How bad is this yellow stuff ? Should I remove it?

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Hello so I flipped a rock in my sump and uncovered all this what I think is yellow sponge. I realize as I move more rocks most is covered like this. I have never seen so much before. After doing quick search here Ive read that yellow sponge can be toxic depending on how much and possibly if it’s disturbed. This rock has been in sump for about 8 years with this stuff growing. And I obviously have a lot of it now. I have a lot of corals in this system easily 80 sps frags and 50 lps along with many colonys so worried if the toxins have been causing me issues. I’ve not been as successful as I would like or expected with my setup so been thinking are these toxins holding me back. Anyways would love to hear what others think.
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Sponge is a sign of a healthy established system. If it really worries you, send an ICP. :-) Or send it all to me and I will take care of it right into my sump.
 
A brief response - It’s possible the sponges are causing issues if you have enough of them and/or if they happen to produce anti-coral toxins. Given that cryptic sponges like this generally don’t compete for space against corals, I’d guess (but can’t say for certain) that your sponges here are not highly toxic to corals. If you have enough sponge, it’s possible that you’d see the microbial sponge loop in action and see your tank switch from bacteria that favors corals to bacteria that favors algae, but I don’t think you have enough sponge to cause that based on your photo there. So, all that said, my guess is that your sponge is harmless/beneficial rather than harmful.

The super long response:
Microbial loop info (the longest quote in my response - the only caveat I have to add here is discussed in the last quote below, but it’s that some research now suggests that at least some sponges, if not most/all, process DOC the same whether it’s from corals or algae, but they process DON differently - this may or may not be the case for multiple sponges, and if it is the case, then the incorrect info may have at least partially appeared as a result of DOC being used interchangeably with DOM when DOC is in fact a component of DOM; DOC = Dissolved Organic Carbon, DON = Dissolved Organic Nitrogen, DOM = Dissolved Organic Matter)
Sponges process the DOC released by algae differently than they process the DOC released by corals. Researchers have documented a feedback loop where sponges feed off the algal DOC and release nutrients into the water that promote algae growth which releases more DOC to feed sponges . . . The algal DOC also promotes heterotrophic microbial processes which can cause anoxic conditions around corals negatively affecting them as well as potentially promoting pathogenic shifts in coral microbiomes. So algae is getting a boost from the sponges and reduced competition from corals promoting a phase shift to a sponge and algae dominate system.

If PO4 drops below .03 mg/l corals can be negatively affected. Research done at SOuthampton Unicversity in England with corals maintained in a reef ssytem for over a decade showed a nitrogen/phosphorus imbalance causes phosphorus deficiency and can have very serious consiquences for corals potentially killing them. Depending on the nitrate levels the minimum PO4 needed to prevent a phosphate deficiency can be much higher. The .03 mg/l was the minimum level the researchers identified.

I get critisized for posting research but here's a data bomb anyway:

"Coral Reefs in the Microbial Seas" This video compliments Rohwer's book of the same title (Paper back is ~$20, Kindle is ~$10), both deal with the conflicting roles of the different types of DOC in reef ecosystems. While there is overlap bewteen his book and the video both have information not covered by the other and together give a broader view of the complex relationships found in reef ecosystems

Changing Seas - Mysterious Microbes

Nitrogen cycling in hte coral holobiont

BActeria and Sponges

Maintenance of Coral Reef Health (refferences at the end)

Optical Feedback Loop in Colorful Coral Bleaching

Richard Ross What's up with phosphate"

DOC and microbial links:

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

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

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

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

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.

Visualization of oxygen distribution patterns caused by coral and algae

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.

Microbial ecology: Algae feed a shift on coral reefs

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

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

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)

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

Unseen players shape benthic competition on coral reefs.

Allelochemicals Produced by Brown Macroalgae of the Lobophora Genus Are Active against Coral Larvae and Associated Bacteria, Supporting Pathogenic Shifts to Vibrio Dominance.

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

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

Biophysical and physiological processes causing oxygen loss from coral reefs.

Global microbialization of coral reefs
DDAM Proven

Coral Reef Microorganisms in a Changing Climate, Fig 3

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

Sponge stuff

Element cycling on tropical coral reefs.
This is Jasper de Geoij's ground breaking research on reef sponge finding some species process labile DOC 1000X faster than bacterioplankton. (The introduction is in Dutch but the content is in English.)

Sponge symbionts and the marine P cycle

Phosphorus sequestration in the form of polyphosphate by microbial symbionts in marine sponges

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

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

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.

