Loss of oxygen in lakes and oceans

https://www.sciencedaily.com/releases/2024/07/240715135713.htm

by Brajeshwar • 2 years ago

118 48 2 years ago

sciencedaily.com

quantified• 2 years ago

It's plausible but needs quantification. I doubt it's been truly overlooked.

aszantu• 2 years ago

No numbers on how much O is needed and how it has developed the last few years?

its_ethan• 2 years ago

Re: developed over the last few years, I clicked through 2 layers of referenced articles to get to the actual paper which says oxygen is down 2% on the last 50 years [1]. The rapid falling of oxygen seems to be (as far as I can tell from the various linked articles) is somewhat localized to the Gulf of St. Lawrence [2].

[1] https://www.nature.com/articles/s41558-018-0263-1

[2] https://www.sciencealert.com/this-stretch-of-water-is-losing...

A_D_E_P_T• 2 years ago

The scientific paper underlying the article is here: https://www.nature.com/articles/s41559-024-02448-y

There's a different article, and to my mind a more readable one, here: https://www.sciencedaily.com/releases/2024/07/240715135713.h...

"Lakes and reservoirs have experienced oxygen losses of 5.5% and 18.6% respectively since 1980. The oceans have experienced oxygen losses of around 2% since 1960 and, although that number is smaller, it represents a more geographically and volumetrically extensive mass. Marine ecosystems have also experienced substantial variability in oxygen depletion. For example, the midwaters off of Central California have lost 40% of their oxygen in the last few decades."

If that holds true worldwide, and not just at a selection of measuring sites, it's a rapid and very concerning shift. It'll be interesting to see if their measurements are corroborated.

OgsyedIE• 2 years ago

Skimming the conclusion of the paper it seems that, unless there are overlooked measurement errors the effect is robust. The immediate question this suggests to me is this: are there any naturally occurring multi-year (or multi-decade) oxygen concentration cycles in the ocean analogous to already-known salinity cycles?

burningChrome• 2 years ago

This was where I immediately started thinking. Is this something that cyclical? The article is long on effect and very short on causes.

"Reducing greenhouse gas emissions, nutrient runoff and organic carbon inputs (for example, raw sewage loading) would slow or potentially reverse deoxygenation," they write.

And what exactly is "raw sewage loading" they talk about as a way to reverse this? I did some quick googling and couldn't find anything about what exactly it is.

dang• 2 years ago

Thanks! I've switched the URL above to your second link (instead of the absurdly baity https://www.sciencealert.com/earths-water-is-rapidly-losing-...).

throwaway57522• 2 years ago

"Relevant, critical oxygen thresholds are being approached at rates comparable to other planetary boundary processes."

https://www.researchgate.net/publication/372847863_Anoxia_Be... is a previous paper, I can't find this. The author is qualified and has produced a good deal of original and field research on the topic.

This is a good example of where just reacting to a bad or clickbait headline would be to your detriment. This actually is new information and bad news.

dbcooper2• 2 years ago

Gas solubility in water decreases pretty strongly due to the gaseous phase being more entropic (in governing thermodynamic potentials the entropic term is -T•∆S). Unfortunately this is unavoidable with rising temperatures.

f1shy• 2 years ago

With 1 degree? Honest question. Is clear that is some places is more, but also some places (ask me how I know) are colder. The avg. is “just” 1 degree.

dbcooper2• 2 years ago

Across all aquatic ecosystems, from streams and rivers, lakes, reservoirs, and ponds to estuaries, coasts, and the open ocean, dissolved oxygen (DO) concentrations have rapidly and substantially declined in recent decades. Lakes and reservoirs have experienced oxygen losses of 5.5% and 18.6% respectively since 1980. The oceans have experienced oxygen losses of around 2% since 1960 and, although that number is smaller, it represents a more geographically and volumetrically extensive mass.
For example, the midwaters off of Central California have lost 40% of their oxygen in the last few decades.

As the oxygen carrying capacity of water is very low, an increase in temperature, that increases the overall consumption rates of organisms near the surface, could cause large magnitude changes in DO concentrations.

colechristensen2• 2 years ago

Alternate, positive headline "Earth's water sinking more carbon, oxygen loss shows".

CO2 is a potent fertilizer and is going to cause a lot of "blooms" and general more life which is going to affect oxygen levels. Loss of oxygen is a dampening effect on this.

Every environmental article has to be about "danger" instead of just stating facts about what is happening now.

jacobolus• 2 years ago

It seems fairly straightforward to claim that significantly changing water chemistry is very bad, or at least very risky, for aquatic ecosystems many of whose species are very sensitive to water chemistry.

The "positive" here is supposed to be that widespread destruction of land ecosystems might be even more severe if not for the oceans also taking some of the damage? (I doubt that is true in the long run. Many global processes are dependent on functioning living oceans.)

Johnny5552• 2 years ago

Kind of like how fertilizer runoff is a good thing since it causes algae blooms, and more life is good right? Except that it disrupts existing ecosystems and can cause vast oxygen-free dead zones.

colechristensen2• 2 years ago

One of the things we should be doing is intentionally fertilizing oceans, particularly the "deserts" where not much grows at all, as an intentional way to cause blooms and sink carbon.

shicholas• 2 years ago

eating less meat seems like the biggest thing individuals can do here. Animal waste/fertilizer runoff/agricultural waste seems like the biggest contributor.

any other suggestions?

goda90• 2 years ago

Regenerative agriculture. No till, no spray, cover crops. Managed grazing of ruminants and poultry on the same land that crops are grown on to build top soil and serve as pest control.

