Are we overexposing our dragons to UV?

Taterbug":9n8cx3ln said:

Personally, I'm much more wary of supplements than I am of lights. I might be misguided on that though.

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kingofnobbys":1p9u33ph said:

I aim for about 180 to 200 microW UVB / sq.cm and 1 mW UVA / sq.cm at my centrals' basking spots I wont repeat (ad nauseum) why these are good UV irradiation levels for a bearded dragon .

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claudiusx":e0ocjqyp said:

kingofnobbys":e0ocjqyp said:

I aim for about 180 to 200 microW UVB / sq.cm and 1 mW UVA / sq.cm at my centrals' basking spots I wont repeat (ad nauseum) why these are good UV irradiation levels for a bearded dragon .

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Thanks for your opinion.
But that's what it is, just like all of ours. There has been no scientific study on anything in regards to how much a dragon needs. No blood testing under different levels. No baseline of what is the optimal range. There hasn't even been tracking done on dragons where sensors are placed on them to monitor how often they are even exposed to the sun, and at what times and what intensities. Data of uvi averages is shakey ground to stand on. If a dragon is basking at noon with a uvi level of 12, but it's only out there for 5 minutes, it doesnt make sense to base what you provide for 14 hours straight on that 5 minutes of basking.
Sorry if you are confused , the 14 hours relates more to the number of hours per day for the pet dragon to metabolize it's food.
Is more heat related ,and for the wild dragon, food source and scarcity controlled , this is time needed to actually find the food it needs , no one is buying bugs for it and giving these to it , or herbs either.

.

We've already discussed in another thread how mW uvb doesn't = UVI. Different bulbs can produce different UVI levels at the same mW reading. You have both of these meters, you can test it out for yourself to confirm if you want to buy a couple different types of uvb bulbs.

For all intents and purposes, the unit of measurement of this thread will be UVI reading.
And from past posts of your's I believe you recommend 5-7 UVI at the basking surface? You can chime in and confirm or deny that, but I will just use that for now, and edit it if you tell me that's not what you do.

<<< Bang on about inferred UV-Index and your INDIRECT connection to VitD3 synthetic reaction rates all you like.
In other threads I've given a wealth of peer reviewed physical data and cited scientific papers by professional herpetogists and links to all these , anyone is free to review this stuff . I see little point in repeating all that yet again.

In science we talk in terms of DIRECT measurements ( in this case the SI unit for UV flux / irradiance is specified internationally as microW , milliW and W per square centimeter ( this is what is measured by satellites ).
Whether you that or not you personally accept that is irrelevant.

Kindly refrain from cherry picking to try to skew the discussion and hide relevant actual scientific / physical and behavioural studies simply because they do not help your case.

BTW - you are not a moderator on this board

You skipped over a couple questions and points so i'd like you to answer them if you can, to help contribute to the discussion.

So, your recommendation of 5-7 uvi -

1.Do you think it's acceptable to recommend that to a dragon with a skin mutation such as a trans, or even a leatherback? Yes , it's the same species , so it'll be fine. If it's more efficient at absorbing UV irradiance than a wild or normally scaled bearded dragon (which has not been solidly proven by anyone to my knowledge, it will simply spend less time basking , so the key is to set up a good UVA & UVB gradient from high to low or even zero in the tank it lives it. The dragon will regulate the amount of UV irradiance according to it's instincts and biological needs of it's own accord IF IT"S HEALTHY and has the opportunity.
Do you think no "personalized" suggestion should be made for a dragon who isn't as protected from uv rays as a wild dragon? No need to change depending on morph, I know of no one here in Australia who makes such meaningless provisions based on dubious claims by some breeders other than being careful about which morphs are paired , and maybe a little LTC when reduced scaled morphs shed .

Or, do you disagree that a skin mutation would cause a dragon to be less protected from uv rays? see above . Refer to "A Guide to …. Australian Dragons in Captivity " by Brown , Dr.D (BVSc , BSc).

Simple yes or no question - do you believe that uv Rays can be harmful? UVC and some higher energy bands of UVB = yes , from poorly built uv sources (leaky silica tubes and silica bulbs , poor phosphors) .
BUT pogona species (all of them) have evolved to cope with tropical and subtropical southern hemisphere UVC irradiation levels.