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

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

Sponge symbionts and the marine P cycle

Phosphorus sequestration in the form of polyphosphate by microbial symbionts in marine sponges

And since we're discussing favorable and not so favorable bacteria here's a paper looking at how different corals and polyps are influencing the bacteria in the water column.
Aura-biomes are present in the water layer above coral reef benthic macro-organisms

de Angelo and Wiedenmann's research at Southampton University

An Experimental Mesocosm for Longterm Studies of Reef Corals

Phosphate Deficiency:
Nutrient enrichment can increase the susceptibility of reef corals to bleaching:

Ultrastructural Biomarkers in Symbiotic Algae Reflect the Availability of Dissolved Inorganic Nutrients and Particulate Food to the Reef Coral Holobiont:

Phosphate deficiency promotes coral bleaching and is reflected by the ultrastructure of symbiotic dinoflagellates

Nitrogen and phosphorus stuff

Effects of phosphate on growth and skeletal density in the scleractinian coral Acropora muricata: A controlled experimental approach

High phosphate uptake requirements of the scleractinian coral Stylophora pistillata

Phosphorus metabolism of reef organisms with algal symbionts


Ammonium Uptake by Symbiotic and Aposymbiotic Reef Corals

Amino acids a source of nitrogen for corals

Urea a source of nitrogen for corals

Diazotrpophs a source of nitrogen for corals

Context Dependant Effects of Nutrient Loading on the Coral-Algal Mutualism

And a couple of jpg's

Fig 4 from "Phosphorus Metabolism of Reef Organisms with Algal Symbionts"
DIP DOP POP.jpg

Fig. 3 from "Context Dependant Nutrient Loading on the Coral-Algal Mutualism"
Context‐dependent effects of nutrient loading on the coral–algal mutualism(1).png
Sponge toxin info:
To preface this, I’m not an expert - I’ve been doing a lot of reading up sponges, but I’m not an expert. So, with that out of the way, I know this is vague and somewhat unhelpful, but it depends on the sponge.

Some sponges are highly toxic, some moderately toxic, some mildly toxic, and some not toxic at all. Generally speaking though, sponges produce toxins to avoid predation and/or parasites, or (like some corals) as a form of chemical warfare to compete for territory. With these toxins, some of them are specifically anti-fish, some anti-echinoderm, some anti-parasite, some anti-coral, etc. As I understand it, some of these toxins are deadly to other marine species, and some just make the sponge taste bad or be less preferred by predators.

To address your actual questions now, though, some sponges constantly put out toxins (I know this one has been demonstrated), I’ve heard but can’t at this moment confirm that some might only put out toxins if disturbed/threatened (as you suggested in your post) and some might only be toxic if eaten (this one I find highly likely, but, again, I can’t confirm it at present), and - as mentioned above - some species aren’t toxic at all, so they don’t put out toxins period.

Whether or not a sponge’s toxins are harmful to fish, corals, etc. is - as I hinted at above - dependent on the toxins produced by the sponge and the quantity produced. To give an idea here, sea cucumber toxins (known as holothurin) are ichthyotoxins, meaning they are primarily toxic to fish. So, if a sea cucumber releases their toxins into a tank at a low dose, the fish in the tank will likely suffer (and possibly die) even though the amount of toxin is small, but other inhabitants will likely be unaffected. At a high dosage, however, these other inhabitants may suffer (and/or die) as well.

So, if a sponge produces fish or coral specific toxins, those may suffer or die even if the amount of toxin produced is small. Similarly, if the toxin produced is not a coral or fish specific toxin but the sponge produces a large amount of it, those might still suffer or die regardless.

I’ve never heard of a fish dying from just swimming by a toxic sponge (I’ve only heard of fish dying from eating highly toxic sponges in a laboratory, force-feeding setting at the moment), so I would assume that sponge toxicity is not a big concern under normal circumstances. If you happen to have a highly toxic (either in potency or quantity) sponge that is not being eaten, however, I suppose it’s possible it could pose some health concerns for your tank’s inhabitants, particularly if you don’t do regular water changes or run carbon.

Now, all of that said, I would guess that, in most circumstances, sponges in our tanks are probably either mildly toxic (probably edible but not preferred as a food) or only seriously toxic when consumed (and most tank inhabitants, being chemically sensitive, would likely know better than to eat highly toxic sponges). So, I would guess that in the overwhelming majority of cases, the sponges in our tanks are essentially perfectly reef safe and harmless (though, much like many soft corals, I suspect they would engage in manageable levels of chemical warfare for space in the tank - in that regard I guess you could argue that they are detrimental to corals). This is just a guess, but - like WheatToast - I’ve never heard of a sponge’s toxins causing issues in a tank.

Also, for anyone who’s interested, only a handful of sponges are really considered toxic to humans - they basically give an itchy, painful, swollen rash when touched (contact dermatitis), usually a few hours to days after the contact is made.
General sponge info:
The info I’ve compiled on sponges so far:

Most sponges that I’ve looked into primarily consume Dissolved Organic Matter (DOM - sometimes called Dissolved Organic Carbon, or DOC, which is actually a component of DOM) and specific kinds of bacteria (which kinds vary at least a little from one sponge to another). Most of them seem to have no preference for where their DOC comes from, but they have a preference for algal-derived Dissolved Organic Nitrogen (i.e. DON produced by algae). Giant Barrel Sponges and some Boring Sponges have had their diets analyzed, and they primarily consume DOM (~80% of their total diet, with the remaining ~20% coming from Particulate Organic Matter (POM - primarily phytoplankton and bacteria, though, as mentioned above, bacteria is taken in much higher quantities than phyto). This ratio of approximately 80/20 seems to be pretty typical(though it can vary from what I've seen by +/-15% or so one way or another) for most sponges from what I can find.

