Lighting as it applies to nature and to our home aquariums.

[Agape1love4ever]

I had a question about lighting that I’ve been thinking on a lot. When I think about the ocean and the reef systems within the ocean, I could imagine that the corals experience major light fluctuations throughout the day and from one week to the another, considering that there could be weather changes and cloud coverage and multiple things that could fluctuate the light intensity within one day compared to the next.

And then I think about our home aquariums. If corals in the wild can tolerate the fluctuations from the light they are receiving from the sun, why do our corals within our reef tanks have a potential of getting damaged when we raise or lower light intensity or switch from one type of light to another, like going from an LED to a T5, or vice versa?

To me, it seems like corals should be able to tolerate these kind of changes if they’re able to do that in the wild.

I have not thought this through or done a lot of research. I’m sure there’s an answer out there but I thought I would like to get your opinions on how this works.

 

[Spare time]

If I had to guess its because changes in the wild occur over long time periods.

 

[Agape1love4ever]

So, to clarify, what I mean is, say that there is a storm about to come over a reef system. That reef system has been exposed to complete sunlight for hours, and then all of a sudden a storm crosses over and blocks out the sun for a couple hours, and then the sun shines through the clouds again and then vice versa back-and-forth. Wouldn’t this inconsistency mess with the wild Corals?

 

[Spare time]

So, to clarify, what I mean is, say that there is a storm about to come over a reef system. That reef system has been exposed to complete sunlight for hours, and then all of a sudden a storm crosses over and blocks out the sun for a couple hours, and then the sun shines through the clouds again and then vice versa back-and-forth. Wouldn’t this inconsistency mess with the wild Corals?

I think corals care about a sudden increase from what they are used to, rather than simply a change. Corals don't seem to care about sudden decreases in light.

 

[AydenLincoln]

You have to think in the wild a few huge variables are happening. First most corals are huge massive colonies. Secondly the sun being the light source is thousands of miles away although it’s stronger it’s a natural light source and water depth affects how much light is received the farther you go down the less light and clouds and current are affecting it greatly. Versus if you think of our lights they are artificial and giving out a set amount of light over a short period of time and are inches to feet away and not more than that.

 

[ISpeakForTheSeas]

To me, it seems like corals should be able to tolerate these kind of changes if they’re able to do that in the wild.

A few things come to mind:

1 ) In our tanks, the lighting is constant and stable, whereas in nature, the lighting varies daily (sometimes from one moment to another); yes, it's all coming from the same light source (the sun), but the intensity can vary drastically depending on weather, season, water conditions, etc. - corals in the wild are adapted to dealing with these constant little changes, but corals in our tanks are adapted to things being constant.

2 ) Changes in lighting in nature are generally small, spread out over time and/or temporary, and primarily impact intensity (though there are small changes in spectrum too); in our tanks, though, changes in lighting are usually instant, they're usually permanent, and they usually involve big changes in both spectrum and intensity - so the actual change is likely much more drastic than it seems to us.

3 ) Because the corals in our tanks are adapted to very specific lighting conditions and don't have little, regular changes like in nature, they likely only really have one kind of zooxanthellae growing in them, whereas in nature, corals would likely have more of the various kinds growing in them and enabling them to adapt/transfer to different light conditions more readily.

4 ) If we were to slowly adapt our corals to regular, small lighting changes like they would be exposed to in nature, then they could likely handle those changes without issues - again, though, the lighting changes in our tanks are usually pretty major changes whether we realize it or not.

 

[Agape1love4ever]

A few things come to mind:

1 ) In our tanks, the lighting is constant and stable, whereas in nature, the lighting varies daily (sometimes from one moment to another); yes, it's all coming from the same light source (the sun), but the intensity can vary drastically depending on weather, season, water conditions, etc. - corals in the wild are adapted to dealing with these constant little changes, but corals in our tanks are adapted to things being constant.

2 ) Changes in lighting in nature are generally small, spread out over time and/or temporary, and primarily impact intensity (though there are small changes in spectrum too); in our tanks, though, changes in lighting are usually instant, they're usually permanent, and they usually involve big changes in both spectrum and intensity - so the actual change is likely much more drastic than it seems to us.

3 ) Because the corals in our tanks are adapted to very specific lighting conditions and don't have little, regular changes like in nature, they likely only really have one kind of zooxanthellae growing in them, whereas in nature, corals would likely have more of the various kinds growing in them and enabling them to adapt/transfer to different light conditions more readily.

4 ) If we were to slowly adapt our corals to regular, small lighting changes like they would be exposed to in nature, then they could likely handle those changes without issues - again, though, the lighting changes in our tanks are usually pretty major changes whether we realize it or not.

Thank you for this answer. It actually does make a lot of sense in the fact that when we change our lights in our tanks, it’s an instant change instead of a small change over time. Not too sure about the zooxanthellae. I would like to hear a bit more about how that works in nature compared to our tanks.

 

[ISpeakForTheSeas]

Not too sure about the zooxanthellae. I would like to hear a bit more about how that works in nature compared to our tanks.

Basically, there are different clades of zooxanthellae, and each clade handles different spectrums of light better than others - with corals in our tanks being adapted to only one dominant spectrum rather than a constantly (albeit slowly) changing spectrum, they likely have one very dominant clade of zooxanthellae, and very little of the other clades; I don't know for sure (it has been a while since I looked), but it would make sense to me that wild corals exposed to more regular (albeit small) changes in spectrum would have slightly more zooxanthellae from the other clades than captive ones do.

Hopefully someone will correct me if I'm wrong though (as mentioned, its been awhile since I last read up on it).

 

[strich]

You also have to remember that in the real world, light covers a much wider wavelength band compared to the LED lights used at home. In particular, the low bands like UV (<350nm) aren't as affected by cloud cover as other visible light bands. So even though weather can greatly affect visible light, the coral will still be receiving a good amount of non-visible or low wavelength banded light. I imagine that could assist in providing much lower but subsisting energy.

 

[Agape1love4ever]

You also have to remember that in the real world, light covers a much wider wavelength band compared to the LED lights used at home. In particular, the low bands like UV (<350nm) aren't as affected by cloud cover as other visible light bands. So even though weather can greatly affect visible light, the coral will still be receiving a good amount of non-visible or low wavelength banded light. I imagine that could assist in providing much lower but subsisting energy.

This is a very good observation. And it makes sense. I think you’re right. The lower wavelength that we don’t detect is most certainly reaching into the ocean. How deep into the ocean is a different story but the fact that they’re getting some kind of light probably does help with keeping these corals from getting shocked with changes like that consistently over time.