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  #101  
Old 04/08/2004, 09:30 AM
Poriferaphile Poriferaphile is offline
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Originally posted by 571958
do you implied that both Vodka dosing and Zeovit is a DOC agent?


Hi Max, Yes vodka counts as DOC. Zeovit, as I understand it, is a multipart system, and I don't know what all the parts are (I'm not sure I really want to know) the zeolite itself is a mineral and contains no DOC.
-Rick
  #102  
Old 04/08/2004, 10:07 AM
Randy Holmes-Farley Randy Holmes-Farley is offline
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All three of my quoted articles mention that ethylene is produced photochemically from dissolved organic carbon, and I believe that ethanol qualifies as DOC. Also, as I mentioned, zeolite catalysis is a well-established method of ethylene synthesis, and zeolites are widely used in aquaria.
.


Yes, but none of them indicate that ethanol is a likely precursor. Your hypothesis that ethanol is doing something unusual would suggest that it should be a better precursor than organics already there for it to be important. I don't have any reason to believe that is the case.

You can dehydrate ethanol to ethylene at high temperature on appropriate catalysts. I do not believe that that process proceeds in water at room temperature. I also agree that intense UV can accelerate the dehydration of ethanol.

So I agree that this is an interesting suggestion, but I do not really see any evidence that it actually happens.

To address your points more specifically:

1. Ethylene is a powerful hormone controlling life cycle and gene expression in plants and animals, and we would be wise to learn more about it.

That could be an interesting, if complicated thing to pursue, I agree.

2. Natural processes in aquaria can produce ethylene in quantities that may affect overall aquarium health, and adding ethanol can be a significant source of that ethylene.

Perhaps. Perhaps not. How do you know that sufficient quantities are formed to be significant?

3. High variability may be at play in the system - if we decide PO4 is too high and add zeolite, change the lighting, a plant becomes mature, etc.

True, whether we are talking about ethylene, ethanol, or any other organic compounds that might be present.

4. It is important to be informed about the ways in which we may be putting our treasured work at risk. In trying to make things better, we would do well not to take undue risk.

True. But after some folks have taken the risk, and observed positive effects, what then?

I'm not a fan of adding ethanol, but it seems no more risky to me than many other actions aquarists take (garlic, other medications, not changing wtaer frequently, using imperfect artificial seawater, compressing animals unusually closely together, etc.
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  #103  
Old 04/08/2004, 06:00 PM
Marc Euschen Marc Euschen is offline
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Hi @ all

at the end of last year I started some test series on these vodka method.

The results weren't all that nice in Lab and later on in the aquarias !

I do know arround 30 aquarists in europe that lost some big quantity of their stony corals... mostly due to
bacterial infections.

The ethanol boosts the growth of almost any bacteria in the tank, some people even reported some withe slimy film
on the aquaria glass. In some tanks the coral died because of "starvation", since PO4 and/or NO3 went down to zero in no time.
Some other ones dies because of the mysterious PO4 increase.

I did a some test in my Lab here in switzerland over period of about 2 month. I did these with some enriched bacteria cultures of my
tanks sediments. When the PO4/NO3 ration was around 1/16, there was a good decrease of PO4 and NO3. If not so, the one or the other
element was the limiting factor stopping or slowing the bacterial bloom. As soon as these happened, the PO4 went up. The answer to that
is, that the dying bacteria where releasing the Phosphorus they previously got out of the PO4.
In a normal tank the skimmer should eliminate most of the biomass resulting from the bacterial bloom. But if the skimmer is
to slow or the biomass to big, then the tank would suffer a massive PO4 peak.
In one tank I was able to measure these, the PO4 went up to 2mg in 18 houres ! If we wouldn't have been monitoring these tank
so closely, then these would have been the end of another aquarium... but we where able to bring enough PO4 Adsorber in to the System
to remove it just in time...


