An Attempt to Generate Benthic Biofilm for Substrate Feeders

[livinlifeinBKK]

@Randy Holmes-Farley I have a few questions for you when you have a minute that relate to my experimental design.

#1- The current plan is to use natural seawater in order to keep nutrient levels at a level approximately equal to that of where the benthic biofilm is located because fluctuating nutrients can cause unpredictable variations in composition.
However, I have suspicions that nutrient levels would vary with depth and other factors as the seafloor is approached. If this is true, it might just make more sense to use artificial seawater in the culture tank and keep it as constant as possible through periodic testing.

#2- Something else I wanted your advice on revolves around the early formation of biofilm on the glass microscope slides suspended in the water. While it strikes me as being most natural to wait for the slow spread of whatever organism will colonize first, would it perhaps be a useful idea to add a small amount of a select supplement (Zeovit Zeofood Plus) that will form a biofilm fairly quickly? An advantage of adding this or a similar product would be possible accelerated growth of the biofilm and associated microfauna due to the amino acids and vitamins. However , these same amino acids and vitamins may interact in an unwanted way or somehow alter the composition.

I'd love to hear your opinions on how I can heighten my chances of achieving the desired result.

 

[livinlifeinBKK]

@Randy Holmes-Farley are you online?

 

[livinlifeinBKK]

@Randy Holmes-Farley I have a few questions for you when you have a minute that relate to my experimental design.

#1- The current plan is to use natural seawater in order to keep nutrient levels at a level approximately equal to that of where the benthic biofilm is located because fluctuating nutrients can cause unpredictable variations in composition.
However, I have suspicions that nutrient levels would vary with depth and other factors as the seafloor is approached. If this is true, it might just make more sense to use artificial seawater in the culture tank and keep it as constant as possible through periodic testing.

#2- Something else I wanted your advice on revolves around the early formation of biofilm on the glass microscope slides suspended in the water. While it strikes me as being most natural to wait for the slow spread of whatever organism will colonize first, would it perhaps be a useful idea to add a small amount of a select supplement (Zeovit Zeofood Plus) that will form a biofilm fairly quickly? An advantage of adding this or a similar product would be possible accelerated growth of the biofilm and associated microfauna due to the amino acids and vitamins. However , these same amino acids and vitamins may interact in an unwanted way or somehow alter the composition.

I'd love to hear your opinions on how I can heighten my chances of achieving the desired result.

Hey @Randy Holmes-Farley when you have the time I'd really appreciate it if you could look this first draft over for me...the rest is on the first page but I just put two bullet points on this page for review...

 

[livinlifeinBKK]

@Randy Holmes-Farley please read the second page in particular because I was hoping for your advice...

 

[Timfish]

I wish you luck! My sporadic success with linckia certainly suggests to me certain composition in biofilms is likely needed. Expect it to be a long uphill process. Besides the above suggestion checking with Aquabiomics I'd suggest searching google scholor and see if you can find marine microbiologists or researchers working with echnoderms who might have suggestions fo rspecific things to look for.

 

[livinlifeinBKK]

I wish you luck! My sporadic success with linckia certainly suggests to me certain composition in biofilms is likely needed. Expect it to be a long uphill process. Besides the above suggestion checking with Aquabiomics I'd suggest searching google scholor and see if you can find marine microbiologists or researchers working with echnoderms who might have suggestions fo rspecific things to look for.

I've actually been doing extensive research on my own and I have no doubt it's going to be a challenging task...not only have I been studying Echinoderm biology but marine microbiology as well. I'm going to try to use my location to my advantage since I'm living in Thailand where some of these species are native to.

 

[livinlifeinBKK]

I've actually been doing extensive research on my own and I have no doubt it's going to be a challenging task...not only have I been studying Echinoderm biology but marine microbiology as well. I'm going to try to use my location to my advantage since I'm living in Thailand where some of these species are native to.

CN you tell me a little more about your sporadic success? @Timfish

 

[Randy Holmes-Farley]

@Randy Holmes-Farley are you online?

Yes, but not usually in this forum. Nutrient levels at the top and especially the bottom of a biofilm may be quite different than the bulk water, and I see it being quite hard to measure or control it.

 

[Randy Holmes-Farley]

IMO, if the goal is to grow biofilms to feed organisms, I’d focus on that. Doesn’t matter if they look like natural films. You need to grow them fast and thick. White films of bacteria may all be similarly nutritious, if eaten.

if the goal is to understand natural biofilms (very complicated and not a diy) then you need to decide what aspects you want to understand.

