Sea life bounced back fast after the ‘mother of mass extinctions’
nature.com
nature.com
But I do agree there's some really interesting key differences. For one, speciation on land is often driven by geological barriers that split populations apart. But these types of barriers are much less common in the ocean where this only really happens to organisms that are restricted to shallow waters (and even then "island-hopping" happens much more commonly)
Depth is a thing and can separate disparate communuties on seamounts like alpine species on mountain tops. The difference is most Maine species have a pelagic larval stage and can disperse widely, so barriers to gene flow are more limited than on land.
Different terrestrial and marine habitats and assemblages come to mind where one may be more complex than another but overall if the degree of niche partitioning at any given trophic level was a wash between land and sea water, I think marine may take the cake on complexity just due to the webs being longer and thus room for more edges between nodes https://pubmed.ncbi.nlm.nih.gov/27322123/
“Ages ago, life was born in the primitive sea. Young life forms constantly evolved in order to survive. Some prospered — some did not. All sorts of life ebbed and flowed like the tide. In the quiet rhythm of the mother sea, life grew, always seeking to survive and flourish.”
https://www.nationalgeographic.org/activity/save-the-plankto...
When I dived in different oceans, I was surprised to see the same fish (most popular ones). It's hard to imagine the same on land. Finding a niche is much easier on land, especially in mountains.
Mountains are like smaller caps - there is a lot more alpha, higher volatility but opportunity size is only a fraction.
Would be cool to make a procedural rendering of the financial markets as a landscape/globe map. "Got a cold front blowing across the tech sector today"
Not true at the extremes I say because pelagic ecosystems have small single cells handling their primary productivity, you have microscopic copepods starting the grazing at the same size as the smallest herbivorous insects, and until recently you had stellars sea cow weighing in at 8-10 t, more than an African elephant.
And some of the algae and the predators even gang up on the zooplankton: https://en.m.wikipedia.org/wiki/Zooxanthellae
There can be an impressive degree of niche partitioning in somd marine habitats though!
You're over simplying it because you think the oceans are more complicated or something.
if you ignore all the non mammal life...
and even considering only mammals, that's only a fraction of the food chain
for example: boars or rats
There's a little exaggeration in that comment but directionally it holds true, marine food chains are longer, in part because primary production in pelagic ecosystems is single cell phytoplankton instead of plants, and the small size of things a lot of room for higher trophic levels in terms of energetics.
no it doesn't.
We are not predators and are not herbivores.
swines are not herbivore but not predators.
But in fairness it's not very common, the real point is that if we look at the data, mammals are mostly carnivores, 63% of them is, but that doesn't imply being a predator.
The other point is that the cycle is not predator eats herbivore which eats plants.
That is a mammal-centric view that completely removes from the equation the majority of lifeforms on Earth, 'cause mammals are a minority of the species in nature.
Many predators also feed from other lesser predators, example: snakes. Snakes don't eat herbivores, they eat small rodents that usually eat other smaller animals.
Truth is the cycle is a lot more about bacteria that eats a substance (that probably comes from the putrefaction of some dead animal) that creates some other substance that other bacteria live on and they too produce something that simple life forms use to produce energy and after many of these steps, maybe there's some plant or fungi that consumes those nutrients in the soil and then "do you have time to talk about our lords and saviors the insects, the 900 thousands species of them?"
Oceans are not absolutely more complex than terrestrial life and why should they be? Life on Earth evolved over hundreds of millions of years, it makes sense that it adapted to every ecosystem the Earth has to offer.
> marine food chains are longer
a bit longer doesn't mean what the original comments was about.
The study also says that the chain is longer in the lowest segment of the chain where the size is microscopic.
So when you arrive at the zooplankton level, you are already at very large animal eats helpless food (plants or soup of proteins) and then get eaten by a predator or it's too big to be annoyed by anybody (elephants and whales, for example)
> We are not predators and are not herbivores.
> swines are not herbivore but not predators.
Yet.. both of those examples are exactly that, omnivores, and both are also sometimes functionally predators.
