shaded parts of acropora

[redadeath]

what heppend to the shaded parts of an acro colony that light doesnt reach
how does it benefits from light

if we have an acro there should always places the become shaded and the light is not intense
i wonder does the whole colony including the shaded parts benefits from other parts that expose to lights as it is impossible to expose the whole colony to the same direct light

 

[discus513]

The undersides of the branches and the spots that get less light will have less color, but if you were frag that branch and stand it up so that light shines on both sides it will color back up pretty quickly.

 

[redadeath]

so less light will not kill it at the base ??

 

[29reef]

It might, this is partly why most wild acropora colony's are so hard to care for. Frags that are grown in a tank are much hardier.

 

[power boat jim]

As coral colonies grow and the base gets evermore shade the base usually dies back. Coral does seem to be able to transfer energy a short distance to some less shaded areas and keep them tissue covered, like the underside of branches.

 

[Alex T.]

This is fairly common in the wild as well. On a recent snorkeling trip to the Caribbean I saw an Elkhorn coral the size of a small car. The growing branches were the only healthy part of the coral while the stabilizing rooted branch was all bleached. IMHO it's just something that happens and doesn't necessarily mean the death of a coral.

Good luck.

 

[redadeath]

so thats' means that the whole colony is not connected

so if some polyps is feeding they donot transfer food to other places of the coral
am i right?

 

[Alex T.]

I'm no marine biologist, but I've even had a base on a blue stag sprout another colony while the other was receded in the shade. These are really complex animals that we are still in the infancy of starting to understand. I wish I could answer that for you.

 

[rmalone]

I have a valida colony that has stn'd in the shadiest areas, yet is encrusting like mad on the "sunny side" and the top looks very nice. I don't think nutrient transport involves moving a long way through the skin to unlit parts, perhaps some, but a little stn in shady areas seems to be common with sps so I would think that those areas are simply not being fed.

If I had the gumption, I would like to take one of those Kessil led's and aim it at an angle back into that shady area and see if it starts to re-encrust where it lost tissue....but I don't have enough desire to go there. I wonder if aiming a group of kessils near the edge of the tank back into the center would help with keeping all areas better lit. Anyone got 8 kessils for me to give it a try, lol.

 

[franklypre]

I was having fits over this issue in my 58 show that had an icecap setup using a 400w halide. I had great growth but all the bases and shaded parts would bleach/brown/or die all together. I added two PAR38 from rapid and it seems to have resolved the die off for the most part. I think most who experience this use halides, I haven't noticed it as much with the T5s. I know it is overkill but I'm wanting to add 2 or 3 T5s to the front of the tank just to see if it would eliminate what little bit of shade there is in my tank.

 

[MammothReefer]

I find this situation is exactly where a combination of point source, and non-point source lighting really helps. Things like T5/VHO spread light from the entire length of the bulb. Which do a good job at filling in shadows caused by halides/leds since they are emitting light from a single point. (or multiple single points if it's an led)

But in some cases it's unavoidable.. I have Efflos that shadow there own foot, some recede a bit others don't. I think it depends on flow and feeding, or if light can reflect. Don't know for sure but this is what I suspect.

 

[Alex T.]

Well, again, I'm no scientist but there's a mature oak tree in my backyard that's got to be at least 50 years old and I have to prune the dead branches off the bottom every few years. Every Spring it shows its' glory with beautiful green leaves that whistle in the wind on a warm summer's night.

After seeing countless videos and having the opportunity to see some of the world's reefs first hand, I can attest to many SPS colonies bleaching and/or receding on the the bottom areas, whether shaded or not. We could point the finger at the sun being a "point" light source like metal halide, but that would be inaccurate since the sun is a point source that moves over and around those wild corals every day, with the same result. The only speculative observation I see is that much like my oak tree and other plants, the newly budded leaves and branches are always more bright and beautiful.

I think it's just nature's way. I almost never see this happening to a new, growing frag. It's always on a mature colony that is growing at a much faster rate.

 

[samuelkl]

I agree t5s definitely help with light coverage and limit shaded areas. I've seen large colonies where the shaded parts have a lot less color but are still alive if provided enough flow. If no flow and no light, I believe you will get stn.

I'm not sure if acros are like acans where you feed one mouth and it feeds the whole colony tho

 

[redadeath]

my acropora is bleaching at the base because no light is reaching there

so does bleaching at the base mens the whole colony will bleach?

 

[rmalone]

Usually no the whole thing doesn't bleach, the part bleaching, at least for me, usually stn's but it doesn't progress throughout the whole coral.