 

[Timfish]

CN you tell me a little more about your sporadic success? @Timfish

The experience with Fromia that convinced me they should not be kept was when I ordered a dozen and put them in 10 different systems. They all did well initially but all died within a few weeks of being in the systems 6 months. Best explainaitons are either a family, genus or species specific disease or they all starved. The latter seems to me the more likely scenario considering how closely they all died to each other. I'm pretty sure I've had some live longer than that but that time frame seemed about how long when I'd seen others others live.

For the most part Linkia live less than a year. I suspect even though they look well initially I suspect they don't ship well and there doesn't seem to be much difference between the appearance of one dying within days or weeks - white slimey blotches appearing and limbs disentigrating and crawling off from the main body. I've had a few (2-3) live a couple years. The one "success" is one that lived about 12 years. What is unique is the system it was in. The 8' long 240 gallon system was built into a house that was sold and the seller kept all the pumps and filtration and just left the tank, some T12 fluorescents and water in it with a few fish no corals, minimal landscaping and 3 urchins, 2 huge diadems and 1 pencil. Through an "interesting" series of decisions on the part of the buyers I ended up maintaining the system as is with no extrernal or internal filtration, just 4 power heads and a couple air pumps and a UV sterilizor (UV was turned off after a couple years). A few years ago one of the diadem urchins was removed. Roughly a year later the blue Linkia seemed to be getting smaller and after a couple months it was noticied it had stayed in one place for several days and looked "deflated". From what I've read and seen in my systems the last 4 decades it seems like your idea of trying to figure out how to quantify biofilms in general and more specifically how they impact the survival of some of the organisms we keep like starfish would be good to know.

Sooooo, some of the questions I can't answer are:

How long do Linkia starfish live? Was it old age?

Was it associated with the removal of the Diadem urchin? The Linkia never stayed out in the light very long and there was no apparent feeding on algae or food added so was it feeding off biofilms? We know corals have to shed and renew their mucus layers as the microbiomes age so it seems reasonable the same is happening on other biofilms in our systems. What is the effect urchins have on biofilms and renewing them as they feed on algae?

What is the effect of skimmers and other forms of filtration used on biofilms? We know skimmers are arbitrarily removing just the hydrophobic subset of the microbiomes in a system. How does this onging process skew the biofilms in a system?

It's hard to determine the actual fish bioload as there were a lower number of fish but there were show size sailfin and naso but how does fish population and bioload affect the biofilms?

Good luck!

 

[Dan_P]

Hey guys, so as some of you already know, I'm trying to develop a solution to feeding substrate-feeding starfish such as Fromias and Linckias among others in an effort to make it possible for more people to keep them. This is just one idea among others I've had over the past week and just thought I'd post it. I will admit that there are plenty of holes in the idea I still need to solve for and am working diligently on. Also keep in mind that I wrote this up pretty quickly so some details have been left out...partly due to time constraint and partly due to the fact I doubt many people would care to read through it all if I included every detail. If successful, the end result will be a small filter pad covered in the biofilm which would be a very easy and simple way to feed.

-----Obtain live rock fresh from the ocean (preferably covered in coralline, sponges, bryozoans, and even small levels of fungal growth). These naturally cultured rocks will serve to inoculate other rocks, culture media, and growth pads. (A pre-sterilized tank will be used.)

-----Several swabs of the rocks will be taken and agar plates will be inoculated with the microfauna as soon as possible in order to grow samples before more alteration to the microbiome has a chance to occur.

-----Use REAL ocean water collected in close proximity to the native habitats of these stars. As DOM in the surrounding benthic community has been shown to exert a strong influence on the structure and succession of marine biofilm communities, I aim to avoid causing a nutrient imbalance at this early stage. The bioavailability of DOC also influences composition and even affects the uptake and utilization of other nutrients.

-----Place small pieces of sterile dry rock, several glass microscope slides, glass fiber filters, and a dead coral skeleton into the aquarium as well.

-----Make use of a standard HOB filter to aid in water movement.

-----Some glass slides will be suspended in the water column where the circulation of the water will allow for the natural inoculation of microalgae which will begin the process of biofilm generation. Other glass slides will be swabbed with mature biofilm. Some glass fiber filters will be put in contact with the mature rocks to test the tendency and ease of spread of the biofilm present.

-----Once biofilm has been established on the glass slides, a comparison will be made between its consistency and the consistency of the original culture plates.
The pads will then be inoculated and tests will be conducted to ensure the biofilm is accepted as a food source by benthic organisms.