And it absolutely follows that you can put an omnivore at half trophic step between a primary consumer (i.e. a predator of herbivores) and an herbivore. The way trophic levels are described are in fractional numbers of the mean trophic level of what you eat. Predator is a functional group rather than a descriptor trophic level, but when it comes down to it very few animals are pure functional specialists and very rarely does one sit perfectly at a given trophic level - to use your snakes example, they absolutely eat herbivores sometimes even if they are usually eating things that eat animals. Cows consume the occasional insect, I've seen algae-specialist green sea turtles opportunistically eat dead fish, and some shark species eat a non-negligible amount of grass. But I'm going to continue calling sea turtles grazing herbivores and sharks consumers and predators, because that is true to a first approximation.
Regarding ecosystem complexity, I don't believe I mentioned it other than length of trophic chains. However I'll point out that this
> Oceans are not absolutely more complex than terrestrial life and why should they be? Life on Earth evolved over hundreds of millions of years, it makes sense that it adapted to every ecosystem the Earth has to offer.
Doesn't follow. Sure, life evolved everywhere, speciation occured and niches have been pretty well filled. That doesn't mean ecosystem complexity is the same everywhere, there are a number of identified drivers of species richness and functional diversity (e.g. latitude) and decades of theory to try to explain why, because a rainforest is more complex than a sweetgrass prarie, and a coral reef is too. A rainforest probably beats a lot of marine ecosystems, say a soft sediment continental shelf in terms of complexity due to greater species richness, simply more connections between species at many levels and lots of niche partitioning.
Can't say I understand your point about food chains being longer due to microscopic primary producers. That is still the energetic pathway that feeds into the rest of the ecosystem.
> a bit longer doesn't mean what the original comments was about.
My reading of that comment was exactly that, that marine food chains are longer. That commenter exaggerated a bit the degree to which that is true. That study I linked provides some plausible mechanisms of why that may be.
omnivores are not something in between a predator and an herbivore.
we are facultative carnivores, we can eat vegetables, but we are not predators.
> And it absolutely follows that you can put an omnivore at half trophic step between a primary consumer (i.e. a predator of herbivores) and an herbivore
it doesn't follow.
Pigs are prey too, but they can eat meat.
Above all there is us, humans, but, generally speaking there are the apex predators, which is not "all the predators".
A pig or an ape sits above an ant, which is one of the most formidable predator of the animal kingdom.
> they absolutely eat herbivores sometimes
of course they do.
it doesn't change the fact that some of their preys are predators themselves.
because they eat them for their meat, not because they are labeled "preys" in the encyclopedia.
> That doesn't mean ecosystem complexity is the same everywhere
if that's the argument, it doesn't follow that watery ecosystems are the same everywhere too and that they are more complex than any other ecosystem.
> Can't say I understand your point
was quoting the original comment which goes like this
algae-Zooplankton--Predator-Predator-Predator-Predator-Predator-Predator-Predator
at the zooplankton level you already have whales eating it.
end of the chain.
so zooplankton is the equivalent of terrestrial ants that eat plants and then some bird eats the ants and then some small predator eat the bird and then some bigger predator eat the small bird eater then some even bigger predator eat it, until you arrive to an apex predator (a bear, for example).
What's the difference?
> that marine food chains are longer
but not because algae-Zooplankton--Predator-Predator-Predator-Predator-Predator-Predator-Predator
but because
eukaryotes-bacteria-bacteria-bacteria-bacteria-bacteria-bacteria-Valonia ventricosa
No, we are omnivores, both behaviorally and physiologically. As I mentioned, predator is a functional class, but we are absolutely are predators - predation is killing something to eat it. Perhaps you mean we aren't obligate predators.
Regarding the trophic position of omnivores and the existence of multiple trophic levels of consumers, which I acknowledged in my first post, it doesn't really matter - you can calculate trophic position by the mean trophic level of the things you eat. Half grass and half cow would be 2.5. Humans are around 2.2 [1], because we are omnivores.
> at the zooplankton level you already have whales eating it.
Well, blue whales are krill specialists and yes have a fairly low trophic level - 3.2 - but it is a cherrypicked example of course. The equivalent is saying an African elephant is a browsing herbivore and generally aren't bothered by predators, which is one less trophic level than the whale example. In reality, both can be preyed upon especially when young or infirm or old [2] and in practice it may be better to not cherrypick.
