When macro's glow... Questions on red macroalgae

[WheatToast]

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When green and brown macroalgae begin to die, they turn pale/darkened in coloration (I assume the Fucoxanthin in brown macroalgae/Chlorophyll in green macroalgae that colors the algae is breaking down) before melting away. However, red macroalgae goes neon-orange and fluoresces under blue light before melting. Does the Phycoerythrin in the red algae just break down differently? Is something else at play?
Also, if red macroalgae does glow orange when dying, does this mean that the desirable coloration in Halymenia dilatata or dragon's breath (that is brought out under intense lighting) is the result of poor health? Does the dying tissue protect the rest of the algae like sunscreen? I am just so curious about this phenomenon!

 

[taricha]

Does the Phycoerythrin in the red algae just break down differently?

yes. phycoerythrin is an accessory pigment and normally does a handoff of energy from phycoerythrin through other pigments to chl a in an intact phycobilisome

now imagine in a dead cell or otherwise damaged phycobilisome, the coupling between phycoerythrin and the other pigments is broken. So instead of handing off that energy down the chain, it fluoresces at ~570nm and longer which looks orange.

you can see this by putting a little vinegar on some coralline algae...

Something happens to the pigment centers when the algae dies or is damaged. The red pigment fluoresces orange instead of pink.....

bottom left: two pebbles with coralline algae.
bottom right: under fluorescent blacklight (~365nm) they glow pink
top: after a drop of vinegar, the pebble on the right fluoresces brighter and orange.

Also, if red macroalgae does glow orange when dying, does this mean that the desirable coloration in Halymenia dilatata or dragon's breath (that is brought out under intense lighting) is the result of poor health?

maybe, but probably not. it might just generate more sunscreen pigments (carotenoids or similar). Also photosynthetic organisms have ways of turning down their photosynthetic machinery when the light is too high. This might change the look.

 

[shootingstar_reef]

Oh this is interesting I didn't know that. What I have seen in my tank with the similar species Halymenia durvillei is that the tip will start going pale then white; then die off. This is an interesting algae biology question...

 

[WheatToast]

Oh this is interesting I didn't know that. What I have seen in my tank with the similar species Halymenia durvillei is that the tip will start going pale then white; then die off. This is an interesting algae biology question...

Oh sorry! I did mean Halymenia durvillei (Dragon’s breath), not Halymenia dilatata (Dragon’s tongue) in the original post. I think both will turn fluorescent under intense light, but I have never kept Halymenia dilatata so I cannot confirm.

 

[shootingstar_reef]

All good. Are they really separate species? What exactly makes them different cause I don't think I would be able to tell them apart if I ever saw them haha

 

[Ohmegg]

I have the same thing with my current outbreak of "hair algae " that's similar in struggle to bryopsis bit branches out like a shrub from the base. Ever now and again I see a yellow or green fluorescing segment of one of the dying tips of the algae or a part that broke off.

 

[WheatToast]

All good. Are they really separate species? What exactly makes them different cause I don't think I would be able to tell them apart if I ever saw them haha

Halymenia durvillei has blade-like fronds while the Halymenia dilatata in the trade has has finer growth. Images of wild Halymenia dilatata feature the algae with ruffled fronds, which may be the result of environmental factors or “hobby” Halymenia dilatata might be a separate species.

Halymenia durvillei (no fluorescence):

Halymenia durvillei (with fluorescence):

Halymenia dilatata (trade):

Halymenia dilatata (wild):

Oh, and the second image on my original post features Gracilaria parvispora.

@reddevilant probably knows more about Halymenia dilatata.

 

[shootingstar_reef]

Halymenia durvillei has blade-like fronds while the Halymenia dilatata in the trade has has finer growth. Images of wild Halymenia dilatata feature the algae with ruffled fronds, which may be the result of environmental factors or “hobby” Halymenia dilatata might be a separate species.

Halymenia durvillei (no fluorescence):

Halymenia durvillei (with fluorescence):

Halymenia dilatata (trade):

Halymenia dilatata (wild):

Oh, and the second image on my original post features Gracilaria parvispora.

@reddevilant probably knows more about Halymenia dilatata.

This is exactly what I've been looking for thanks! I think I mostly see H. durvillei labeled as both 'tongue' and 'breathe.' they actually seem to be quite different

 

[reddevilant]

Halymenia durvillei has blade-like fronds while the Halymenia dilatata in the trade has has finer growth. Images of wild Halymenia dilatata feature the algae with ruffled fronds, which may be the result of environmental factors or “hobby” Halymenia dilatata might be a separate species.

Halymenia durvillei (no fluorescence):

Halymenia durvillei (with fluorescence):

Halymenia dilatata (trade):

Halymenia dilatata (wild):

Oh, and the second image on my original post features Gracilaria parvispora.

@reddevilant probably knows more about Halymenia dilatata.

This is exactly what I've been looking for thanks! I think I mostly see H. durvillei labeled as both 'tongue' and 'breathe.' they actually seem to be quite different

Yeah I really wish we could outlaw the terms Dragon's breathe/tongue and ogo lol. Every red leafy or branching macro is labeled by those names even though there are many different species that have slight morphological differences.

When it comes to Halymenia dilatata, I believe it is wildly misidentified by vendors. I'm fairly certain the almost orange hypnea, bush looking version that vendors sell is not dilatata at all but, I'm not sure what exact species it could be. It does not resemble the images that you see on the WoRMS and AlgaeBase databases when it grows out. It more resembles durvillei but the "leaves" are kind of longer, thinner, and more rounded. I'll try to take a picture of mine I when I get home.

It's actually really strange how grown out pieces don't look like that little orange bush at all. My thought is that it is collected at a very early life stage after growing from spores after an "adult" specimen went sexual rather than growing from fragmentation. That might explain the different morphology and why the bush version is so hard to come by, because you have to find it at the right time and circumstance.

 

[ReeferSpot]

I have what I assume to be Dragons breathe in my sump. It has a lot of orange tips under blue light but it is steadily growing. None of it seems to be dying off.