halimeda and light

[munki]

my halimeda is not dead, but if i buy better lights will it grow its nice and green right now, but its not very long.
just wonderin-
-thanks

[sasquatch]

Hey Munki, lights dont matter very much, if your alc/calc are where they should be, you'll see it grow daily. Steve

[michael_cb_125]

I have low light in my seahorse tank. And low Ca levels aswell. I never put any halimedia in either, but i got it growin all over my rock

[munki]

Originally Posted by michael_cb_125

I have low light in my seahorse tank. And low Ca levels aswell. I never put any halimedia in either, but i got it growin all over my rock

how low is your light?

[munki]

i dont think it has grown at all. you sure lights dont matter?

[michael_cb_125]

3 watts per gallon, 70 watt MH over 24 gallon AquaPod.

[munki]

Originally Posted by michael_cb_125

3 watts per gallon, 70 watt MH over 24 gallon AquaPod.

lol thats a lot more than i have

[michael_cb_125]

Aw. Ok what i ure wattage. And what do you keep in there

[munki]

real low. just macro. thats why i think its not growing. because of low light.
so what do you think?

[michael_cb_125]

Thats probably it. Halimedia also depends on Calcium and alkalinity as well. If your Ca. and Alk. levels are high and your water parameters are good, then it is probably a lack of light.

[aquaman3680]

I had halimeda under a eclipse hood before, didnt grow that fast but it did grow! When it is growing you will see little white things on top of the leaf. Check your calcuim as that is more than likely the problem!

Matt

[Snappy]

It is a green photosynthetic plant, so it needs light. It doesn't have to be intense but it needs a reasonable amount of light to grow. And yes it does need good levels of calcium as well. I have lots in my refugium.

[prow]

you pick an interesting algae. a well studied one too. here is a study for ya with links to other studies within it. it gets kinda complicated but basically yes halimedia needs light. but its more of an activation of a certain proton pump. wait, my explantion can get long here. i will just let yous read for your selves and only say that calcification in halimeda is more ph dependant, which means CO2 and O2 levels are more of factor because of there relationship with ph, photosynthesis=CO2 uptake= a shift in ph. here is where it gets complicated because of the make up of the algae, calcification is not the same in corals as it is with halimeda. the articles name is "Photosynthesis and calcification in the calcifying algae Halimeda discoidea studied with microsensorshere" here the abstract and introduction.

Abstract
With microsensors, we measured the steady-state microprofiles of O2, pH and Ca2+ on the topside of young segments of Halimeda discoidea, as well as the surface dynamics upon light–dark shifts. The effect of several inhibitors was studied. The steady-state measurements showed that under high light intensity, calcium and protons were taken up, while O2 was produced. In the dark, O2 was consumed, the pH decreased to below seawater level and Ca2+ uptake was reduced to 50%. At low light intensity (12 mmol photons m-2 s-1), Ca2+ efflux was observed. Upon light–dark shifts, a complicated pattern of both the pH and calcium surface dynamics was observed. Illumination caused an initial pH decrease, followed by a gradual pH increase: this indicated that the surface pH of H. discoidea is determined by more than one light-induced process. When photosynthesis was inhibited by dichlorophenyl dimethyl urea (DCMU), a strong acidification was observed upon illumination. The nature and physiological function of this putative pump is not known. The calcium dynamics followed all pH dynamics closely, both in the presence and absence of DCMU. The Ca-channel blockers verapamil and nifedipine had no effect on the Ca2+ dynamics and steady-state profiles. Thus, in H. discoidea, calcification is not regulated by the alga, but is a consequence of pH increase during photosynthesis. Acetazolamide had no effect on photosynthesis, whereas ethoxyzolamide inhibited photosynthesis at higher light intensities. Therefore, all carbonic anhydrase activity is intracellular. Carbonic anhydrase is required to alleviate the CO2 limitation. Calcification cannot supply sufficient protons and CO2 to sustain photosynthesis.

Introduction Go to sectionTop of pageAbstractIntroductionMaterials and methodsResultsDiscussionConclusionsAcknowledgments ReferencesThis article is cited by:
Calcification is a common phenomenon in aquatic photosynthetic communities, particularly in marine environments (Borowitzka 1984). Reef-building corals are the most spectacular examples; however, micro- and macroalgae are also important calcifiers, even in coral reef systems (Gattuso et al. 1997; Larkum 1999). Biogenic calcification is closely coupled to photosynthesis, because of the shift in the carbonate system by CO2 uptake and the concomitant pH increase, which enhances the calcium carbonate precipitation (Borowitzka 1984; McConnaughey 1987). As the calcification reaction produces H+ and CO2, it decreases the changes in pH and CO2 concentration induced by photosynthesis. It is hypothesized that in the green alga Chara (McConnaughey & Falk 1991; McConnaughey 1991) and in foraminifera (Erez 1983), calcification enhances photosynthesis by reducing alkalinity and increasing the availability of CO2.

Extensive studies have been performed on calcification in Halimeda tuna and Halimeda cylindrica (Borowitzka & Larkum 1976a, b; c, d). In Halimeda, aragonite crystals are deposited in the intercellular spaces (Borowitzka & Larkum 1976a), separated from the seawater by a layer of appressed cells (utricles), in which the photosynthetic activity is concentrated. Solutes, exchanging with seawater, have to pass through the utricle layer as well as the mass boundary layer adjacent to the tissue. It was hypothesized that during photosynthesis, the diffusion barrier allows the development of a microenvironment with a high pH, suitable for aragonite precipitation (Borowitzka & Larkum 1976b, c, d). Thus, in Halimeda, calcification is thought to be regulated by the morphology of the algae: the tissue does not have a regulatory influence except through the uptake of CO2 by photosynthesis and maybe as a nucleation site for calcification (Borowitzka 1989). Recently, we reported on a microsensor study on corals, showing that calcium uptake at the tissue was influenced directly by photosynthesis (de Beer et al. 2000). We concluded that this might be an active regulatory mechanism to fine-tune the pH regulation within the tissue of corals. Here, we used microsensor techniques to explore the relationship between photosynthesis and calcification in the calcifying alga Halimeda discoidea.

the rest of the study can found here. Blackwell Synergy - Cookie Absent
also follow some of links to other studies lots of good info throughout, though its kinda technical.

[prow]

yeah, i finially got to use that link. its been in my fav's for years.

[saltwaterfarm]

Munki... how long have you had this? The reason I ask is because it really doesn't grow overnight... It takes time for it to grow enough that you will notice it. I think I read another of your posts earlier talking about you getting it.
Exactly what lights do you have? How many watts per gallon?