Not liking 10,000K MH bulbs
- Thread starter dkedrowitsch
- Start date
Thats a really good point, I always think of corals like plants with regards to light which is clearly not accurate. However for High light loving corals witch generate 99% of thier food from thier zooxanthelle(sp), then more light = more food. So for SOME corals this may hold true, even if its just from better feeding, its still a direct result of a more intense light.
You speak of proper feeding as being the accelerating factor, but this is an irrelivant factor. IF the corals are being fed, then they may be larger, more healthy, have more zooxanthelle and may gain other benifits from the extra light.
Let me give you an example, I know its a plant example give it a thought, as zooxanthelle are photosynthetic and basically are a plant cell, right?
If you increase light to a plant, it will not nessesarily grow faster, If there is a lack of food for the plant, increased light will do nothing. Now accelerate feeding, introduce CO2, and now all of a sudden your bright lights are yeilding volumes of growth.
And vise-vera, if you add the extra CO2 and food, without the light, the plant will not be able to make full use of the extra light. I know its not exactly the same but I would guess it is pretty similar.
I think these may be some studies we are missing in the industry/hobby, how light effects zooanthelle growth and if corals are able to accelerate feeding by having healthier and more zooanthelle availible?
Just some thoughts, its getting to the point of logical thinking and I have nothing to backup these claims...just thoughts nothing more
mark78":1i8qug18 said:
This is a good hypothesis as it relates to photosynthesis. the differentiator is that the coral controls the ETR (electron transport rate) and it regulates that pretty strictly. What this means for us is that there is a "saturation point" for energy created via photosynthesis through the symbiotic relationship with the zooxanthellae. Suprisingly the maximum amount of light that Acropora Aspera can use (in the wild :roll: so I guess it doesn't apply) is the equivalent of sunlight at 8a.m. or 4p.m. in the great barrier reef. brighter light actually causes the coral to "down regulate" its ETR.
liquid":3n8k7fpj said:Yeah I was thinking of Sanjay's home tank. DOH
BTW, I think you guys will be very interested in reading an article in our June issue of AAOLM. I can't say much more other than watch for the 15th and check out the Feature Article.
Shane
c'mon, you're just asking for another 7 pages to get added to this thread after that article comes out! :wink:
DaisyPolyp":3jfl9etg said:
This is the information that appears in the graphs you posted eariler, correct? Those graphs seemed to show that once intensities reached the 700+ PPFD range the "down regulation" was triggered in the corals studied.
Check out this article by Mike Kirda that measured PPFD levels in actual aquariums. I think you'll find that most of the setups aren't getting this much light to their corals.
http://www.advancedaquarist.com/issues/august2003/feature.htm
The brightest tank measured (2 X 400 watt halides + 330 watts VHO) had a hot spot or two right at the very top of the water column that was up in this range.
Also, do we have any idea as to what effect plankton levels would have on ETR? Would having less planktonic nutrition and having to depend more on photosynthesis for energy needs (as would be the case in most home aquaria) have any effect on this scenario?
ack, I was hoping to avoid this, but the units of measurement in the 2 studies for PPFD are not the same. In the AAOL study, the unit of uE/m2 is used to describe the energy of a monochromatic source of photons (in this case the "monochromatic" source was actually a composite of PAR wavelengths (400-700nm)). In the university of sydney study I cited (via use of their graph), the researchers use umol m-2 s-1 which is a measurement of the amount of photons present at the location of measurement. The univeristy of sydney's study used a DIVING-PAM (submersible pulse modulated florometer) which measures photons in a much wider spectrum than PAR. This makes the PPFD numbers in the graphs much higher than would be measured by a Li-Cor or similar instrument.
Not to be a PITA (I know, too late, right?... ), but I'm just trying to understand this...
I'm not so sure about that...
It's my understanding that 1 micromole (umole) = 1 microEinstein (uE) = 6.02 X 10^17 photons. Therefore 1 umole/m^2/s should = 1 uE/m^2/s. At least that is my understanding after taking Sanjay's lighting class.
