Daphnia: higher carotenoids when provided good light

RobM

RobM

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Unfortunately I don't have access to the full article but thought this sentence gave food for thought :wink::
"Females reared in the light contain three times as much carotenoid as similarly fed females reared in the dark"
Source: Carotenoids in daphnia - J.Green

Although I don't know the parameters and conditions used in the tests, it could certainly means that those of us who try to culture our own daphnia, should provide adequate lighting if we want to develop those good natural newt colours!
 
makes good sense. Anytime I see Daphnia in the wild, they swarm in the sunniest and warmest part of a pond. I put light on mine. I kinda like it when I can actually see them, too.
 
My understanding is that Daphnia tend to produce ephippia with low light levels.
Maybe there's a correlation between the carotenoid levels/light levels and photoperiod/ephippia production.

Btw, John has written a great article on Daphnia
 
My first thought was to associate the quality light with good algal growth, which would explain the carotenoid levels as the Daphnia accumulate them from the algae.
 
Ken Worthington said:
Btw, John has written a great article on Daphnia
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Thanks Ken, already read it twice :p

Azhael said:
My first thought was to associate the quality light with good algal growth, which would explain the carotenoid levels as the Daphnia accumulate them from the algae.
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It is possible, but it says they were similarly fed, which I would assume would mean access to the same food, with the same nutritional properties?
 
in my Daphnia tubs, I get the green fuzz algae that covers the glass, but not the fre--floating ones the Daphnia eat. Then again, it's possible the Daphnia simply eliminate those and they never have a chance to grow.
 
Molch said:
Then again, it's possible the Daphnia simply eliminate those and they never have a chance to grow.
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I believe that is the case, in culture documents that I have read it, usually says that the daphnia will out compete the culture of algae. This is why yeast, bacteria etc is normally suggested. I assume because Daphnia are explosive breeders that they take advantage of booms in food supply.
 
Too bad we can't see the whole article. It appears that all daphnia in the experiments were being fed algae. I wonder what kind of "light" was used as the light source?

In terms of captive care, this would suggest that there could be a benefit to using strong lights over daphnia. I wonder if anyone has ever tested to see what part of the light spectrum causes the increase in carotenoids. There could be a greater benefit to some particular types of lighting.
 
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This article has some additional clues:
Zooplankton
but it still doesn't tell me whether UV itself is required to cause the daphnia to store more carotenoids.
 
Thanks Jen, another piece of the puzzle!

I wonder if it's the same for caudates then? I know mostly the colourations dependent on carotenes are found on the underside of a lot of species of caudate, but for example the Notophthalmus viridescens do have top colourations formed from carotenes.
Wild animals often have much redder colourations than captive bred animals, in addition to the carotene rich food they may eat, perhaps the light they are exposed to is also important?
 
If would appear carotenoids are better at absorbing light in the blue area of the light spectrum, which according to this article:http://www.aslo.org/lo/toc/vol_20/issue_4/0564.pdf may also be the part of the spectrum that daphnia are also most responsive to (coincidence?).
(also says that blue seems to penetrate deeper into water and that daphnia also may have periods within the day they are more active in.)
I have only skimmed this material so far, but thought I would post encase people want to have a read themselves, as for me I am far too tired and will re-read in the morning!
 
That is excellent information, Jen, cheers!

Rob, in the case of Notophthalmus viridescens it appears the purpose of the striking red coloration of the juveniles is to alert predators. They are after all, quite toxic. Toxic enough to dare walk around during the day, i believe, much like dendrobatids do.
 
Azhael said:
Rob, in the case of Notophthalmus viridescens it appears the purpose of the striking red coloration of the juveniles is to alert predators. They are after all, quite toxic. Toxic enough to dare walk around during the day, i believe, much like dendrobatids do.
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I was referring to the little orange/red spots on their backs, which is found in both the adults and juveniles. You are in luck, because the other day I saved the resource I read this information in!