> What's the difference?
The difference is in the pelagic ecosystem there are often more levels. The difference is due to trophic efficiency, energy gets moved from primary productivity up the chain faster and with less loss.
>but not because algae-Zooplankton--Predator-Predator-Predator-Predator-Predator-Predator-Predator
No, that's exactly why.
Extending Briand and Cohen (1987), we reconsidered which class of ecosystems supports the longest food chains. Among all 113 food webs of Briand and Cohen (Briand and Cohen 1987; Cohen et al. 1990), and also among the 28 webs in three-dimensional habitats, ecosystems with one-celled plant producers have the longest maximum food chains. By “pelagic” ecosystems, we here mean those based on single-celled primary producers (phytoplankton). Among these 113 food webs, the 10 ecosystems with longest maximal chains all had single-celled (phytoplankton) primary producers (fig. 1A). Of the 28 three-dimensional webs, the 16 webs with the longest food chains also had single-celled (phytoplankton) primary producers (fig. 1B). In all, about half (56) of the 113 Briand and Cohen webs and 21 of the 28 three-dimensional webs were supported by single-celled plants. The 10 webs with longest food chains were all aquatic: eight were from pelagic three-dimensional ecosystems (six in oceans and two in lakes) [3]
You may have misinterpreted the study from the abstract but full pdf available from googling the name.
[1] https://www.pnas.org/doi/10.1073/pnas.1305827110 [2] https://onlinelibrary.wiley.com/doi/epdf/10.1111/mms.12906 [3] https://www.journals.uchicago.edu/doi/full/10.1086/686880
After the mother of all extinctions, it would be a field epoch for the scavengers.
The terrestrial food chains information is just incorrect. Fungi are absent in that description. Insects are eaten by countless prey species, apex predators have multiple trophic levels below them. There are countless insect, fungal, and animal carrion feeders.
A post that is so factually inaccurate should not be so upvoted. We shouldn't meta comment, but the rapid decrease in submission and comment quality on Hacker News is really a problem.
And the fact that land animals evolve to marine lifestyles is just expected, oceans are more than 70% of Earth's surface. The lack of marine, pelagic animals is notable in that sense.
Come to think of it, I talk to a lot of five years olds which has definitely impacted how I approach topics.
First, sea life bounced back faster than expected, not faster than other life. Sea life is believed to have been disportionately impacted by the P-Tr extinction phases. Plenty of terrestrial life survived the extinction period. Unless you or anyone else knows better, the worst impacted was on marine life that relied on calcium carbonate. Lots of life survived this extinction event, terrestrial and marine. This paper is not comparing terrestrial and marine recovery rates.
Second, the statement about terrestrial food chains is not simplifying, it is reductive to the point of being incorrect. What does an earthworm eat (or other annelids)? How many trophic layers are present in soil microbiomes? Terrestrial food chains are wonderfully deep and complex, even if marine ones are moreso. You don't have to detract from one emphasize the other. That reduces peoples' understanding.
Third, life originally evolved in marine environment, and migrated to land. Life evolves back and forth between the marine and terrestrial over time. Both are great, and life particularly likes the boundary. Saying "land animals keep going back to the ocean" ignores parts of the story, and also reduces peoples' understanding by giving an incomplete picture.
A good example of "simplify[ing] something and retain[ing] the essence of a valid point" is a wonderful thing, but I have have sincere issues with the degree of simplification and retention here.
2. I replied to the comment to point out that it was a slight exaggeration but directionally is correct. I took it to indicate exactly that, a comparison between length of food chains in either domain. And mentioning complexity among sediments and annelids among them doesn't change that because ocean has very similar and complex communities (and annelids assemblages). I doubt anyone came away from that message thinking that there really are no predators of predators on land but I could be wrong. Really, after intially replying about the shortcoming of the answer, after reading replies I was then left wondering what the commenter did wrong.
I dunno, I'm an ecologist and reasonably familiar with trophic ecology so I suppose it's possible the comment comes across as more misleading than I think to others, (maybe I'm filling in the gaps without realising it)
3. Life does keep coming back to the ocean. Sure there were separate emergences from it, but take tetrapods - I am pretty sure the current understanding is just one event close to 400 million years ago? OTOH dolphins, seals, and manatees all arose from separate ancestors much more recently.
