Why Too Much Light Can Be Harmful to Zooxanthellae

[anth]

Depends. If we equate rate of photosynthesis to coral growth, then the amount of light matters. If the 'higher PAR at short duration' does not exceed the point where photosynthesis is inhibited, then coral growth should be good. If the amount of light causes dynamic photoinhibition - or worse, chronic photoinhibition, then growth might be reduced, and in worse case the coral could bleach. In hort, I don't think there is much reason to deviate from a 'natural' 12-hour photoperiod. In best case, the light intensity in this photoperiod would be just at the photosaturation point. Now, if we're discussing coloration, that's another matter altogether.

I understand
I have no intention to do this but ithas had my brain ticking for a few weeks now
Thanks
Anth

 

[anth]

What is it that causes a coral to reset its photosaturation point ready for the next light cycle? Is it an extended amount of time without light ie the 12 hour rest period between light cycles?
Purely curiosity.

When a coral adds mass to its skeleton, does this happen during the light period or the dark? And also which part (beginning, middle, end or the entirety of the light or dark)?
I ask this as I dose all major and minor elements 12 times a day distributed evenly throughout the day and was wondering if its worth targeting a specific time in the on/off light cycle so i am adding in as the coral is taking out.

Please feel free to tell me to to open a new thread if this is to far off topic.

 

[Dana Riddle]

I understand
I have no intention to do this but ithas had my brain ticking for a few weeks now
Thanks
Anth

There has been some discussion of the 'zig zag' or 'saw tooth' lighting regimen, but I haven't seen any hard data on it - just anecdotal.

 

[MabuyaQ]

What is it that causes a coral to reset its photosaturation point ready for the next light cycle? Is it an extended amount of time without light ie the 12 hour rest period between light cycles?
Purely curiosity.

When a coral adds mass to its skeleton, does this happen during the light period or the dark? And also which part (beginning, middle, end or the entirety of the light or dark)?
I ask this as I dose all major and minor elements 12 times a day distributed evenly throughout the day and was wondering if its worth targeting a specific time in the on/off light cycle so i am adding in as the coral is taking out.

Please feel free to tell me to to open a new thread if this is to far off topic.

You might want to do a search on LEC (Light Enhanced Calcification)

 

[Dana Riddle]

What is it that causes a coral to reset its photosaturation point ready for the next light cycle? Is it an extended amount of time without light ie the 12 hour rest period between light cycles?
Purely curiosity.

When a coral adds mass to its skeleton, does this happen during the light period or the dark? And also which part (beginning, middle, end or the entirety of the light or dark)?
I ask this as I dose all major and minor elements 12 times a day distributed evenly throughout the day and was wondering if its worth targeting a specific time in the on/off light cycle so i am adding in as the coral is taking out.

Please feel free to tell me to to open a new thread if this is to far off topic.

The photosaturation point is etched in stone (more or less.) Think of the minimum amount of light required (the compensation point, where oxygen production by zoox meets their respiratory requirements) as a car setting at idle -it's running but not going anywhere. The saturation point is tantamount to a car's engine running as fast as it. These don't change (much). In biological situations, the equivalents are 'shade' and 'sun' plants. While these have some ability to adapt, a 'sun' plant will not thrive in a 'shade' situation, and vice versa.
I'd have to review calcification, particularly the early works by Yonge and Goreau. I do recall one paper that found Pocillopora damicornis added calcium (and other elements) to its skeleton at onset of darkness.

 

[anth]

The photosaturation point is etched in stone (more or less.) Think of the minimum amount of light required (the compensation point, where oxygen production by zoox meets their respiratory requirements) as a car setting at idle -it's running but not going anywhere. The saturation point is tantamount to a car's engine running as fast as it. These don't change (much). In biological situations, the equivalents are 'shade' and 'sun' plants. While these have some ability to adapt, a 'sun' plant will not thrive in a 'shade' situation, and vice versa.
I'd have to review calcification, particularly the early works by Yonge and Goreau. I do recall one paper that found Pocillopora damicornis added calcium (and other elements) to its skeleton at onset of darkness.

Thanks for the explanation, much appreciated.
Is there any kind of chart that exists to show the saturation points of different coral species?
As for dosing, do you think that dosing elements as they are being up-taken by corals in order to maintain as little fluctuation as possible is beneficial or are the benefits negligible?

 

[anth]

You might want to do a search on LEC (Light Enhanced Calcification)

I have done and have found an article. I’ve read the introduction and am looking forward to reading the rest when my child is in bed.

thanks

 

[anth]

There has been some discussion of the 'zig zag' or 'saw tooth' lighting regimen, but I haven't seen any hard data on it - just anecdotal.

I have not come across this yet.
Is there anybody using this method who has claimed any difference in calcification or colouration?

 

[Dana Riddle]

I have not come across this yet.
Is there anybody using this method who has claimed any difference in calcification or colouration?

Yes, Saxby in the UK and Mike Paletta among others. I don't dispute they have fabulous tanks, would like to see some PAR numbers and lighting schedules to understand what's going on.

 

[anth]

Yes, Saxby in the UK and Mike Paletta among others. I don't dispute they have fabulous tanks, would like to see some PAR numbers and lighting schedules to understand what's going on.

Yes, i do not have the knowledge to investigate this myself but would love to read your take on how this works should you ever take a look at it yourself.

