Lighting advice for dart frogs

Q&A
| QUESTIONS & ANSWERS
these heights, simply because the heat and UVB
decreases in power as the light travels down to
the living space.
Currently, T5 is still by far the best way to
provide full spectrum light for plant growth. I
would certainly stay well away from LED tiles
that only have red and blue LEDs. Lamps like the
freshwater pro provide a very high colour
rendition index (CRI) that will make your
enclosure look fresh and provide the high levels
of light (LUX) and PAR required for good plant
growth. Plants themselves also use UVA and UVB
in small amounts.
Amphibians and UVB
Lighting advice
for dart frogs
&
Please advise me about
lighting a vivarium for
dart frogs. Should I
provide lamps just for live
plant growth or
incorporate areas of UV as
well? Are LED sources of
light sufficient to grow plants in the ways that
we see on the web and at shows?
There have been many advances in LED
technology in recent years, with a huge array of
LED plant grow products now on offer.
Unfortunately, these are largely ineffective
because of a misunderstanding of the way that
plants use light. It is required in two main
wavelengths for good photosynthesis, with
plants needing light in the blue spectrum
between 410-480nm, and also light in the red
spectrum, from 610-680nm.
Light provided at these wavelengths will
cause good vegetative growth, but only if the
photosynthetically active radiation (PAR) is high
enough to sustain the reactions in the plants.
Although essential to PAR, blues and deep reds
do not have all the
energy required by
plants to grow well.
The inclusion of a
third colour, in the
correct intensity, is
essential to increase
the PAR for this
purpose. Full spectrum
light in nature includes all
of the colours in the correct
balance. At Arcadia, we have been
working on maximising live plant growth
with LEDs for a long time now, and we have
almost cracked it, but this technology is far from
cheap.
The Europeans are tending to use high
intensity discharge (HID) or metal halide systems
in their dartfrog enclosures alongside T5 gro
lamps. This provides columns of high potency
UVB in the vivariums that the occupants can
seek out when required. But it is worth stressing
that these enclosures tend to be very, very big.
The ones that I have seen were over 1.5m (5ft)
high. HID can be safely used for amphibians at
Dartfrogs will actively seek out UVB, using
specialised vision to find the power that they
require. We know that a 15% reduction in bone
mass in amphibians can be seen easily on an
X-ray and better morph rates and healthier
adults have been recorded in groups that are
kept with the provision of a natural UV index.
As in every avenue of herp keeping, so the
only way to ascertain the correct exposure to
light for a particular species is to start with the
wild animal. Look for the average UV index of the
amphibian’s country of origin and the habitat
where it occurs. Increase or decrease the UV
depending on local surroundings and the height
above sea level. Provide more light to those
species that are found in the hills or in
less dense jungle areas.
What is known as leaf scatter
illumination provides potent
light in millions of shafts all
over the jungle. A dartfrog
simply needs to position
itself in one of these
shafts, to benefit from
the available energy
available. Even
crepuscular and
nocturnal species can
benefit from the energy of
light when they are in the
open, even if they are sleeping.
Technology is catching up with
our requirements and we will
eventually have a more effective lighting
solution for amphibians in vivariums, tailored
very closely to their needs. The perfect answer
would be a high PAR lamp that provides the
correct UVB emission. The closest that we have
so far is the D3 HO T5, at 6% UVB and a Kelvin of
6k. In the future, I hope to see a hybrid of proven
LED technology and T5 UVB lamps that will really
offer the power that plants require, as well as
providing the animals with the energy from light
that they must have to meet their needs.
John Courteney-Smith.
Arcadia Reptile Products Manager.
JANUARY 2013 | 53