An Attempt to Generate Benthic Biofilm for Substrate Feeders

[livinlifeinBKK]

It's a little late here so I haven't read all the links you sent me (thanks btw!)...further reading mentioned Fromia indica stars feeding on encrusting sponges (which is what I had suspected due to my observations)...my mind is a little foggy right now but I feel a little discouraged right now if he needs encrusting sponge species or colonial organisms...that seems like it would be particularly difficult to get very reliably...I guess I'll have to continue even more research to see if I can solve this issue...
@Timfish

 

[livinlifeinBKK]

@Timfish hey, does it sound plausible that maybe instead of needing to eat the microbes in the biofilm, what the star really needs is just the EPS secreted by the biofilm for the polysaccharides and other compounds?

 

[Breadbox]

Maybe you can try setting up different systems, dose a ton of Bacter AE in some of them and not the others and see how the stars do. the product supposedly promote the proliferation of biofilms(tho I suspect they get consumed directly most of the time).

 

[taricha]

@Timfish hey, does it sound plausible that maybe instead of needing to eat the microbes in the biofilm, what the star really needs is just the EPS secreted by the biofilm for the polysaccharides and other compounds?

not likely. EPS is everywhere in biofilms, but if that were what's needed by the starfish, people wouldn't have such difficulty with their longer term survival.

 

[Timfish]

@Timfish hey, does it sound plausible that maybe instead of needing to eat the microbes in the biofilm, what the star really needs is just the EPS secreted by the biofilm for the polysaccharides and other compounds?

It' seems pretty obvious from what I've seen Linkia and Fromia species starfish are not able to get enough to eat to stay healthy. I've seen very different sponge populations in systems I've maintianed the same way and I've seen the species of sponge change over time. Research shows biofilms age and change over time. It seems reasonable to me biofilms and/or sponges may be playing a role in the survival or death of these animals. But I have to emphasize at this point it's just guesswork as to what extent biofilms or sponges actually play a role. As to actually demonstrating they do or don't is likely going to be very tedious and time consuming. I'd start by networking with researchers already working with marine biofilms or echnoderms (has someone actually looked at their stomack contents?) so they can help you set up the expeirements needed to identify what these animals feed on.

 

[taricha]

Considering the fact that you do not know the actual choice food of this starfish, and it's likely that nobody else does either, you might take the approach of delivering live phyto to the system, to increase the nutrition of the organisms that colonize the rock etc, since you know that's where the starfish grazes for food.
Live phyto will cast a very wide net of organisms that it will grow and support: sponges, tunicate, fan worms, tube snails, pods, small bivalves, other filter feeders etc.
It's a similar principle to feeding amino acids and organic carbon, but you can likely deliver more nutrition to the surfaces with phyto cells than you can with the amount of amino and organic carbon that it's practical to put in a tank.
T-iso can be finicky, but it's one of the best phytos for difficult fish breeding, which is basically the same problem you are trying to solve. Delivery of nutrients to a target through multiple intermediate organisms.

(but I'd do a search first and see if this has been tried before I started a live phyto culture.)

 

[livinlifeinBKK]

It' seems pretty obvious from what I've seen Linkia and Fromia species starfish are not able to get enough to eat to stay healthy. I've seen very different sponge populations in systems I've maintianed the same way and I've seen the species of sponge change over time. Research shows biofilms age and change over time. It seems reasonable to me biofilms and/or sponges may be playing a role in the survival or death of these animals. But I have to emphasize at this point it's just guesswork as to what extent biofilms or sponges actually play a role. As to actually demonstrating they do or don't is likely going to be very tedious and time consuming. I'd start by networking with researchers already working with marine biofilms or echnoderms (has someone actually looked at their stomack contents?) so they can help you set up the expeirements needed to identify what these animals feed on.

There are a few books that dive pretty deep into echinoderm biology that I've been reading through and I think I'll try to contact some of the researchers and authors to see if maybe they have some theories as to what might be restricting long term success in captivity... I was thinking that possibly their natural diet is important because starfish lack any type of specialized excretory organ for waste removal. The waste generated from digestion is primarily ammonia which has to be passed into the coelomic fluid and diffused through the body wall somehow. A theory that I see as plausible is that the bacteria and other microorganisms consumed aid in nitrogen transformations that the starfish can't otherwise carry out inside it's body to detoxify the ammonia. This would make sense since many of the microorganisms we think they're consuming naturally have this capability and sponges also contain nitrogen transforming prokaryotes...maybe instead of slowly starving to death, they're slowly being poisoned over time if they don't consume enough of these microorganisms with other foods. Since many species feed extraorally like Linckias and Fromias they might have trouble retaining these microorganisms although the ammonia would be retained in their bodies until it had time to slowly diffuse out over time.

