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Accelerated coralline algae growth experimentation for reef restoration

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TetrisPetris

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Hi reefers!
I'm an engineer and erstwhile reefkeeper working with a nonprofit to investigate new technology in coral farming to help restore reefs. I posted a bit back about cultivating nuisance algae to experiment on which received some really helpful replies, and now I'm investigating the potential for using coralline algae to help reduce the need to clean hair algae in coral farms.

Since some context is helpful, here's a link to a little doc where I typed up a few thoughts, or here's a TLDR version:
  • Reefs are rapidly dying due to climate change
  • Some individual coral have high temperature resistance and are able to survive mass bleaching events, but the population remaining on a given reef is often below extinction threshold
  • The marine biology community believes that active restoration could be the answer - planting breeding populations of temperature-resistant coral
  • The size of the intervention needed is massive, so efforts need to be scaled up dramatically with cost per coral lowered dramatically
  • The most significant labor cost in large scale coral farming is often manual algae removal (because it can choke coral)
  • Algae overgrowth is a problem partly because farms will need to use natural natural sunlight and seawater (variable and sometimes nutrient-rich) for cost reasons
  • Natural grazers can help, but balancing populations across many tanks can become a significant logistical hurdle, so preventing algae growth (particularly near growing coral) would be a huge help
  • Coralline algae looks promising because it can deny substrate to nuisance algae while being easy for coral to grow on, but it grows very slowly
So what I'm investigating now is: how fast can coralline algae be grown on coral substrate?

I'm thinking about a few approaches like breaking up live coralline algae and gluing a bunch of fragments of it to a frag plug (like a salted margarita rim), with the idea that only a little more growth would need to happen for complete coverage. I'm also thinking about trying using high concentration purple helix on some frag plugs to seed them with a crazy amount of spores, maybe in conjunction with purple up to help accelerate growth.

I'd love to hear the community's thoughts about how to approach this!

Also shoutout to Michael (@H2OPlayar) for generously meeting up with me and offering to host some experiments :)

Thanks very much!
Peter

P.S. If you'd rather chat than type I'd be happy to! Just PM me and we can find a time

P.P.S. If you're curious about reef restoration, it's getting to be a pretty exciting and important topic!
 
Would be interesting to see the correlation between coraline algae and reduction of "nuisance" algae. I get the idea is that "something got there first" but does coraline actually reduce other types of algae growth? I seem to recall nuisance algae having no problem growing on coraline covered rocks.
 
sfsuphysics said:
Would be interesting to see the correlation between coraline algae and reduction of "nuisance" algae. I get the idea is that "something got there first" but does coraline actually reduce other types of algae growth? I seem to recall nuisance algae having no problem growing on coraline covered rocks.
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Ooh, good call. We can run a dual experiment in my other tank that grows hair algae, even on mature rocks (due to minimal herbivores and no extra tech on the tank)
 
Another factor that can limit coralline algae growth is urchins. In our classroom our main tank has quite a few urchins who scour the rock, so we fight algae growing on corals.
 
sfsuphysics said:
Would be interesting to see the correlation between coraline algae and reduction of "nuisance" algae. I get the idea is that "something got there first" but does coraline actually reduce other types of algae growth? I seem to recall nuisance algae having no problem growing on coraline covered rocks.
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Agreed. I have always heard that, but I have a frag tank that is a mess of tough green algae which may or may not be bryopsis, which is growing on some coralline-covered rocks.
 
H2OPlayar said:
Ooh, good call. We can run a dual experiment in my other tank that grows hair algae, even on mature rocks (due to minimal herbivores and no extra tech on the tank)
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sfsuphysics said:
Would be interesting to see the correlation between coraline algae and reduction of "nuisance" algae. I get the idea is that "something got there first" but does coraline actually reduce other types of algae growth? I seem to recall nuisance algae having no problem growing on coraline covered rocks.
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Agreed, this would be interesting to test further, since I don't have a rigorous understanding of the level of prevention coralline algae might offer vs other types.

