Cave Environment --Infrared Photosynthesis - Bookshelf 6G

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Cave Environment - Infrared Photosynthesis - Bookshelf 6G

Note: this project is not going to be a marine tank, but the general concept, an aquarium covered to exclude light and create a very dark environment, might be of interest for reef aquarium ideas. So I post it here. Depending upon my final livestock choices, setup will be either brackish or freshwater.

I've been working on a few different projects testing out Cyanobacteria as display organisms. While Cyanobacteria are usually viewed as pests in aquariums, they have fascinating biology and ecology as well as compelling features for model ecosystem culture. Some Cyanobacteria have extreme desiccation tolerance and can spring back to action if watered after long periods of drying out. They also produce their own food with light energy and Cyanobacteria species have distinct colors, textures and morphologies. Cyanobacteria are keystone species in unique microbial ecosystems, such as stromatolites and desert biocrusts.

Here is a vertical garden piece I made along with a few others in a series. It grows the Cyanobacteria, Tolypolthrix and Anabaena on a clay panel along with mini Ferns, Peperomia, Mosses and a Liverwort...

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Certain Cyanobacteria are especially interesting as extremophiles, organisms that live and grow at extreme temperatures, pH, salinity or other conditions that would kill most living things. I recently learned about a newly described extremophile ecosystem supported by Cyanobacteria photosynthesizing with the very small amounts of natural light that penetrate deep within caves. These conditions are not only dimly lit, but due to the differential absorption and reflection of light wavelengths from limestone surfaces, they have light mainly in the far-red and near-infrared spectrums (700nm-800nm). The upper end of this range is invisible to human eyes and has hundreds of times less energy than light in the visible spectrum, but the cave Cyanobacteria are nevertheless able to use it as an energy source for photosynthesis and very slow growth. This is amazing!

Among other adaptations, these Cyanobacteria make use of chlorophyll f and chlorophyll d, photosynthetic pigments able to absorb this long-wavelength light. Plants do not have these forms of chlorophyll. Chlorphyll f was discovered recently, in 2010, in another special microbial habitat, the stromatolites of Shark Bay, Australia...

https://www.science.org/doi/10.1126/science.1191127

There are just a few articles published to date on the cave Cyanobacteria, but here's the one I downloaded and read to learn more about the topic...

https://ami-journals.onlinelibrary.wiley.com/doi/10.1111/1462-2920.14774

23-I-24-Cave-Environment-II.jpg


The common Cyanobacteria that you can purchase as live cultures or find growing wild are less likely to produce chlorophyll f and chlorophyll d and grow in cave conditions. My plan is to build this terrarium/paludarium setup as a representation of the environment to stand on its own, then add cave Cyanobacteria if I am able to lawfully and ethically source them from somewhere. Maybe I can write some emails and find a cave biology researcher who will take interest if I explain the project. If I do manage to find any kind of promising Cyanobacteria it will be a real challenge to get them to grow at all. But again, I am as interested in just creating the environment and working through some of the visual scaping and layout ideas for this different kind of setup. I also have a couple of cave livestock ideas—more on these later—among animals available in the trade.

I got the project enclosure, a Lifegard Aquatics 6-gallon tank, and set it up on this shelf...

23-I-24-Cave-Environment-III.jpg


I really like bookshelf aquariums. You can make something rather expansive, but with a relatively compact, lightweight and affordable format. That 36" light is not for the setup; I just put it there for a view of the aquarium. For the project I am going to build a strip with a driver, heat sink and these 1-watt, 740nm star LEDs...

23-I-24-Cave-Environment-IV.jpg


I haven't wired them up and turned them on yet, but these LEDs do not shine with a strictly 740nm light. They instead produce a range of far-red (including some deep-red visible light) and infrared light with 740nm as the spectrum peak wavelength.

I have some more electronics and other components to add and I'll explain those as I get them organized. My layout concept is to just use a sand bed covered with about 1" of water and with an arrangement of partially submerged limestone aquascaping rocks . I will not attempt to build rock features like the characteristic forms that develop in caves, but just assemble the stones and sand in a pleasing scape for the bookshelf tank format and with varied, moist rock surfaces for potential Cyanobacteria and livestock inhabitants. I think Seiryu stone will look really nice like this...

Seiryu Stone

Thanks for reading! Updates on the way pretty soon.
 