Some other experiments in these area where about the bacterial diversity. The diversity decreased in all cultures and aquarias after
a short while, when feeding it whit ethanol or vodka. In some closed cultures I ended up with just one bacterial strain left in the culture within a week.

Since then I used ethanol only for "jump starting" new systems, so I could get very fast a good bacterial density in a fresh tank.

I believe that ethanol is very dangerous, since its unpredictable what the bacteria growth will be in a certain tank. Ethanol will boost almost
any bacterial, even some marine pathogens. Depending on the conditions, those bacterias might take over the system.

Marc
  #104  
Old 04/08/2004, 07:34 PM
wasp wasp is offline
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Some very worthwhile research Marc.
A question for you. - If vodka dosing was combined with very aggressive skimming, would this remove most of the bacteria from the water column, including the P they contain, and thereby prevent some of the problems you just mentioned, from being able to happen?
  #105  
Old 04/08/2004, 09:03 PM
Poriferaphile Poriferaphile is offline
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Randy,
I admit I don’t have hard evidence that ethylene is produced in the aquarium, but I certainly do seem to fall more on the curious side of the equation than you do. I read something like this (from The Plant Cell article cited above): “ethylene is one of the major alkene[s] in seawater produced by photochemical reactions of the dissolved organic carbon,� I am not inclined to think “they are not saying ethanol is a likely precursor,� knowing full well that ethanol is not present in seawater like it is in dosed aquariums. Frankly your logic sounds more curmudgeonly than open-minded. If I had to think up good precursors for ethylene, ethanol would be pretty darn close to the top of the list. I’m not saying that I know for certain thus-and-so, but I am saying here are some interesting facts that may or may not account for some of the behavior we observe, like otherwise inexplicable algae blooms, say. Better to light a candle than curse the darkness.

-Rick
  #106  
Old 04/08/2004, 09:48 PM
bertoni bertoni is offline
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Rick,

I don't want to jump into the technical discussion, but I personally thought the personal attack in your previous message was not constructive.

Jon
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  #107  
Old 04/09/2004, 01:08 AM
Poriferaphile Poriferaphile is offline
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Quote:
Originally posted by bertoni
Rick,
I don't want to jump into the technical discussion, but I personally thought the personal attack in your previous message was not constructive.
Jon
Jon,
Well perhaps, if you think of "curmudgeonly" is an "attack." As someone who can be a curmudgeon sometimes myself, I thought of it as a mild way to express frustration at what seemed to me to be a needless refutation and even willful disregard of what had been written. For instance, the quote “I don't have any reason to believe [ethylene] is naturally produced from ethanol,� treats the clearly stated hypotheses as if they had never been laid out. To have been constructive, he could have said, “how can we determine if that is in fact happening?� Or, “is there an assay for ethylene in seawater?� Or, “what concentrations are we talking about here?� Something more in the spirit of learning and intellectual inquiry, rather than what had appeared to me to be dismissive refutation. To me that was the real “personal attack.� What was truly “unconstructive� here seemed to me the framing of the discussion in a needlessly oppositional way that had the effect of cutting off inquiry, not a mild personal gibe.

That having been said, I realize it probably would have been better to have expressed my frustration as I just did, and avoiding "curmudgeonly." So I guess that ultimately you are right, and I apologize.
Thanks, Jon.
-Rick

Last edited by Poriferaphile; 04/09/2004 at 01:33 AM.
  #108  
Old 04/09/2004, 01:30 AM
JoeMack JoeMack is offline
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wow, you guys are very smart and I can only comprehend some of the material I just read in these 5 pages but why would you want to use vodca in your tank? When you can't get rid of NO3 and PO4 by other means??

I ellimated them by doing things the so called right way (RO/DI & a fuge & no flake food) to ellimate the problem before it starts its cycle again. Interesting in all and i'm not trying to bash this because this is very interesting and I love learning new ideas but I guess some people cant get rid of their NO3 and PO4? I would love for this thread to get 10+ pages long but I do not understand why we would do this.

