LIght Intensity (PAR) and Tridacna Clams

Dana Riddle

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The following are from my 25-year old notebook:
"Tridacna": 180 PPFD (PAR)
"Tridacna": 85
T. maxima: 160
T. maxima: 250
T. gigas: 120
T. gigas: 286 - Smithsonian tank. Clam was 10 years old.
T. gigas: 130
Hippopus hippopus: 400
These measurements were made in tanks from Baltimore to Seattle. Instrument was a Li-Cor quantum meter with submersible probe, calibrated for underwater readings. The question that arose in another thread was now to 'balance' light intensities to satisfy both Tridacna and Acropora. PPFD of 300 should be that balance.
 
REEFTIDE

oreo5457

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I almost hate to mention this but which measurements were before Li- Cor corrected the software error that didn' t apply the water correction factor?
See BRS..
About 7:54...

I assume the glitch doesn' t go back 25 years... :)
 
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Dana Riddle

Dana Riddle

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The Li-Cor meter I used was purchased in the mid-90's and had a manual adjustment for air and water, so I doubt there was an error. Unfortunately, the Li-Cor meter I used them died after about 50,000 measurements so I can't go back and check. Even if the was a 32% error, as BRS found, Tridacnas can thrive at relatively low light levels.
 

jda

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This is dangerous, IMO. From all indications, light requirements are different for smaller and larger clams. Larger clams don't seem to need too much light, but the smaller ones all seem to do better with more. All of this said, they certainly can handle a bunch of light if you give it to them. 300 seems reasonable for most with maybe even a bit less for T. Deresa, but I don't want anybody to get the idea that they can raise a T. clam under 85 PAR... odds would likely be against you unless the clam was really large.

If anybody wants to see something crazy, google Gigas Clam Low Tide.
 

oreo5457

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Paper

A depth profile of DF/Fm0 of wild stock giant clams
were obtained in Dahab in May 2007, where T. maxima
(n = 29) was investigated down to 17 m (the deepest depth
for this species found during this study) and T. squamosa
(n = 16) down to 33 m. Measurements from different days
were assembled to produce the depth profile. Ambient light
intensities recorded by the internal light sensor of the
Diving PAM were logged simultaneously with each DF/
Fm0 measurement.
To simulate the metabolic performance of T. maxima
and T. squamosa in shallow and deep waters respectively,
netting was used to reduce light levels to 468 ± 104
(mean ± SE) lmol quanta m-2 s-1, corresponding to
3 m water depth, and 128 ± 59 (mean ± SE) lmol
quanta m-2 s-1, corresponding to * 20 m water depth

Also..
 
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Mywifeisgunnakillme

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I have bright white new shell growth (about 1/4 inch) on blue squamosa's (3 to 5 inches in size) purchased this summer ranging from 300 to 650 PAR, with 8 or 9 hours of full daylight spectrum and 12 hours of total light.

6 t5's (3 blue plus, 1 coral plus, 1 actinic, 1 purpleplus), two kessil 360's, and 2 reefbrites, scheduled with ramp up and ramp down.

I feed live phyto daily (reef nutrition), once or twice, because i have xmas tree worms and nps coral in the tank too. I also feed oyster feast and some dried coral food, a few times a week.

My nitrates are high 20 to 40ppm and my phosphate ranges from 0.04 to 0.2.

Calcium and mag are normal to higher on the typical recommended range.

Ph ranges from 7.9 to 8.3, not everyday but fluctuates.

Alk is 8.5 to 9.5 typically

Interestingly my small maximas and small crocea's died.

Clams are cool, but i consider anything but deresa living a small miracle.

SPS, LPS, and softies and NPS all thrive. No weird coral deaths and nuisance algae, acros do well, tank on cruise control. It's a heavy in and heavy out system for sure.

I poked a clam to show growrh, lol.

20220102_223125.jpg


Screenshot_20220102-223436_Gallery.jpg
 
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Mywifeisgunnakillme

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Paper



Also..
the first paper, if i read correctly, says maximas are near total light dependant and squamosas use light and organics for food.

this makes sense to me. My squamosas do well with 300 to 650 par and daily feedings and high nitrates. But my maximas died.
 

oreo5457

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the first paper, if i read correctly, says maximas are near total light dependant and squamosas use light and organics for food.

this makes sense to me. My squamosas do well with 300 to 650 par and daily feedings and high nitrates. But my maximas died.
Yea but all this is kind of tricky due to the fact that the study uses err "spot" PPFD as opposed to DLI.
In a day a clam may get a higher total photon count at a steady state delivery over 10-12 hrs vs "nature" with a max par of 250 yet over 12 hours it goes from 0-50-100-150-200- 250 then back to zero.
Average (DLI) may be lower than 12 hrs of 200...
Anyways a natural distribution by "PAR".
Their shallow test was ..
128 ± 59 "PAR"
clam.JPG


You may find this interesting as well..
However, Roa-Quiaoit (2005) accumulated abundances at all depths less than 3 m, while we differentiated even between the 0.5, 1.5, and 3 m depth levels and thereby found that although T. maxima shows the highest density at 3 m, abundances in shallower depths are significantly reduced. Furthermore, we found only a few specimens of T. maxima at water depths between 5 and 11 m. This finding is similar to previous studies describing T. maxima as being mostly restricted to reefs shallower than 10 m, principally reef flats and edges (Van Wynsberge et al., 2016). This depth distribution is most likely a result from a trade-off between maximizing light-dependent photosynthesis while minimizing temperature stress, UV irradiation, wave exposure, and/or emersion stress. All these stressors have been previously reported to lead to massive bleaching and mass die-off events in T. maxima (Addessi, 2001) and prevent settlement and recruitment in the shallow waters of the reef flat (Watson et al., 2012). The average size of T. maxima specimens at the sheltered reef was 16.6±5.1 cm (± SD), similar to previous studies on this species in the Red Sea (Roa-Quiaoit, 2005), corresponding, according to the size classification by Manu and Sone (1995), to broodstock (i.e. sexually mature individuals) hermaphrodites. However, the number of small, juvenile specimens (<4 cm) is potentially underestimated, as they are extremely cryptic (Munro and Heslinga, 1983).
 
