Sugar deposits found under seagrass meadows | Hacker News Reader

Sugar deposits found under seagrass meadows

theweathernetwork.com

204 pointsnradov134 comments

Original paper:

> "Here, we show that the seagrass, Posidonia oceanica excretes sugars, mainly sucrose, into its rhizosphere. These sugars accumulate to µM concentrations—nearly 80 times higher than previously observed in marine environments. This finding is unexpected as sugars are readily consumed by microorganisms. Our experiments indicated that under low oxygen conditions, phenolic compounds from P. oceanica inhibited microbial consumption of sucrose."

https://www.nature.com/articles/s41559-022-01740-z

A sugar like glucose is ~180 grams/mol. A µM concentration of glucose is going to be less than a milligram of sugar per liter of ocean water. In contrast, a liter of Coke contains ~120 grams of sugar (~ 0.6 M).

It's kind of interesting because the seagrass appears to be feeding sugar to bacteria, which might be doing nitrogen fixation in return, but it's hardly 'mountains of sugar'.

Yes, and the carbon storage of all the seagrass sugar in the world is roughly equivalent to one day of automobile driving in the USA. But everywhere in the article it is phrased to make it appear like a world changing amount of carbon. Why?

I think the point of the article is that understanding how seagrass captures carbon is useful and interesting.

For more relevant numbers, I did a very quick calculation (tell me if you spot a mistake).

Using these numbers [0, 1], the worlds seagrass captures ~5% of US automobile emissions per year.

Another number of interest, the amount of seagrass carbon sequestration is 2 - 4x greater than mature tropical rainforests (per hectare) [0].

Seems to me that seagrass is an organism worth understanding.

[0] https://www.thebluecarboninitiative.org/about-blue-carbon

[1] https://www.statista.com/statistics/1120499/us-road-vehicle-...

> I think the point of the article is that understanding how seagrass captures carbon is useful and interesting.

You’ve perfectly described why pure research science has merit in its own right.

Application of knowledge comes a little later.

It's my understanding that early steam engines were pretty rubbish until the underlying thermodynamics were understood and then you could engineer your way to a Watt Engine [0] that was revolutionary. The nearly two order of magnitude superiority of this sea grass on this metric is tantalizing.

[0]https://en.wikipedia.org/wiki/Watt_steam_engine

The ocean is big though. I think the headline writer was imagining the piles of sugar if you pulled it all out of the water and stacked it up.

I mean with that logic, there are mountains of lint in people's pockets. And mountains of cobwebs in their basements.

Just about everything forms a mountain if you combine all instances of it in the world into a big pile.

If anything, it'd only be notable if something didn't form a mountain when piled.

Imagine if lint was a well known food for bacteria and all the sudden it might be notable if bacteria were leaving it alone in pockets

Are you Dutch? 1g of lint per human is ~8,000 tons, which at 4g/cm3 is a cube of ~14m. Mountains are huge ;)

It's notable because it's free energy that isn't being consumed for some reason. Sprinkle some sugar on the ground outside and ants will swoop in and grab it in minutes.

> ants will swoop in and grab it in minutes.

That's not universally true. Saying that because I've personally accidentally dropped a 1kg bag of white sugar on the ground outside years ago which split open.

I just left the sugar there, figuring ants would clean it up.

Nope. Nothing touched it for around a week, until it rained, at which point it went away. Maybe the ants had a glucose syrup snack instead. ;)

Seagrass only grows in the shallows.

Not as big, but still pretty big.

For alternative points of reference, ~120 g of sugar is ~140 mL or ~0.60 US cups.

“That is roughly comparable to the amount of sugar in 32 billion cans of Coke!”

That's a unique unit of measure I've not seen before. I know in one of Gary Larson's old books he had a comment on his "skeletonize a cow in less than a minute" comic about how he loves weird units of measurement like this.

https://ifunny.co/picture/MMQBLmZr5

A billion hours ago, human life appeared on earth. A billion minutes ago, Christianity emerged. A billion seconds ago, the Beatles changed music. A billion Coca-Colas ago was yesterday morning.

—Robert Goizueta, chief executive of the Coca-Cola Company, April 1997

so that represents between 32 and 64 days of coca cola production of 1997.

One evening as the sun went down

And the basalt fire was burning

Down the track came a mermaid swimming

and he say "Boys I'm not turning"

I'm headed for a pond that's far away

beside the seagrass fountains

so come with me and we'll go and see

The big rock candy mountains.

