Talk:Microbial mat

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Philcha (talk) 10:31, 9 July 2008 (UTC)


Bundi Hill Sandstone, Indargarh area, Rajasthan] - wrinkles as evidence of mats.

N.B. stromatolites are produced by mats. Philcha (talk) 23:28, 1 July 2008 (UTC)

Uses of mats[edit]

-- Philcha (talk) 12:26, 17 July 2008 (UTC)


I've sorted out the timeline. It has defaulted to the International standard colours for the timeline periods, which do look a bit horrible, I'll admit - I don't know whether you want to let aesthetics override convention in this case? (syntax is period3-colour=anythingbutbrightpink)

I took the opportunitu to grab an image of a particularly nice (and somewhat infamous) microbial mat while in Sweden, which I'll put up when I've connected my camera. Don't let me forget!

And nice work with article, and the DYK, by the way. A little publicity never hurts!!

Best, Martin (Smith609 – Talk) 11:46, 15 July 2008 (UTC)

Timeline - invert?[edit]

The timeline currently runs the conventional way, with the present at the top. I think it might be better the other way up, so that it keeps pace with the chronological account of section "Role in the history of life". Any comments? -- Philcha (talk) 14:57, 16 July 2008 (UTC)

I'd be inclined to keep it the right way up; anything else will only breed confusion. Martin (Smith609 – Talk) 15:33, 16 July 2008 (UTC)

Thoughts after a read through[edit]

A great read - nice work! I suspect that there are a couple of points presented as established fact that some would take exception to, and the "hydrothermal first" hypothesis is an interesting one which I haven't seen considered seriously before (probably due to my limited reading - you probably know more about these things than I do, now!) - as always, I'm sure you could find a differing viewpoint if you looked around hard enough, but there is perhaps no need. The article is coherent and comprehensive, and besides a couple of notes I've left as hidden comments, gets my solid thumbs up!

One area that I might be inclined to cover in a little more detail is the chemical gradients - the depth of oxygen penetration and the sulphidic zone - and you could also make a little more of the migration up and down of the zones throughout the day, which I find fascinating. But you may consider this to be unnecessary detail.

Again, good stuff! What's next, I wonder? Martin (Smith609 – Talk) 15:58, 17 July 2008 (UTC)