------Measurements of consumption will be taken.

Again, this is a very basic methodology I'm not close to finished with yet. Biofilm is actually VERY complex and to my knowledge nobody has attempted this before so even though I plan to edit and modify my methods a bit, I wouldn't expect success the first time around but that doesn't concern me.

Biofilms form quite easily in aquaria. I agree they are very complex and changing ecologies. Question, will a bacteria biofilm suffice as a food source? These should be the easiest to create. Carbon dosing can create quite thick films quickly and cheaply. Dosing sand directly might be a strategy to encourage growth in the sand.

Older aquaria with a heavy feeding schedule would have quite a rich biofilm in the sand.

Are photosynthetic organisms part of the diet? That will be tricky trying to growit and and keep it pretty looking.

Growing biofilm should be easy, measuring the amount in the sand it will be tough.

I have no idea about sea star health, but would guess if it is not moving and looking for food, it is “sick”.

 

[livinlifeinBKK]

Biofilms form quite easily in aquaria. I agree they are very complex and changing ecologies. Question, will a bacteria biofilm suffice as a food source? These should be the easiest to create. Carbon dosing can create quite thick films quickly and cheaply. Dosing sand directly might be a strategy to encourage growth in the sand.

Older aquaria with a heavy feeding schedule would have quite a rich biofilm in the sand.

Are photosynthetic organisms part of the diet? That will be tricky trying to growit and and keep it pretty looking.

Growing biofilm should be easy, measuring the amount in the sand it will be tough.

I have no idea about sea star health, but would guess if it is not moving and looking for food, it is “sick”.

That's just it!...were not exactly sure what component of the biofilm they need for proper nutrition. When I say biofilm I mean all the organisms tied together in symbiotic relationships as a whole (not just the microalgal or bacterial film) and while I'm aware that carbon dosing can help develop a type of biofilm, that biofilm likely differs greatly from benthic biofilms that are fed on by these starfish species in bacterial makeup. Since the benthic biofilms receive little light I doubt photosynthetic organisms are the primary prey but other microfauna may be an important source of food and be difficult to grow. I'm trying to use close observation as a tool to help me make educated guesses as to what is most important for their survival but that involves a fair amount of guesswork too.

 

[livinlifeinBKK]

The experience with Fromia that convinced me they should not be kept was when I ordered a dozen and put them in 10 different systems. They all did well initially but all died within a few weeks of being in the systems 6 months. Best explainaitons are either a family, genus or species specific disease or they all starved. The latter seems to me the more likely scenario considering how closely they all died to each other. I'm pretty sure I've had some live longer than that but that time frame seemed about how long when I'd seen others others live.

For the most part Linkia live less than a year. I suspect even though they look well initially I suspect they don't ship well and there doesn't seem to be much difference between the appearance of one dying within days or weeks - white slimey blotches appearing and limbs disentigrating and crawling off from the main body. I've had a few (2-3) live a couple years. The one "success" is one that lived about 12 years. What is unique is the system it was in. The 8' long 240 gallon system was built into a house that was sold and the seller kept all the pumps and filtration and just left the tank, some T12 fluorescents and water in it with a few fish no corals, minimal landscaping and 3 urchins, 2 huge diadems and 1 pencil. Through an "interesting" series of decisions on the part of the buyers I ended up maintaining the system as is with no extrernal or internal filtration, just 4 power heads and a couple air pumps and a UV sterilizor (UV was turned off after a couple years). A few years ago one of the diadem urchins was removed. Roughly a year later the blue Linkia seemed to be getting smaller and after a couple months it was noticied it had stayed in one place for several days and looked "deflated". From what I've read and seen in my systems the last 4 decades it seems like your idea of trying to figure out how to quantify biofilms in general and more specifically how they impact the survival of some of the organisms we keep like starfish would be good to know.

Sooooo, some of the questions I can't answer are:

How long do Linkia starfish live? Was it old age?

Was it associated with the removal of the Diadem urchin? The Linkia never stayed out in the light very long and there was no apparent feeding on algae or food added so was it feeding off biofilms? We know corals have to shed and renew their mucus layers as the microbiomes age so it seems reasonable the same is happening on other biofilms in our systems. What is the effect urchins have on biofilms and renewing them as they feed on algae?

What is the effect of skimmers and other forms of filtration used on biofilms? We know skimmers are arbitrarily removing just the hydrophobic subset of the microbiomes in a system. How does this onging process skew the biofilms in a system?