_heimdall6• 2 years ago

Regenerative ag is a ton of work, and at least in my anecdotal experience I didn't see any meaningful gains from it.

We rotated our cows once or twice a day, carefully tracking how much space they got each day based on the animals' weight and quality of forage. The animals got by okay, but honestly they seemed to act more like prisoners than cows. It shows even when you watch some of the biggest names in regenerative move their animals - the animals dive past the line into the space. Those animals are hungry and stressed by being so densely kept that they feel they need to eat before it's all gone.

Today we keep our cows in what anyone else would consider a much too low stocking density. We move them occasionally between 3 different pastures, on the order of weeks or months between each move. The animals seem less stressed, they're definitely happier, and they've created familial bonds and hierarchy that wasn't obvious when we kept them in closer quarters with frequent moves.

_heimdall6• 2 years ago

I'd caveat this by saying eating less industrially raised and processed meat would help. The same goes for industrial produce though, they cause a ton of damage that few people ever see or think about.

If we want realistic solutions, they'll all be incremental like using less plastic or Turing lights off when you aren't home. If we want recommendations that would actually help, we would need to completely reorganize societies and our daily lives.

We don't need cars, air travel, grocery stores, or even air conditioning to survive. Those are all modern inventions on the order of decades old. People aren't going to do that willingly though, including me. I live a very different, and more simple, life than the average American but the idea of throwing out so many things that we have today only because we've enslaved natural fuel sources is scary as hell.

mihaic• 2 years ago

Whatever the solutions are, let's not push burden on the individual. Resources are like highway lanes: even if you don't drive your car, someone will use it just.

adrianN• 2 years ago

Vote for politicians who want to do something about climate change and convince others to do the same.

srverma• 2 years ago

I'm not a biologist, so I'm curious to understand the implication of less oxygen in water. I can intuitively think that less life will survive, but what else happens? Is there a way to "inject" oxygen into the ocean?

throwaway57522• 2 years ago

This applies to oceans and freshwater.

Hot water holds less oxygen then cold water. Oxygen, by itself, happily will go into solution with H2O if conditions are favorable. We can "inject" oxygen by slowing and reversing global warming.

_heimdall6• 2 years ago

One of my ponds has issues with low oxygen in the summer, the pond is too shallow and it can overheat when it's 95F and sunny out.

We lost quite a few fish last year (our first summer here). The pond also ends up with duckweed covering most of the surface - from what I've found duckweed does well in a low oxygen environment and does actually help to cool down and reoxygenate back into the water. When the duckweed overgrows, though, it blocks out too much light and can lead to an algae bloom that is really bad for the whole system.

I built a solar powered pond fountsin a month ago, it only runs for a few hours a day but seems to be helping quite a bit so far.

I raise this only to show how much can happen when a half acre pond is low on oxygen. On the scale of an ocean, I have to expect that it would take much more to get to that level of a problem, but if it did get there the cascading issues would have to be exponentially worse too.

quesera2• 2 years ago

I built a solar powered pond fountsin a month ago

Interesting! What kind of aeration/water exchange/GPM are you finding effective for a half acre pond?

I would love to click your links. :)

stainablesteel2• 2 years ago

i can't read the article but this seems like a strange conclusion

there should be more dissolved oxygen as water becomes warmer, i thought climate change was the big disaster we were supposed to be worried about?

less dissolved oxygen would suggest the water is cooler

ditn• 2 years ago

Someone failed highschool chemistry. More gas can dissolve in cold water vs hot. The opposite of solids.

stainablesteel2• 2 years ago

you know what, i did

HappySweeney• 2 years ago

This is incorrect. When dissolving a gas into a liquid, the colder the liquid is, the more gas can be dissolved.

0x138d5• 2 years ago

there should be more dissolved oxygen as water becomes warmer,

Oxygen solubility in water is inversely correlated with temperature and salinity.

MisterBastahrd• 2 years ago

Tell ya what, take two cans of coke. One, just open and pour into a glass. The second, pour into a glass and microwave it for a couple minutes. Take a sip of each and let us know how much gas is in each glass.

There's a reason that Starbucks isn't selling hot nitro brew.

bogota• 2 years ago

I love how my comment gets flagged for pointing out the original rage bait headline. Then the headline is changed. What a bunch of shit.

lordfrito• 2 years ago

So it's no longer H2O but just H2?

jauntywundrkind• 2 years ago

Isn't part of the reason we stopped using bunker fuel with such high sulfur levels because it caused acidification? That also greatly damages oxygen available to organisms, I think?

I forget exactly how hypoxia and acidification are related but they're often mentioned together. For example, https://www.eea.europa.eu/en/newsroom/news/warming-acidifica...

This paper seems to be saying that low Dissolved Oxygen can quickly turn into or make acidification issues worse, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4892234/

Loss of oxygen in lakes and oceans

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