 

[livinlifeinBKK]

Considering the fact that you do not know the actual choice food of this starfish, and it's likely that nobody else does either, you might take the approach of delivering live phyto to the system, to increase the nutrition of the organisms that colonize the rock etc, since you know that's where the starfish grazes for food.
Live phyto will cast a very wide net of organisms that it will grow and support: sponges, tunicate, fan worms, tube snails, pods, small bivalves, other filter feeders etc.
It's a similar principle to feeding amino acids and organic carbon, but you can likely deliver more nutrition to the surfaces with phyto cells than you can with the amount of amino and organic carbon that it's practical to put in a tank.
T-iso can be finicky, but it's one of the best phytos for difficult fish breeding, which is basically the same problem you are trying to solve. Delivery of nutrients to a target through multiple intermediate organisms.

(but I'd do a search first and see if this has been tried before I started a live phyto culture.)

I think that's a good idea and I actually do feed live phyto to the tank regularly! I think adding live phyto is probably one of the most beneficial things i can be doing especially considering the fact that I have filter feeders as well.

 

[Timfish]

There are a few books that dive pretty deep into echinoderm biology that I've been reading through and I think I'll try to contact some of the researchers and authors to see if maybe they have some theories as to what might be restricting long term success in captivity... I was thinking that possibly their natural diet is important because starfish lack any type of specialized excretory organ for waste removal. The waste generated from digestion is primarily ammonia which has to be passed into the coelomic fluid and diffused through the body wall somehow. A theory that I see as plausible is that the bacteria and other microorganisms consumed aid in nitrogen transformations that the starfish can't otherwise carry out inside it's body to detoxify the ammonia. This would make sense since many of the microorganisms we think they're consuming naturally have this capability and sponges also contain nitrogen transforming prokaryotes...maybe instead of slowly starving to death, they're slowly being poisoned over time if they don't consume enough of these microorganisms with other foods. Since many species feed extraorally like Linckias and Fromias they might have trouble retaining these microorganisms although the ammonia would be retained in their bodies until it had time to slowly diffuse out over time.

Interesting! I'm inclined to think ammonia would be something that kills quickly though. Gotta love this hobby, there's always a lot of stuff to learn. Google Scholar can be a useful tool if you're not familiar with it.

 

[livinlifeinBKK]

Interesting! I'm inclined to think ammonia would be something that kills quickly though. Gotta love this hobby, there's always a lot of stuff to learn. Google Scholar can be a useful tool if you're not familiar with it.

I'm just trying to think from different angles and maybe something will click...and ikr, this hobby never ceases to amaze me! I've been using Google Scholar and have found it to be very useful along with the few books I've found online on Echinoderm biology...I like to use their references to give me leads as to where to look next. I'm also thankful for a resource like this one where I can share ideas and thoughts with people like you who share an interest in topics like these!

 

[livinlifeinBKK]

@Timfish btw, you mentioned buying a dozen Fromia stars and placing them in different systems and they all died around the six month mark...do you remember how they looked physically when they died? Also what were the systems like? Did you spot feed them at all? Sorry for all the questions but this seems like an experience that could hold a lot of answers...

 

[Timfish]

@Timfish btw, you mentioned buying a dozen Fromia stars and placing them in different systems and they all died around the six month mark...do you remember how they looked physically when they died? Also what were the systems like? Did you spot feed them at all? Sorry for all the questions but this seems like an experience that could hold a lot of answers...

No worries! They went into different clients systems. The majority had just simple sumps without skimmers or reactors, however one went into the sump/refugiumless system with the linkia mentioned above and one did go into a system with a calcium reactor and skimmer. Since the systems are only maintained weekly in some cases the Fromia were badly decomposed and one or two were never found but last seen in the time span the others died. As feeding is primarily pellets in autofeeders none of the Fromia or Linkia mentioned above were target fed.

