacuzzi of Despair, it's roughly four times saltier than the surrounding ocean. The brine was squeezed upwards by the salt tectonics and some gasses that were also trapped beneath the sediment layers. And since the salty brine is much denser than regular seawater, it pooled up on the ocean floor.

Because the Jacuzzi of Despair contains some hydrocarbon gas leakage, it's also considered to be a cold seep, a name that just comes from the fact that it's cold relative to hydrothermal vents, which can reach temperatures over 400 degrees Celsius.

Specifically, the Jacuzzi is saturated with methane. And, there's also non-hydrocarbon gases, like the very toxic hydrogen sulfide. But, one gas you won't really find in that super salty water is oxygen.

What little there was in the brine pool to begin with got used up in chemical reactions, like organic stuff decomposing. And oxygen doesn't get replenished, because the huge difference in density at the pool's surface keeps gases from the nearby seawater from entering the brine.

The anoxia and other toxic gases makes the Jacuzzi of Despair deadly to most life except extremophile bacteria and archaea. Like, there's some chemosynthetic bacteria that use chemical reactions with the sulfur in the pool to make the energy they need to live, instead of sunlight.

But, the unlucky or fish that venture into the Jacuzzi of despair don't just die. Because of the brine's high salt content, they're effectively pickled, the water sucked from their cells in a doomed effort to balance the concentration of salt inside and outside their bodies.

And yet, there are complex organisms making a life down there. The Jacuzzi of Despair is surrounded by 3-meter-high walls built from precipitated minerals from the brine like Barite. All along these walls live massive colonies of mussels with chemosynthetic bacteria in their gills. They can use the methane from the pool as a source of energy and of carbon.

You'll also find shrimp, crabs, and amphopods crawling around down there. It's not the most diverse ecosystem on the planet, but these creatures are on the edge of instant death, so maybe give them a break.

Besides telling us about our own planet, studying extreme underwater places like

brine pools can also help us figure out how life might thrive on other water worlds, objects with liquid water in our solar system and beyond.

Saturn's moon, Enceladus, for instance, is probably the best candidate for extraterrestrial life that we found so far. In April 2017, the Cassini mission detected hydrogen gas in the moon's southern water plumes. Coming from what researchers think is a big sub-surface lake.

This hydrogen gas, along with carbon dioxide, could be used as a food source by chemosynthetic life that makes methane as a byproduct. And, any methane could be used by other kinds of microbes, like the bacteria living inside the mussels near the Jacuzzi of Despair.

Because the Cassini mission is about to end. We may have to wait decades to get more definitive answers. Until then, we can study more brine pools to get a peek at some of the strangest life on Earth and maybe predict what else could survive in extreme environments throughout the universe.

It goes to show that life is incredibly determined. Living things will make a home out of just about any environment they're given. Just ask the organisms hanging out in a giant pool of asphalt. Here's Hank with the details.

On the Caribbean island of Trinidad, there is a huge, oily lake made from millions of tons of asphalt and it contains the remains of lots of unlucky creatures. But it's not just some giant pond of pavement. Or death. In fact, this pool of oil and dirt has taught us a lot about life, from what it might look like elsewhere in the universe to how we can save what we have here on Earth.

Pitch Lake is the largest naturally-occurring asphalt lake on the planet, and I know what you're thinking right now. You're thinking, "there's more than one?!" Well, there isn't a ton of competition for the title. We only know about a handful of such lakes.

Still they've gained something of a reputation as places of doom and destruction, and for good reason! Instead of water, the liquid in Pitch Lake is mostly oil, what chemists call

hydrocarbons. According to one theory, the lake formed when one tectonic plate forced its way under another. That pushed oil deposits upward from the bowels of the Earth. The lighter components of the oil floated to the top and evaporated, leaving behind a heavy slick, which mixed with water, mud, and other things in the surrounding environment to form a dark, thick sludge. 