And last question - what do you say about much weaker levels of uv (as they were all that was available in the past) being suitable for dragons of the past? dragons breed and kept before the better more modern UV sources were available will have been basking longer each day to get their needs of UVA & UVB irradiance dose than then need to now.
Simply took longer for them to get the same doseage then.

Same reason why it will be necessary for dragon to get natural sun exposure for maybe 1 hour per day in more temperate latitudes , while they only need maybe 1 hour per week of natural sun exposure here in Australia ( my latitude (33 S) and maybe 30mins at Townsville in QLD).

Very simple high school physics.

Please try to answer all my questions as it adds to the discussion.

-Brandon

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claudiusx":1gyxectq said:

If you could refrain from making degrading comments that would be appreciated. Otherwise I'd ask you refrain from posting here. No need to belittle other opinions that differ from your own.

I will disagree with you on the skin. Same species, different skin. You made a comment yourself in another thread about the difference in humans of white skin vs dark skin and UV exposure. Humans of different skin colors, same species... different skin characteristics.
Beardie with different skin morphs... same species... different skin characteristics.

<<< do I need to link to my exact comment ? again , please stop taking my comments out context or cherry picking only the parts you like.
I invite others to review my thread to see EXACTLY what I said. (summary = unwise to assume pogona skin which is entirely different biologically to human skin will behave similarly to UV irradiation, no scientific evidence available that supports that model for any pogona species.

The morphs of pogona vitticeps you are talking about are still the same species , even if they have been selectively bred look different cosmetically , ie to have reduced scales or no scales , and for fancy skin pigments , the skin remains Pogona vitticeps skin .
Uptake these morphs are ONLY SUPERFICIALLY DIFFERENT in appearance with only cosmetic changes .

I wasnt talking about artificial uv Ray's being harmful, I was talking in general, can uv rays be harmful. And based off your response, it seems like your answer is yes.

So with agreeing that UV can be harmful, does it not make sense to only expose them to as much as they need? But that's the kicker, we dont know how much they need.

Exactly my point in your last response.
Is a lower dose over a longer period of time, safer than a higher dose over a shorter period. You elude to the fact that the weaker bulbs did work, which is the first time I've seen you actually admit it.

The dragons will have been getting very similar accumulated dosages of UV , only they had to bask longer each day to get it.
I think you need to learn more physics. You do understand what Watts are ?
You are incorrect and your comments are misleading and potentially harmful IMO as few people on this board seem to have sufficient photoperiods to allow their pet dragons to get sufficient daily UV irradiation especially if they follow your lead.
It's not a hard calculation to work out the equivalent daily dosage for different levels of UV in microW / sq.cm , not so easy if you rely on UV-Index ONLY as you have convert back to actual Flux and no Solarmeter UV-Index meter models that particularly well as I showed in my thread.
Add the different modeling used by different companies in their UV-Index meters and it's a mess .

So now the question is, what's better, lower dose over a longer period, or higher dose over a shorter period.

I'm glad you decided to actually discuss my points and questions because it led into a new thought which is that last question I just asked.

The beauty of discussion and letting opinions fly, new questions to ponder arise.

-Brandon

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The morphs of pogona vitticeps you are talking about are still the same species , even if they have been selective bred to have reduced scales or no scales , and for fancy skin pigments , the skin remains Pogona vitticeps skin .
Uptake these morphs are ONLY SUPERFICIALLY DIFFERENT in appearance with only cosmetic changes .

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kingofnobbys":3gttmg70 said:

The dragons will have been getting very similar accumulated dosages of UV , only they had to bask longer each day to get it.
I think you need to learn more physics. You do understand what Watts are ?
You are incorrect and your comments are misleading and potentially harmful IMO as few people on this board seem to have sufficient photoperiods to allow their pet dragons to get sufficient daily UV irradiation especially if they follow your lead.
It's not a hard calculation to work out the equivalent daily dosage for different levels of UV in microW / sq.cm , not so easy if you rely on UV-Index ONLY as you have convert back to actual Flux.

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claudiusx":3ebnyqgx said:

If you could refrain from making degrading comments that would be appreciated. Otherwise I'd ask you refrain from posting here. No need to belittle other opinions that differ from your own.