 

[livinlifeinBKK]

No worries! They went into different clients systems. The majority had just simple sumps without skimmers or reactors, however one went into the sump/refugiumless system with the linkia mentioned above and one did go into a system with a calcium reactor and skimmer. Since the systems are only maintained weekly in some cases the Fromia were badly decomposed and one or two were never found but last seen in the time span the others died. As feeding is primarily pellets in autofeeders none of the Fromia or Linkia mentioned above were target fed.

The way most stars typically just disintegrate and fall apart in aquariums is also typical of Sea Star Wasting Disease which has occured in epidemic proportions in recent years. Some recent studies show that symptoms and progression of SSWD can be exacerbated and possibly caused by high nutrient levels in the water column which promotes high bacterial growth and can lead to slightly lowered oxygen levels. These slightly lower oxygen levels are thought to make oxygen exchange difficult for starfish even though it's only a slight difference. Perhaps not using a skimmer or airstone contributed to ill health? I noticed the system with the Linckia that lived so long was pretty basic but did make use of an airstone which may have helped it along with the large system able to supply more natural food... just another thought but since we already know they can be really sensitive to parameter changes maybe they're particularly sensitive to oxygen levels as well and efforts to feed them by increasing biofilm growth through increasing nutrient levels can actually lead to a sort of slow suffocation (supported by studies of SSWD causes) and variations between time until mortality among different species could be a function of varying rates of respiration. Spot feeding (which to my knowledge isn't a common practice) might actually be the best way of ensuring adequate food intake, although I'm still inclined to believe that biofilms and sponges might be important for some biological function since they likely make up such a large portion of the natural diet of Fromias and some other species.

 

[livinlifeinBKK]

I'm pretty far down the starfish rabbit hole by now if that's not already obvious! Even if it does turn out to be impractical to keep most stars I'd still like to figure out what the issue is and would love to come up with some solution!

 

[ISpeakForTheSeas]

The way most stars typically just disintegrate and fall apart in aquariums is also typical of Sea Star Wasting Disease which has occured in epidemic proportions in recent years. Some recent studies show that symptoms and progression of SSWD can be exacerbated and possibly caused by high nutrient levels in the water column which promotes high bacterial growth and can lead to slightly lowered oxygen levels. These slightly lower oxygen levels are thought to make oxygen exchange difficult for starfish even though it's only a slight difference. Perhaps not using a skimmer or airstone contributed to ill health? I noticed the system with the Linckia that lived so long was pretty basic but did make use of an airstone which may have helped it along with the large system able to supply more natural food... just another thought but since we already know they can be really sensitive to parameter changes maybe they're particularly sensitive to oxygen levels as well and efforts to feed them by increasing biofilm growth through increasing nutrient levels can actually lead to a sort of slow suffocation (supported by studies of SSWD causes). Spot feeding (which to my knowledge isn't a common practice) might actually be the best way of ensuring adequate food intake, although I'm still inclined to believe that biofilms and sponges might be important for some biological function since they likely make up such a large portion of the natural diet of Fromias and some other species.

From what I’ve seen when researching SSWD (articles from 2021), it seems like it’s specific bacterias that end up basically coating the starfish’s body (they basically breathe through their skin, and the bacteria forms a biofilm on the skin) and absorbing the oxygen that should be reaching the star. The high nutrients play a role in that the bacterias which form the killer biofilm are copiotrophic, and so prefer/grow faster at higher nutrient levels, but the lack of oxygen is what actually damages the star (see the quote from the link below). So, keeping the oxygen level high in the water, trying to keep nutrients low, and possibly keeping the water temp a little colder are all things that could help prevent wasting. Unfortunately, this all goes pretty much directly against enabling good biofilm formation, so it might just be best to aim for higher oxygen levels in the starfish display tank, and growing the biofilms in another tank. Just the higher oxygen might be able to keep the star alive, but I’m not sure. Also, something that might be of interest to you, Point Defiance Zoo and Aquarium got hit with SSWD a few years ago and lost about half of their stars, but they were able to successfully treat the others with antibiotics - they don’t say which antibiotics though).

Frontiers | Evidence That Microorganisms at the Animal-Water Interface Drive Sea Star Wasting Disease

Sea star wasting (SSW) disease describes a condition affecting asteroids that resulted in significant Northeastern Pacific population decline following a mas...

www.frontiersin.org

“SSW was also induced by modestly (∼39%) depleted O2 conditions in aquaria, suggesting that small perturbations in dissolved O2 may exacerbate the condition.”