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Mywifeisgunnakillme

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Also, when it comes to Par, not all spectrum contribute to photosynthesis.
Thats is in particular why i am running a lot of full spectrum and chose kessils for LEDs and run t5s . It seems kessils have a wide spectrum and t5s have always worked for me.
 
Fritz

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Thats is in particular why i am running a lot of full spectrum and chose kessils for LEDs and run t5s . It seems kessils have a wide spectrum and t5s have always worked for me.
Correct me if I'm wrong. If a spectrum is not utilised by zooxanthelle, then it does not directly contribute to the energetic need of the clam.

So compare a wide spectrum light to, say, a narrow but usable spectrum of light. The former needs a lot more "Par" to achieve the same photosynthetic output.
 
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Dana Riddle

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This is dangerous, IMO. From all indications, light requirements are different for smaller and larger clams. Larger clams don't seem to need too much light, but the smaller ones all seem to do better with more. All of this said, they certainly can handle a bunch of light if you give it to them. 300 seems reasonable for most with maybe even a bit less for T. Deresa, but I don't want anybody to get the idea that they can raise a T. clam under 85 PAR... odds would likely be against you unless the clam was really large.

If anybody wants to see something crazy, google Gigas Clam Low Tide.
Only clams that were exhibiting shell growths were included. Unfortunately, I did not note size of the clam in my notes. I wouldn't recommend low PAR either, and I think I stated that.
 
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Dana Riddle

Dana Riddle

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Yea but all this is kind of tricky due to the fact that the study uses err "spot" PPFD as opposed to DLI.
In a day a clam may get a higher total photon count at a steady state delivery over 10-12 hrs vs "nature" with a max par of 250 yet over 12 hours it goes from 0-50-100-150-200- 250 then back to zero.
Average (DLI) may be lower than 12 hrs of 200...
Anyways a natural distribution by "PAR".
Their shallow test was ..

clam.JPG


You may find this interesting as well..
Thanks! Well worth a read!
 

Mywifeisgunnakillme

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Correct me if I'm wrong. If a spectrum is not utilised by zooxanthelle, then it does not directly contribute to the energetic need of the clam.

So compare a wide spectrum light to, say, a narrow but usable spectrum of light. The former needs a lot more "Par" to achieve the same photosynthetic output.
I just do not know what spectrum, so i give them all of it-- and lots of it --to cover by bases. Also, if they are shallower dwelling critters, i assume full spectrum is closer to what they like.
 
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I have added a squamosa clam to my aquarium one week ago. Within the week, the clam showed marked change in the contrast of the mantle.

PSX_20220114_173405.jpg


So perhaps Par and spectrum could change the look of a tridacna, to a certain extent.
Just give it plenty of light and make sure you see new shell growth underneath the mantle. Those changes are probably from a different spectrum of light or how the light is hitting the clam. Also, clams have the ability to move or change where the zooxanthellae reside in their mantles. Zooxanthellae aren't the only thing that produces pigment in the mantle.
 

djf91

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I have a relatively new system (6 months old) set up to be a mixed reef with mostly SPS. Does system maturity matter much for tridacna? I’m not sure if there is a microfaunal/plankton requirement for these clams that you would get with a mature tank. I’m looking to add T. maxima. I was thinking that my lighting could substitute for the lack of planktonic food and nutrients. Lights are 400 watt Radium metal halide. I do have some GHA and cyano from phosphate bound dry rock. Alk. Is solid at 7, cal. 480., Phos. 1.0, nitrate 5.

Sorry don’t mean to derail this thread, just wondering if high par in a new system could make up for nutrients requirements?
 

jda

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If your phosphate is really at 1.0, that could affect the zoox in the mantle. If not using a good tool like a Hannah, then I would not just guess. Microalgae, like dinoflagellates, are affected by high residual nitrate and phosphate levels, but at different levels for different kinds and sometimes the hosts can shield them a bit from super high levels.

I would kinda be shocked if it was really 1.0 if you have cyano... usually matting bacteria is growth-limited at this level, but who know and there are many different kinds.

T. Maxima do shift color a bit as they get larger... usually the same color, just not as intense. I am talking like at 75% of their max size.
 

djf91

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If your phosphate is really at 1.0, that could affect the zoox in the mantle. If not using a good tool like a Hannah, then I would not just guess. Microalgae, like dinoflagellates, are affected by high residual nitrate and phosphate levels, but at different levels for different kinds and sometimes the hosts can shield them a bit from super high levels.

I would kinda be shocked if it was really 1.0 if you have cyano... usually matting bacteria is growth-limited at this level, but who know and there are many different kinds.

T. Maxima do shift color a bit as they get larger... usually the same color, just not as intense. I am talking like at 75% of their max size.
Dangit, I meant 0.1* from hanna checker. Sorry about that. Would like to get it down to 0.05
 
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