UV-B-indices from Madagascar

[Alexl]

Finally, after several months of work, the UV-B-indexes I measured all around Madagascar are online at www.madcham.com . The less nice thing is, the website's still only available in German - but even google translator can help for sure. You can use the "search" function top right to look for a region or city, then you will get results for several chameleon species and locals of F. pardalis for this region.

E.g. here's the one for Sambava (northern east coast): http://madcham.com/?p=520 The Graph for UVB hast the UV-Index on y-axis and daytime ("Tageszeit" in German) on x-axis. Weather is shown by little suns, clouds etc. inside the graph. The red line is full sun, the orange line half shadow, and the blue line is shadow. Sunrises is at 6.00 am and sunset at 06.00 pm (and yes, there can be sun at the sky without any UVB measured in sunny places ).

The UVI have been measured with Solarmeter 6.5 and I always took minimum (shadow) and maximum (sun) reachable UVI depending on weather conditions. All data have been measured during March and April, which is the end of the rainy season in Madagascar. Until now, I got charts of parts of the West coast, North and East coast. Maybe next year I'll be able to do some measurments in the south, too.

Hope it's a little to think about, even if it's "only" done during my holidays. Think there's still a real lot to do about UVB in Madagascar and for captive kept chameleons, too... (especially since I still see many cases of mbd and insufficient UVB setup at work). I would really like to have measurements of every interesting place for every time of the year.

 

[NHenn]

Alex,

Thanks for posting this information! I truly enjoy being able to learn more about Madagascar and being able to change and modify our setups to better model their natural environments.

If you don't mind, I do have one question. The chart represents the UV index as measured from your Solarmeter 6.5, is there any way to convert or correlate that to actual UVB measurements? I'm use to measuring and taking readings with a Solarmeter 6.2 which gives you UVB readings in uW/cm². I would love to be able to tell what UVB the chameleons are actually basking in during the peak periods as well as the overall daily average.

Nick

 

[Alexl]

Hi Nick,

Sarina from www.licht-im-terrarium.de is physicist and answers your exact question on her website, so I'll try to translate it: Yes, you can convert UVI into µW/cm², UVI=1 corresponds to 2.5µW/cm². But be careful, because the number you get via converting is smaller than the µW/cm² measured with Solarmeter 6.2 due to another measurement peak in 6.5. Therefore it's not really useful to compare values of 6.2 with values of 6.5.

I use Solarmeter 6.5 with SiC photodiode, because its congruence with the Vit. D 3 synthesis curve of reptiles is more than 90 %. Solarmeter 6.3 matches about 75% of the synthesis curve (you'd find the formula to calculate it here), so this one would be my 2nd choice. You can also use the 6.5/6.2-ratio to compare measurments, but this mainly gives information about whether UV-B radiation is more short- or long-waved.

Alex

 

[nightanole]

Alex,

Thanks for posting this information! I truly enjoy being able to learn more about Madagascar and being able to change and modify our setups to better model their natural environments.

If you don't mind, I do have one question. The chart represents the UV index as measured from your Solarmeter 6.5, is there any way to convert or correlate that to actual UVB measurements? I'm use to measuring and taking readings with a Solarmeter 6.2 which gives you UVB readings in uW/cm². I would love to be able to tell what UVB the chameleons are actually basking in during the peak periods as well as the overall daily average.

Nick

https://www.chameleonforums.com/uvb-10-harmful-128206/index2.html#post1121612

 

[nightanole]

Hi Nick,

Sarina from www.licht-im-terrarium.de is physicist and answers your exact question on her website, so I'll try to translate it: Yes, you can convert UVI into µW/cm², UVI=1 corresponds to 2.5µW/cm². But be careful, because the number you get via converting is smaller than the µW/cm² measured with Solarmeter 6.2 due to another measurement peak in 6.5. Therefore it's not really useful to compare values of 6.2 with values of 6.5.

I use Solarmeter 6.5 with SiC photodiode, because its congruence with the Vit. D 3 synthesis curve of reptiles is more than 90 %. Solarmeter 6.3 matches about 75% of the synthesis curve (you'd find the formula to calculate it here), so this one would be my 2nd choice. You can also use the 6.5/6.2-ratio to compare measurments, but this mainly gives information about whether UV-B radiation is more short- or long-waved.

Alex

It cant be UVI=1 corresponds to 2.5µW/cm². Since the highest on earth is only a 8.0, that would only be a µW/cm² of 20, which is when some people change their bulbs because its so low. Full sun can be well over 400 µW/cm²

 

[NHenn]

Thanks for the responses!

Night, I saw that you posted a panther should be 30-35. I guess my main goal of trying to convert the readings is to determine the actual number they are receiving in the wild. I feel it would be much high than that amount which makes me wonder if 30-35 isn't nearly enough?

 

[nightanole]

Thanks for the responses!

Night, I saw that you posted a panther should be 30-35. I guess my main goal of trying to convert the readings is to determine the actual number they are receiving in the wild. I feel it would be much high than that amount which makes me wonder if 30-35 isn't nearly enough?

They are shade creatures that only need 30min of full sun a day tops. Notice they are always in the deep canopy, not sitting on logs.

With a little d3 powder, they only need .2 to .3 uv index. Remember the most popular bulb on the forums is the repisun 5.0 and it only puts out less than 15µW/cm² at 12".