The vodka seems like a easy fuge to me. Is this maybe going to replace a fuge (it does the same thing)? I'm very sorry for my ignorance and I might of missed then when reading the paragraphs where it didn't ring a dime to me.

Thanks again all.

Joey
  #109  
Old 04/09/2004, 02:50 AM
Poriferaphile Poriferaphile is offline
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Quote:
Originally posted by Marc Euschen
I believe that ethanol is very dangerous, since its unpredictable what the bacteria growth will be in a certain tank. Ethanol will boost almost any bacterial, even some marine pathogens. Depending on the conditions, those bacterias might take over the system.
Marc
Marc, when it comes to using ethanol for NO3 and PO4 reduction, I tend to agree with your view. The one area where the jury is still out for me, however, is whether ethanol could be used as a nutrient for the general plankton population - as a way of feeding the higher animals, rather than just nutrient export. So, your notes on tests that showed a reduced biodiversity are of great interest. I wonder what dose you used in those tests, and whether a smaller dose would have a similar effect.
Quote:
Originally posted by JoeMack
The vodka seems like a easy fuge to me. Is this maybe going to replace a fuge (it does the same thing)?
Extremely doubtful. It seems you are doing the right things already.
-Rick
  #110  
Old 04/09/2004, 05:40 AM
Marc Euschen Marc Euschen is offline
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@WASP: You're probably right, it should theoreticly be possible to remove the bacterias these way and thus the PO4 with it.
But what if your skimmer isen't 100% effective ? And even if it would be so, then you would still have deal with shift in biodiversity.

One other thing that I'm quit sure for my self is, that PO4 and NO3 should stay in a certain ration to each other. Everytime
I shift these ration in one of my tanks, I get cyanobacterias as result ! When I bring the one or the other level back to a normal state,
then these cyano films start to dissolve again...

I don't know what I'm doing differently to others, but I never had a problem with PO4 nor NO3, well in the opposite way I did. These means
I have to add PO4 and some times even NO3. But in my tanks PO4 is the limiting factor that reduces coral growth. I can see these when the
parts of corals that are in the shadow start to bleach !
To compensate these I add Phytoplankton to my tank several times a day. These seams to be a other possible source for the basic element.
It is still unclear today if SPS are feeding on Phyto or not. But there are two beneficial ways that Phyto goes... one it takes up PO4, NO3 and some Silicates while it is in the tank and removes these through the skimmer, the other thing is that when it "dies" in the tank it releases some Microdoses of its basic elements, these then act as a food source for the corals.

@Poriferaphile: I don't think that ethanol contributes to a better Plankton diversity. It increases the amount of bacterias but not its diversity ! The increase in the bacterial amount could contribute to a better growth of small Zooplankton that feed on bacterias, maybe the same is true for some corals. But since I've seen so many dying corals because of Ethanol, I wouldn't realy
take these as a good way to go.... There are better ways of increasing the Plankton in a aquarium.

Like I mentioned above, the addition of Phytoplankton is one of these ways. The reduction of skimming the system might be another thing, since skimmer remove about all the Plankton in a tank there is !

Marc
  #111  
Old 04/09/2004, 06:09 AM
Randy Holmes-Farley Randy Holmes-Farley is offline
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Frankly your logic sounds more curmudgeonly than open-minded.

Sorry. I'd like to characterize it is skeptical, but everyone is entitled to a different opinion. Lots of things sound like reasonable theories, but end up being wrong.

I am saying here are some interesting facts that may or may not account for some of the behavior we observe, like otherwise inexplicable algae blooms

I guess that I am missing the whole unexplained effects part. If you add a great carbon source, you expect blooms of microorgansims, unless somethign else is limiting. Since such organisms can be limited by lots of different things (organic carbon, inorganic carbon, nitrogen, phosphorus, iron, silica, space, oxygen, light, etc), it seems clear that different aquaria with different assemblies of microorganisms might respond differently.