2. My biggest problem was with the level of reduction of terrestrial, not directionality.
3. That is a fair point, and I know you could have listed even more examples than just tetrapods. But the gills to lungs is also a much bigger step, and none of those examples have reacquired gills. So it comes back to the ocean, but with an asterisk.
My thanks for the stimulating discussion.
2. Yeah, since my first take before reading replies to point out it was exaggerated I reckon we don't fundamentally disagree. It has occurred to me since, the reason I probably saw this comment as useful is because while things are really way, way more complex as you've mentioned, when we seek to understand it, we usually do simplify things back down as far as possible while still capturing the essence of whatever aspect of the complexity. For example, simply calculating mean trophic level and simplifying organisms to a single number based on the average trophic level of what they eat [1] which enables modelling key aspects of the system [2]. Then you can do something like.. compare commonalities between a soil ecosystem, which may indeed have a three levels of consumers, to an African savannah. But you are right that it is important to consider a web and not a chain as the fundamental topology, but again if you want to look at one aspect, max lengths of the web, there's a good reason to pull out a single chain. For someone that can drown in complexity, I feel a debt of gratitude for people that have demonstrated when highly simplified models can capture aspects of trophic ecology.
Regarding point three, that's an interesting point. You might be interested in this recent study [3] that suggests that the purpose of gills was originally electrolyte balance, not gas exchange for respiration. If that's the case, terrestrial animals might not have the impetus to 're-evolve' gills. There's no right way to make a living in the ocean though, I reckon as soon as your lifecycle has no obligate terrestrial phases, you've made it.
Until next time, 10 y.o. 'throwaway' account!
[1] https://doi.org/10.1006/jmsc.1997.0280 [2] https://doi.org/10.1093/icesjms/fsr062 [3] https://www.nature.com/articles/s41586-022-05331-7
“ there is roughly 80 times more biomass on land than in the oceans. ”
The majority of animal biomass is in the oceans. the reason for the massive 80x disparity is the study cited by that reference was doing a census based on weight of carbon, and that figure is dominated by largely metabolically inert wood.
By biomass, primary producers in the oceans are indeed much lower, but energetic turnover of phytoplankton is very efficient.. imagine that anywhere the water is greenish it is full of photosynthesizers (and everywhere it is crystal clear as well).
In terms of biomass of non-plants, note that pelagic fish are so hyperabundant that ships with sonar thought they were the seafloor wikipedia.org/wiki/Deep_scattering_layer
https://www.amazon.com/Metazoa-Animal-Life-Birth-Mind-ebook/...
[1] https://www.noaa.gov/education/resource-collections/ocean-co...
Vs. with astronomers, physicists, and such...a phrase like "extremely bright" could mean "the comet will be visible with binoculars, if you know exactly where to look". Or, it could mean "if there were any Earth-like planets in that galaxy...well, there aren't now".
But I really think the "all life is screwed" mantra is damaging to us, especially our youth. There needs to be a balanced take on this, because saying that all life is screwed gives no hope or even purpose to the kids growing up now who will inevitably need to fix what we're leaving them. I'm mid-20's and I grew up with some level of media telling me that the world was ending, but it was pretty muted and didn't make me feel like there was no way we could fix things.
I'm not saying people won't die or people won't have to massively change how they live to adapt to climate change in the future, but we need to stop basically saying that every single human dying is an inevitability with climate change.
As a thought experiment: Let's say in ~50 years 10% of humans die in a 5 year span due to catastrophic climate change (~800 million based on current pop.). What is the incentive at that point for governments to NOT force radical regulation legislation to go through? Money? In the past few years we've gotten to the point where renewable energy is simply cheaper than the alternative. Now imagine we have better batteries years down the line. Exactly who is profiting at that point? The oil companies? They can just invest in renewables and save the money they'd lose fighting uprisings from the people in their countries who have lost, in this thought experiment, 800 million fellow humans.
All this to say, climate change is a BIG DEAL. But let's stop wallowing in that fact, and let's focus all that energy in pushing for governments to force companies to do the right thing.