 

[oreo54]

Yes, i do not have the knowledge to investigate this myself but would love to read your take on how this works should you ever take a look at it yourself.

Mike Paletta/David Saxby settings for Radions

So I want to try an experiment to see how well the saw-tooth lighting pattern works with growing corals. Mike Paletta has said he uses this pattern. My big question is what are his settings? I've looked for them, but only find that he has all lights at 100% for an hour then drops to all blue for...

www.reef2reef.com

 

[anth]

Mike Paletta/David Saxby settings for Radions

So I want to try an experiment to see how well the saw-tooth lighting pattern works with growing corals. Mike Paletta has said he uses this pattern. My big question is what are his settings? I've looked for them, but only find that he has all lights at 100% for an hour then drops to all blue for...

www.reef2reef.com

Thanks for that

 

[Dana Riddle]

Mike Paletta/David Saxby settings for Radions

So I want to try an experiment to see how well the saw-tooth lighting pattern works with growing corals. Mike Paletta has said he uses this pattern. My big question is what are his settings? I've looked for them, but only find that he has all lights at 100% for an hour then drops to all blue for...

www.reef2reef.com

Thanks!

 

[JCOLE]

@Dana Riddle I believe I am at this point right now. My Seneye is showing 500+ par at the sandbed and 1200+ par at the top of the rocks. SPS is growing, but very slowly. I think that I am stunting their growth.

Wouldnt bleaching occur if too much light was thrown at them? Or is it possible to stunt their growth without bleaching?

 

[Dana Riddle]

@Dana Riddle I believe I am at this point right now. My Seneye is showing 500+ par at the sandbed and 1200+ par at the top of the rocks. SPS is growing, but very slowly. I think that I am stunting their growth.

Wouldnt bleaching occur if too much light was thrown at them? Or is it possible to stunt their growth without bleaching?

Lots to consider here. Are those light intensities the maximum during the photoperiod? Corals have an arsenal to protect them from excessive light, but only to a point. Reflective or fluorescent proteins can shunt light energy away from photosynthesis. So can xanthophylls and carotenes. With SPS (or any branching/folding coral) self-shading can help to prevent bleaching. I made some observations while in Hawaii of shallow tide pool corals and found areas exposed to 'full-strength' sunlight were bleached (even though they still had a brownish coloration) while shaded areas had high zoox populations. My point is that the human eye is apparently poor at distinguishing bleaching unless it is total. As for stunting growth without bleaching, yes, I think that is possible when light intensity exceeds the photosaturation point but does not rise to chronic photoinhibition.

 

[KenO]

Yes, Saxby in the UK and Mike Paletta among others. I don't dispute they have fabulous tanks, would like to see some PAR numbers and lighting schedules to understand what's going on.

Instead of creating a saw tooth pattern, could one use the cloud option feature in most LED controllers to simulate the saw tooth pattern?

 

[Nano sapiens]

What is it that causes a coral to reset its photosaturation point ready for the next light cycle? Is it an extended amount of time without light ie the 12 hour rest period between light cycles?
Purely curiosity.

When a coral adds mass to its skeleton, does this happen during the light period or the dark? And also which part (beginning, middle, end or the entirety of the light or dark)?
I ask this as I dose all major and minor elements 12 times a day distributed evenly throughout the day and was wondering if its worth targeting a specific time in the on/off light cycle so i am adding in as the coral is taking out.

Please feel free to tell me to to open a new thread if this is to far off topic.

This coral calcification study (using Stylophora pistillata) was done using constant intensity lighting (12h on, 12h off):

https://jeb.biologists.org/content/209/17/3413

Main takeaways:

1. Light cycle produced a 2.6 fold calcification increase over dark cycle.

2. Differences in calcification for the 12h light cycle were minimal (near constant calcification rates at a constant light intensity).

 

[Lostreefin]

Carbonate levels in ocean water affect the availability of CO2 to corals. Instead, the enzyme carbonic anhydrase within corals converts carbonate to CO2 which becomes the carbon source for photosynthesis.

This reminds me that plants can uptake and utilize more CO2 than what is currently in the atmosphere and available to them. People gas grow rooms with CO2 to increase the yields on vegetables and other plants, some claim to increase growth and/or yields by 30%. If you increased the CO2 that the corals are up taking or that is available would corals grow faster if they weren't nutrient limited by anything else? Very interesting topic!!

 

[Dana Riddle]

This reminds me that plants can uptake and utilize more CO2 than what is currently in the atmosphere and available to them. People gas grow rooms with CO2 to increase the yields on vegetables and other plants, some claim to increase growth and/or yields by 30%. If you increased the CO2 that the corals are up taking or that is available would corals grow faster if they weren't nutrient limited by anything else? Very interesting topic!!

Experiments with CO2 injection would be an interesting project as long as the carbonate chemistry isn't really negatively impacted. CO2 passes through biological membranes with relative ease when compared to carbonates, so it would be a juggling act.

 

[Dana Riddle]

Instead of creating a saw tooth pattern, could one use the cloud option feature in most LED controllers to simulate the saw tooth pattern?

Sure that would work. The saw tooth pattern (or simulated cloud cover) would be of benefit only if it drops light intensity below the dynamic photoinhibition level (which varies due to the photoadaptive ability of the zoox clade.)