Bacteria relationship with coral.

[Flippers4pups]

This is the new frontier, in my mind's eye for all of us who keep reef tanks.

Microbial studies, in-depth studies are needed to fully understand coral health and their complete relationship at this level.

Good read:

https://cosmosmagazine.com/biology/barrier-reef-not-dying-but-changing-says-leading-scientist

 

[Flippers4pups]

@Diesel, @Dana Riddle, aside of the global warming issues, what's your take on the article I posted?

 

[Diesel]

IMO there isn't enough evidence that corals can suffer from bacteria deceases, yet I know of studies that acro's can have some kind of bacteria issues.
Let me see if I can find that write up.

 

[Dana Riddle]

It has always been my opinion that we simply don't understand the dynamics of mutualism and symbioses seen on (and in) coral reefs. My favorite reference on the subject - the discovery of Symbiodinium thermophilum, a symbiont of corals in the Arabian Sea where seawater temperatures are among the highest known. Corals containing these zoox are tolerant of these temps. An interesting point - the Arabian Sea is only a few thousand years old yet corals have adapted and thrive. How this adaptation was achieved is unknown to me (but it is known that this zoox clade differs very little from the common clade C15 as seen by genetic fingerprinting.) If I may be so bold - coral reefs may go through a succession something like a forest after a fire.

 

[Flippers4pups]

It has always been my opinion that we simply don't understand the dynamics of mutualism and symbioses seen on (and in) coral reefs. My favorite reference on the subject - the discovery of Symbiodinium thermophilum, a symbiont of corals in the Arabian Sea where seawater temperatures are among the highest known. Corals containing these zoox are tolerant of these temps. An interesting point - the Arabian Sea is only a few thousand years old yet corals have adapted and thrive. How this adaptation was achieved is unknown to me (but it is known that this zoox clade differs very little from the common clade C15 as seen by genetic fingerprinting.) If I may be so bold - coral reefs may go through a succession something like a forest after a fire.

I've always wondered what that relationship between the coral, especially the tissues and zooxanthellae, has in relationship to bacteria in regards to coral health.

 

[Ty1e]

I think bacteria is an effective part of coral tissue and coral health, if we look at bacteria's role on the surface of our own skin, they do much to keep us healthy and balanced, preventing many other more dangerous bacteria from having a foot hold and etc.
We can look at the result of over washing our hands or over using sanitizing liquids, these ones who do this tend to get sick easily and stay sick longer; as well the skin itself is dryer, low elasticity, cracking, bleeding etc.
There was an article(coral mag i believe) a bit ago about how the DNA from curtain bacteria could pass through the cell walls of coral and change their own DNA structure allowing them to adapt to different temps. Very interesting stuff.

 

[Dana Riddle]

DeSilva did a lot of work with corals/bacteria. It has been quite a while since I've reviewed his works, but he found interstitial spaces in the coral skeleton hosted a number of aerobes and anaerobes. The presence of nitrogen-fixing bacteria is also known and could play an important role in supplying inorganic nitrogen to zoox (probably in the form of ammonia but nitrifiers could convert it to nitrate.) Roseobacter (I think I spelled that right) are known to be/produce a chemical cue important to settlement of coral planulae. Bruce Carlson told me a story years ago - He observed a bleached reef somewhere in the south Pacific and returned a few years later expecting to see a barren aquatic wasteland. To his surprise, the reef had recovered and was vibrant, but it was different. Soft corals were the rule, much different than before. I don't know if this relates to an increased and sustained increased water temperature/bacterial shifts, but I think of his story when I hear of reefs disappearing in a few years.
There are a number of bacteria harmful to corals - Vibrio comes to mind (the coral 'white plague'), Oscillatoria causes black band disease... the list could go on and on. Desulfovibrio, Beggiatoa, etc. Of those there are bacteria that are good for corals - many coral species farm bacteria that feed on their mucus, which farms protozoa that feed on the bacteria, and so on. Any shift in the populations might have harmful effects.

 

[Randy Holmes-Farley]

This seems to me to be an unbelievably "academic" comment (meaning sounds hot and sexy but in reality is of no actual use):

“The issue with climate change, and associated bleaching events and even acidification, is you’re losing the structure of the reefs,” he says. “The idea of 3D printing is to actually maintain that structural complexity and that will help all the small organisms that require hiding holes to avoid predation.”

