Nutrient Management by “Old School” Reefer

[Subsea]

In September of 1971, I entered the Texas Maritime Academy on Pelican Island next to the Galveston ship channel. It was educational/amusing to see the 18 year olds in the Cadet Core marching around campus. I had just discharged from 4 years active duty with four 90 day tours of duty in Cambodia. We did’t spit shine our boots in the jungles.

As a marine engineer student, the first technical elective I took that first semester was Chemical Oceanography 101 in which I was introduced to the concept of Dynamic Equilibrium where carbon dioxide in the atmosphere and calcium carbonate in limestone sediments acted to maintain alkalinity in our oceans. So with this limited knowledge, I decided to set up a 55G glass tank as a Galveston Bay theme. I used standard undergravel filter with crushed up oyster shells purchased from chicken feed store. I found a large oyster cluster in Galveston Bay with fan & tube worms for live rock center piece in tank. From the grass flats & marsh reeds, grass shrimp and green mollies were collected . Anemones from the jetties in Galveston completed stocking this 55G tank. All movement for filtration was provided by one air pump on uplift tubes. I dragged that tank around for 10 yrs. The last time I moved that tank in 1980, I showed off the tanks fish and commented about the beautiful dark burgundy carpet over the ugly crushed up oyster shell. A visitor looking at my tank asked me why I had the cynobacteria mat so thick everywhere. We have come a long way from that day.

As my fascination with the marine aquarium hobby continued and my career took me offshore into “Blue Water” as a subsea engineer whose department was underwater blowout preventers. Depending on locations in the world, work schedule was 14/14 or 28/28 on/off. So with a 150G reef tank in my new home, I plumbed a remote sump that grew into 1000G of algae refugiums and two propagation/growout troughs that were 4’ by 8’ by 12” high. With zero nutrient export, I feed heavy when home on days off but no food was added to tank when I was away. Even though I didn’t know all the details, I did know by cause & effect that my algae filter refugium was a two way street with recycling nutrients. This is the focus of the thread: Recycling Nutrients

I briefly described how CO2 as a gas can seek equilibrium with water to combine with alkalinity & photosynthesis to produce glucose which is carbon. So, let’s follow nitrogen as a gas, as it seeks solubility equilibrium to dissolve in water. Add bacteria, like Cynobacteria, to convert free nitrogen gas into available nitrogen in a process called “nitrogen fixation”.

[Nitrogen (N2) fixation is the microbially mediated conversion of relatively inert dinitrogen gas to biologically available ammonia. ... In the marine environment, N2 fixation occurs in numerous ecologically diverse nearshore, coastal and open-ocean environments.]

www.sciencedirect.com
Nitrogen fixation in the marine environment: relating genetic potential to nitrogenase activity
Nitrogen fixation can be an important source of nitrogen for biological productivity in the marine environment. Biological nitrogen fixation is cataly…
www.sciencedirect.com www.sciencedirect.com

Abstract
[Nitrogen fixation can be an important source of nitrogen for biological productivity in the marine environment. Biological nitrogen fixation is catalyzed by the enzyme nitrogenase, which is possessed by diverse microorganisms representing virtually all phylogenetic groups. Interest in nitrogen fixation in the sea has usually been focused on rates of nitrogen fixation, but information on the types of species present with the capability for nitrogen fixation can be important for predicting nitrogen fixation rates in situ. Molecular tools for detection and characterization of the nitrogenase (nif) genes and immunoassays for nitrogenase protein can provide new information on the factors regulating the distribution and activity of diverse nitrogen fixing organisms in the marine environment. Amplification and characterization of nifH sequences has made it possible to identify the type(s) of organism responsible for nitrogen fixation, such as in aggregates of the cyanobacterium Trichodesmium. Differences in nitrogen fixation patterns have been linked to genetic differences between Trichodesmium strains. Further development of these approaches will provide new and powerful ways to link the genetic potential for nitrogen fixation to nitrogen fixation rates in the ocean.]