"hydrothermal first" has been around for years. My biggest doubt is that I've seen estimates that the life-time of modern vents is of the order of 10K years. But the Earth had a lot more decaying radioactive elements then to power volcanism etc., so perhaps vents lasted much longer.
More volcanism would probably make them last for less time, as the ridges would spread faster, transporting them away from the heat source more quickly. But that's by the by - if you're convinced that's fine. Martin (Smith609 – Talk) 19:07, 17 July 2008 (UTC)
If you can supply good sources for other views, I'm interested. The heat+minerals+gases argument for vents looks good, but the 10K years life-time of modern vents bothers me a bit. -- Philcha (talk) 20:22, 17 July 2008 (UTC)
Hmm, vents & I.R. photosynthesis rings vague bells, in fact. It's a while since I learned about these and I never managed to muster up quite the excitement you seem to have done about the subject, so the details are somewhat slippery in my mind! Martin (Smith609 – Talk) 21:29, 17 July 2008 (UTC)
I could only spell "microbial mat" a month ago. But I admit I got enthusiastic, especially about the implications of each step forward in photosynthesis and about the possibility that mats were the birthplace of eukaryotes. -- Philcha (talk) 22:17, 17 July 2008 (UTC)
Re your hidden notes:
  • After "Although the Cambrian substrate revolution opened up new niches for animals, it was not catastrophic for microbial mats". Apart from the stats cited, the CSR only deprived mats of one type of environment - and there's an awful lot of deep-sea floor. Mathematically it's not a surprise - losing a few % made little difference to microbial mats but a big difference to animals (crumbs from the rich microbes' table).
Hmm, I guess my definition of "microbial mat" is more restricted than it could be. Fair enough... Martin (Smith609 – Talk) 19:07, 17 July 2008 (UTC)
What's the definition of "microbial mat" that you're used to? Krumbein & co's appears to be "biofilm that's thick enough to see". If there's another well-supported one, there's more work to do. -- Philcha (talk) 20:22, 17 July 2008 (UTC)
That does the job perfectly; I should have used the word "idea" in place of "definition" to avoid ambiguity. Martin (Smith609 – Talk) 21:29, 17 July 2008 (UTC)
  • Re photosynthesis, you noted "From my memories, the consensus is that it was definitely present 2200Ma, and probably present beforehand. This is worth checking out in other sources if possible - Andy Knoll has written a lot on this subject." My impression is that the paucity of hard evidence means: there are relatively few researchers, so the meaning of "consensus" is stretched a bit thin; they're all vague about timing, so it's hard to tell what they might be in consensus about. Getting back to WP:RS, there are also sources for photosynthesis 3,500 million years ago, one of whom is William "the Godfather" Schopf. We could make the article 50% longer by going into all the debates about dates, and AFAIK it would still be inconclusive. I'm deliberately trolling Murphy's Law here in the hope that something will turn up, but I doubt if Murphy responds to trolling.
Well, there is undisputed evidence of photosynthesis at 2200Ma, and only "good" evidence before then. Maybe this article isn't the place to delve into this.Martin (Smith609 – Talk) 19:07, 17 July 2008 (UTC)
"undisputed evidence of photosynthesis at 2200Ma" - is this referring to oxygenic or non-oxygenic photosynthesis? Either way, Nisbet and Fowler go for early dates. I agree with your "Maybe this article isn't the place to delve into this." -- Philcha (talk) 20:22, 17 July 2008 (UTC)
  • "Most[verification needed] sedimentary rocks and ore deposits have grown by a reef-like build-up rather than by "falling" out of the water" - Krumbein et al p 17. I've removed the "verification needed" tag. Of course if another RS said the opposite we'd have to include it. -- Philcha (talk) 16:46, 17 July 2008 (UTC)
There's a big difference between "microbially modified" (as in source) and "[growing in a] reef-like build up". Martin (Smith609 – Talk) 19:07, 17 July 2008 (UTC)
Krumbein & co's expression is at times almost Hegelian, so it's easy for either of us to misunderstand. On yet another look the problem about the 3rd sentence on p. 17 ("Practically all sedimentary rocks ...") is that "... instead of a concept of physical sedimentation deposited by gravity ..." could be in contrast to (a) the whole sentence up to that point; or (b) only to "if not microbially generated ...". This time round I think it's (b), but next time ...? Can you think of any other good sources to help us settle on an interpretation? -- Philcha (talk) 20:22, 17 July 2008 (UTC)
I'm not sure about sources, but can speak from experience. 99% (and I use that figure as it seems to keep cropping up in Krumbein) of sedimentary rocks I've seen have beautiful sedimentary structures which have formed as a result of gravity deposition. Microbial reefs have been important in their day, for sure - but most sediments are deposited by gravity.
In fact, the more I flick through, I have to express my reservations about some of the comments in Krubmein. 99.9% of biomass, as he seems to suggest (p19), is a hell of a big estimate for the proportion of like that's biomats. What about all those plankton, trees and grasses that cover 99% (that sounds about right, doesn't it?) of the earth's surface? In any model of the carbon cycle I see, these get a mention, with a healthy flux of a few gigatonnes per year passing through their systems, whereas microbial mats don't get a look in. Either all our climate change models need re-writing to take these microbes into account, or the book might benefit from a couple of [citation needed] tags!
Who's Krubmein? Did you forget CTRL-C and CTRL-V?  :-)
I admit the almost mystical tone of some of the writing bothered me. OTOH I read quite a while ago that bacteria and archea accounted for the great majority of the Earth's biomass, so 99% didn't worry me too much. And I'm quite happy with the idea that marine biomats account for most of that biomass and activity, since the other environments of micro-organisms have disadvantages - especially that dessication forces sub-aerial mats and films to spend a lot of their time dormant.
However it would be very desirable to have some other sources. -- Philcha (talk) 22:17, 17 July 2008 (UTC)
this chap can hardly be called conservative but states an accepted range of 5-25% of the primary production - which he ramps up a lot, but you still can't magnify that to 99.9% of life. A scholar search (for "bacteria biomass") threw up a number of other results, for example this one. Neither directly answer the question but they give an indication of Krumbein's error. Martin (Smith609 – Talk) 08:26, 18 July 2008 (UTC)
It's always helpful to view things with a cynical eye, and question the reliability of anything you didn't write yourself. The title alone immediately set me on edge before I had even read one badly-constructed sentence of the chapter... I suspect that any armchair scientist with a dose of enthusiasm and a few spare evenings could knock out a better written and more accurate summary of microbial mats in the space of... well, how long did it take you? Martin (Smith609 – Talk) 21:29, 17 July 2008 (UTC)
It took me about a week, starting from near-total ignorance - fools rush in!
I put "Krubmein"'s poor sentence construction down to English as a 2nd language - and as the artilce had 3 co-authors for whom English may also have been a 2nd language, I'd like to have been a fly on the wall!
There's another source (compilation by Schieber, J., Bose, P, Eriksson, P.G., Banerjee, S., Sarkar, S., Altermann, W., and Catuneanu, O - 2007) I can check out - it's a good sign that I've just skimmed the first 2 pages without hitting a sentence that made me scratch my poor head.
"question the reliability of anything you didn't write yourself" is my attitude, too, but this is Wikipedia! -- Philcha (talk) 22:17, 17 July 2008 (UTC)
Schieber et al (2007) is almost entirely about how to tell whether a sediment contains remains or traces of mats. I'm out of sources for now. -- Philcha (talk) 07:28, 18 July 2008 (UTC)
This is the closest source I could find (not that I had time to search too hard) to amplifying microbe's role in sediment formation. Most of what I see, and what has perhaps confused Krumbie, refers to microbes' role in diagenesis - initiating mineral deposition and the like - which I have far less difficulty accepting. 99% of rocks are probably affected by microbial action between deposition and the end of diagenesis, but I refuse to believe that 99% of deposition is microbially mediated. Martin (Smith609 – Talk) 08:26, 18 July 2008 (UTC)