It's hard to determine the actual fish bioload as there were a lower number of fish but there were show size sailfin and naso but how does fish population and bioload affect the biofilms?

Good luck!

Through the research I've done so far, Ive learned about their sensitivity to environmental changes like pH swings, nutrient levels varying, and other similar changes which may seem very subtle so I think their fragility probably leads to high stress levels which shortens their lives either directly or indirectly.
The biofilms present in benthic habitats such as where they live can be altered in bacterial composition very easily by environmental factors like nutrient levels rising or falling which is a common occurrence in aquariums. I would guess that these changes in bacterial makeup also cause shifts in other microfauna populations as well. Btw, I highly doubt that they obtain much if anything from the algae
Itself and tend to believe the algaes primary contribution (if there is one) is it's tendency to help certain bacteria colonize surfaces easier. Recalling how fragile they are, it is certainly possible that these shifts in the benthic microbiome can cause an unhealthy shift in their own microbiome internally which could possibly cause disease due to the proliferation of particular bacteria which aren't being kept to their natural population similar to what happens when a coral's microbiome is altered in a certain way. Maybe this inhibits digestion or nutrient absorption in some way as their digestive system is very unique. As for the urchin, that's very interesting to me. A pure guess might be that the reduced level of grazing somehow caused a shift in the biofilm the Linckia was feeding on. If I'm not mistaken, algal exudates release compounds that can have an effect on the water chemistry and perhaps microbiome as well, although it seems unlikely that the reduced grazing could have increased levels of algal exudates high enough to cause such a significant change, especially in such a large tank. NOTE: I don't have a much knowledge on algal exudates, I do recall that they definitely differ from those released by corals but that's probably neither here nor there.
As for skimming, I have a gut feeling it harms these starfish in some way or another. I don't know precisely why I feel this way but I think it may have to do with fluctuations in nutrient levels perhaps? Very many hobbyists constantly run skimmers these days and coincidentally these are the systems people try to house Linckias in due to the supposed adequate size as opposed to systems without skimmers which tend to be much smaller---this is just a guess though and not backed up by science.
Keeping in mind that Fromias and Linckias are both native to deeper benthic habitats, I think it's worth trying to measure how much nutrient levels fluctuate naturally which has likely already been measured at some point or other.
I've been spending a good amount of time making observations regarding my Fromias tendencies and behaviors with the hope that this will provide clues to some questions which remain unanswered. For example, one interesting observation I made a while back involved a chunk of sponge I suspect to be a benthic species growing on a small live rock fragment. The star showed what I consider to be a strong feeding response for a lengthy amount of time which leads me to believe he was in fact feeding on microbes since we know sponges are particularly rich in bacteria. He completely ignored a different species of sponge however which Im pretty sure came from a much different habitat. I have a second tank that's pretty mature and some of the rocks in it have what is either multiple species of sponges or at least one species of marine fungi. I placed this rock into the tank with my Fromia relatively close to it and just like with the first sponge, he exhibited a strong feeding behavior and this time it lasted for hours at least. Now, these stars can sense olfactory cues which sometimes leads them to dead shellfish and other very unlikely sources of food but I'd expect these two sponge species to give off very, very little scent (or perhaps I should say much different and less pronounced than a dead oyster) so it seems logical that they've evolved to detect these very faint but possibly distinct scents since they are a food source. Perhaps analysis of these sponge species' microbiome (particularly on the surface) could yield some useful information.

The experience with Fromia that convinced me they should not be kept was when I ordered a dozen and put them in 10 different systems. They all did well initially but all died within a few weeks of being in the systems 6 months. Best explainaitons are either a family, genus or species specific disease or they all starved. The latter seems to me the more likely scenario considering how closely they all died to each other. I'm pretty sure I've had some live longer than that but that time frame seemed about how long when I'd seen others others live.

For the most part Linkia live less than a year. I suspect even though they look well initially I suspect they don't ship well and there doesn't seem to be much difference between the appearance of one dying within days or weeks - white slimey blotches appearing and limbs disentigrating and crawling off from the main body. I've had a few (2-3) live a couple years. The one "success" is one that lived about 12 years. What is unique is the system it was in. The 8' long 240 gallon system was built into a house that was sold and the seller kept all the pumps and filtration and just left the tank, some T12 fluorescents and water in it with a few fish no corals, minimal landscaping and 3 urchins, 2 huge diadems and 1 pencil. Through an "interesting" series of decisions on the part of the buyers I ended up maintaining the system as is with no extrernal or internal filtration, just 4 power heads and a couple air pumps and a UV sterilizor (UV was turned off after a couple years). A few years ago one of the diadem urchins was removed. Roughly a year later the blue Linkia seemed to be getting smaller and after a couple months it was noticied it had stayed in one place for several days and looked "deflated". From what I've read and seen in my systems the last 4 decades it seems like your idea of trying to figure out how to quantify biofilms in general and more specifically how they impact the survival of some of the organisms we keep like starfish would be good to know.