Here we are in Dec 2020. I am not sure my methods have changed much since 1971. I just know more about why the method works.

I have been practicing the Trident Method for > 45yrs but without the skimmer.

 

[Subsea]

As I see the Trident Method, DOC are exudates from photosynthesis and coral & macro on opposite light cycles trade DOC.

@Timfish posted some information about how coral exudates were proteins & lipids and macro exudates were carbohydrates, which the author compared to junk food. I always thought that carbohydrates were a required building block at the core of body mass and I am sticking to it.

As I feed heavy, both coral & macro benefit. As I feed corals, sponges, apples and scallops the whole tank clouds up. Within two hours display tank is crystal clear.

 

[Subsea]

[I briefly described how CO2 as a gas can seek equilibrium with water to combine with alkalinity & photosynthesis to produce glucose which is carbon. So, let’s follow nitrogen as a gas, as it seeks solubility equilibrium to dissolve in water. Add bacteria, like Cynobacteria, to convert free nitrogen gas into available nitrogen in a process called “nitrogen fixation”.]

Let’s look at another process with N2 gas. Denitrification is the process in which bacteria in low oxygen environment scavenge oxygen from NO3 to release free nitrogen gas to be exported by gas exchange.

Air Fractionators, protein skimmers, are excellent for gas exchange, but from my point of view, skimmate is carbon for the reef, so I don’t use protein skimmer. Tumbling & cascading water as it drains to sump is very efficient gas exchange. Aggressive circulation of surface in display tank is a third excellent method of gas exchange.

PS. @Lasse puts skimmate underneath his plenum to be consumed by anarobic bacteria. In municiple waste water treatment, this would be called an
“anaerobic digester”.

 

[blasterman]

The problem here is our tanks aren't the open ocean.

The ocean doesn't pH shift in 24hours like the tank in your living room does with the windows closed. Also, the PO4 and nitrogen levels in a captive tank even at ULN levels can be 1000x of times higher than the ocean.

The micro chemical process at play are the same, but the density and dilution factors are orders of magnitude different. Always appreciate a discussion with an educated reefer who isn't just a youtube consumer though

 

[Subsea]

@blasterman

Yes, density & magnitude are differrent. I don’t see that as a problem.

“Most reef tanks are nutrient deficient compared to the “microbial highway” on the wild reef.’
Charles Delbrick, Curator of San Francisco Aquarium


You are incorrect about pH shift on the wild reef. World wide pH shifts dramatically, depending on the location.

In this research paper, PH fluctuated 8.7 to 7.8. One pH unit is a multitude of 10 fold change. So, I say the ocean pH fluctuates plenty.

Coral calcification under daily oxygen saturation and pH dynamics reveals the important role of oxygen

ABSTRACT. Coral reefs are essential to many nations, and are currently in global decline. Although climate models predict decreases in seawater pH (∼0.3 units) and oxygen saturation (∼5 percentage points), these are exceeded by the current daily pH and oxygen fluctuations on many reefs...

bio.biologists.org

[Coral reefs are essential to many nations, and are currently in global decline. Although climate models predict decreases in seawater pH (∼0.3 units) and oxygen saturation (∼5 percentage points), these are exceeded by the current daily pH and oxygen fluctuations on many reefs (pH 7.8–8.7 and 27–241% O2 saturation). We investigated the effect of oxygen and pH fluctuations on coral calcification in the laboratory using the model species Acropora millepora. Light calcification rates were greatly enhanced (+178%) by increased seawater pH, but only at normoxia; hyperoxia completely negated this positive effect. Dark calcification rates were significantly inhibited (51–75%) at hypoxia, whereas pH had no effect. Our preliminary results suggest that within the current oxygen and pH range, oxygen has substantial control over coral growth, whereas the role of pH is limited. This has implications for reef formation in this era of rapid climate change, which is accompanied by a decrease in seawater oxygen saturation owing to higher water temperatures and coastal eutrophication.]