So what are we trying to explain again?
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  #112  
Old 04/09/2004, 06:13 AM
Randy Holmes-Farley Randy Holmes-Farley is offline
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The results weren't all that nice in Lab and later on in the aquarias !

Wow, thanks for giving those results. That certainly should keep people thinking of using it in a more cautionary mode.

The ethanol boosts the growth of almost any bacteria in the tank

That is certainly my expectation, and is part of the reason why I am unconvinced when folks claim that drops in nitrate on adding carbon sources necessarily takes place in low oxygen environments. A simple bloom is an equally, if not more likely explanation.
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  #113  
Old 04/09/2004, 06:13 AM
wasp wasp is offline
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You have to ADD Po4 Marc ??
Wish I had that problem!
  #114  
Old 04/09/2004, 06:37 AM
Marc Euschen Marc Euschen is offline
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@WASP: Yup I do have to "feed" my tank with Phosphate !

These was only possible after I matched the PO4/NO3 Ratio of 1/16 or so. I did these by the use of a sulfur filter and some PO4 Adsorbent. I found out that in my tank there is a thing like a critical level of 4-5mg NO3. When I get belove these 4mg NO3 I will not be able to hold it there ! It will decrease by itself without any special filtration... the same is for PO4 arround 0.02mg.
The intrusting thing is, is that above 4mg NO3 the level would slowly rise to about 12mg and stop there, but then the level is way out of its ration to PO4.

During the time I tryed these out, my corals have grown that much, that PO4 and some times NO3 have gotten the limiting factors in "my reef". Today I do not use the sulfur filter or any Adsorbent anymore and the levels have staye these way for more then 10 month now.

Most of the time I feed the PO4 in form of some F/2 Media that has not been completly deepletet by the Phytoplankton I feed.

But I must add to these, that my tanks (2 of them) are standing in the office of my Lab. So I have plenty of time and possibilities to play arround it !

@Randy: I'm on your side regarding the "low oxygen environments" ! I did the tests in Lab flasks, on a stirring and "shaking" system. So these culture have 100% not been low in oxigen ! I added some amount of PO4 to each culture, bu I would have to consult my notes to tell you how much ... I then mesured these cultures by Ion Chromatography, directly after filtering the samples or after "digesting" the Biomass and messuring the "fixated" Phospate levels. The results where absolutly clear, the bacterias deepleted the Phosphorous source quiet quickly, the same is for Nitrogen. But these works only if you have them in the right ratio for the specifiy mix of bacterias, then otherways you were lowering just one part of it !

Since there is now way of controling all these parameters at same timem there will be now possibilty to control such a methode. If one source gets depleeted to early, the bloom would crash an so would your tank !!!

Marc
  #115  
Old 04/09/2004, 06:58 AM
wasp wasp is offline
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Marc, How is your tank set up?
I would loke to know how such excellent phosphate control is achieved.
  #116  
Old 04/09/2004, 07:02 AM
Randy Holmes-Farley Randy Holmes-Farley is offline
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Rick:

One of the areas that I think could be a new frontier for reefkeeping is how specific organics might increase growth and/or reproduction (spawning).

Coral farmers, in particular, would be very interested in anything they could add to double growth rates. Further, if we could induce spawning (and successful settlement and growth) of many of the corals that we keep (especially LPS and others that are hard to frag), that would open up whole new species to coral farming.

I think that organics have a big role to play in those actions. Starting with one that would be simple to add (like ethylene) would seem like a worthwhile activity for someone who wanted to study these areas.

One can buy a cylinder of ethylene gas and bubble it into a tank of corals. Maybe it will kill everything. Maybe things will grow faster. Maybe nothing will happen. But that's an easy experiment.

Other hormones/growth regulators/etc. would be potentially much harder to study. First they'd have to be identified, then likely synthesized and purified, and finally tested.
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  #117  
Old 04/09/2004, 07:40 AM
Marc Euschen Marc Euschen is offline
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@Randy: I do believe that Ethylen would not do much better than Ethanol. Rohwer and some resent ongoing Studies of Eric Borneman will show that
the composition of Bacteria on and arround corals is vital to them. Even small changes can kill some of the more delicate ones.
Because of these I would say that anything that alters the Bacterial composition will have it's negative effects.

