PAR in the Wild at Depth

[VR28man]

So I have this article about PAR and BTA/bubble time anemones / entacmaea quadricolor at depth.

I'm especially interested in this chart.

Am I interpreting it correctly in saying:

- PAR in open water at 0m is like 1800 (as we generally measure this in the reef hobby) on a presumably clear day around noontime. It goes down to 600 PAR at 10m, and only gets to 300 (something many people recommend as a "high amount of light) at around 30m. (which is already quite deep. You'll start seeing relatively few photosynthetyic corals by this depth)

- PAR at even 40m at this site (Aqaba, Jordan - I presume with very clear water, much like the Kona Coast or places like Osprey Reef in the Coral Sea where there's been a lot of "mesophotic reef" research) is still around 150.

(this is actually what I'm most interested: how to roughly capture a certain form of reef ecosystem in the aquarium. In this case, if I wanted a "mesophotic biotope" with the cnidarians you might find at such sites at 40m - e.g. acropora enchinata, granulosa, carduus, BTAs - I might want to keep PAR at no less than 150 for at least a few hours a day. Assuming that the specimens I get from, say, ORA can actually be adapted to thrive in such light levels, which is a completely separate question.

- BTAs can be found in areas that have from 50-700 PAR at noontime in the wild

- ergo, the amount of PAR that most hobbyists strive for in our tanks is actually not that much compared to a wild reef in ideal clear light conditions. (I won't go into the question of "should we seek 1000 PAR for, say, Acropora millepora, and how long we should do so", because I think that question is basically settled by practical experience)

 

[Copingwithpods]

Wow those par numbers are a little humbling. I wonder what the pur values were at those depths, be interesting to see if we're close atleast on that. Very interesting thanks for sharing.

 

[oreo54]

Imitating Natural Light Quality, Intensity, and Dosage in a Reef Aquarium – Do We Really Want To?

When it comes to reef aquariums, Mother Nature has always been the de facto benchmark aquarists aspire towards. Dana investigates in great detail the quality and quantity of light over natural reefs in order to lay the groundwork to answer the age-old question: what is the best light for...

reefs.com

 

[VR28man]

Imitating Natural Light Quality, Intensity, and Dosage in a Reef Aquarium – Do We Really Want To?

When it comes to reef aquariums, Mother Nature has always been the de facto benchmark aquarists aspire towards. Dana investigates in great detail the quality and quantity of light over natural reefs in order to lay the groundwork to answer the age-old question: what is the best light for...

reefs.com

Thanks, @oreo5457 ! I remember Dana had addressed this in some article somewhere but didn't know where off the top of my head.

Overall the data looks pretty consistent between those two articles. (again, the Kona coast Dana surveyed is, and this Aqaba site appears to be, an area with pretty clear water).

FYI, here's what things look like at about 23m (roughly 350 PAR in open water) at Honanaunau, one of Dana's sites, in a video filmed mostly with ambient light by Dr. Bruce Carlson. Note that by this depth, as with most places in Hawaii, most of the coral cover IIRC is Porites compressa, an endemic species, with appearances of very common globablly distrubited species like Porites lobata and Pocillopora eydouxi.

 

[Lasse]

Overall the data looks pretty consistent between those two articles. (again, the Kona coast Dana surveyed is, and this Aqaba site appears to be, an area with pretty clear water).

Not at all - the article in the first post is relative the depth in m and Danas article - the PAR value is relative the depth in feet (1 m = 0.3 feet) IMO the article you refer too seems not be true - 300 PAR at 40 m - I do not believe in that! @Dana Riddle - please read through it and say what you think.

Sincerely Lasse

 

[jda]

The light quality is not good enough to run at sunlight levels.

I kept corals outside in a rubber made tub one summer when we lived in Missouri. The grew like crazy and absolutely thrived. Par about 1500-1900 - hard to measure and had to borrow an expensive meter from my local university since Apogee did not exist then.

If you do much more than 1000-1200 PAR from a MH, then corals start to suffer and burn.

if you do much more than 400-450 PAR from a LED, then corals will burn.

Since this is not quantity thing, it has to be quality.

