Effects of light intensity and spectral composition on the growth and adaptation of Acropora corals

[ReeferA]

Published January 2023 - https://link.springer.com/article/10.1007/s00338-023-02348-w#citeas.

Light affects physiological aspects of coral growth. However, it is unclear how light conditions (photoperiod, intensity, and spectrum) influence growth physiology. We examined the effects of various light conditions on skeletal growth promotion and the physiological mechanisms responsible for growth in Acroporid corals. Acroporid corals (Acropora tenuis, A. muricata, and A. intermedia) were reared for 2 months under various photoperiods (hours of light/dark = 8:16, 12:12, and 16:8) and light intensities (100 and 200 µEm−2 s−1). Growth was greater in all coral species under longer photoperiods and at higher light intensities. Next, we used a photoperiod of 16:10 (hours of light/dark) and 200 µEm−2 s−1 light of three spectral composition from a light-emitting diode. The growth of A. tenuis and A. intermedia increased with increasing wavelength. The symbiotic algae density increased as the photoperiod increased. Symbiotic algae density and chlorophyll content were affected by the light spectrum but were not associated with the degree of growth. Therefore, changes in light conditions can induce coral growth without changing symbiotic algae density or chlorophyll content. Real-time quantitative polymerase chain reaction analysis revealed that the level of carbonic anhydrase mRNA changed with coral growth, suggesting that light accelerates coral calcification via photosynthesis by algal symbionts.

 

[Doctorgori]

I re read that twice, it the gist corals actually grow more in extended photoperiods above 12 hrs?
I’ll re read again:

The growth of A. tenuis and A. intermedia increased with increasing wavelength.

as in more red? not blue

what blasphemy lol

 

[ReeferA]

Yes, that's what the study found as the extended period was up to 16 hours/day. I think this study agrees with Dana Riddle's 2009 article which showed that intensity is the not the key for faster growth. However, red spectrum or any one spectrum alone will damage the coral.
There is another study also was done November 2023 which showed that Blue light increases thermal bleaching tolerance of coral.

 

[Doctorgori]

Yes, that's what the study found as the extended period was up to 16 hours/day. I think this study agrees with Dana Riddle's 2009 article which showed that intensity is the not the key for faster growth. However, red spectrum or any one spectrum alone will damage the coral.
There is another study also was done November 2023 which showed that Blue light increases thermal bleaching tolerance of coral.

goes to show you can’t ever take the ever changing reef dogmas at the time:
“ do not exceed photoperiods over 12hrs” … or so says my Red Sea LED’s

then there is the whole blue vs red wavelength thing with dozens of assorted parroted dogmas:
- white or red light equals algae
- you ONLY need blue light to grow corals or it grows them a lot faster
- red light inhibits growth

anyway, my take is there is a element of truth in all those but no absolutes…
appreciate the article, refreshing …thanks

 

[taricha]

I re read that twice, it the gist corals actually grow more in extended photoperiods above 12 hrs?

I dunno. If this the data in front of me.....

...I'd describe it as, "turn off your lights at 12hrs - no benefit to growth from keeping them on longer, unless you are running low light (100 vs 200 PAR) then 16hrs may increase growth rate."

 

[GlassMunky]

I dunno. If this the data in front of me.....

...I'd describe it as, "turn off your lights at 12hrs - no benefit to growth from keeping them on longer, unless you are running low light (100 vs 200 PAR) then 16hrs may increase growth rate."

almost as if DLI is a thing.... lol