As long as your cham can get 6" close to the T8 bulb, and can get to full shade, it will regulate itself for uv exposure.


As a recommendation, i run the arcadia 6% for 4ft enclosures, because the 30-35 range is 2ft away, which makes a 2ft play area, and 2ft of full shade. On the other hand i would not put a 6% on a 2ft cage, because the cham could never escape and regulate, without a excellent placing of alot of shrubbery.

 

[NHenn]

That makes sense. I know they will come out in the morning and before dusk to pick up some rays but during the hot days they will retreat to the dense cover.

I agree with you recommendation and I only use T5 Arcadia for all my setups. If you use a 6% bulb in a double fixture it produces a very nice gradient for them to bask in. Also, even if you use it on a smaller cage (24" high), you would be surprised how it directs the ray down directly below the fixture so as soon as they move forward out from below the fixture the readings drop to 0 so extreme cover isn't absolutely necessary.

I just feel like we are all still missing something. 12 hours on 12 hours off at low levels of UVB is not even close to how it actually happens in nature. I would love to know what the UVB levels are when they are out basking in Madagascar in the morning and late afternoon.

 

[nightanole]

Uhh thats what the OPS post was.

If you look they posted full sun/semishade/full shade for each island. If you look semi shade is a uv index of about .5 for the whole day.

 

[NHenn]

Ok and your saying a close enough conversion is 40 to 1 so that would be around 20 µW/cm²?

 

[nightanole]

Ok and your saying a close enough conversion is 40 to 1 so that would be around 20 µW/cm²?

40-1 is what the US government uses. So a .5 uv index would be 20 µW/cm², and most recommend changing bulbs at 10 µW/cm² min.

 

[NHenn]

Excellent! Thank you.

 

[Alexl]

It cant be UVI=1 corresponds to 2.5µW/cm². Since the highest on earth is only a 8.0, that would only be a µW/cm² of 20, which is when some people change their bulbs because its so low.

I think there is a misunderstanding, and I hope my English's good enough to explain. At least I'll try . The highest UVI on Earth is surely not 8,0. I and several other people measured UVIs of 12 in Madagascar, and I'm quite sure it's not the highest possible value - but said that, it's only about the Solarmeter 6.5 model. The difference in converting UVI to µW/cm² has to do with the different measurement peak (not range) of Solarmeter 6.5 compared to Solarmeter 6.2 (this graph shows well the difference). Therefore you will always get a lower µW/cm² value when converting from 6.5 to 6.2 than if you would measure with 6.2 itself at the same place.

That's why, as I said, it's not really helpful or recommendable to convert and compare the values measured by those two different tools. Or let's generalize, it's not recommendable to compare values of different measuring tools at all as long as you don't know which peak and range each of those got.

They are shade creatures that only need 30min of full sun a day tops. Notice they are always in the deep canopy, not sitting on logs.

From what I've seen in Madagascar, I would not agree that panther chameleons are "shade creatures". I've also found several basking in the sun at full midtime sun (although many prefer to pass the sunniest day in the canopy). Maybe "shadier" creatures than some other Malagasy lizards...ok, that's nitpicking . But there are much chameleons which hide a lot more from the sun or don't bask at midtime at all than panther chameleons in Madagascar.

I just feel like we are all still missing something. 12 hours on 12 hours off at low levels of UVB is not even close to how it actually happens in nature. I would love to know what the UVB levels are when they are out basking in Madagascar in the morning and late afternoon.

Some belgians measured UVI with Solarmeter 6.5 in october exactly at the place they've found chameleons in Madagascar. One got a very interesting chart. I can give you contact data if you're interested in this chart - since I don't know if I'm allowed to pass it on. I was really astonished about some very high UVI they've found chameleons basking in.

Apart from that, UVB levels depend mainly on weather conditions, that's why I've put the symbols in my charts. I tried to get some kind of "normal course of the day" in sunny weather for each place to get some data of UVI in Madagascar and what a reptile there can get in each location at all. And of cause... it's important to know which wavelengths of UVB you're interested in. If it's all about Vit. D3 synthesis, Solarmeter 6.5 may be one of the most helpful tools on the market up to date. If you want to measure complete UVB-radiation and not a special part of it, you need to look for another tool. It's not easy at all to get a "natural" lightning setup in cages, still less if you want to imitate reality as close as possible.

 

[nightanole]

Sorry that 8.0 was for OHIO :/

Still even with a borrowed 6.2, and my 6.5 I got these numbers from a fresh reptisun 10.0

ZooMed Reptisun 10.0 tube, at 12 inches distance no screen (assume no reflector):
6.2 reading: 24 µW/cm².
6.5 reading: UV Index 0.7"

If i used your 2.5µW/cm² conversion, i would get a 1.75µW/cm² calculation. And reptisun 10.0's have been measured over and over at around 30µW/cm² at 12" for years by several testers.

Your source ( i have trouble translating) says the 6.5 can be converted to 6.2 with a 2.5 conversion, however it has a chart at the bottom with the correct ratios.

Beurteilung:

lists 50:1 for high uvb
lists 30:1 for low uvb
lists 13:1 for high uvc (the bad 2006 cfls)

So my ratio of 40:1 still works for an average for vitamin D production in reptiles.