"Carotenoids have also been identified as responsible for the red spots of the red-spotted newt, Notophthalmus viridescens (Forbes et al, 1973)"
Source: Carotenoids and amphibian colouration


EDIT: PS. Just found this video that demonstrates the different behavior exhibited by daphnia under different light: http://www.youtube.com/watch?v=NWij3uO_5x8
 
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RobM said:
I know mostly the colourations dependent on carotenes are found on the underside of a lot of species of caudate, but for example the Notophthalmus viridescens do have top colourations formed from carotenes.
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It would seem that C. pyrrhogaster can store carotenoids on the upper side, judging by the photos of the abnormally red individuals. Interestingly Bombina orientalis have yellow pigments from both pterins and carotenoids on their backs, but carotenoids alone on their bellies.

I'd be very interested in seeing the full article. It's not at all clear from the abstract whether light causes more carotenoids to be stored in the body, or whether it causes more to be stored as free carotenoids as opposed to being bound in carotenoproteins. The high hydrophobicity of carotenoids means that it's difficult for any organism to 'intentionally' excrete them- highly hydrophobic compounds (e.g. DDT) will accumulate in almost anything that ingests them.

I have heard anecdotal evidence that sun-reared Daphnia are redder than those in low light, but this could well be related to increased algae in their diet.

Incidentally, carotenoproteins should also be effective in intensifying amphibian colour- gammarus have (as I understand it) most of their carotenoids bound up in proteins (hence the blue-green, rather than orange, colour), and they work very well for colour feeding.
 
I haven’t read as much about this as I would have liked (yet it is still way more than I have posted), but I feel it’s best to post something while it is still fresh. Now I haven’t found a scientifically proven reason (yet) why daphnia reared in light would contain more carotenoids, but I am going to summarise some thoughts:

1) Daphnia retain more carotenoids to protect themselves from the UV light (Thank you Jen) (specifically blue part of the spectrum? Because carotenes are most effective at working with this area of the spectrum)
2) Food sources gain more energy/nutrition through photosynthesis due to the increase in light (Thank you Rodrigo). This is then passed onto the daphnia that eat these food sources?

Daphnia appear to be most receptive to blue light. Now I think it is strange that if daphnia require extra protection specifically to blue light (which would make them retain more carotenes), that they would approach the surface where the light is going to be brighter. So I think some theories about blue light are needed too, especially as it seems that blue light is important to daphnia.
Blue light thoughts:

1) Daphnia head for the surface to feed on food sources that thrive on blue light? (a preferred source of food?)
2) Blue light penetrates deeper into water so they would still require UV protection at a deeper level. This prompts them to go up to feed on algae and such that thrive on this blue light (and likely to be carotene rich).
3) Blue light makes them more exposed at lower depth, therefore they head up to take safety in numbers (such as herd animals do)

I know I do not have a specific and sound reason for my assumptions that blue light is the best and preferred light to house daphnia in for carotenoid richness. But I feel confident in saying that it is fairly likely, if not definitely the case? I believe this for the following reasons:

1) Daphnia are more active in blue light (may eat more)
2) It is the preferred area of the spectrum for carotenoid absorbtion (more carotene rich food)

Now blue-green algae apparently photosynthesises deep red better and is much much less able to deal with blue light, so does anyone know an algae type that thrives on blue light?

All comments are welcome, I would love to see both complimentary and contradictory ideas and thoughts, I know I haven’t got things perfect.

I would love to know whether some of these same theories/thoughts are applicable to caudates too, I think especially the relation between carotenoid retention and light would be interesting.

PS. I apologise that I am not going to re-read my post, it is difficult enough for me to put stuff in my head into words, if I re-read it will all probably change again, I am sure I have missed things I have thought and read anyway.
 
caleb said:
I have heard anecdotal evidence that sun-reared Daphnia are redder than those in low light, but this could well be related to increased algae in their diet.
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Based on the article Rob linked to, this absolutely SHOULD be true, and may not even depend on algae in the diet.

I think I can get access to that article from work, I'll look into it tomorrow.
 
Jennewt said:
Based on the article Rob linked to, this absolutely SHOULD be true, and may not even depend on algae in the diet.

I think I can get access to that article from work, I'll look into it tomorrow.
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One article I read had a fair amount of information about UV protection between lighter and darker individuals, it is definitely all linked.

*fingers crossed that you can get the article* I hope it does not end up to be an experiment full of holes.
 
I have the 1957 article. If you want it, please email/PM your preferred email address to me. It is interesting reading, but doesn't quite answer all the questions. For the daphnia grown in light, they used some kind of mercury lamp, which suggests full spectrum, including UV.
 
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