Come on, they are going to print new coral reefs? lol

 

[Flippers4pups]

DeSilva did a lot of work with corals/bacteria. It has been quite a while since I've reviewed his works, but he found interstitial spaces in the coral skeleton hosted a number of aerobes and anaerobes. The presence of nitrogen-fixing bacteria is also known and could play an important role in supplying inorganic nitrogen to zoox (probably in the form of ammonia but nitrifiers could convert it to nitrate.) Roseobacter (I think I spelled that right) are known to be/produce a chemical cue important to settlement of coral planulae. Bruce Carlson told me a story years ago - He observed a bleached reef somewhere in the south Pacific and returned a few years later expecting to see a barren aquatic wasteland. To his surprise, the reef had recovered and was vibrant, but it was different. Soft corals were the rule, much different than before. I don't know if this relates to an increased and sustained increased water temperature/bacterial shifts, but I think of his story when I hear of reefs disappearing in a few years.
There are a number of bacteria harmful to corals - Vibrio comes to mind (the coral 'white plague'), Oscillatoria causes black band disease... the list could go on and on. Desulfovibrio, Beggiatoa, etc. Of those there are bacteria that are good for corals - many coral species farm bacteria that feed on their mucus, which farms protozoa that feed on the bacteria, and so on. Any shift in the populations might have harmful effects.

So vibrio and other harmful bacteria could be the root of some of the issues the reefing community has and still encounters in the forum of "RTN"? I'm aware of other issues that can cause this condition, such as alkalinity swings, etc........

Please excuse my naivete on this, as im still learning about the role of bacteria and it's relationship with coral. I am fascinated by this subject.

Found this info on common coral diseases, much of which is "bacteria' related:

http://www.artificialreefs.org/Corals/diseasesfiles/Common Identified Coral Diseases.htm

 

[Dana Riddle]

So vibrio and other harmful bacteria could be the root of some of the issues the reefing community has and still encounters in the forum of "RTN"? I'm aware of other issues that can cause this condition, such as alkalinity swings, etc........

Please excuse my naivete on this, as im still learning about the role of bacteria and it's relationship with coral. I am fascinated by this subject.

Yes. Vibrio can cause bleaching and other nasty things. I tend to think a coral, when stressed, could create enough mucus to smother it (with bacteria consuming oxygen) especially in conditions of low flow. There's probably a way to test this, but it escapes me. On a side note, I tested for sulfur-reducing bacteria in some tanks. Freshly mixed artificial salts tested negative, but tested 'highly aggressive' in seasoned seawater from coral tanks.

 

[Dana Riddle]

This seems to me to be an unbelievably "academic" comment (meaning sounds hot and sexy but in reality is of no actual use):

“The issue with climate change, and associated bleaching events and even acidification, is you’re losing the structure of the reefs,” he says. “The idea of 3D printing is to actually maintain that structural complexity and that will help all the small organisms that require hiding holes to avoid predation.”

Come on, they are going to print new coral reefs? lol

I wonder if they're thinking of something along the lines in this video. Printing on land, of course, and dropping them into the ocean? A multi-year project for sure.
https://www.bing.com/videos/search?...2AFA15A089E02C4E75582AFA15A089E02C4&FORM=VIRE

 

[Flippers4pups]

Yes. Vibrio can cause bleaching and other nasty things. I tend to think a coral, when stressed, could create enough mucus to smother it (with bacteria consuming oxygen) especially in conditions of low flow. There's probably a way to test this, but it escapes me. On a side note, I tested for sulfur-reducing bacteria in some tanks. Freshly mixed artificial salts tested negative, but tested 'highly aggressive' in seasoned seawater from coral tanks.

Interesting Dana. From my quick skimming over some of the common coral diseases, some are gram negative bacteria.

 

[Dana Riddle]

Interesting Dana. From my quick skimming over some of the common coral diseases, some are gram negative bacteria.

Many are gram negative. I always had to be concerned about cuts and scratches from diving - gram positive bac-T could be indicative of human pollution. But gram negatives are there too.

 

[Flippers4pups]

Many are gram negative. I always had to be concerned about cuts and scratches from diving - gram positive bac-T could be indicative of human pollution. But gram negatives are there too.

I have a LOT of reading to do!