Unfortunately, we don’t have an easy, hobbyist way to measure DOM, DOC, DON, or POM (or POC or PON) that I’m aware of, so we don't really have any way to determine if the sponges are getting enough food consistently to thrive (to say nothing of measuring the amounts of specific bacteria in our tanks), but there you have it.

If you do some reading on sponge keeping here on R2R, you'll probably find pretty quickly that most people recommend low lighting low flow for sponges (exceptions for photosynthetic sponges), but the truth is this also depends on the sponge species. The most common photosynthetic sponges in the hobby are the photosynthetic plating sponges (like you can find/buy on LiveAquaria's site), but there are quite a few other sponges that are photosynthetic too (such as Aplysina cauliformis, for example), and these would benefit from high lighting. Similarly, some species of sponge do best in very high flow areas, including high flow areas with laminar flow (a lot of people talk about random flow on the site, which would be called turbulent flow, as they're trying to get the water moving basically randomly throughout the tank - laminar flow is just a continuous flow that doesn't change, so the water keeps going the same direction nonstop and there's nothing random about it). If you're not sure if the sponge is photosynthetic or not, you can try starting it in one lighting (such as low lighting), see how it does and then compare it to a different lighting (moderate or high) and figure out its needs from that. Same with the flow. Light will probably be the most important part for photosynthetic species and the food/flow the most important for NPS species - some people have found stirring up their sand to be an effective food source for sponges, likely because it puts bacteria and DOM into the water column. It’s probably safest to start low light/flow and move up, rather than starting high and moving lower.

Some sponges do well in some tanks but not in others for no discernible reason, and some some sponges travel well while other sponges don't. Plus, sometimes a sponge will basically disintegrate into a ton of tiny pieces and look like it's dying, but it'll then proceed to grow and live on afterwards. Similarly, some sponges grow invasively while others grow incredibly slowly, so a lot of keeping these guys at this point really just depends on the luck of the draw (so to speak).
 
Why does the quick search I do here show some people saying yellow sponge releases toxins?
Many Marine Sponges are well known source of various Bioactive Compounds ( antiviral, anti-fungal, cytotoxic) and are actively studied by various pharmaceutical firms. I am not sure if those are yellow sponges in particular. I have a feeling ( not a scientific prove) that sponges may become toxic when either ingested or when they die. Most of reef aquarists find sponges as beneficial organisms.
 
Why does the quick search I do here show some people saying yellow sponge releases toxins?
Probably because people have heard that most sponges produce toxins and interpreted that to mean that most of them are dangerous/deadly. In reality, most sessile (stationary) creatures in the ocean produce toxins - corals included. The important thing for sponge toxicity as it relates to this conversation though is that many toxins are only harmful in huge quantities or to specific organisms.

Think of it like the allelopathy (chemical warfare) of soft corals like leathers; they produce different chemicals to try and protect themselves/allow themselves room to grow unharmed. These chemicals save them from being eaten/grown over, and may push other corals competing for room on the reef back so the leather can grow some more. Some of the chemicals they produce may harm/be detrimental to other corals/organisms in the tank as part of that competing process. In large enough quantities, some of these chemicals may be considered toxins that could kill another coral. That said, personally, I've never heard of a leather coral nuking a tank, so these mild toxins are not really an issue.

It's the same thing with sponges - they produce chemicals (toxins) to defend themselves and to allow themselves room to spread on the reef. Sometimes these toxins are potent (like the ichthyotoxins of the Loggerhead Sponge, Spheciospongia vesparium, which sponge is still sometimes consumed by angelfish), and sometimes they're mild. How potent the toxin is and how much toxin is produced varies from one species of sponge to the next, but - generally speaking - the only time a sponge toxin is an issue in our tanks is when it allows the sponge to outcompete the corals (as demonstrated by the sponge growing over the coral and smothering it - showing that the chemical defenses of the corals were outcompeted by the chemical defenses of the sponge). So, basically, the toxic sponges we care about in our tanks are usually the ones that are invasively smothering corals, as the other toxic sponges don't really cause any problems.

As a final note here, there are a huge number of yellow sponge species out there -some (like the Loggerhead Sponge mentioned above) are highly toxic, and some are totally harmless. So it's technically possible that some random species of yellow sponge produces and releases enough toxin into the water around it that it could cause problems in our tanks, but it's also extremely unlikely.

TLDR; if it can't move and it lives in the ocean, it's probably toxic to one degree or another. Most of these toxic things (like corals and most sponges) are actually harmless though.
 
Sorry to revive an old thread but I cant help but asking - Did you ever remove this sponge? And were there any perceivable changes in the tank if so?
 

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