That sludge also happens to be a balmy 32 to 56 degrees celsius. And over millennia, it has served as kind of a natural trap for wildlife. Though a lot of the lake is solid enough to sustain a person's weight, other parts are more like quicksand. And in those spots, unwary animals can get stuck and sink, something which has happened a lot.

Lots of fossils and skeletons and even archaeological artifacts have been removed from the muck in pristine conditions, since the sticky goo prevents them from decomposing or being degraded by the elements or scavengers. In fact, such finds are what Pitch Lake's smaller cousin, the La Brea Tar Pits in California, is famous for.

But don't let that fool you into thinking asphalt lakes are giant pools of death. Even though there's very little water or oxygen in its "waters," Pitch Lake is actually teeming with life. For example, one 2011 study published in the journal Astrobiology found up to ten million organisms can live in a single gram of sludge from Pitch Lake.

Though that's about half of what you'd get from, say, a gram of water from one of the Great Lakes in Michigan, it's still a lot of microbes. And we're not talking about just one type of organism, either. Genetic sequencing revealed an incredible diversity of bacteria and other microbes living within the asphalt. And around 30% of the species were previously unknown to science.

But that was not what excited the team most. See the reason this study was published in the journal Astrobiology instead of a regular microbial journal is that there are lakes on other

worlds which look a heck of a lot like Pitch Lake. Specifically the ones on Saturn's moon, Titan. Previous studies had already suggested Titan's lakes may check many of the boxes for sustaining life, with one main exception: there's not enough water.

The lakes are full of hydrocarbons like methane instead, so it was thought that life simply couldn't survive in them. But very little water and lots of hydrocarbons seem to be no issue for Pitch Lake's microbes. So their mere existence suggests it's possible there's life on Titan, too. Of course, there's still some liquid water in Pitch Lake, which is warm and that's not necessarily true of Titan's methane lakes which are very cold.

And there's a big difference between an environment that's able to sustain life and having life arise in it. Still, even if Pitch Lake's microbes aren't a preview of life on Titan, they have a lot to offer their fellow earthlings. They could help us combat infectious diseases, for example.

In a 2018 study, researchers were able to isolate cholic acid derivatives from a Pitch Lake bacterium, molecules generally used to prevent other bacteria from growing. So, Pitch Lake's microbes could help us develop new antibiotics, which would be very helpful, given that lots of nasty things are becoming resistant to the ones we have.

And in addition to saving lives, studying the flora of Pitch Lake could help save the environment. A 2014 study published in Science analyzed minuscule water droplets from the oils of Pitch Lake, and concluded that they contain microbes which actively eat the hydrocarbons in their surrounding environment.

Other studies examining the soils next to the lake have also found bacteria that dine on these oils. Which is very good, because hydrocarbons are notoriously difficult to break down. Taking together these results could have implications for cleaning up oil spills, whether they're on land or in water. Scientists could, for example, introduce oil-eating bacteria

to an area to remove a spill more efficiently. And they may not even need the bacteria themselves. It may be possible to isolate the enzymes the microbes use to digest hydrocarbons and use those to develop a way of cleaning up oil on a much larger scale.

So yeah, even if Pitch Lake doesn't sound to you like an ideal vacation spot, it's a pretty great thing that so many microbes disagree. And by studying the organisms that think a large, hot lake of asphalt is prime real estate, we can learn a lot of useful things and maybe even get a glimpse of what awaits us on other worlds.

It's kind of weird how terrible environments like these might actually be the most welcoming environments on other planets. But these extreme places don't just support a few hardy species. Even on our planet, one unfriendly lake might be playing a big role in protecting all life on Earth. Here's what's going on there.

Imagine living in a place where you're surrounded by the sharp smell of ozone and hot, dry air. And, around 300 nights per year, the sky is lit up by nearly ten hours of continuous lightning strikes that can be seen from hundreds of kilometers away. In fact, during peak thunderstorm season, an average of 28 lightning strikes per minute hit the surface of Venezuela's Lake Maracaibo.

This lake and its weird lightning have been a scientific mystery for decades. But nowadays researchers think that a perfect storm of environmental factors is causing this everlasting light show. The phenomenon is known as Catatumbo lightning, named after the river that flows into the southern part of Lake Maracaibo.