Inducing spawning in corals would indeed be a big progress. But our systems today do not allow any planktonic Organisms to survive very long
I think one place to start is to make Plankton safer tank systems. In europe we have a lot of activities in these field since Phytoplankton is
becoming more and more important over here.

@WASP: My tank is really simple... a Berline like System, lots of live Rock an some sort of mechanical filter containing some live rocks and some
smaller filter media. A skimmer that operates only 6 hours a day and thats more or less it ! A payed a lot of attention on the flow rates in the tank and in the filter system. I do have 1000 liter tank, I have no idea how many gallons these is !? I have about 25 fish in it and a lot of LPS and SPS.
If your interested you can visit my small web page http://www.euschen.ch, it has some picures and a Webcam on one of the tanks.

One thing I'd like to mention here is something that most europeans forgot or didn't understand when they started the Vodka dosing.
Phosphorus can not be reduced the same way as Nitrogen. Nitrogen can be reduced to Oxigen and Nitrogen Gas, these way it is able to exit
the system. Phosphorus is a solid element and has to stay within the system, as soon as a Cell dyes it releases its Phosphorus, the P. will then
"regroup" with Oxigen and become PO4 again. The only way to get rid of PO4 is, to remove in a solid form or to have it built in to organic matter.

Marc
  #118  
Old 04/09/2004, 07:49 AM
Randy Holmes-Farley Randy Holmes-Farley is offline
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Randy: I do believe that Ethylen would not do much better than Ethanol. Rohwer and some resent ongoing Studies of Eric Borneman will show that
the composition of Bacteria on and arround corals is vital to them. Even small changes can kill some of the more delicate ones.
Because of these I would say that anything that alters the Bacterial composition will have it's negative effects.


I'm not sure we are connecting here. The ethylene is not intended to have an impact of nitrate or phosphate (or bacteria), but to act directly on the biochemical regulatory pathways of corals and other tank inhabitants.

You don't think that it is more likely to have such effects than ethanol?

I'm also not suggesting that it be done in a reef aquarium, but in an experimental coral farm.
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  #119  
Old 04/09/2004, 07:59 AM
Marc Euschen Marc Euschen is offline
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@Randy: You're right about the difference of Ethanol and Ethylen. But don't you think that the changes in methobolism of the corals could also occure in bacterias ? And therefore also change the balance of them ?

It could be interesting to make these tests !

Ethylen is used in biology for a hole bunch of things... the simplest is to ripe fruits faster... I have to read and think about that for a bit more since I'm not really familiar with Ethylen and its usage.

Marc
  #120  
Old 04/09/2004, 08:03 AM
Marc Euschen Marc Euschen is offline
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@WASP: Just a small view on the top of my reef
Attached Images
File Type: jpg reefinzurich.jpg (45.7 KB, 438 views)
  #121  
Old 04/09/2004, 08:07 AM
Randy Holmes-Farley Randy Holmes-Farley is offline
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The effect of specific organics can be very particular, or widespread. Many species use highly unusual compounds specifically so they do not get "confused" by signals coming from other organisms.

Ethylene is farily widespread, at least in nonmarine environmenbts, so it won't be unique to a single species, but I do not know if that extends down to marine bacteria or not (it apparently does not impact some, but it may impact others). It is known to impact phytoplankton. But the effects may be quite different in an LPS coral than in a bacterium.
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  #122  
Old 04/09/2004, 08:27 AM
Marc Euschen Marc Euschen is offline
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@Randy: Now you've got me... what are the effects of Ethylen on Phytoplankton ? I'm working for some years now on Phyto and its needs, but Ehtylen never crossed my mind nor did I ever read anything about it.
  #123  
Old 04/09/2004, 08:51 AM
Randy Holmes-Farley Randy Holmes-Farley is offline
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Perhaps "Known to impact phytoplankton" was an overstatement of mine. Better would have been "believed to be associated with phytoplankton" .