Also, keep in mind that nearly every coral that we have in this hobby was collected on one breath - easily 90%. Mask, scuba and rebreathers are to catch deepwater fish, which command WAY more money than a coral. When we took an excursion in the Coral Sea, they collected in waist deep water most of the time, and the acropora shelfs out a little ways were about 2m under the water. Some lagunal species were collected in ankle deep water when the tide was low.

 

[jda]

Also, natural light does ramp and even super high light reef tanks usually do not ramp very much, if at all.

 

[VR28man]

Not at all - the article in the first post is relative the depth in m and Danas article - the PAR value is relative the depth in feet (1 m = 0.3 feet) IMO the article you refer too seems not be true - 300 PAR at 40 m - I do not believe in that! @Dana Riddle - please read through it and say what you think.

Sincerely Lasse

Thanks, Lasse. You are correct that Dana's data is in feet while the Aqaba data is in meters, but compensating for this I thought they seemed roughly consistent (down to 700 PAR at 40ft/13m on a sunny day when Dana's data ends)?

 

[VR28man]

Funny, @jda I was kind of hoping you (among a few others) would respond, and had some of your posts in mind when I punted off the question of "should we imitate this in our tanks" in the OP.

Anyway.....

The light quality is not good enough to run at sunlight levels.

I kept corals outside in a rubber made tub one summer when we lived in Missouri. The grew like crazy and absolutely thrived. Par about 1500-1900 - hard to measure and had to borrow an expensive meter from my local university since Apogee did not exist then.

If you do much more than 1000-1200 PAR from a MH, then corals start to suffer and burn.

if you do much more than 400-450 PAR from a LED, then corals will burn.

yup, I remember you saying similar before.

But yeah, I'd imagine sunlight is best for them. I know Pacific East grows their acros in a greenhouse, as I believe does ORA for at least some colonies (eg the Red Planet mother colony). How was the color when you grew them outside?

Also, keep in mind that nearly every coral that we have in this hobby was collected on one breath - easily 90%. Mask, scuba and rebreathers are to catch deepwater fish, which command WAY more money than a coral. When we took an excursion in the Coral Sea, they collected in waist deep water most of the time, and the acropora shelfs out a little ways were about 2m under the water. Some lagunal species were collected in ankle deep water when the tide was low.

Also, natural light does ramp and even super high light reef tanks usually do not ramp very much, if at all.

For the first point, I'm not so sure that's correct anymore - the aqua cultured corals are grown at snorkel depth (Bali Aquarium has video of this) and Cairns Marine has videos of them going coral hunting with scuba.

As to the second point, yes, this is definitely a problem. Back when I ran LEDs I would try that - ramp up to 80% over a few hours, keeping it there for much of the day, and then 100% power the few hours around noontime. But a) I'm not sure that anyone reallly does this ergo I'm not sure how necessary it is b) I think you can replicate this with the more advanced T5 fixtures, but not really with MHs. So again, I'm not so sure if/should/how we could replicate this effect with artificial light.

 

[Dana Riddle]

Spent way too much time on this comparative chart. Converted meters to feet and normalized data. The data from Jordan is higher than what I saw in Hawaii, but considering the difficulties in obtaining measurements, I'm not surprised.

 

[VR28man]

Thanks @Dana Riddle ! It is different, but it's only by like a factor of like +100 or so; the lines are roughly parallel. (in fact, I was pleased to see they were parallel) The difference might very well be due to data sampling/measurement/methodology factors (and is not substantial for practical purposes, I think).

 

[Dana Riddle]

Thanks @Dana Riddle ! It is different, but it's only by like a factor of like +100 or so; the lines are roughly parallel. (in fact, I was pleased to see they were parallel) The difference might very well be due to data sampling/measurement/methodology factors (and is not substantial for practical purposes, I think).

Thanks. It took several attempts to get that data in Hawaii. First of all, it had to be taken at noon, which meant the day started early. I did shore dives, using my dive computer to estimate depth, while holding the PAR meter and recording PPFD with a pencil on a dive slate. The caustic network (glitter/shimmer) caused readings to vary wildly, so I had to estimate an average over the course of a minute or so. Even on a clear day, volcanic smoke (vog) was always present in at least small amounts. My little self-funded lab never had the resources available at universities, so I too am pleased the results compare as well as they do.