My current leads on this are some advisors from ORA, Monterey Bay Aquarium, and Coral Vita commenting that they have successfully used coralline algae to prevent other nuisance algae from growing. The purple helix product also claims "Purple Helix blend algae strains are highly epiphytic stains that will help to outcompete other nuisance algae and diatoms." As far as I know, epiphytic just refers to plants which grow on other plants, so maybe they're saying it's "anti-epiphytic"? Or perhaps that it will grow on top of nuisance algae?

Clearly some experimentation is in order!
 
dochou said:
Coraline grows fast on plastics and on acrylic. Finding out the reason why, might help you to grow coraline faster onto rocks.
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Good thought! I also have noticed that it seems to prefer plastic, and wonder if it has something to do with smoothness or surface energy vs typical reef rock
 
TetrisPetris said:
It might be, the product page says it raises calcium and trace elements which doesn't sound particularly unique, but I figured it might be worth testing to see if their formula makes a measurable improvement in growth speed vs normal healthy reef tank parameters ¯\_(ツ)_/¯
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Fair enough, but I don’t. Think it will help. It’s mostly water. Not cost effective.
 
I’m not sure about any of the assumptions in the first post, actually. Might help to spend more time on the hypotheses, like reading research journals instead of collecting anecdotal sound bytes.

The corals of the ocean are not going to be saved by planting temperature resistant corals where corals are dying. I think I’m probably a little testy from people planting false hope there, which is dangerous because then we figure we can keep on damaging the environment because we’ll GMO the corals. There are scientists that have been working on an approach to transfer temperature flexible zooxanthellae/symbionts, but these zooxanthellae don’t allow the corals to grow as fast, so then they have even less chance to recover between climate change related events like hurricanes, runoff, oil spills or temp spikes. It would be a good start to check how much progress they’ve made there in 15+ years. In any case there’s no hurry because it might work after we’ve corrected climate change effects in like the 100 year timescale, but only because we were forced to because our existence was threatened (not because corals are dying). For example, it’s hard to believe but this year there is a serious debate over putting a new oil pipeline into the Red Sea just a mile north of coral reefs, which could then be the first oil spill to kill reefs as well as the usual suspects. So we’re nowhere near saving reefs yet in the public consciousness.

Like others have said, coralline doesn’t grow over or prevent other algaes. Ask anyone with hair algae experience. What prevents nuisance algae is animals that eat the algae or the algae spores being removed by filter feeders, etc. Obviously it’s easier for urchins or whatever to eat soft algae than coralline (except in the cases where the nuisance algae already has grown too large to be palatable). So prevention with clean up crew is how you beat nuisance algae. Now in the wild, if there is a heavy rain that washes farm fertilizer offshore, upsetting the nutrient balance, algae will explode faster than urchins can multiply but can you get coralline to grow even faster? Doesn’t matter because the nuisance algae will still grow in that scenario when there is a nutrient spike and coralline does not do much if anything to prevent nuisance algae. And, if you bred a coralline so virulent that other algaes can’t grow over it, then you probably are also making it more difficult for corals to encrust over the coralline which would be bad right?
 
And the fact that people are still buying products like Purple Helix from that charlatan company ARCReef is just too much. BRS please do your diligence and do a “BRS investigates” on this product.
 
Chromis said:
And the fact that people are still buying products like Purple Helix from that charlatan company ARCReef is just too much. BRS please do your diligence and do a “BRS investigates” on this product.
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If BRS sells this stuff, they'll actually promote the heck out of it! And make up some fake science to prove it works.
 
In general I agree with what @Chromis said with 1 important exception- coralline algae coverage of growth surfaces does reduce nuisance algae growth. It’s not a 100% prevention, but it does make a very noticeable difference. It’s not some special property of coralline algae per se, it’s just that uncolonized surfaces are one of the limited resources that attaching algae/coral/bacteria compete for. If one algae occupies all the surfaces it makes it harder for the next algae to get hold. Not impossible, but harder. Coralline algae is not the only desirable lifeform to do this in our tank and in the wild- anything that coats the surface of rock with a tough living biofilm will do it.