It isn't something that I know much about, but in looking through some references to address the earlier questions in this thread, I came across these papers:


Ethylene and methane in the upper water column of the subtropical Atlantic. Seifert, Richard; Delling, Nikolai; Richnow, Hans Hermann; Kempe, Stephan; Hefter, Jens; Michaelis, Walter. Institut fur Biogeochemie und Meereschemie, Universitat Hamburg, Hamburg, Germany. Biogeochemistry (1999), 44(1), 73-91.

Abstract

The vertical distributions of ethylene and methane in the upper water column of the subtropical Atlantic were measured along a transect from Madeira to the Caribbean and compared with temp., salinity, O, nutrients, chlorophyll a, and dissolved org. C (DOC). Methane concns. 41.6-60.7 nL/L were found in the upper 20 m of the water column giving a calcd. av. flux of methane into the atm. of 0.82 mg/m2-h. Methane profiles reveal several distinct maxima in the upper 500 m of the water column and short-time variations which are presumably partly related to the vertical migration of zooplankton. Ethylene concns. in near surface waters were 1.8-8.2 nL/L. Calcd. flux rates for ethylene into the atm. were 0.41-1.35 mg/m2-h with a mean of 0.83 mg/m2-h. Maximum concns. of £39.2 nL/L were detected directly below the pycnocline in the western Atlantic. The vertical distributions of ethylene generally showed one max. at the pycnocline (.apprx.100 m depth) where elevated concns. of chlorophyll a, dissolved O, and nutrients were also found; no ethylene was detected below 270 m depth. This suggests that ethylene release is mainly related to one, probably phytoplankton assocd., source, while for methane, enhanced net prodn. occurs at various depth horizons. For surface waters, a simple correlation between ethylene and chlorophyll a or DOC concns. could not be obsd. No considerable diurnal variation was obsd. for the distribution and concn. of ethylene in the upper water column.

Emissions of hydrocarbons from marine phytoplankton-some results from controlled laboratory experiments. McKay, W. A.; Turner, M. F.; Jones, B. M. R.; Halliwell, C. M. AEA Technology, Natl. Environmental Technology centre, Culham, Abingdon, Oxfordshire, UK. Atmospheric Environment (1996), 30(14), 2583-2593.

Abstract

Lab. expts. have been carried out to help assess and quantify the role of marine phytoplankton in the prodn. of non-methane hydrocarbons. Evidence is presented here that supports the hypothesis that some short-chain hydrocarbons are produced during diatom and dinoflagellate lifecycles. The pattern of their emissions to the air above axenic unicultures of diatoms and dinoflagellates has been followed. The results suggest that ethane, ethene, propane and propene are produced during the autolysis of some phytoplankton, possibly by the oxidn. of polyunsatd. lipids released into their culture medium. In contrast, isoprene and hexane appear during phytoplankton growth and are thus most likely produced either directly by the plankton or through the oxidn. of exuded dissolved org. carbon.





This one does not specifically mention ethylene, but is discussing the kind of signaling that I was referring to in the context of simple hydrocrbons:

Trophic interactions in the sea: an ecological role for climate relevant volatiles? Steinke, Michael; Malin, Gill; Liss, Peter S. School of Environmental Sciences, University of East Anglia, Norwich, UK. Journal of Phycology (2002), 38(4), 630-638.
Abstract