 

[livinlifeinBKK]

From what I’ve seen when researching SSWD (articles from 2021), it seems like it’s specific bacterias that end up basically coating the starfish’s body (they basically breathe through their skin, and the bacteria forms a biofilm on the skin) and absorbing the oxygen that should be reaching the star. The high nutrients play a role in that the bacterias which form the killer biofilm are copiotrophic, and so prefer/grow faster at higher nutrient levels, but the lack of oxygen is what actually damages the star (see the quote from the link below). So, keeping the oxygen level high in the water, trying to keep nutrients low, and possibly keeping the water temp a little colder are all things that could help prevent wasting. Unfortunately, this all goes pretty much directly against enabling good biofilm formation, so it might just be best to aim for higher oxygen levels in the starfish display tank, and growing the biofilms in another tank. Just the higher oxygen might be able to keep the star alive, but I’m not sure. Also, something that might be of interest to you, Point Defiance Zoo and Aquarium got hit with SSWD a few years ago and lost about half of their stars, but they were able to successfully treat the others with antibiotics - they don’t say which antibiotics though).

Frontiers | Evidence That Microorganisms at the Animal-Water Interface Drive Sea Star Wasting Disease

Sea star wasting (SSW) disease describes a condition affecting asteroids that resulted in significant Northeastern Pacific population decline following a mas...

www.frontiersin.org

“SSW was also induced by modestly (∼39%) depleted O2 conditions in aquaria, suggesting that small perturbations in dissolved O2 may exacerbate the condition.”

This is actually the exact study I've been reading from! I actually started running an airstone in my tank last week after reading through it and I agree that it might be better to grow the biofilms in another tank (in my other thread I was planning on growing Biofilm on pieces of glass filter paper which could easily be transferred)

 

[livinlifeinBKK]

@ISpeakForTheSeas btw, what do you think the issue might be with keeping stars? Do you think they're just starving?

 

[ISpeakForTheSeas]

@ISpeakForTheSeas btw, what do you think the issue might be with keeping stars? Do you think they're just starving?

If I had to guess (a shot in the dark with no current supporting basis), I’d say that, in a way, yes, they probably are starving.

The caveats to that are, as you mentioned in a couple of your other posts, 1 ) the way they die in aquariums seems very similar to SSWD, and 2 ) stars naturally produce substances to prevent microfouling organisms (such as biofilm forming bacterias) from colonizing their surface. My current guess is that the bacteria normally responsible for SSWD is one that naturally has an easier time penetrating the star’s chemical defenses than other bacteria, which is why we see it happen in nature to otherwise healthy stars, but stars in aquariums having less than ideal diets would eventually see a decline in their antimicrobial defenses, which likely enables other, less potent bacterias to colonize them in the same, lethal manner.

So, basically, my current guess (subject to change with new information) is that stars in aquariums - due to imperfect diet - are eventually weakened to the point that their body can no longer fend off bacterial colonization, and that bacterial colony slowly suffocates them. Essentially, a slow starvation (nutritionally, not necessarily quantity wise) leading to a weakened immune response, leading to an opportunistic infection, leading to death.

This guess could be wrong (and if anyone has refuting evidence, I will gladly accept it), but currently that seems to me to be the most plausible explanation I can think of for why the stars are able to hold on for months seemingly fine only to die in a matter of days. It could also be related to some unknown condition of our aquariums, but this seems like a decent explanation to explore for now, as it would seem to explain why some people with large tanks can keep stars long term when others can’t (different bacterias and quantities of bacteria for the stars to feed on) and why the “West African Biscuit Star” (discussed in another thread) which apparently feeds primarily on algae can be kept long term when most other stars can’t.*

*Just as note here for anyone wondering why we can then keep brittle stars and serpent stars and Aquilonastra (“Asterina”) stars, my guess is Aquilonastra stars (being so small) need very little food to maintain good health and can reach food in places other stars can’t, and brittle and serpent stars (being from a different taxonomic class) have different dietary needs. Plus, for one reason or another, they don’t seem to be effected by SSWD, so they likely don’t need to maintain as good of health to stay alive. Just my guesses.

 

[livinlifeinBKK]

If I had to guess (a shot in the dark with no current supporting basis), I’d say that, in a way, yes, they probably are starving.

