I have a Millepora and in the end of some of their branches some stains of green color have appeared, I believe that they are algae but I am not sure. Can you tell me what I can make to eliminate these stains?.

Eric Borneman

I would assume that it has died in those spots. Not much to do, and eliminating stains isn't going to help. Keep the coral in a lot of light and a lot of water flow....I assume the coral is still nicely brown/golden brown/mustard in the other spots?

Walt Smith

Sorry, but I would suggest that if indeed you have filimentatious algae growing in strains at the end/tips of you Millepora it could possibly be already too late. Unfortunately, this type of coral is sometimes very hard to tell if it is dead or alive because much like its cousin " Distichopora " it will very often retain it's color even after death. I would assume by now that you may start to notice the algae starting to take hold and spread. If not, you may be lucky! One way to check is to hold a magnifying glass to it in the middle of its normal light cycle (if possible) and see if you can detect tiny hair like follicles on the surface(like on page 618 in Veron). If you can detect this then it is still alive and feeding (or trying to). Millepora usually lives on the exposed reef edge in plenty of current. I have noticed that if we do not provide a similar environment in our facility the hair algae will move in. Lighting does not seem to be a major factor for this species as I have observed it two feet from the surface in the bright sun as well as under ledges and in both cases in huge gardens. I have also noticed in my own tank where I have a piece that has doubled in size in the past 6 months that growth can be monitored by the presence of "white tips" on the ends of the branches. Good luck, as this is usually a very hardy coral from my experience.

Eric Borneman

I think you are thinking of Stylaster . Both Stylaster and Disichopora are characterized by the incorporation of the pigments astaxanthin and zeaxanthin in their skeleton. Millepora does not incorporate pigments into the skeleton. Coloration that remains would probably be from endolithic algae.

Perhaps it's tried to move on to the next stage of life if in the correct lighting and conditions? Every abused Millepora I've seen was bleached white at first.... I saw no mention of that?

The next stage of life? Yes, perhaps the afterlife? ;-)

Millepora does bleach easily, and will show white or pale growth tips and margins, but a coral that has bleached will remain white until there is tissue death and algae can invade or cover the skeleton. It's possible that endolithic algae or fungal hyphae are showing through the transparent tissue in scleractinia, imparting a green tone, but the living tissue of Millepora is contained mostly within the skeleton instead of external in a veneer covering the corallites. Millepora , being a hydrocoral and not a true coral, does not have corallites. In terms of distinguishing the type of algae, it could be any of several dozen or hundred types, single celled films or invasive/boring, filamentous,etc.

Walt Smith

I am sure that you are correct to point out that pigments incorporated in the skeleton of both Distichopora and Stylaster is characteristic of these species. However, I have never seen a bleached "white" colony of Millepora in the thousands (perhaps millions) of colonies observed in the wild. Your comment about the coloration remaining (after death) due to the presence of endolithic algae is exactly my point .... even when dead it retains it's mustard/gold appearance. I might also add that massive colonies covered in algae will (over time) go from their original color to a darker brown "gradually" but I have never seen a bleached white colony even when a major bleaching event is taking place on the surrounding reef. Have you ever seen a bleached white Millepora ? I would be curious to know if this phenomena only occurs in a captive environment where artificial lighting and additives could sometimes vary greatly from the natural setting.

Eric Borneman

Bear with me till I get to your question here. The color of the healthy coral is, as I am sure you are aware, due to the presence of the golden brown symbionts, the zooxanthellae. The endolithic algae and fungae I refer to are those present within the skeleton, not in the tissue...such as Ostreobium quekettii and many types of fungi (see Le campion-Alsumard, Golubic and Priess 1995. Fungi in corals symbiosis or disease? Interaction between polyps and fungi causes parl-like skeleton biominerlaization Mar Ecol Prog Ser 117 137-147 and Kendrick, B., a et al. Amphibious microborers bioeroding fungi isolated from live corals Bull Mar Sci 32 862-867)

I would suspect that the color you are noticing is perhaps due to diatom films and maybe other encroaching microalgae and cyanobacteria that would also explain the darkening you have seen....that or the corals aren't dead? LOL If the color both dead and alive is similar, it is not going to be due to retention of the zooxanthellae after mortality. The skeletons are so porous that the microalgae can grow inside the pore structure without showing any tangible mass on the surface. Recently dead or bleached Millepora I have seen do seem to accumulate brown diatom films very similar to the original color of many Millepora . In any event, the endolithic algae are fairly bright green and the fungi a darkish green to gray-black and not golden brown.

and I might also add that massive colonies covered in algae will (over time) go from their original color to a darker brown "gradually" but I have never seen a bleached white colony even when a major bleaching event is taking place on the surrounding reef. Have you ever seen a bleached white millepora?

Yes, quite often in M. complanata and M. alcicornis but I've never seen a bleached M. squarrosa at all. From partially bleahed to whole colonies and areas stark white. Even when nearby corals are unbleached. And yet M. squarrosa can still have some creamy color to it when other corals around are bleached. I would suspect they harbor different symbionts, but some M. squarrosa are so pale they look almost bleached anyway..

I would be curious to know if this phenomena only occurs in a captive environment where artificial lighting and additives could sometimes vary greatly from the natural setting

Couldn't tell you. I don't see many Millepora in aquaria, and most of the ones I see in stores are dead or dying already.