Sooooo, some of the questions I can't answer are:

How long do Linkia starfish live? Was it old age?

Was it associated with the removal of the Diadem urchin? The Linkia never stayed out in the light very long and there was no apparent feeding on algae or food added so was it feeding off biofilms? We know corals have to shed and renew their mucus layers as the microbiomes age so it seems reasonable the same is happening on other biofilms in our systems. What is the effect urchins have on biofilms and renewing them as they feed on algae?

What is the effect of skimmers and other forms of filtration used on biofilms? We know skimmers are arbitrarily removing just the hydrophobic subset of the microbiomes in a system. How does this onging process skew the biofilms in a system?

It's hard to determine the actual fish bioload as there were a lower number of fish but there were show size sailfin and naso but how does fish population and bioload affect the biofilms?

Good luck!

The experience with Fromia that convinced me they should not be kept was when I ordered a dozen and put them in 10 different systems. They all did well initially but all died within a few weeks of being in the systems 6 months. Best explainaitons are either a family, genus or species specific disease or they all starved. The latter seems to me the more likely scenario considering how closely they all died to each other. I'm pretty sure I've had some live longer than that but that time frame seemed about how long when I'd seen others others live.

For the most part Linkia live less than a year. I suspect even though they look well initially I suspect they don't ship well and there doesn't seem to be much difference between the appearance of one dying within days or weeks - white slimey blotches appearing and limbs disentigrating and crawling off from the main body. I've had a few (2-3) live a couple years. The one "success" is one that lived about 12 years. What is unique is the system it was in. The 8' long 240 gallon system was built into a house that was sold and the seller kept all the pumps and filtration and just left the tank, some T12 fluorescents and water in it with a few fish no corals, minimal landscaping and 3 urchins, 2 huge diadems and 1 pencil. Through an "interesting" series of decisions on the part of the buyers I ended up maintaining the system as is with no extrernal or internal filtration, just 4 power heads and a couple air pumps and a UV sterilizor (UV was turned off after a couple years). A few years ago one of the diadem urchins was removed. Roughly a year later the blue Linkia seemed to be getting smaller and after a couple months it was noticied it had stayed in one place for several days and looked "deflated". From what I've read and seen in my systems the last 4 decades it seems like your idea of trying to figure out how to quantify biofilms in general and more specifically how they impact the survival of some of the organisms we keep like starfish would be good to know.

Sooooo, some of the questions I can't answer are:

How long do Linkia starfish live? Was it old age?

Was it associated with the removal of the Diadem urchin? The Linkia never stayed out in the light very long and there was no apparent feeding on algae or food added so was it feeding off biofilms? We know corals have to shed and renew their mucus layers as the microbiomes age so it seems reasonable the same is happening on other biofilms in our systems. What is the effect urchins have on biofilms and renewing them as they feed on algae?

What is the effect of skimmers and other forms of filtration used on biofilms? We know skimmers are arbitrarily removing just the hydrophobic subset of the microbiomes in a system. How does this onging process skew the biofilms in a system?

It's hard to determine the actual fish bioload as there were a lower number of fish but there were show size sailfin and naso but how does fish population and bioload affect the biofilms?

Good luck!

 

[Dan_P]

That's just it!...were not exactly sure what component of the biofilm they need for proper nutrition. When I say biofilm I mean all the organisms tied together in symbiotic relationships as a whole (not just the microalgal or bacterial film) and while I'm aware that carbon dosing can help develop a type of biofilm, that biofilm likely differs greatly from benthic biofilms that are fed on by these starfish species in bacterial makeup. Since the benthic biofilms receive little light I doubt photosynthetic organisms are the primary prey but other microfauna may be an important source of food and be difficult to grow. I'm trying to use close observation as a tool to help me make educated guesses as to what is most important for their survival but that involves a fair amount of guesswork too.