I believe Mike mentions uE/m^s in error in his write-up (because that wouldn't make any sense if the statement above is true) when in fact it should read uE/m^2/s.
I believe that's exactly how the equipment works - it's counting photons and essentially multiplying by some average energy value per photon in the 400-700nm range to determine the reading.
Unfortunately, that's just an approximation of what's really happening because all photons are not created equal. As you know, the shorter light wavelengths contain more energy (per photon).
In fact I think you (earlier) pointed out your dislike for comparing lamps by PPFD for this very reason... I guess that's why we need to see those spectral curves as well...
On Li-Cor's site it mentions that their instrument has "equal response to all photons in the 400-700nm wavelength" implying that it is counting photons. I think we're basically talking about the same units here.
That part doesn't make sense to me. Why would we be measuring PPFD in wavelengths outside the range that is known to be responsible for photosynthesis (ie. PAR range = 400-700nm)? Also, what wavelengths outside the PAR range would be present at depth in the ocean? Shouldn't most stuff outside of the violet/blue/green range have been attenuated?
I'm not sure how the florometer works - maybe it keeps track of photons in the different wavelengths and is assigning the correct energy values, thereby giving a more accurate PPFD figure?
...sheesh, you guys are really making me work at this now...
), but I'm just trying to understand this...DaisyPolyp":1g079env said:
I'm not so sure about that...
It's my understanding that 1 micromole (umole) = 1 microEinstein (uE) = 6.02 X 10^17 photons. Therefore 1 umole/m^2/s should = 1 uE/m^2/s. At least that is my understanding after taking Sanjay's lighting class.
I believe Mike mentions uE/m^s in error in his write-up (because that wouldn't make any sense if the statement above is true) when in fact it should read uE/m^2/s.
DaisyPolyp":1g079env said:
I believe that's exactly how the equipment works - it's counting photons and essentially multiplying by some average energy value per photon in the 400-700nm range to determine the reading.
Unfortunately, that's just an approximation of what's really happening because all photons are not created equal. As you know, the shorter light wavelengths contain more energy (per photon).
In fact I think you (earlier) pointed out your dislike for comparing lamps by PPFD for this very reason...
I guess that's why we need to see those spectral curves as well...DaisyPolyp":1g079env said:
On Li-Cor's site it mentions that their instrument has "equal response to all photons in the 400-700nm wavelength" implying that it is counting photons. I think we're basically talking about the same units here.
DaisyPolyp":1g079env said:
That part doesn't make sense to me. Why would we be measuring PPFD in wavelengths outside the range that is known to be responsible for photosynthesis (ie. PAR range = 400-700nm)? Also, what wavelengths outside the PAR range would be present at depth in the ocean? Shouldn't most stuff outside of the violet/blue/green range have been attenuated?
I'm not sure how the florometer works - maybe it keeps track of photons in the different wavelengths and is assigning the correct energy values, thereby giving a more accurate PPFD figure?
...sheesh, you guys are really making me work at this now...
Chris, good question. I am interested if anyone has more information on the DIVING-PAM meter and what it is typically used for as far as field research goes. In response to your questions, theoretically as reef aquarist there is no reason to measure energy outside of the range of photosynthesis because this is of no use to the corals which we keep. That being said, I'm curious if the DIVING-PAM meter used in this study is typically used for purposes outside of the biology realm.
As I'm sure you're aware of, as depth increases most wavelengths of light are attenuated with the exception of the blue/violet end of the spectrum, which is within the 300-700nm PAR range. If the DIVING-PAM instrument is typically used to study lighting conditions at depth within the ocean, then values obtained at depth from this meter may be of use to us as reef aquarists because the wavelengths outside the PAR range would have been attenuated. If this instrument was used immediately below a lamp, such as in the setup that Sanjay and I used during our recent articles, then the data will be of little value to us however because the meter records energy outside of the PAR range.