There's a meme that americans will use anything to avoid metric system. Typically with examples like "hole in the road with the size of 2 washing machines".

There's a great Simpsons joke where Grandpa says, "the metric system is the tool of the devil, my car gets 40 rods to the hog's head, and that's the way I like it!"

https://www.youtube.com/watch?v=z5-s-4KPtD8

For those who are curious, 1 rod is 0.003125 miles. Thus, 40 rods is 0.125 miles. 1 hogshead is 1/63 of a US gallon.

Thus, 40 rods to the hog's head is 7.875 miles per gallon, 29.87 L/100km, or 3.348 km/L.

EDIT: sorry, 1 hogshead is 63 US gallons. This comes to about 0.002 miles per gallon... yikes! (divide all the numbers in the previous paragraph by 63^2)

Huh. Why is a hogshead so small? If you had asked me to guess I would have said like 3 1/32nd (or some weird small additional amount) gallons.

Wait. I’m seeing that hogshead is like 63 “wine” gallons, not 1/63 gallon. (Not sure conversion of wine gallons to usual gallons though.)

Ooh you're totally right, thank you for pointing it out!

I think my brain was subconsciously seeking a miles-per-gallon result in a "reasonable" order of magnitude. Edited original comment.

They don’t make hogs like they used to

From a quick search it seems both a normal gallon and a wine gallon are measured at 231 cubic cm of liquid, so they're the same. There is a proof gallon which only counts the ethanol content of the liquid towards the gallon, so a 100 proof alcohol would require 2 gallons of liquid to equal 1 proof gallon of liquor.

Those are/were real units

https://en.wikipedia.org/wiki/Hogshead

https://en.wikipedia.org/wiki/Rod_(unit)

That's why it's Grandpa and funny.

So his car takes roughly 300l to move 200m in SI units, or 45000l/100km.

Are there, by chance, any fake units that exist?

I’m fond of the shit ton.

The Canadian metric equivalent is the metric crap tonne.

Buttload is not fake however

Us brits have “shed load”

https://en.wikipedia.org/wiki/List_of_humorous_units_of_meas...

Does the Register's measurement converter count?

https://www.theregister.com/Design/page/reg-standards-conver...

The shit tonne and the fuck load come to mind.

F**stick?

Yes, the smoot

The greatest Simpsons car-and-measurement-unit bit is of course this one: "She'll go 300 hectares on a single tank of kerosene" which maybe makes sense if you're plowing a field... Part of a pretty amazing 20 second bit. Pure old Simpsons gold.

https://www.youtube.com/watch?v=07vdtBMG4Kg

If you wish that 20 seconds would last a little longer, and also be remixed into a song, check out "Put it in H" by Dankmus.

https://www.youtube.com/watch?v=9HXT7fDkf9I

I like the "Large boulder the size of a small boulder" measurement system by the San Miguel Sheriff. - https://twitter.com/SheriffAlert/status/1221881862244749315

This is great lol

It can get more extremes than memes. Some government agencies have policies specifically avoiding the metric system in public announcements. Issue a statement about a 30 centimeter wave event and a good percentage of people in coastal areas might panic. Trial attorneys also coach witnesses to never speak in metric as at least one person on every jury won't be able to follow ... and two more will hate you for forcing them to remember words they last heard in highschool.

American here, lived in Europe a while, but back.

I got decent with meters. Recently, I've been thinking about ways to visualize a billion. Here's one:

There's a billion cubic millimeters in a cubic meter (cubic yard). If you take a meter (yardstick) and visualize the 1000 millimeters in it, then make a plane of that 1000x1000, i.e. a million, then stack a thousand of those, that's a billion.

I still can't get my head around it, TBH. A billion is a lot!

But "billion cubes" are a nice unit; you can stack up a lot of them to get more billions.

I mean that's easier to visualize than saying a "hole in the road that is about 92 cubic centimeters."

I think that's because they're not really equivalent. At least for me, a hole the size of 2 washing machines is something that will look close to two washing machines put together. That limits the shape it can have. On the other hand, 92 cubic centimeters doesn't. It could be a 1cm x 1cm x 92cm hole, which wouldn't be possible with 2 washing machines.

If we assume that the two washing machines are side to side, and that the average washing machine is 60cm x 60cm x 85 cm (height), that would be a hole 1.20m width x 60 cm depth x 85 cm height. The washing machine example is still easier to visualize, but it's also better than "a 612 000 cubic centimeters hole".