Coral can grow over coralline algae and other biofilms only because it is more aggressive and able to kill it along it’s margins. Sometimes it fails at this and you see the coralline algae killing and growing over the coral! It’s just a battle for surfaces.

This process of coating all the surfaces with something not obnoxious is a big part of what is happening when a new tank exits the ugly phase. Algae grazers help immensely because they eat macroalgae, giving the other types of biofilms the advantage in the fight.

All that said, I don’t think promoting coralline algae has any chance of helping the coral reef problem in the wild. It could help in your proposed coral farms, but I’d need to know more about it to say anything useful. For example, if you are talking about large outdoor artificial tanks/troughs like they use in macroalgae farms, with tons of uncolonized surfaces, then yes you need something to form a biofilm, and coralline algae is one option. Maybe not the best option in large mostly unattended systems, since it grows slowly and can attack/overgrow coral. Just letting the coral farm tanks mature on their own with ocean water cycling through and lots of grazing snails and fish will form the biofilm you need pretty quickly, maybe 3 months or so. I don’t really see a point in trying to optimize this further personally.

And those coralline algae promoting products are BS in my opinion- Purple Up is just calcium carbonate dosing as far as I know (and not a very effective way). For Purple Helix the theory of what they say for that product makes sense but I don’t have any personal experience with the product, and that company is not trustworthy.
 
Thank you all for the instructive discussion!

I appreciate the warnings on available coralline-focused products, that's helpful!

Again, agreed that more testing is needed to determine the degree to which coralline algae can deter settling of common nuisance algae species. I don't think coralline algae will be a silver bullet, but potentially another useful tool.
One detail I didn't mention is that "seasoning" frag plugs with coralline algae (such as by leaving them in the ocean for a few months) is common practice in coral sexual reproduction research circles, because coralline algae helps trigger larval settlement while offering some protection against other types of algae. I've attached a figure from David Vaughan's excellent "Active Coral Restoration" book showing a sexually reproduced Acropora palmata (elkhorn) individual growing over a frag plug encrusted with coralline algae.

Also just to clarify the scope of potential application, I'm curious about using it in terrestrial farming scenarios in raceway tanks to help reduce manpower needed for daily nuisance algae control (some coral farms for the hobby spend over half their labor budget on this issue). Control of algae blooms in eutrophic zones is outside the scope of this investigation.

Re: active coral restoration interventions - this is not considered a solution to climate change, but rather a way to buy time for reefs while global CO2 emissions to be brought under control. Time is of the essence because if no interventions are taken, some estimates indicate 90% of coral reefs will die in the next few decades, which will cause ecosystem collapses with dire consequences (including loss of commercial fisheries). Active coral restoration using temperature-resistant genotypes hasn't been tested massive scale yet and is not guaranteed to work, but that's the calculus of the climate crisis :p

My collaborators and I have interviewed most of the experts in reef restoration and found the community is bafflingly small relative to the scale of the problem, so there's massive potential for positive impact!

Returning to the original post - does anyone have additional suggestions for ways to accelerate colonization of surfaces by coralline algae?
 

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I recommend getting chunks of coralline algae from an established system, generally flaked off of a flat surface like the glass. Break it up into tiny pieces, and spread it around. Then just need to keep tank parameters good for growing stony corals (alk, Ca, Mg, pH, light, etc) and it’ll spread. As it starts to grow better in some areas than others, repeat the process.
 
I think purple-up might have some iodine supplements, which are often low in some tanks.

My experience:
Hair algae does not grow as easily on established healthy Coraline as it does on bare rock.
So it does make a difference.
Unfortunately, that is not really relevant, because it is hard to grow the Coraline FIRST.
On dead coral or raw rock, hair algae takes over long before Coraline gets a start.
And then the battle is lost.

There is only one way to battle hair algae: Nutrient reduction to starve it, and herbivores to eat it.

On a side note: Coraline does not seem to like intense LED lighting.
I have thick Coraline UNDERNEATH rocks. And it grows great on the sides of the tank.
 
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