Hopefully Sanjay will join in and add further information to this interesting thread.
Fluorometers are fluorescence-based devices that broadcasts a monochromatic spectrum and measures the fluorescent radiation "bounced" back to the sensor. It's got a lot of applications in the field including biological apps such as measuring for certain types of Chlorophyll (which can subsequently detect density and type of phytoplantkon) I'm not sure it's used for the same purpose as the LiCor unit. It's method of operation is certainly different, and I think what it quantifies is completely different too. But I admittedly don't know much about fluorometers except the cursory mentions if it I've read in scattered articles.
you are very close on most of that... I think we are beginning to close that loop! :wink:
Let me start with the last one first:
At the time of this study (1996) the DIVING-PAM had just been developed as a submersible version of the MINI-PAM (Walz, Germany) which is used significantly for the study of terrestrial plant photosynthesis. That being the case, this would be the first time that in situ measurements could be made, and the researchers did not want to preclude the possibility that wavelengths outside of the visible spectrum play a role in this process as UV radiation has significant penetration in seawater. It is important to note that Tridacna Maxima and Heteractis anemones were also included in this study. Other than that the only difference is that the DIVING-PAM was measuring the amount of photons present in mols (1 mol = the amount of atoms in a gram of carbon-12)
the Li-Cor device (like the one used in the AAOL article) measures the energy carried by the photons in the 400-700nm wavelength. We often use uE and uMol interchangeably for our purposes, and normally that is fine except when you step outside of the PAR spectrum.
Actually it measures the charge created by photons striking a membrane.
Exactly
Let me start with the last one first:
At the time of this study (1996) the DIVING-PAM had just been developed as a submersible version of the MINI-PAM (Walz, Germany) which is used significantly for the study of terrestrial plant photosynthesis. That being the case, this would be the first time that in situ measurements could be made, and the researchers did not want to preclude the possibility that wavelengths outside of the visible spectrum play a role in this process as UV radiation has significant penetration in seawater. It is important to note that Tridacna Maxima and Heteractis anemones were also included in this study. Other than that the only difference is that the DIVING-PAM was measuring the amount of photons present in mols (1 mol = the amount of atoms in a gram of carbon-12)
the Li-Cor device (like the one used in the AAOL article) measures the energy carried by the photons in the 400-700nm wavelength. We often use uE and uMol interchangeably for our purposes, and normally that is fine except when you step outside of the PAR spectrum.
Actually it measures the charge created by photons striking a membrane.
Exactly
It appears (according to Matt's link) Mr. Delbeek doesn't seem to feel there's any significant phytoplankton levels in our home aquaria. Anyone have any information to the contrary?
Also, what's the bottom line with comparing the GBR study with Kirda's numbers? Are they somewhat comparable, or are we talking apples to oranges here?
If so, does anyone know of any numbers comparable to Mike's that show when corals will start to see photoinhibition so we can see how that stacks up to the lighting setups he tested?
Also, what's the bottom line with comparing the GBR study with Kirda's numbers? Are they somewhat comparable, or are we talking apples to oranges here?
If so, does anyone know of any numbers comparable to Mike's that show when corals will start to see photoinhibition so we can see how that stacks up to the lighting setups he tested?
That's a good link, I wonder how we could test for phytoplankton levels... any ideas?
The GBR study we know is reporting larger numbers than we're interested in, but how much larger I don't know. I will look through some other studies I have to see if we can find "the missing link" as it were, between the two.
The GBR study we know is reporting larger numbers than we're interested in, but how much larger I don't know. I will look through some other studies I have to see if we can find "the missing link" as it were, between the two.
DaisyPolyp":x9xo0cra said:
Get out a microscope, and put some tank water under it. I've done this, and there's none apparent to me. Granted I hardly even know how to use a scope. If you're truly interested you might ask Dr. Ron as well. He likes doing this kind of thing.
Here are some pics of phytoplankton additives done by MattM:
http://reefs.org/phpBB2/viewtopic.php?t=7845&start=0
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