I think 'hole in the road' comes with its own visualisation more likely to be accurate than anything you get from 'two washing machines'.

How do you accurately visualize whether "hole in the road" means you saying "what was that?" And driving on without slowing. Or whether the hole will require a crane to get your car to a place where it can be towed if you, possibly inadvertently, attempt to drive over it?

I meant regarding shape.

holes can be all sorts of shapes

But rarely like washing machines. (Which can also be all sorts of shapes anyway.)

Aside from side by side vs stackable, every washing machine I've ever encountered is roughly the same shape. Some edges are rounder and the door might be on the front or the top but the shape is the same.

The vast majority are approximately cuboid boxes, sure. Ever seen a hole in the road like that?

Yes, all the time when I lived in Atlanta. They frequently do road construction where they dig up rectangular underground vaults, then cover them up with giant “temporary” steel plates for years at a time. When the steel plates get dislodged, which they always do because they are not supposed to be permanent repairs, it leaves a gaping rectangular hole. I would estimate that the remaining hole is around the 4-washing machine size. When I was working on my MS at Ga Tech, a friend drove over one at speed, the car made it past but it sheared the oil pan right off the engine. Any Atlanta resident can validate that this is not BS. https://www.atlantamagazine.com/news-culture-articles/why-at...

You'd say something like "2 cubic metres". Which is roughly the size of 2 washing machines.

So like 1/20th of a cubic fathom?

> hole in the road that is about 92 cubic centimeters

92 cubic centimeters is a pretty small hole...

a hole in the road 1.5mx80cmx60cm is pretty easy to understand or imagine, when you know metric system and absolutely trivial to convert: ~0.70 cubic meters or ~700 liters or ~700.000 cubic centimeters

Washing machines comes of all sizes.

Is it like the slim one I have at home to save space or like the ones I find in laundromats?

Metric units have standards.

I don't know how many people would understand "a hole in the road the size of 137 trays of home made tiramisù"

TBF here too when the media want to make analogies, they are pretty terrible: "an asteroid the size of 8 soccer fields" means nothing to me, ~800 meters makes much more sense.

Where I’m from, we’d just say “There’s a big ass hole in the road”

Is that an imperial ass or a metric ass?

Around here that's just a normal morning commute

A big bottle of soda is 1000 or 2000 cubic centimeters. A can of soda is 200 or 300 cubic centimeters. A glass of water has 200 or 300 cubic centimeters. 92 cubic centimeters is half a glass of water.

I wonder if folks do that because its easier to picture a hole the size of two washing machines. That would be like 4-6 sq ft which can be more difficult to visualize.

How many libraries of congresses is that?

Doesn’t “avoid” imply that Americans are actually giving the metric system any thought?

I’m fond of odd measures. I like to say that something is the size of a ⸻'s head, for example, “that burger is the size of a cat’s head.” I also will describe a date as being a week and a half from some arbitrary date.

I dread my coming house move because of how many billies of books I have :-).

My problem with moving is always that once I've unpacked the books and the music stuff, I tend to lose interest so I end up with boxes of stuff lurking for months afterwards. Being married helps a bit, but my wife has her own blind spots and we still have boxes in the basement eleven years later that have yet to be unpacked.

If you threw them all out unopened, how many more years would it take before anyone noticed?

When it comes to moving books I measure in how many days it will take to stop being sore.

I do a very similar thing. Sometimes when I describe my height, I'm "five and a half foot, nine"

I used to work in a produce department, so I do the same thing but with fruits and veggies.

V. useful for your next pregnancy

> That's a unique unit of measure I've not seen before.

There are some fun Wikipedia entries on the subject:

https://en.wikipedia.org/wiki/List_of_unusual_units_of_measu...

https://en.wikipedia.org/wiki/List_of_humorous_units_of_meas...

Putting it that way made me immediately think that that's less than 4 cans per person. I would have thought that more actual cans of coke were in circulation.

Well they apparently sell nearly 2 billion bottles a day.

Did you see where OP changed the units of measure from cans to bottles...

> The study reported that the giant piles of excess sugar were not being consumed by the bacteria due to phenolic compounds released by the seagrass, which cannot be digested by many microorganisms. This was a key finding for the researchers, as it confirms that the carbon in the sugar stays in these underwater ecosystems and out of the atmosphere.