It's been recorded as early as 1598, when the poet Lope de Vega recounted how it helped thwart a surprise attack by the English privateer, Sir Francis Drake. And on a molecular level, Catatumbo lightning is pretty normal. Lightning is a buildup and release of electric charge between one cloud and another, or between clouds and the surface of the Earth. 

When rain and icy dust particles collide during a thunderstorm, the clouds become polarized with clusters of positively and negatively charged particles. Basically, we think that upward currents

of air push some molecules skyward, while heavier particles drop down and collide with them, snagging electrons along the way. Since electrons are negatively charged, the bottom of the cloud gets more negatively charged and the top gets more positively charged. And, because like repels like, the negative bottoms of these clouds repel electrons on the ground, trees, or buildings below, leaving them with a more positive charge.

And all this charge separation keeps building up, creating a strong electric field. Most of the time, this leads to negative lightning, where streams of negative charges from the bottom of the cloud branch towards the Earth. That negative stream is met by an opposite stream of positive charges flying skyward, and when that happens, they exchange energy that manifests as a bright lightning strike.

These strikes can heat the surrounding air to a ridiculously high temperature of nearly 30,000 degrees Celsius, around five times hotter than the surface of the sun. Now, scientists have been baffled by the fact that Catatumbo lightning happens in the same place, night after night, with an estimated 1.2 million strikes per year.

One Venezuelan scientist who surveyed the area in the 1960s took a guess that uranium deposits in the nearby bedrock might actlike a lightning magnet, drawing a disproportionate number of ground strikes, but that idea was a dead end.

Another researcher thought that all this lightning was thanks to an excess of methane oozing up from nearby oil fields and swamps. Specifically, he thought that methane's molecular geometry increased the separation of positive and negative charges inside the storm clouds, which is an important step in making lightning.

But neither of these hypotheses have been thoroughly supported by other scientists, so they fall short to a simpler explanation. Nowadays, researchers mostly attribute Catatumbo lightning to the area's unique topography, the shape of the Earth's surface in a given area.

Many of the world's lightning hotspots are linked to geographical features, like curved coastlines and nearby mountain ranges, plus winds that help cook up thunderstorms. Lake Maracaibo is surrounded by the Andes Mountains and other branching ranges to the southwest and east. And they trap warm winds flowing over the lake from the Caribbean Sea. When that warm, damp air collides with the colder mountain air,

it rises quickly into the atmosphere, helping thunderclouds form in the stormy sweetspot. So, Lake Maracaibo probably just has all the ingredients for a thunderstorm almost every day of the year, and that's the reason for all this lightning.

Besides being a natural marvel, some scientists also argue that the Catatumbo lightning might play a critical role in generating ozone in the atmosphere. Ozone is a molecule made from three oxygen atoms and helps contribute to a protective shield around the Earth in the upper atmosphere. And the ozone layer absorbs potentially harmful, high-energy ultraviolet rays from the sun before they reach the planet's surface and cause damage to living things.

When a lightning bolt rips down from the clouds and heats the nearby air, the energy release triggers chemical reactions that produce nitrogen oxides, which can then react with other molecules to form ozone. So, Lake Maracaibo's other claim to fame might be that it's the largest natural source of ozone in the world. But, most scientists say that this probably won't help with human-caused ozone depletion, because that lightning-generated ozone doesn't make it into the upper atmosphere.

So, Lake Maracaibo has become quite the tourist attraction. But for scientists, it's a chance to dive deeper into why some parts of the world are a little more electric than others.

So, plenty of weird lakes play important roles in supporting life. But, there is one type of lake that was just never meant to be lived in. Hank's got the scoop.

Earth is covered in lakes. Mostly, these are cool, watery affairs, full of life, a great place for a relaxing vacation. Lava lakes are a little less serene. They're scorching, seething pools of molten rock. They're also pretty rare; outside of Minecraft, permanent lava only exists in a few places around the globe. 