You might fortify your observations with experimentation if you can measure how a sea star responds, for example, gaining weight, moving more or less. You might start by feeding a sea star a bacterial biofilm generated from carbon dosing. Another experiment would be feeding the sea star different mixtures of sand from different sources. A source would be a collection location or from different aquaria fed different nutrients. The key is figuring out how to measure the sea star’s response. Good luck!

 

[livinlifeinBKK]

You might fortify your observations with experimentation if you can measure how a sea star responds, for example, gaining weight, moving more or less. You might start by feeding a sea star a bacterial biofilm generated from carbon dosing. Another experiment would be feeding the sea star different mixtures of sand from different sources. A source would be a collection location or from different aquaria fed different nutrients. The key is figuring out how to measure the sea star’s response. Good luck!

I'd be interested in an approach like the one you just suggested if we could verify that the star was in fact eating and digesting the bacterial biofilm offered but that's difficult to be sure of since most eat by expelling their stomachs to digest the food. As for the sand, I believe they strongly prefer to feed off rocky substrate and like you said, I'm not sure how you could measure the response but I'll do some thinking about it.

 

[damsels are not mean]

I'd be interested in an approach like the one you just suggested if we could verify that the star was in fact eating and digesting the bacterial biofilm offered but that's difficult to be sure of since most eat by expelling their stomachs to digest the food. As for the sand, I believe they strongly prefer to feed off rocky substrate and like you said, I'm not sure how you could measure the response but I'll do some thinking about it.

Cut a leg and see if it grows back

 

[livinlifeinBKK]

Cut a leg and see if it grows back

No, I don't want to take any risk if stressing or weakening him...he is being active though and it doesn't appear to me that a lot of biofouling has occurred on him which are position signs

 

[livinlifeinBKK]

My current holdup is getting real live rock from the ocean...I want really good quality.

 

[livinlifeinBKK]

New job/hobby to aspire towards- breeding starfish!

 

[Timfish]

. . . If I'm not mistaken, algal exudates release compounds that can have an effect on the water chemistry and perhaps microbiome as well, although it seems unlikely that the reduced grazing could have increased levels of algal exudates high enough to cause such a significant change, especially in such a large tank. NOTE: I don't have a much knowledge on algal exudates, I do recall that they definitely differ from those released by corals but that's probably neither here nor there.
. . . one interesting observation I made a while back involved a chunk of sponge I suspect to be a benthic species growing on a small live rock fragment. The star showed what I consider to be a strong feeding response for a lengthy amount of time which leads me to believe he was in fact feeding on microbes since we know sponges are particularly rich in bacteria. He completely ignored a different species of sponge however which Im pretty sure came from a much different habitat. . . .

Just a couple additional notes: Labile DOC, aka carbon dosing or algae exudates, is not a good thing as it shifts microbiomes from autotrophic to heterotrophic. Coral DOC is largely refractory, ie, it's not easily utilized by bacteria as a food source. Algal DOC is largely labile DOC and depending on species large amounts may be released. Heterotrophic bacteria can utilize labile DOC to feed of refractory DOC and reduce oxygen levels. With removal of one of the two urchins that heavily grazed on algae there would have been more labile DOC produced. Unfortubnately there's was no way to determine how much then and it is still likely not easily done, Aquabiomics is certainly one place to start. There is research looking at sponges with "high" and "low" microbial levels, it certainly would be fascinating if your expieremnts eventually show they are in fact feeding off certain cryptic sponges.

Here's some papers you might be interested in:

Microbiome dynamics in a large seawater aquarium, Microbial levels varied dramaticaly even with a tightly controlled system.

https://journals.asm.org/doi/pdf/10.1128/AEM.00179-18

Differential recycling of coral and algal dissolved organic matter via the sponge loop.
Sponges treat DOC from algae differently than DOC from corals

Error - Cookies Turned Off

besjournals.onlinelibrary.wiley.com

A Vicious Circle? Altered Carbon and Nutrient Cycling May Explain the Low Resilience of Caribbean Coral Reefs

Vicious Circle? Altered Carbon and Nutrient Cycling May Explain the Low Resilience of Caribbean Coral Reefs

Coral reefs are economically important ecosystems that have suffered unprecedented losses of corals in the recent past. Why have Caribbean reefs in particular t

academic.oup.com

Surviving in a Marine Desert The Sponge Loop Retains Resources Within Coral Reefs
Dissolved organic carbon and nitrogen are quickly processed by sponges and released back into the reef food web in hours as carbon and nitrogen rich detritus.