 

[Diesel]

I've done that reading and it got me where I am now and am pretty happy with it.
That good and bad bacteria on especially SPS corals is just a form of unhappy corals in a bad environment.
When tank is stable it might be present but it won't infect your corals, just wonder why corals have a slime coat or slime up so bad and one more than the other?

 

[B-rad]

I've done some reading into free-scientific literature on this sort of stuff and I'm sure just like humans, coral microbiomes can have a large impact on coral health, such as Actinomycelates and Burkholderiales, where they may assist with aspects of coral health much like they do in their symbiotic relations with other photosynthetic systems. Even dense colonies of bacteria present on the surface mucus layer could play an indirect role by competing for real-estate with coral diseases. However I found that they could've done without the mention of a 3d printed reef.

 

[Hans-Werner]

Sounds not good to me. Usually when humans try to manipulate nature it ends up in a catastrophy. Remember the cats that where introduced to islands to catch rats or the foxes that where introduced to Australia to catch rabbits or the introduction of Bufo marinus to Australia. Human ideas are seldom complex enough to cope with nature.

 

[Reef Monkie]

This is the new frontier, in my mind's eye for all of us who keep reef tanks.

Microbial studies, in-depth studies are needed to fully understand coral health and their complete relationship at this level.

Advanced Aquarist has a couple of interesting articles about the role of bacteria on the reef and in tanks.

Corals consume (lots of) bacteria

The Carbon Continuum: Heterotrophic Bacterioplankton and Reef Food Webs

Bacterial Counts in Reef Aquarium Water: Baseline Values and Modulation by Carbon Dosing, Protein Skimming, and Granular Activated Carbon Filtration

some interesting quotes, first article:

"When we put the corals in the tanks, the microbes in the sea water were drastically reduced in numbers," Apprill says. "We observed that the corals were selectively feeding on several types of bacteria—Rhodobacteraceae, Synechococcus, and SAR11, which are most abundant groups of bacteria in the ocean. We then took the corals out of the sea water tanks, and we observed a strong increase in these microbes."

"It's not just the mucus that's causing the microbes in the water to become more active," says Apprill. "It's actually what the coral is releasing, which is still an undefined group of compounds."

"This study shows that corals do in fact influence the picoplankton community by selecting specific lineages of picoplankton for removal and also by potentially using the complex carbon compounds excreted by the coral to promote the growth of these lineages," adds Rachel Parsons, a microbial oceanographer at BIOS and coauthor of the paper.

second article:

Significantly, a large proportion of DOC and POC is redirected to the lowest trophic levels. This is largely due to infection of bacteria by viruses; infection leads to cell rupture, resulting in the spilling of DOC and POC, which is again taken up by bacteria in an endless cycle referred to as the microbial loop. As much as 60% of the energy in a marine ecosystem can be invested in this pathway.

Thus, coral exudates strongly promote the growth of heterotrophic bacteria that dwell in the water column. Reef-associated bacteria consequently proliferate at a rate that is approximately 50 times higher than that of those inhabiting the open ocean.

In stark contrast to oceanic bacteria, the growth rates of reef bacteria are not strongly linked to phytoplankton productivity. This suggests that reef-associated heterotrophic bacteria are not highly dependent upon phytoplanktonic sources of carbon; they rather rely principally upon organic materials secreted by benthic organisms. Not only chemical makeup, but also microbial activity, regulate the specific allocation of this recycled dissolved carbon. So, heterotrophic bacteria have a considerably stronger influence on the trophic structure of a reef than that of open-ocean habitats (which is governed primarily by phytoplankton productivity).

Amazingly, bacteria make up 37-73% of the total biomass in the heterotrophic plankton over coral reefs, where they commonly occur in densities of a million cells per milliliter. In one important respect, reef bacteria serve as compensation for the relative sparseness of reef phytoplankton (and, by extension, phytoplanktivorous zooplankton). In marine food webs, over 95% of organic matter is composed of large, complex molecules such as proteins and lipids. Therefore, little DOM is available to higher organisms through direct uptake. Moreover, while these compounds are rich in carbon, they are typically lacking in nitrogen and phosphorus. Due to the release of exudates by benthic organisms, DOM production is high in reef environments. After enriching it through the parallel uptake of phosphorous and nitrogen, reef bacteria redirect this organic carbon source back into the food web where it may be passed on and on to higher trophic levels.