One of the strangest lava lakes is atop Mt. Erebus on the frozen continent of Antarctica. Probably the weirdest thing about this lake is that it's constantly releasing gas and the composition of that gas changes on a roughly ten-minute cycle. Erebus was a Greek god, the son of Chaos, which is kinda fitting for a place made of ice and fire. Mt. Erebus is the tallest peak on Ross Island,

which lies close to the Antarctic mainland and is usually connected by ice sheets. It's an active volcano that's been bubbling away for decades, occasionally throwing off larger eruptions.

The lava lake is around 20 meters deep and it sits in a crater which is itself inside of Mt. Erebus's main crater. Under that lake is a conduit, a tube that leads down to a chamber filled with magma (underground lava, in other words). So the lake is basically like a bowl with a hole in the bottom, sitting on top of a pipe. Like a sink, I guess you could say, except it goes the other way. Instead of going down, it goes up. And all of it's about 1,000 degrees Celsius.

Even in the frigid Antarctic air, the lake's surface won't cool into solid rock thanks to the convection currents that feed the lake with a steady supply of hot stuff. Hot magma rises to the top of the lake, then spreads outward, cooling off along the way. As it cools, it gets denser, so it sinks back down again, and the convection cycle continues.

Lava lakes need that crater, conduit, and magma chamber combo to exist. And not many volcanoes have all of those components so well aligned. That's why molten lava lakes are super rare, and there are only about five on Earth that have remained persistently active in recent years.

So the Mt. Erebus lava lake is an unusual and remote place. But thanks to some intrepid scientists, it's an area of active research. Scientists have braved freezing slopes and burning lava bombs (that's the technical term for flying blobs of lava), and they've installed remote sensors to keep tabs on the lake 24/7.

One mystery they're working on is the lake's persistent gas emissions. For years, Erebus has been steadily releasing a gas plume, and there's a weird cycle to it. Over the course of ten minutes or so, there's a repetitive shift in both the amount of gas produced and its composition, the overall mix.

For example, the carbon dioxide to carbon monoxide ratio changes, as do emission levels of water vapor and sulfur dioxide. Researchers have been trying to figure out why there's this repeating cycle, and based on sensor data and computer modelling, they think it has to do with two main sources of gas.

One comes from the conduit. And the other comes from diffusion in the lake. The carbon dioxide-rich gas is always rising up from the conduit, and it's basically constant –

the amount and composition doesn't really change. But the conduit also occasionally, like every ten minutes or so, burps out a large blob of magma from deeper in the chamber, like a kind of literal one-way lava lamp. Once the blob gets nearer the surface of the lake, it releases a fresh set of gases, which adds to the total amount of gas detected and changes the overall composition because it's rich in water vapor and sulfur dioxide.

In addition to these shorter cycles, the lava lake has what researchers call explosive degassing. These less-frequent but more impressive belches cause small eruptions, hurling lava bombs into the main crater. The two systems seem to work independently: the composition of the gas from the explosive degassing is different from the gas from the shorter cycle and appears to come from much deeper in the volcano's magma chamber.

There is still a lot left to learn about Erebus and lava lakes in general. For example, there are gas cycles with other cycle lengths that aren't as well studied. Working out if they're connected and how will build up a better model of the inner workings of Mt. Erebus.

Mt. Erebus also contains a rare type of magma called phonolite. It's much thicker than the more common basalt variety, which probably affects the fluid dynamics inside the magma chamber and lake. So, hopefully the recent studies on Erebus will be useful for scientists working on other lakes around the world.

These lakes may be rare, but having good models from the few examples around the world will help geologists understand the similarities and differences between them, and the overall rules about how they work.

Leave it to Antarctica to have one of the hottest, weirdest lakes on Earth. And that's just a taste of what's out there! There are still plenty of other weird lakes and other weird places to explore.

Thank you for watching this episode of SciShow. And if you liked learning about these weird lakes, we're also selling a pack of postcards based on each one of them. You can get yours over at dftba.com/scishow or at the link in the description.

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