I will disagree with you on the skin. Same species, different skin. You made a comment yourself in another thread about the difference in humans of white skin vs dark skin and UV exposure. Humans of different skin colors, same species... different skin characteristics.
Beardie with different skin morphs... same species... different skin characteristics.

I wasnt talking about artificial uv Ray's being harmful, I was talking in general, can uv rays be harmful. And based off your response, it seems like your answer is yes.
So with agreeing that UV can be harmful, does it not make sense to only expose them to as much as they need? But that's the kicker, we dont know how much they need.

The pet dragon will self regulate it's irradiation to combined UV , same as It does to thermoregulate IF ITS HEALTHY and able to.

How many times does that need to be pointed out ?

Exactly my point in your last response.
Is a lower dose over a longer period of time, safer than a higher dose over a shorter period. You elude to the fact that the weaker bulbs did work, which is the first time I've seen you actually admit it.

The risk with forcing a pet dragon bask longer to get it's needed UV irradiance is it's also forced to remain at the basking spot for longer and can very easily become heat stressed .

Safer to provide higher levels of UV flux so the pet dragon is not forced to remain in the warm zone and at the basking spot longer it needs to metabolise it's food and thermoregulate.

Going back to field observations of the basking behavior of wild pogona in their natural range , it's been observed and reported by professional herpetogists and anyone who actually lives in these area that pogona are active foraging and basking (short periods) through out the day even at the height of summer.

Pogona have evolved the neat evolutionary trick of being able to adjust the IR and UV reflectivity / emissivity of their skin at will.
We've all see this with our pet bearded dragons . NO HUMAN or mammal can do this at will in a literally a few minutes.

With a scanning reflectivity meter for UV bands (these exist - I've used one) it would not be hard to tie this behavioural quirk evolved by pogona species and produce a physical / mathematical model of the UV absorbance response of pogona skin on live animals in the laboratory under a tuneable UV source over the full range of UV frequencies.
Perhaps a good research project for a BSc Zoology or BSc VSc student in their honors year.


So now the question is, what's better, lower dose over a longer period, or higher dose over a shorter period.

Higher available with access to a good UVA & UVB gradient from high to low (even zero) , the dragon will instinctively bask only as long as it needs to.
As will skinks, snakes, monitors and crocodiles
I'm glad you decided to actually discuss my points and questions because it led into a new thought which is that last question I just asked.

The beauty of discussion and letting opinions fly, new questions to ponder arise.

-Brandon

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claudiusx":3qk2bmqy said:

The morphs of pogona vitticeps you are talking about are still the same species , even if they have been selective bred to have reduced scales or no scales , and for fancy skin pigments , the skin remains Pogona vitticeps skin .
Uptake these morphs are ONLY SUPERFICIALLY DIFFERENT in appearance with only cosmetic changes .

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That is incorrect. Look at the trans gene for example. Or the hypo gene. These are not superficial mutations.
And I dont think you comprehended what I was speaking of. I'll ask that you go and re read what i said about the same species having different skin traits, as you yourself have pointed out in humans.

kingofnobbys":3qk2bmqy said:

The dragons will have been getting very similar accumulated dosages of UV , only they had to bask longer each day to get it.
I think you need to learn more physics. You do understand what Watts are ?
You are incorrect and your comments are misleading and potentially harmful IMO as few people on this board seem to have sufficient photoperiods to allow their pet dragons to get sufficient daily UV irradiation especially if they follow your lead.
It's not a hard calculation to work out the equivalent daily dosage for different levels of UV in microW / sq.cm , not so easy if you rely on UV-Index ONLY as you have convert back to actual Flux.

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Once again, of you cant bring your points and opinion to fruition without degrading comments added to them, you can stop posting here.

Do you care to elaborate on your comment that few people here have adequate photoperiod times. Because in your last post you just admitted that things were fine with the weaker bulbs, they just needed more time under them. So which is it, could they get enough uv from them or not?

Many here advocate 12 hour photoperiods , even less. That is inadequate and is closer to winter time photoperiods in the natural range of all pogona species and stems from a lack of the pet owners about actual conditions here , and an unwillingness to find out. ( It's not hard to get information ).

