[Coral-List] Caribbean Acropora and artificial lights

[info]

Hi Damien,

We've grown palmata and cervicornis under both short band LEDs,
multi-spectrum LEDs, and different types of T5s.  About 5-7 years ago, we
did a matrix quality/dose light experiment to determine optimal light
growing conditions.

Weirdest thing, we've really never seen an abundance of fluorescence with
Acropora palmata, even under the different light and feed-composition
conditions.  Cervicornis fluoresces in blue and green wavelengths.

We did find that under only-blue-band wavelength LEDs (400 nm-490nm),
palmata grew the slowest.  They need red, from 720-780 nm.  Best growing
conditions was a "shallow daylight" spectra that went from 374 nm all the
way to 740.  Couple of T5 manufacturers have this.  Watch out though, after
about 3-5 weeks, like all fluorescence lights, you get UV creep.  Some of
the creep is geometric or exponential increasing UV bandwidth and umoles of
photons m-2 s-1 -  depending on manufacturer and even lot #.  When we grow
coral for lab ecotox experiments, we have to monitor and detect changes in
light quality from our specified standard.  This means changing out the
HE/HO T5 bulbs more than the hobbyist would even think about.

I don't know of very many coral culture companies that still use halides.
LED and T5 supplement is normally what the big boys use.  Halides are just
too expensive if you have a large operation.

For LEDs, also make sure you don't get "LED pin burns"  Either have a diode
cover that defracts/reflects a focused beam, or... we use starfire glass
covers (allows for UV penetrance).  The condensation on the tank side of the
glass make an ideal scatterer.

Photon flux density matters, at least for palmata.  You can drop it to 100
umoles photons m/s, but palmata puts down a weak skeleton at that PPFD - yes
we did X-ray densitometry to determine this.  We found to get the density of
palmata that we see in Cuba (was our field reference sites until the water
quality plummeted), you need at least 300 umoles.

Craig


Craig A. Downs, Ph.D.
Executive Director, Haereticus Environmental Laboratory
A 501(c)(3) non-profit scientific research organization

P.O. Box 92
Clifford, Virginia 24533, United States of America

Phone: 434-263-5740
www.haereticus-lab.org




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Message: 1
Date: Fri, 20 Oct 2017 19:57:36 -0400
From: Damien Beri <beridl at g.cofc.edu>
Subject: [Coral-List] Fluorescence of A. palmata/cervicornis under LED
	lighting.
To: coral-list at coral.aoml.noaa.gov
Message-ID: <9D803845-9770-4BD5-B2B3-A347712DEEDA at g.cofc.edu>
Content-Type: text/plain;	charset=utf-8

Hello Coral-list,

Has anyone grown A. palmata or A. cervicornis under high powered LEDs used
for commercial coral aquaculture? I am curious if these corals, given time
grown under intense but specific spectrum LED lighting would fluoresce like
many Acropora sp. It?s my understanding aquaculture has mainly been 10-20k
metal halides.  The advancement of modern LEDs could show their beauty much
more and help give these endangered corals more of a fight. Even if it?s
just time a lapse of a single branch fluorescing.

What is the scientific value to figuring something like this out?

Warm regards,
Damien Beri