The caveats to that are, as you mentioned in a couple of your other posts, 1 ) the way they die in aquariums seems very similar to SSWD, and 2 ) stars naturally produce substances to prevent microfouling organisms (such as biofilm forming bacterias) from colonizing their surface. My current guess is that the bacteria normally responsible for SSWD is one that naturally has an easier time penetrating the star’s chemical defenses than other bacteria, which is why we see it happen in nature to otherwise healthy stars, but stars in aquariums having less than ideal diets would eventually see a decline in their antimicrobial defenses, which likely enables other, less potent bacterias to colonize them in the same, lethal manner.

So, basically, my current guess (subject to change with new information) is that stars in aquariums - due to imperfect diet - are eventually weakened to the point that their body can no longer fend off bacterial colonization, and that bacterial colony slowly suffocates them. Essentially, a slow starvation (nutritionally, not necessarily quantity wise) leading to a weakened immune response, leading to an opportunistic infection, leading to death.

This guess could be wrong (and if anyone has refuting evidence, I will gladly accept it), but currently that seems to me to be the most plausible explanation I can think of for why the stars are able to hold on for months seemingly fine only to die in a matter of days. It could also be related to some unknown condition of our aquariums, but this seems like a decent explanation to explore for now, as it would seem to explain why some people with large tanks can keep stars long term when others can’t (different bacterias and quantities of bacteria for the stars to feed on) and why the “West African Biscuit Star” (discussed in another thread) which apparently feeds primarily on algae can be kept long term when most other stars can’t.*

*Just as note here for anyone wondering why we can then keep brittle stars and serpent stars and Aquilonastra (“Asterina”) stars, my guess is Aquilonastra stars (being so small) need very little food to maintain good health and can reach food in places other stars can’t, and brittle and serpent stars (being from a different taxonomic class) have different dietary needs. Plus, for one reason or another, they don’t seem to be effected by SSWD, so they likely don’t need to maintain as good of health to stay alive. Just my guesses.

That certainly sounds plausible...I just wonder to what extent spot feeding could help since it's generally accepted that most stars are generalist feeders...as I mentioned before though I would certainly suspect that since it seems biofilms and foods like encrusting sponges make up most of some stars wild diets some biological functions likely rely on those food sources for proper health and/or their internal microbiome might be negatively disrupted by too dramatic a change in diet which might weaken their immune system. I also wonder if a balance between natural food production and adequate oxygenation can be reached in a smaller tank. I have a feeling it's possible but it's gonna take plenty more research and experimentation to find out these answers...

 

[ISpeakForTheSeas]

That certainly sounds plausible...I just wonder to what extent spot feeding could help since it's generally accepted that most stars are generalist feeders...as I mentioned before though I would certainly suspect that since it seems biofilms and foods like encrusting sponges make up most of some stars wild diets some biological functions likely rely on those food sources for proper health and/or their internal microbiome might be negatively disrupted by too dramatic a change in diet which might weaken their immune system. I also wonder if a balance between natural food production and adequate oxygenation can be reached in a smaller tank. I have a feeling it's possible but it's gonna take plenty more research and experimentation to find out these answers...

With the spot feeding, the easiest way I can think to test this would be with multiple identical aquarium setups and multiple stars of the same size and species (preferably collected from the same area at the same time). Have a control with no supplemental feeding, and the test group with supplemental feedings. If the difference in lifespan ends up being statistically significant (even by just a month or two), the feedings make a difference, if not, they don't. Unfortunately, such a study would be pretty expensive and time consuming, and there may be some ethical issues involved too due to the risk to the stars. Plus, if the lifespan was not drastically increased or decreased, it wouldn't necessarily help explain why the feedings would make a difference.

Some other kind of interruption to the microbiome/chemical defenses of the star is possible, I'm just not sure what that interruption would be.

I'm sure a balance can be worked out (though the amount of effort necessary to figure out that balance could potentially be enormous), but I don't know if it would be able to provide enough food for a star without some severe hands-on intervention (something like rotational grazing for sheep and cattle). Additionally, I don't know if it would be plausible for a mixed species tank in smaller sizes - in other words, the setup may need to be a species specific tank to accommodate the star's diet. This would be an interesting one to find out for certain on in the future though. Something that has been coming up on the forum lately that might be of interest/use to you for providing more oxygen to the tank is the Venturi Injector concept. Supposedly (I need to do some research on this, but this is what has been stated in the threads), venturi injectors can add more oxygen (or really just more atmospheric air) to the tank than normal methods (water movement via pumps, skimmers, air stones, etc.). I can't vouch for the accuracy of that state at this point, but it might be worth looking into.