So... are you going to use your meters to test that mW does not equal uvi? Since you completely ignored that part of my post. And you've ignored it every time I've brought it up to you in other threads. You have the means to test and see for yourself.

No , I don't need to .
I know from the physics they are not the same Refer to Solarmeters own "calibration charts" and sensitivity with wavelength charts that I've already provided.
My meters are all properly calibrated so conform to Solarmeter's specifications.

There is no good correlation as their models of UV-Index are quite poor.

The UVB Flux is the measurement that is reliable and meets scientific standards.

So the bulk of it is this, did our weaker levels of uvb in the past work or not? Simple yes or no question.

See my other posts.

-Brandon

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claudiusx":55h8ruji said:

Honestly, if you cant state your opinion without also degrading other opinions, you aren't welcome here on this thread. I'm trying to be all inclusive and let everyone voice their opinions and concerns and thoughts, but I wont allow you to come into another thread and get it locked simply because you cant state your opinion without bashing others.

12 hour photoperiods are inadequate in what sense? We dont know how much uv they need. There has been no testing. They could get the d3 they need after 5 minutes of basking, or it could take 3 hours. WE DONT KNOW.
What we do know as a fact is that in the past with weaker bulbs, even with what you consider to be short day night cycles, we didnt get dragons developing mbd.

The question of a higher dose and shorter times or a lower dose for longer times is a good subject for discussion. In almost every case you compare it to, smaller doses are safer than larger doses of almost any comparison you can think of. Including humans and sunlight.

What do you feel is wrong with them having to bask for longer periods? You stated they might get too warm before getting enough uv? But on the flipside what if with your setup, they get too much uv before getting warm enough? The point is you dont know either way, so no reason to act so harshly either way.

-Brandon

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claudiusx":28zf8j6x said:

You're not welcome on this thread anymore. And you wont be responded to anymore. It's a shame that personal attacks are more important to you than discussion. Start your own thread if you want to voice your opinion on this subject.

-Brandon

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Measurements of global spectral irradiance in the UV and visible range were carried out during December 1995 and January 1996 in Townsville, Australia (19.33 degS, 30 m above sea level ) were carried out during December 1995 and January 1996 in Townsville, Australia
using the mobile [scanning] spectroradiometer [provided by the Fraunhofer Institute for Atmospheric Environmental Research].

[ my comment : typical latitude for pogona species , you will note there is no mention of UV-index in this peer reviewed scientific paper ]

The maximum erythemally weighted (UVB) irradiance measured during the campaign was 429 mW/m^2 ( 429 microW / sq.cm) , and the average daily erythemal irradiation for this period was 6.06 kJ/m^2 .

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For the year 1991, the December and January values of the monthly mean daily erythemal irradiation found in the survey for Darwin, Brisbane and Perth are as follows:
Darwin, 5.70 kJ/m^2 (December) and 3.72 kJ/m^2 (January)
Brisbane 4.76 kJ/m^2 (December) and 4.47 kJ/m^2 (January)
Perth 5.30 kJ/m^2 (December) and 5.77 kJ/m^2 (January).

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The albedo of sand is about 10% in the UV [Blumthalear & Ambach]. According to model calculations UV levels for "desert areas" [dry grasslands and dry woodlands are regarded by these researchers from Germany as "deserts"] should be approximately 3% higher than for forested land.

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P. vitticeps modify both visible (UV-Vis range) and NIR reflectance to accommodate requirements of signalling or camouflage and thermoregulation during light phases, they are in a rest state during dark phases and have little need to display colour change for other purposes, which may explain their higher proportion of UV-Vis reflectance.
This variation in the proportion of UV reflectance is a function of a change in the spacing of reflecting platelets in iridophores , in combination with melanosome dispersion.

The scales on a reptile act as a barrier for moisture loss , and are highly transparent in UVA & UVB bands.

(OBSERVE MAMMALS (ie humans) DO NOT HAVE THIS ADAPTATION).

Light acts as a stimulus for the pituitary to release MSH, resulting in the dispersion of melanosomes and the aggregation of reflecting platelets. The aggregated reflecting platelets is thus associated with a decrease in the proportion of UV reflectance in relation to NIR reflectance, although the mechanisms moderating NIR reflectance are currently unknown.

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