There will be mass starvations, mass migrations, mass extinctions, and more, but that doesn't mean life will cease for humans. We will see worse storms, and a generally less livable planet, but if we can have both Eskimos and Bedouin thriving on the same planet, it's weird to think we'd suddenly lose our extreme adaptability.
Humanity has gone through cycles of famine, war, exploration in the past. Feels like this could be the 21st Century parallel maybe...
Probably would also help to have a single figure who can unite us to share more and all take personal responsibility for the collective good.
Part of me feels like climate change is this single figure. Instead of a single person rising up and saying "We need change and this is how we do it", it's the planet that we all share that's forcing our hand. I think that's great in a certain respect, it's reality smacking us and screaming into our faces. Of course it will mean a lot of death, but sometimes it seems we need to experience loss to stimulate progress.
Now, of course, this doesn't mean these benefits will be evenly distributed (this is going to even further increase wealth inequality and be a deadly disaster for many people), and we are pretty terrible at prioritizing e.g. protecting natural ecosystem biodiversity. There will certainly be irreversible (in human timescale) losses to our ecosystem and therefore the knowledge and potential of future civilizations from this. And there are even some truly catastrophic death spiral scenarios possible. But it's likely that even the cynical reality will end up being something of a widespread unfairly distributed uptick in disaster risk and continuation of the mass extinction we've already started - slowing quality of life improvements for much of the world, but not stopping them - with an eventual strong recovery in all areas if/when we engage our new levels of technological advancement and begin re-wilding programs to purposefully regrow thriving natural habitats. (This is somewhat inevitable if/when the average quality of life of people is high enough they have room to care about such things. Industrial processes applied to helping nature thrive would do a lot)
This is the "human nature sucks at scale and we're slow to change course" cynical view but with a "technology and industry is crazy good in the long term at achieving its goals and uplifting people" bullish caveat prediction - which I believe to be the age-old trend. We clearly need better global-level response organization to deter the worst effects of climate change and help distribute risk so it's not all falling on the poorest people, but industry-wise - if we have to dump a trillion into something stupid-inefficient like direct carbon capture machines, we will. (My preferred solution is mass-farming kelp - far cheaper per CO2 ton and numerous additional beneficial products that basically make it pay for itself at scale). The world isn't coming to an end. It's coming to a recession/depression - which will be felt to different degrees very unfairly - and it's spurring new responses.
https://www.sci.news/paleontology/guiyang-biota-11644.html
Also see the related (linked) discussion of the cause of the Permian extinction:
> "The team’s findings showed that volcanic eruptions in Siberian Traps released immense amounts of carbon dioxide into the atmosphere. This release lasted several millennia and led to a strong greenhouse effect on the late Permian world, causing extreme warming and acidification of the ocean."
> "Dramatic changes in chemical weathering on land altered productivity and nutrient cycling in the ocean, and ultimately led to vast de-oxygenation of the ocean. The resulting multiple environmental stressors combined to wipe out a wide variety of animal and plant groups."
It's worth noting that current fossil fuel emission rates of CO2 to the atmosphere are as much as 14X the rates during the Permian extinction, although humans have only really been at it for 150 years or so, compared to thousands of years during the Permian era.
And a rate of 14x times 150 years yields the equivalent of 2100 years of Siberian Traps pollution.
Current knowledge is that this activity preceded the Permian extinction for 250K years [0]. That might seem like "Oh, we're only around 1% there".
But, critically, the authors of the paper point out:
“We don’t know if a little erupted for 250,000 years, and right before the extinction, boom, a vast amount did, or if it was more slow and steady, where the atmosphere reaches a tipping point, and across that point you have mass extinction, but before that you just have critically stressed biospheres,”
We are creating serious danger here with this massive uncontrolled experiment on the climate. Once the food web breaks, we're fooked, with no way to recover in time.
[0] https://news.mit.edu/2015/siberian-traps-end-permian-extinct...
There's a vast difference between what we were releasing 150 years ago, or even 50 years ago compared to now.
The output is also accelerating, despite efforts to contain it. The only thing that seemed to cause a dip was the beginning of the pandemic.
But by all means, please continue to provide an example of the kind of dismissive opposition that is and will be faced by people trying to fix the problem, even when the food web is already collapsing.