third article:

A coral's holobiont is comprised of close associations between the coral animal itself, its symbiotic zooxanthellae, and a diversity of associated microbes including bacteria, archaea, algae, and fungi. These associations can take place in the coral's immediate environment, on its surface, within its tissues, and within its skeleton (if present). This paradigm emphasizes the potential contributions of each component to the overall function and health of the coral (Rypien, 2010). The dynamic nature of these relationships can be seen in a comparison between freshly collected corals from the Red Sea region that were then placed into marine aquaria. A microbial community shift in the bacteria inhabiting the surface mucus layer was documented for collected corals when placed into the captive marine aquarium. The differences that emerged between corals from natural and captive environments suggested an adaptation of the mucus bacterial communities to the different conditions (Kooperman, 2007).

The surveyed reef aquariums divided into two distinct sets of husbandry protocols; aggressive and passive (see Fig. 6 for pictures of these aquariums). The aggressive husbandry practices included protein skimming, GAC filtration, and regular water changes in an active effort to scrub the water of nutrients. The passive approach did not involve any of these procedures. Interestingly, the aquaria subjected to passive husbandry exhibited bacterial counts that fell within the range seen on authentic reefs; 200 - 1000K/mL. On the other hand, the tanks that "benefited" from careful attention to nutrient removal protocols displayed bacteria/mL counts that fell far short of these numbers; only 90-140K/mL. In addition to monitoring water column bacteria counts, the TOC (Total Organic Carbon, see Feldman, 2008) levels were examined as well. Not surprisingly, the tanks with "unpurified" water exhibited TOC levels greater than those seen with the skimmed/GAC-filtered tanks. The "purified" aquaria's TOC levels fall within the typical TOC range seen on authentic, healthy reefs (Feldman, 2008); the passively husbandry tanks were 2-3x higher.

So it seems corals feed on bacteria but also feed bacteria and seem to be able to influence the type of bacteria they want to have around them. Some of our husbandry techniques are also influencing the amount of bacteria in the tank and possibly their type (if skimmers selectively remove some bacteria over other). 'Aggressive husbandry' (skimmer/GAC/water changes) successfully keep TOC at the level typically found on reefs but have bacterial counts 10x less than that of a natural reef. Skimmers seem to be stripping nutrients/trace elements from the tank that are concentrated in water-column bacteria but these bacteria are important elements in the food web because they concentrate these elements and make them available to corals.

A fascinating topic and I will resist the urge to say, food for though.

 

[Hans-Werner]

The theory that bacteria in reefs feed on organic carbon released by the corals and the corals feed on the bacteria in the reefs is quite old. It was already published by the Russian microbiologist Sorokin in his book "Coral Reef Ecology" in 1993 and in articles maybe earlier. For Sorokin it is part of a phosphate enrichment mechanism since bacteria have a good ability to take up phosphate from very low concentrations. In this way the coral reef acts as a gigantic phosphate filter.

The observation that corals mainly feed on a selection of marine bacteria is interesting and in good agreement with my observation that certain kinds of polymeric organic substances show a markedly positive effect on polyp extension, growth and coloration of corals. I think that these special organic substances feed these specific marine bacteria and have a specific prebiotic effect on corals.

Bacteria also live on the outer and inner surfaces of corals and are part of the "coral holobiont". These bacteria feed on the slime and other organic substances the corals excrete. Well fed and supplied with energy in this way they can do heterotrophic nitrogen fixation. In this way the coral holobiont is kind of autotrophic regarding nitrogen nutrition. They can satisfy at least part of their nitrogen needs with their mutualistic bacterial symbionts and need only a reduced external nitrogen (i. e. nitrate) supply.

 

[Dana Riddle]

Sounds not good to me. Usually when humans try to manipulate nature it ends up in a catastrophy. Remember the cats that where introduced to islands to catch rats or the foxes that where introduced to Australia to catch rabbits or the introduction of Bufo marinus to Australia. Human ideas are seldom complex enough to cope with nature.

True enough. Hawaii authorities introduced mongooses to control the rat population. Just one problem, rats are nocturnal and mongooses are not, so they never meet. They also introduced a fish in hopes of boosting sports fishing but Hawaiians won't eat them - they appear very similar to a fish they consider sacred. Time will tell what will happen with probiotics being introduced to aquaria.