Unbelievable numbers[edit]

"They colonize environments ranging in altitude from 10 km above sea level to more than 20 km below the surface of the oceans and as much as 30 km below the surfaces of rocks and sediments, and in temperature from from –40°C to +120°C."

Highest mountain is less than 9 km high. Do microbial mats fly?

Deepest ocean trench is some 11 km deep.

Kola Superdeep Borehole was about 12 km deep. —Preceding unsigned comment added by (talk) 17:05, 15 August 2008 (UTC)

There's still no land anywhere on earth ten kilometres up. Someone is going to have to fix these numbers.Punkrockrunner (talk) 16:44, 17 January 2009 (UTC)punkrockrunner

Fangorn-Y (talk) 16:34, 19 July 2010 (UTC)2Philcha: there was described here why those numbers are impossible. There is no abundant life buried deep under rocks, or flying in high troposphere. Even if such life can survive without food sources, at temperature ~1000 K (at 25 km deep), we would not be able to research such deep rocks.

The estimations of total biomass of mats also are unbelievable. Photosynthetic microbial mats are restricted now to very specific conditions and very rare - that is good described in this article, and it article Stromatolite. Ocean floor is very "soft" and is not covered any films. But even if whole Earth is full covered by biofilms, these films would not be able to have such mass. Total biomass of known, "eucariotic" organisms is about 2•1012 tonns. If mats are "thin coatings of 99% organic matter", their mass would be >2•1014 tonns. Earth surface is 5•1014 m2. Thus thickness of such "film", covered ALL Earth, would have to be >40 cm!

Therefore these numbers are IMPOSSIBLE and must be deleted, even if they are written in "reliable" books. I don't know what observations these numbers appear from. Maybe the authors mixed mass of biogenic matter (limestones, coal, oxygen :) and mass of living matter (organisms)??

I think such impossible numbers must be excluded from all articles of Wikipedia, even if they have "reliable" sourced and citations (except maybe citations by world-known scientists). If other editors disagree me, let them explain please how such numbers were calculated!

The 2 of us who created Microbial had reservations, see Talk:Microbial_mat#Thoughts_after_a_read_through. But WP:OR and WP:V would forbid any of us to insert our own opinions into the article. Of course if you find contrary citations, you could said the source show a dispute. See WP:NPOV#Undue weight. --Philcha (talk) 20:43, 19 July 2010 (UTC)
Fangorn-Y (talk) 22:31, 19 July 2010 (UTC) I cannot find the citation that microbial mats can't fly :)) and (excuse me) we need not SUCH citations.
We must not write non-sense information in Wikipedia, even if somebody wrote it in scientific magazines. Scientific mistifications must not by copied to Wikipedia. If somebody thing that information is true, let explain: 1) how it was calculated/measured; 2) why statements by 3 editors written above can be wrong. It is very bad even for authority of Wikipedia, that it has articles where PHYSICALLY IMPOSSIBLE THINGS (such as "mats up to 10 km altitude") are written.
Not every scientific article is a reliable source.
However, if you (or somebody more) need citation, there is at least one: Biomass (ecology) has different estimation of mass of living organisms and has citation too:
"The total global biomass has been estimated to be 2000 billion tonnes with 1600 billion of those tonnes in forests.[1][2]"
At the same source: "Total mass in land plants - 1800 billion tonnes"[1]
At least one of these articles MUST be modified.

Fangorn-Y (talk) 23:05, 19 July 2010 (UTC) In addition: WP:OR and WP:V don't prohibite DELETE certainly wrong information. Moreover, sources having such information MUST NOT be considered reliable. In other words, OR are prohibited, but not every statement being not OR is allowed.

Moreover, "Primary sources that have been reliably published may be used in Wikipedia, but only with care, because it is easy to misuse them... A primary source may only be used to make descriptive statements that can be verified by any educated person without specialist knowledge." Is the cite#2 (Krumbein at al.) a primary source? I don't know because I cannot download cite#2 (Krumbein at al.) by the link after many attempts. Please verify the link #2!

  1. ^ a b "Biomass Basic Information". 
  2. ^ "Biomass". 

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