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Wow, that's impressive, love the research that went into building the tank!!


Thank you so much! I hope to have more progress and updates on the way soon. Do you two have current tank projects?

To explain the display concept further, I intend to leave the last 5" of the enclosure open and illuminated with a regular mini white LED to create a cave opening environment with some pieces of limestone and mini plants that might be found there, such as Liverworts or Asplenium ferns. Some of the semi-aquatic Mosses in the aquascaping trade would work especially nice for this area. This arrangement will make the setup a little more interesting to look at while also creating the kind of gradient of visible light transitioning to infrared described in that article.

23-I-24-Cave-Environment-I.jpg



(I hope that above image complies with the concept of Fair Use as an educational depiction of copyrighted material. Please let me know/remove if otherwise. [Source: https://ami-journals.onlinelibrary.wiley.com/doi/10.1111/1462-2920.14774])
 
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Rounding up some more hardware tonight...

I'm going to organize a microcontroller with LCD display and other components on this wall bracket system I've used for a few other projects, including this phytoplankton lamp setup...

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I intend to configure this stackable board with built-in screen as well as plug connections for a temp + humidity and light sensor breakouts...

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I'll have to experiment some more with the micro controller or ask for help somewhere because I was unable to get the compiler to recognize it. I'll figure it out eventually. I will also design and cut out parts for an enclosure + bracket to house the controller and other components together on the wall. Lots of little jobs to do!

The breakouts will both go inside the enclosure. I'll probably seal the light sensor inside of a small glass jar to keep humidity out and extend its life. This particular light sensor should be a good match for this project because it can detect several ranges of wavelength of visible light as well as infrared.

I'm going to position this mini controllable 3W LED over the daylight cave opening area of the display...

26-I-23-Cave-Environment-I.jpg


This little light has its own integrated driver, so all you have to do is send it power and signal.

I've used this kind of ultrasonic fogger in a few other projects. It is just a fogger membrane thingy with PCB, a short length of pipe as a mini water reservoir and a bulkhead for passing through the enclosure top. I'm not going to wire it with a timer or anything, but instead just fill it up and run it manually. This thing isn't really essential, but it will moisten the rock surfaces to encourage potential Cyanobacteria growth and the fog mist will also "look cool" in the setup...

26-I-23-Cave-Environment-III.jpg
 
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I've built a strip with the 740nm LEDs. Of course the instructions packed with the driver/converter are pretty confusing, so I haven't really been able to figure out the current adjustment. I should be able to get three times this much light intensity with the maximum specified current. I'll experiment some more and figure it out.

You can see the visible deep red light here, but supposedly there's a good deal more invisible IR light. It will be interesting to get this on top of the enclosure with the light sensor inside.

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I assembled a temporary light-proof cover to go over the dark portion of the tank. This is just paper foam-core material, but I will use it to design a permanent cover in black acrylic or ABS sheet. In addition to a narrow transparent strip on top lining up with the light fixture, I will also have to cut ports for the sensors, a fan wire, an air line and the ultrasonic fogger.

As mentioned previously, the area at the left end of the tank will remain open and illuminated with a white mini LED. I will extend the cave limestone hardscape into that area and also plant a few mini plants there.

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View inside from the open end with 740nm lamp plugged in.

30-I-23-Cave-Environment-II.jpg
 
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Update!

I cut out a top with the router. Actually there are a couple mistakes here and I will need to redo this part, but I can bolt and wire the lighting and other components with this to get the tank started and then just make an update later on. This textured ABS sheet looks really sharp as a top for a glass tank...

resize-10-II-23-Cave-Environment-IV.jpg


We have a new aquarium shop in the area that has stocked some nice aquascaping material/equipment and I found this nice set of seiryu stone. I stuck them in the tank quick with just. a regular LED strip for an idea of shapes, sizes and textures....

resize-10-II-23-Cave-Environment-II.jpg


Pretty nice!

Here's the tank illuminated with the 740nm LED strip. The right 60% of the enclosure will be covered to exclude ambient light, with only a small opening at the water level to connect the two areas. I'm going to attach the front black plastic panel with hook & loop fasteners for easy removal and a view like this, but only after dark and when the room lights are turned off to maintain the dark cave environment...

resize-10-II-23-Cave-Environment-III.jpg
 
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I'm thinking more about livestock ideas to guide the next steps. I could just make this a microbes + plants dedicated setup, but it would be interesting to also incorporate animals. Any thoughts the reader might have would be appreciated.