When attacked by herbivores, land plants can produce a variety of volatile compds. that attract carnivorous mutualists. Plants and carnivores can benefit from this symbiotic relationship, because the induced defensive interaction increases foraging success of the carnivores, while reducing the grazing pressure exerted by the herbivores on the plants. Here, we examine whether aquatic phytoplankton use volatile chem. cues in analogous tritrophic interactions. Marine algae produce several classes of biogenic gases such as non-methane hydrocarbons, organohalogens, ammonia and methylamines, and dimethylsulfide. The grazing-induced release of marine biogenic volatiles is poorly understood, however, and its effect on the chem. ecol. of plankton and the foraging behavior of predators is essentially unknown. We outline grazing-induced defenses in algae and highlight the biogenic prodn. of volatiles when phytoplankton are attacked by herbivores. The role of chem. signaling in marine ecol. presents several possible avenues for future research, and we believe that progress in this area will result in better understanding of species competition, bloom development, and the structuring of food webs in the sea. This has further implications for biogeochem. cycles, because several key compds. are emitted that influence the chem. of the atm. and global climate.
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  #124  
Old 04/09/2004, 09:09 AM
Randy Holmes-Farley Randy Holmes-Farley is offline
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Here's a reference more on point:

Ethylene production by photosynthetic bacteria, cyanobacteria, and algae. Maillard, Patrick; Thepenier, Catherine; Gudin, Claude. Dep. Physiol. Veg. Ecosyst., CEA Cadarache, Saint Paul Lez Durance, Fr. Journal of Marine Biotechnology (1993), 1(2), 97-100.

Abstract

Ethylene prodn. has been studied in five strains of freshwater photosynthetic bacteria, 11 strains of freshwater cyanobacteria, 17 strains of freshwater algae, and 37 strains of marine algae. Thirty-seven of the 54 strains of algae were unicellular. All these species produce ethylene under std. culture conditions, the range of prodn. varying from 0.6 to 5.2 nmol/g(dw)/day. Small differences were obsd. in ethylene emission between phyla or microalgae classes, but no difference between marine and freshwater algae were detd. In all cases, ethylene emission is significantly increased with the addn. of 1-aminocyclopropane-1-carboxylic acid (ACC), this increase depending on ACC concn. Thus, in all the species tested, there is at least one pathway of ethylene synthesis that is the same as in higher plants: ACC --> C2H4.
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  #125  
Old 04/09/2004, 09:12 AM
Randy Holmes-Farley Randy Holmes-Farley is offline
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This reference shows that ethylene impacts some bacteria and not others:

Inhibition of methanogenesis by ethylene and other unsaturated hydrocarbons. Schink, Bernhard. Fak. Biol., Univ. Konstanz, Konstanz, Fed. Rep. Ger. FEMS Microbiology Ecology (1985), 31(2), 63-8.

Abstract

CH4 [74-82-8] formation in anoxic slurries contg. aquatic sediments was inhibited by 50 and 94% at C2H4 [74-85-1] concns. of .apprx.5 and ³36 mM, resp., with no effect on SO42- redn. C2H2 [74-86-2] at gas-phase concns. of 0.015 and 0.3% inhibited CH4 formation by 50 and 97%, resp. Similar results were obtained with anoxic sewage sludge. CH4 formation from added acetate [71-50-1], MeOH [67-56-1], or H/CO2 in the reactor contg. Canal Grande (Venice, Italy) sediment was inhibited by ³98% at a C2H4 gas phase concn. of 5%; inhibition was .apprx.90% when lactate [113-21-3] used as the substrate. Cyclopentadiene [542-92-7] and cycloheptatriene [544-25-2] were strong inhibitors, and C6H6 [71-43-2], PhMe [108-88-3], isoprene [78-79-5], and n1-hexyne [693-02-7] were moderate inhibitors of methanogenesis. Several unsatd. hydrocarbons had no effect. Pure cultures of Methanospirillum hungatei, Methanothrix soehngenii, and Methanosarcina barkeri were inhibited by 50% at C2H4 concns. of 3.6-7.2 mM. Neither C2H4 nor C2H2 had a significant effect on pure cultures of Acteobacterium woodii, Halobacterium halobium, and Sulfolobus acidocaldarius. C2H4 is recommended as a selective inhibitor of methanogenesis for physiol. and enrichment expts. with sediment and sludge samples.
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Randy Holmes-Farley
 

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