(PDF) 2013 deGoeij Science Sponge loop

PDF | On Jun 23, 2015, Jasper M de Goeij and others published 2013 deGoeij Science Sponge loop | Find, read and cite all the research you need on ResearchGate

www.researchgate.net

Natural Diet of Coral-Excavating Sponges Consists Mainly of Dissolved Organic Carbon (DOC)

Natural Diet of Coral-Excavating Sponges Consists Mainly of Dissolved Organic Carbon (DOC)

Coral-excavating sponges are the most important bioeroders on Caribbean reefs and increase in abundance throughout the region. This increase is commonly attributed to a concomitant increase in food availability due to eutrophication and pollution. We ...

www.ncbi.nlm.nih.gov

The Role of Marine Sponges in Carbon and Nitrogen Cycles of COral Reefs and Nearshore Environments.

The role of marine sponges in carbon and nitrogen cycles of coral reef and nearshore environments - ProQuest

Explore millions of resources from scholarly journals, books, newspapers, videos and more, on the ProQuest Platform.

search.proquest.com

Sponge exhalent seawater contains a unique chemical profile of dissolved organic matter - PubMed

Sponges are efficient filter feeders, removing significant portions of particulate and dissolved organic matter (POM, DOM) from the water column. While the assimilation and respiration of POM and DOM by sponges and their abundant microbial symbiont communities have received much attention, there...

pubmed.ncbi.nlm.nih.gov

https://sfamjournals.onlinelibrary.wiley.com/doi/full/10.1111/1462-2920.12851

Processing of Naturally Sourced Macroalgal- and Coral-Dissolved Organic Matter (DOM) by High and Low Microbial Abundance Encrusting Sponges

Sponges play a key role in (re)cycling of dissolved organic matter (DOM) and inorganic nutrients in coral reef ecosystems. Macroalgae and corals release different quantities of DOM and at different bioavailabilities to sponges and their microbiome. Given the current coral- to algal-dominance...

www.frontiersin.org

Here's some of the links I've collected on algal and coral DOC:

Indirect effects of algae on coral: algae‐mediated, microbe‐induced coral mortality

Error - Cookies Turned Off

onlinelibrary.wiley.com

Influence of coral and algal exudates on microbially mediated reef metabolism.
Coral DOC improves oxygen (autotrophy), algae DOC reduces oxygen (heterotrophy).

Influence of coral and algal exudates on microbially mediated reef metabolism

Benthic primary producers in tropical reef ecosystems can alter biogeochemical cycling and microbial processes in the surrounding seawater. In order to quantify these influences, we measured rates of photosynthesis, respiration, and dissolved organic carbon (DOC) exudate release by the dominant...

peerj.com

Role of elevated organic carbon levels and microbial activity in coral mortality

http://www.int-res.com/articles/meps2006/314/m314p119.pdf

Effects of Coral Reef Benthic Primary Producers on Dissolved Organic Carbon and Microbial Activity
Algae releases significantly more DOC into the water than coral.

Effects of Coral Reef Benthic Primary Producers on Dissolved Organic Carbon and Microbial Activity

Benthic primary producers in marine ecosystems may significantly alter biogeochemical cycling and microbial processes in their surrounding environment. To examine these interactions, we studied dissolved organic matter release by dominant benthic taxa and subsequent microbial remineralization in...

journals.plos.org

Pathologies and mortality rates caused by organic carbon and nutrient stressors in three Caribbean coral species.
DOC caused coral death but not high nitrates, phosphates or ammonium.

http://www.int-res.com/articles/meps2005/294/m294p173.pdf

Visualization of oxygen distribution patterns caused by coral and algae

Visualization of oxygen distribution patterns caused by coral and algae

Planar optodes were used to visualize oxygen distribution patterns associated with a coral reef associated green algae (Chaetomorpha sp.) and a hermatypic coral (Favia sp.) separately, as standalone organisms, and placed in close proximity mimicking coral-algal interactions. Oxygen patterns were...

peerj.com

Biological oxygen demand optode analysis of coral reef-associated microbial communities exposed to algal exudates
Exposure to exudates derived from turf algae stimulated higher oxygen drawdown by the coral-associated bacteria.