Interesting, sugar is so energy dense, isn't it just a matter of time until some organism figures out how to take advantage of it despite the phenols?

I'd guess that's correct. It reminds me of the Carboniferous era when there weren't any organisms around that could eat lignin, so dead trees just piled up until they were so thick, they turned into coal.

https://en.wikipedia.org/wiki/Carboniferous

Note that this hypothesis has been challenged, e.g. here [1] (paper here [2]).

[1] https://www.earthmagazine.org/article/lack-fungi-did-not-lea...

[2] https://www.pnas.org/doi/10.1073/pnas.1517943113

Sugar is a conservant too. Kills organisms by osmosis.

Only in much, much higher concentrations, like those of honey.

It is a very slow process though

Well the purpose of jam is to conserve fruit with sugar so maybe not. Honey also doesn’t spoil even after thousands of years.

Honest question: don’t animals do it? Or do you mean “microorganisms”?

Many (most?) animals cannot digest straight glucose, e.g. cats, which are obligate carnivores. I suspect most animals would have to be able to digest starches to be able to process sugars (though a good exception is the bee, so my surmise could be bogus).

I believe that cats don't even have sweet taste receptors. I've done "experiments" over the years, offering my own food to various of our household (terrestrial) pets. Cats and rodents are the most picky; dogs will eat a proper superset of what cats do, except that I have never had a dog that liked drinking milk (eating cheese, though, sure, and ice cream). Dogs seem OK with sugar (not crazy about it) cats are utterly uninterested.

An ancestor of all cat species lost a gene required for sweet taste, so none of them could taste sugar which could be why they became obligate carnivores.

I was curious, so I just mixed a teaspoon of sugar and water into a paste and put it in my dogs’ bowls. Two completely different breeds. Both went crazy for it. Both love Milk too. Neither dog will eat raw fruit

I had a dog which was absolutely crazy for cucumbers. He was typically sneaking into garden, sniffing for cucumbers among leaves, took it out and eat it. When I was peeling cucumber, he was salivating and whimpering to eat peelings, he would get angry if I didn't share at least some of of them. My current dog eats almost anything (he didn't like raw lemon), including most fabrics, but he's only a year old. Had to electrify the garden though because he digged and tried to eat compost.

I had a cat that was nuts for any dark green veggie. Broccoli, asparagus, kale. No butter, no salt, just steamed. Miss ya little buddy.

My dog loves our fig tree and eats any figs she can get at.

The key here is "despite the phenols". What any such organism would need to develop is not so much a way to use the sugar, but rather a way to safeguard against phenols.

Thanks.

Until some bacteria mutates to digest it. It's definitely not a long-term solution.

I wonder if would taste good fermented and distilled. There's rarely a source of sugars that humans haven't tried to make into booze.

No let's not take any large quantaties of anything else from the ocean. Leave it.

You might be on to something. It already has phenols, which are basically alcohols. /s

Wild. Let’s hope it never becomes an economically viable thing to harvest.

I bet in 1-2 days you will find some twitter users who will write an essay about how we should harvest ocean sugar and plant more wheat instead of corn or sugar beets.

That is really interesting. Can we cultivate sea grass to make carbon capture ponds or forests?

"The research stated that if microorganisms consumed the sucrose stored by the roots of the seagrass, at least 1.54 million tons of carbon dioxide would be released into the atmosphere, which is equivalent to the carbon emissions from by 330,000 cars in one year."

Those number strongly suggest no. "A million tons" and "hundreds of thousands" may sound large but in this context they're tiny. And if we did try to farm these we'd have to displace other ecosystems for the farm land (under ocean).

>And if we did try to farm these we'd have to displace other ecosystems for the farm land (under ocean).

but that isn't necessarily a problem.

Famous last words.

There's a lot of work going into blue carbon efforts at the moment .. better understanding and utilising seagrasses and algaes, mangroves, etc. as carbon sinks.

That said, what I've never understood about the potential of seagrass as a carbon sink (and this sugar thing might go someway to explaining it), is how it works given how short lived individual plants are, and how fragile - and shallow - seagrass ecosystems are.

CO2 / methane (?) released by decaying biomass at depth may stay trapped in sediment, but how realistic is this at depths of 20-40m? Does anyone have any more info?

Isn't what's going on here in particular something to do with symbiotic bacteria capturing carbon into sugars?