 

[VR28man]

Thanks. It took several attempts to get that data in Hawaii. First of all, it had to be taken at noon, which meant the day started early. I did shore dives, using my dive computer to estimate depth, while holding the PAR meter and recording PPFD with a pencil on a dive slate. The caustic network (glitter/shimmer) caused readings to vary wildly, so I had to estimate an average over the course of a minute or so. Even on a clear day, volcanic smoke (vog) was always present in at least small amounts. My little self-funded lab never had the resources available at universities, so I too am pleased the results compare as well as they do.

Ha! On the surface it seems easy to do (go to 40 ft, take a sample, work your way up) but practically I can imagine 1000 nuisances getting in the way of a one-man team. (especially if you didn't get one of those spots right next to the rocks, and had to haul your dive gear from the monument parking lot........)

 

[Dana Riddle]

Ha! On the surface it seems easy to do (go to 40 ft, take a sample, work your way up) but practically I can imagine 1000 nuisances getting in the way of a one-man team. (especially if you didn't get one of those spots right next to the rocks, and had to haul your dive gear from the monument parking lot........)

Thanks! The challenge of getting to a remote site in Hawaii and getting geared up for a SCUBA dive is intimidating enough, plus the recording of data. I lost my pencil twice before getting results recorded. Glad I did this when I was a youngster. LOL.

 

[hikermike]

Latitude of aquaba is 29 degrees while the Kona Coast is 19 degrees...would expect higher par from Hawaii Were they done at the same time of year?

 

[Afm32607]

Just a thought, but shouldn’t these graphs be better interpreted to say the best par levels for btas is between 350 and 250 par? That show the highest concentration of organisms, between 11 and 20 meter, according to graph on the right. The curve in left hand graph indicates par of 350 to 250. Since nems can move freely one could assume their light needs are best met where they Are most concentrated. No?

 

[Streetcred]

Imitating Natural Light Quality, Intensity, and Dosage in a Reef Aquarium – Do We Really Want To?

When it comes to reef aquariums, Mother Nature has always been the de facto benchmark aquarists aspire towards. Dana investigates in great detail the quality and quantity of light over natural reefs in order to lay the groundwork to answer the age-old question: what is the best light for...

reefs.com

Cool ! I especially like this :
" Obtaining light intensity of 511 or 780 µmol photons·m²·sec (light levels needed to reach a DLI of 33.7 or 22.9, respectively, in an aquarium lighted for 12 hours) is certainly possible, but is it desirable? Most likely it is not, based on PAM fluorometer experiments (the PAM fluorometer is a ‘photosynthesis meter’ that estimates rates of electron transport between photosystems through measurements of chlorophyll fluorescence). The information I have gathered so far suggests most corals require only ~400 µmol photons·m²·sec or less in order to reach a maximum rate of photosynthesis (the saturation point). Some corals, such as Montipora capitata, reach a maximum rate of photosynthesis at only ~135 µmol photons·m²·sec, while a Tridacna derasa clam did not reach saturation at light levels of about 550 µmol photons·m²·sec. See here for details: http://www.advancedaquarist.com/2007/3/aafeature1 "

 

[Dana Riddle]

Latitude of aquaba is 29 degrees while the Kona Coast is 19 degrees...would expect higher par from Hawaii Were they done at the same time of year?

The Aqaba measurements were taken in June, mine in July. So many factors could explain the differences.

 

[Belgian Anthias]

As Aqaba is Nord of the Tropic of cancer the sun is at its highest point +- 21 june and the day time a bit longer. I think the measurements taken end of June are comparable with Hawai. This will be completely different end of the year. I have done at least 30 dives in the Golf of Akaba, Dahab, Nuweiba, Wasit, but always during winter months November- April.

 

[blasterman]

You can also roughly calculate this using physics equations based on per square meter energy output of sunlight (at the equator). and then just add the coefficient of absorption in water. No matter how you do it the energy of the sun on shallow reefs in clear water in equatorial zones is pretty astonishing. Corals are simply able to acclimate to our tanks.

If you don't have a PAR meter but a have manual dSLR and an image editing program that can show RGB channels try this: take a picture outdoors of a neutral white target. Now take a picture of your tank at those same manual settings. Now look at the blue channel in Photoshop. Since RGB camera sensors center around 450nm this gives you a decent relative comparison to how much blue light the outdoor target is getting compared to your tank.