 

[Subsea]

[Most reef tanks are nutrient deficient compared to the “microbial highway” on the wild reef.’
Charles Delbrick, Curator of San Francisco Aquarium]

Because I am a simple person, I admit with respect to my reef keeping methods, I did not invent “Old School”. I emulate Nature and how does nature work on a coral reef. Let’s investigate the Coral Holobiont.

Microbes in the coral holobiont: partners through evolution, development, and ecological interactions

In the last two decades, genetic and genomic studies have revealed the astonishing diversity and ubiquity of microorganisms. Emergence and expansion of the human microbiome project has reshaped our thinking about how microbes control host health—not only as pathogens, but also as symbionts. In...

www.frontiersin.org

[Microbes in the coral holobiont: partners through evolution, development, and ecological interactions]

Janelle R. Thompson1*, Hanny E. Rivera1,2, Collin J. Closek3 and Mónica Medina3*
1Civil and Environmental Engineering Department, Massachusetts Institute of Technology, Cambridge, MA, USA
2Department of Biology, Woods Hole Oceanographic Institution, Woods Hole, MA, USA
3Department of Biology, Pennsylvania State University, University Park, PA, USA

[In the last two decades, genetic and genomic studies have revealed the astonishing diversity and ubiquity of microorganisms. Emergence and expansion of the human microbiome project has reshaped our thinking about how microbes control host health—not only as pathogens, but also as symbionts. In coral reef environments, scientists have begun to examine the role that microorganisms play in coral life history. Herein, we review the current literature on coral-microbe interactions within the context of their role in evolution, development, and ecology. We ask the following questions, first posed by McFall-Ngai et al. (2013) in their review of animal evolution, with specific attention to how coral-microbial interactions may be affected under future environmental conditions: (1) How do corals and their microbiome affect each other's genomes? (2) How does coral development depend on microbial partners? (3) How is homeostasis maintained between corals and their microbial symbionts? (4) How can ecological approaches deepen our understanding of the multiple levels of coral-microbial interactions? Elucidating the role that microorganisms play in the structure and function of the holobiont is essential for understanding how corals maintain homeostasis and acclimate to changing environmental conditions.]

So, if I read correctly, bacteria are the “microbial overlords” in the marine environment. Considering quorum sensing bacteria and crosstalk between bacteria in surface film and bacteria in body mass of algae & coral to optimize growth in each, I agree with “microbial overlords”.

PS. In the movie, War of the Worlds, the invading Martians were finally killed by Earth’s “microbial overlords”.

 

[Nano sapiens]

So, if I read correctly, bacteria are the “microbial overlords” in the marine environment. Considering quorum sensing bacteria and crosstalk between bacteria in surface film and bacteria in body mass of algae and coral to optimize growth in each, I agree with “microbial overlords”.

I would say that back in the day, while we didn't have the in depth knowledge of the various microbes present on the reef or in a reef aquarium (and in/on the coral itself) that we have today, we did have a pretty good general idea that microbes were in the driver's seat. It was inconceivable that any competent reef aquarist would add substances/products of any sort that had the potential to disrupt a healthy, properly functioning reef biotope.

Nowadays, with the addition of so many products to 'fix anything' (and so little known about possible long term consequences to the microbial communities)...let's just say that things are 'different' and leave it at that.

 

[Subsea]

I would say that back in the day, while we didn't have the in depth knowledge of the various microbes present on the reef or in a reef aquarium (and in/on the coral itself) that we have today, we did have a pretty good general idea that microbes were in the driver's seat. It was inconceivable that any competent reef aquarist would add substances/products of any sort that had the potential to disrupt a healthy, properly functioning reef biotope.

Nowadays, with the addition of so many products to 'fix anything' (and so little known about possible long term consequences to the microbial communities)...let's just say that things are 'different' and leave it at that.