> And a rate of 14x times 150 years yields the equivalent of 2100 years of Siberian Traps pollution.
From your original comment you display no understanding that the rate isn't constant.
Perhaps instead of lamely defending your original post, you could instead add to the discussion by digging up the actual historical rate of increase and using it to rework the calculation for a more detailed result, and then project the current rate of increase into the future for the next few centuries and see how much of a dent that makes. Come to think of it, why didn't you do that in the first place?
But, thanks for again demonstrating Vladmir Lenin's thesis on how effective Useful Idiots can be in derailing progress. Keep right on helping ensure that no one can make a point that disturbs the status quo, and make sure that nothing changes...
sheesh
That's a lot of words for name calling.
> Perhaps instead of lamely defending your original post
You made a simple error, and yet I'm the one defending? You're projecting. Honestly, it's people like you that put people off doing things climate change related. Self important, with a smart aleck response for everything.
Your entire point is dithering about values of 0.005 vs 0.01 and I was noting that we're somewhere around two orders of magnitude within the greatest climate disaster and extinction in the planet's history, but sure, let's waste our time over that 50% error.
[0] https://www.cia.gov/stories/story/the-art-of-simple-sabotage...
I don't have one. You're encouraging other to though. Finding fault is part of Science, it has nothing to do with disagreeing with your world view.
Finding RELEVANT Fault is part of Science
Of course the rate has changed, but that level of precision is irrelevant to this question. If it was a steady change to this level, then it is off by 50% (straight-line-average), which is irrelevant; if it is a hockey-stick curve that only makes the point stronger, i.e., humans are super-rapidly producing that scale of greenhouse gasses.
The entire point is a very rough estimate that humans are outputting greenhouse gasses APPROACHING THE SCALE OF the greatest climate disaster in the 4.5 billion year history of the planet.
Despite the ordinary expectation that the Siberian Traps' gigantic volcanic activity for more than a quarter-million years dwarfs anything humans could ever do in a few centuries, the fact is that the scale of our output is now in the same playing field as that disaster.
I'm pointing out that we do not have a gnat in the room, we have an elephant. Yet you want to argue that I didn't specify Asian vs African elephant.
I'm not trying to weigh the elephant to the gram, I'm pointing out that we need to do something before it tears down the house.
Your comments about the minutiae, whether or not they might be technically correct, are not science; they are a distraction.
Have a good evening. I'm done here.
A bit off topic - picture of co2 history is available here: https://skepticalscience.com/EmmissionsAcceleration.html
This shows the acceleration of CO2 emissions is more than 2-3X the rate of simple assumption in my original post; i.e., it is more of a straight line up from 1950 vs 1850.
So, while my original simplified calculation overstates a static relationship of human output vs Siberian Traps Permian Extinction output by the same 2-3X, it also shows that we're accelerating into the meaningful danger zone at a far faster rate.
Accelerating into the danger zone at a far faster rate — a steeper slope — will cause far more damage sooner than accelerating more slowly from a high Y-intercept point.
Moreover, despite multiple "Climate Agreements", there is no significant decrease in the slope of fossil fuel consumption or CO2/CH4 outputs (except for a dip in the pandemic).
The original point, that human greenhouse gas outputs relative to that of the greatest extinction in the 4.5 billion year history of the planet, is NOT some trivial 6 orders of magnitute lower as we'd expect from "a quarter million years of volcanic belching". Human output rates are in fact coming within two orders of magnitude the extinction rates, definitely on the same scope and scale, and are rising crazy fast.
The fact that it is mostly in the last 7 decades is not comforting, it is far worse
So, thanks for pointing that out.
Thanks for the explanation of what I provided.
https://en.wikipedia.org/wiki/Anoxic_waters
https://en.wikipedia.org/wiki/Bioaccumulation
rediscovering ancient sea states, this Blue Planet went through extreme anti-fertile stages. "recovery" necessarily includes devolving to those states as a possible outcome
A recovery of the carbon cycle I think I read somewhere in the past alone is 10 or 20 thousand years.
It's amazing how resilient life is once it takes hold.
https://en.wikipedia.org/wiki/Holocene_extinction https://en.wikipedia.org/wiki/Paraceratherium