There are not a whole lot of cave animals in the hobby. The blind cave form of the Mexican Tetra is one example, but these fish are much too big for this setup as it will hold only 1.5 gallons of water. Among cave insects in the trade are Eublaberus sp. "Ivory"—I already have a colony of these—and the Extinct Cave Roach, but these are both terrestrial animals that require a land area, so they are likewise unsuitable.

Here are my two best ideas so far as more feasible livestock choices:
  1. Neocaridina hangjiajiensis Snowball Shrimp
  2. Halocaridina rubra Opae Ula Shrimp
I've looked around and can't find many specifics on the wild habitat of Snowball Shrimp (Neocaridina zhangjiajiensis), but as a whitish, semi-transparent shrimp it would convey the idea of cave animals with reduced pigment colorations. Sometimes the species name is written with the "cf." designation, so apparently there are doubts about the true classification. One reference I found described the wild-type shrimp as grey-brown in color similar to wild N. davidi.

Owing to the limestone pieces and aragonite sand, this setup will quickly develop elevated hardness, so it will be unsuitable for Bee Shrimp (Caridina cantonensis). But there are at least several other Caridina species that occur in limestone caves:
Even though it's not a cave shrimp and in a different genus, the N. hangjiajiensis could serve as a stand-in for one of these species.

Xu-article-screenshot.png


(Above, Caridina sinanensis. Image source: Caridina sinanensis, a new species of stygobiotic atyid shrimp (Decapoda, Caridea, Atyidae) from a karst cave in the Guizhou Province, southwestern China)

I haven't kept Neocaridina for a number of years. How nocturnal are they? I hope that as biofilm develops in the dark area of this setup, shrimp may venture inside to feed.

They are not usually described as cave fauna, but Halocaridina rubra Opae Ula shrimp can survive in darkness for long periods, perhaps many months or even years, in the subterranean tubes connecting their anchialine pool habitats in Hawaii. This is supposedly how they disperse between pools and survive dry periods where the surface anchialine pool water may recede. Opae Ula of course require brackish water habitat, so this is veering away from my concept of trying to Cyanobacteria described from freshwater, inland caves. But I suspect that far red/IR photosynthesis could very well occur deep within Hawaii anchialine pools as well. With the only reason it hasn't been described is simply because nobody has gone to look for it.

Opea Ula are easy enough to find for sale online here, but it would be really great to network and find a contact who can (lawfully and ethically) collect some microbial samples from an anchialine pool and ship to me in trade. Look at the extraordinary bright orange microbial mats formed by Schizothrix calcicola here in Kanonone Waterhole. (Hover over image for Flickr source information and link.)



The green foliage is the brackish-adapted Widgeon Grass (Ruppia maritima). Fascinating! If I could get some samples of S. calcicola, I would probably also build a dedicated larger setup just for it. This species precipitates CaCO3 as calcium sheaths and can even build freshwater stromatolites in the right conditions.





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I finally got the ABS lid with hardware mostly all bolted together. This doesn't look like much, but it took me all night to round up these little parts and assemble everything.

Components:
  • 740nm LED strip
  • ultrasonic fogger with water reservoir
  • airline + wires port
  • 3W white LED
  • mini ventilation fan
I still need to position the temp & humidity and light sensors. Also have to track down a 5v power supply that can handle the current draw from that bight white LED.

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resize-19-II-23-Cave-Environment-IV.jpg
 
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Wow I totally abandoned this project!

I'm thinking about picking it up again, though. I have that top that I made special with the IR LEDs that runs well. My current new favorite idea is the Opea Ula shrimp, but using a small microbial wild field collection to start the algae and other biota in the tank. Do any readers here know anybody in Hawaii who might be able to (lawfully and ethically) get a small field sample with a trade or something?

As far as I can tell, near-infrared/infrared photosynthesis has not yet been described from the anchialine pools + lava cave systems, but I'd be willing to bet that's just because no researchers have gone to look yet. Either way the tank setup with one open end and the rest covered in darkness is a kind of a model for the ecosystem and Opea Ula habitat.

Here's something really interesting I ran into just tonight. This describes an anoxic deep sea benthos environment, so it doesn't really apply to this aquarium idea, but with microbes achieving photosynthesis strictly with thermal energy infrared.

 
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