Biological oxygen demand optode analysis of coral reef-associated microbial communities exposed to algal exudates

Algae-derived dissolved organic matter has been hypothesized to induce mortality of reef building corals. One proposed killing mechanism is a zone of hypoxia created by rapidly growing microbes. To investigate this hypothesis, biological oxygen demand ...

www.ncbi.nlm.nih.gov

Microbial ecology: Algae feed a shift on coral reefs

Microbial ecology: Algae feed a shift on coral reefs - Nature Microbiology

Human pressures on coral reefs are giving macroalgae a competitive advantage over reef-building corals. These algae support larger, and potentially pathogenic, microbial populations that are metabolically primed for less-efficient, yet faster, carbohydrate remineralization, perpetuating a...

www.nature.com

Coral and macroalgal exudates vary in neutral sugar composition and differentially enrich reef bacterioplankton lineages.

Coral and macroalgal exudates vary in neutral sugar composition and differentially enrich reef bacterioplankton lineages - PubMed

Increasing algal cover on tropical reefs worldwide may be maintained through feedbacks whereby algae outcompete coral by altering microbial activity. We hypothesized that algae and coral release compositionally distinct exudates that differentially alter bacterioplankton growth and community...

www.ncbi.nlm.nih.gov

Sugar enrichment provides evidence for a role of nitrogen fixation in coral bleaching

Error - Cookies Turned Off

onlinelibrary.wiley.com

Elevated ammonium delays the impairment of the coral-dinoflagellate symbiosis during labile carbon pollution
(here's an argument for maintaining heavy fish loads if you're carbon dosing)

Elevated ammonium delays the impairment of the coral-dinoflagellate symbiosis during labile carbon pollution

Labile dissolved organic carbon (DOC) is a major pollutant in coastal marine environments affected by anthropogenic impacts, and may significantly con…

www.sciencedirect.com

Excess labile carbon promotes the expression of virulence factors in coral reef bacterioplankton

Excess labile carbon promotes the expression of virulence factors in coral reef bacterioplankton - The ISME Journal

Coastal pollution and algal cover are increasing on many coral reefs, resulting in higher dissolved organic carbon (DOC) concentrations. High DOC concentrations strongly affect microbial activity in reef waters and select for copiotrophic, often potentially virulent microbial populations. High...

www.nature.com

Unseen players shape benthic competition on coral reefs.

Unseen players shape benthic competition on coral reefs - PubMed

Recent work has shown that hydrophilic and hydrophobic organic matter (OM) from algae disrupts the function of the coral holobiont and promotes the invasion of opportunistic pathogens, leading to coral morbidity and mortality. Here we refer to these dynamics as the (3)DAM [dissolved organic...

www.ncbi.nlm.nih.gov

Macroalgae decrease growth and alter microbial community structure of the reef-building coral, Porites astreoides.

Macroalgae decrease growth and alter microbial community structure of the reef-building coral, Porites astreoides - PubMed

With the continued and unprecedented decline of coral reefs worldwide, evaluating the factors that contribute to coral demise is of critical importance. As coral cover declines, macroalgae are becoming more common on tropical reefs. Interactions between these macroalgae and corals may alter the...

www.ncbi.nlm.nih.gov

Macroalgal extracts induce bacterial assemblage shifts and sublethal tissue stress in Caribbean corals.

Macroalgal extracts induce bacterial assemblage shifts and sublethal tissue stress in Caribbean corals - PubMed

Benthic macroalgae can be abundant on present-day coral reefs, especially where rates of herbivory are low and/or dissolved nutrients are high. This study investigated the impact of macroalgal extracts on both coral-associated bacterial assemblages and sublethal stress response of corals. Crude...

www.ncbi.nlm.nih.gov

Biophysical and physiological processes causing oxygen loss from coral reefs.

https://elifesciences.org/articles/49114.pdf

Global microbialization of coral reefs
DDAM Proven

Global microbialization of coral reefs - Nature Microbiology

Analysis of 60 sites in three ocean basins suggests that overgrowth of fleshy algae on coral reefs supports higher microbial abundances dominated by copiotrophic, potentially pathogenic bacteria via the provision of dissolved inorganic carbon.

www.nature.com

Coral Reef Microorganisms in a Changing Climate, Fig 3

Coral Reef Microorganisms in a Changing Climate

Coral reefs are one of the most diverse and productive ecosystems on the planet, yet they have suffered tremendous losses due to anthropogenic disturbances and are predicted to be one of the most adversely affected habitats under future climate change ...

www.ncbi.nlm.nih.gov

Ecosystem Microbiology of Coral Reefs: Linking Genomic, Metabolomic, and Biogeochemical Dynamics from Animal Symbioses to Reefscape Processes

https://msystems.asm.org/content/msys/3/2/e00162-17.full.pdf