Yeah absolutely. My previous understanding was that the main carbon capture potential was simply in what ended up as part of the plant, rather than the portion being excreted / fed on by symbionts. That is fascinating news.

My question is that, given that the "capture" component relies on that carbon not being re-released into the atmosphere, how does "seagrass sequestration" fare given that seagrass meadows mostly occur in shallow waters, where the seafloor tends to experience higher levels of dusturbance compared to the deep sea (tides, currents, predation -of plants and sugars-, human impacts).

Seagrasses are short lived compared to trees. Soil / biomass carbon sinks are potentially easily disturbed. Do seagrasses still have a genuine/reliable/outstanding role to play in the carbon game?

Sea grass already grows pretty much everywhere it can grow, so I don't think we can cultivate a lot more (at least not without disrupting other sensitive marine ecosystems). It's more important to prevent pollution that would kill existing sea grass.

Have you got a reference for that?

This article suggests that "92% of the UK’s seagrass has been lost in the past two centuries, with 39% disappearing just since the 1980s, thanks to pollution from industry, mining and farming, along with dredging, bottom trawling and coastal development."

https://www.theguardian.com/environment/2021/nov/05/seagrass...

What are the limiting factors for it's range? Is there a critical nutrient that can be introduced?

It is grass. It needs sunlight and a substrate on which to grow. That means shallow/clear water over a sandy bottom, not a common thing in the ocean.

Seems like sunlight and substrate is much more common than seagrass is. I found this paper [1] that talks about the difference.

It estimated the area of suitable sunlight and substrate to be 4,320,000 km2 but estimated seagrass coverage of 177,000 km2.

I think this big difference indicates that there are additional factors at play.

https://iopscience.iop.org/article/10.1088/1748-9326/ab7d06

Earth has something like 150 million square kilometers of ocean. 4mil is a tiny corner of that area. Depth/light remains by far the primary limitation for sea grass, preventing it from even attempting to colonize the vast majority of the worlds oceans. Compare other carbon sinks like plankton which can exist across the ocean irrespective of water depth.

Sure, but Im not asking why seagrass doesn't cover the entire ocean or entire planet.

I'm asking why it doesn't cover more area than it currently does it appears that light and substrate is an insufficient answer. 90% of the area with suitable light and substrate is not covered, so something additional is going on.

> What are the limiting factors for it's range?

Fishermen and recreational sports

That’s what https://www.runningtide.com/ is trying to do

So in treacle mines[1] people mine for sugar from a prehistoric sea?

[1] https://en.wikipedia.org/wiki/Treacle_mining

This doesn't seem particularly novel. It's already well understood that plants deposit sugar into the ground they grow in to encourage beneficial bacterial and fungal growth. It's basically the plants gut: https://en.wikipedia.org/wiki/Rhizosphere

I don’t understand the significance of this. What if we found huge quantities of sugar, what does it mean to me, to the oceans, to the environment? Not trying to be flippant, I am not able to make the connection, but can someone dumb it down and spell it out for me?

This is fascinating but how long before some enterprising person mines it and puts it in chic packaging and sells it to bougie consumers as “sea sugar” with implied health benefits?

I wouldn't put that out there on this forum. It's full of entrepreneurial persons who might like that idea.

Or labels it as organic, and green? While actually damaging an ocean ecosystem (that may help fend off climate change)

"between 0.6 and 1.3 million tons of sugar" doesn't sound like a lot? Humankind is adding 35 BILLION tonnes of carbon dioxide per year.

Cool! But let’s give the rampant environmental destruction a break and leave the ocean sugar right where it belongs in its natural ecosystem.

Cool! So everyone will try to harvest that sugar (maybe to produce fuel?) so even more carbon can be released. Hot!

Oh, to live on Sugar Mountain

With the seagrass and their excreted sucrose.

- Neil Young maybe

Come on, Charlie! Let's go to Seagrass Meadows!

New Coke, now made with high sucrose seagrass syrup.

It seems it's not enough to exploit it as fuel.

i dont often observe clickbait rise in these ranks

Thank you for changing the title

Time to get minin'.

> just one square kilometre of seagrass stores nearly twice as much carbon as forests on land at a rate 35 times faster

Time to kill the seagrass meadows

Haha, seriously.

Us humans will completely devastate anything we can get our greedy, shitty little monkey paws on.

Oh no. People are burning down the Brazilian rain forest for even less to gain.

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