Kudos to this post. It baffles me to read abundant post about numerous “snake oil” additives and complete forums on disease tretment and nuisance algae/bacteria forum. Seems to me that quick fix & snake oil treatments are in the drivers seat and knowledge is in the back seat.

 

[stephen wyard]

Its funny for me reading this because twenty years ago when the hobby was just comeing into its own.Here in canada there was no real exsperts no forums just books and some of this information I just didn't like .They said you must have all this apparatus to make a reef work.So not being a scientist or biologest but I love nature so I went out and study how bodyies of water worked.How ponds work and rivers and streams.I discovered back then that they all had one thing in command a type of refusium.So with this in mind I took fine screen and some coursser crushed coral and made a phlem .When you think about it it takes anarobic baterria to brake down waste products and release oxygen into the water.No skimmer just a power head to move water to break the surface and a home made sump to catch large particles.I put this idea in a friends tank that had all kinds of problems and even after the tear down and resetting up he didn't lose anything.It was cloudy for about two hours and with in three days he called me to see his tank.It was cyrstal clear.As far as I know he still runs the tank this way with no algae problems at all.So reading this article just made me think of those days.The hobby has come a long way from those days.

 

[Subsea]

Its funny for me reading this because twenty years ago when the hobby was just comeing into its own.Here in canada there was no real exsperts no forums just books and some of this information I just didn't like .They said you must have all this apparatus to make a reef work.So not being a scientist or biologest but I love nature so I went out and study how bodyies of water worked.How ponds work and rivers and streams.I discovered back then that they all had one thing in command a type of refusium.So with this in mind I took fine screen and some coursser crushed coral and made a phlem .When you think about it it takes anarobic baterria to brake down waste products and release oxygen into the water.No skimmer just a power head to move water to break the surface and a home made sump to catch large particles.I put this idea in a friends tank that had all kinds of problems and even after the tear down and resetting up he didn't lose anything.It was cloudy for about two hours and with in three days he called me to see his tank.It was cyrstal clear.As far as I know he still runs the tank this way with no algae problems at all.So reading this article just made me think of those days.The hobby has come a long way from those days.

A friend, @Timfish has done aquarium maintenance & setup for 30 years here in Austin, recently added 10G of water from a healthy established reef tank to clear up reoccurring cloudy water which previously was kept in check with heavy UV sterilizer use. Go figure.

 

[Subsea]

A friend on RC has been doing Sea Grasses for some years, recently posted that Sea Grasses were more efficient at removing low nutrients from bulk water and would be a better match for low nutrient SPS than macro algae. Any thoughts @Lasse or @Sallstrom

Considering Mark Levin & @Paul B have nitrates > 50ppm, I see little concern with high nitrates.

Considering the culture of vendor induced products to take the place of an informed hobbiest, I say “Houston, we have a problem”.

Patience is a virtue to be embraced. Wisdom is discernment combined with an application of knowledge. For certain there are many methods to operating a reef tank successfully. I choose Laissez Faire and Microbial Overlords.

__________________
As many naturalists and environmentalists have suggested, we should set aside our arrogance,
our desire to conquer and control everything, and walk hand in hand with Mother Nature. -Walter Adey

 

[Subsea]

In further reading this research paper, pH fluctuation of 8.7 to 7.8 did not effect calcification rates of Acropora millepora, but changes in oxygen concentration drastically effected calcification. Considering this, I see the use of an oxygenator combined with H202 as a superior tool for advanced hobbiest. Ask @atoll

Coral calcification under daily oxygen saturation and pH dynamics reveals the important role of oxygen

ABSTRACT. Coral reefs are essential to many nations, and are currently in global decline. Although climate models predict decreases in seawater pH (∼0.3 units) and oxygen saturation (∼5 percentage points), these are exceeded by the current daily pH and oxygen fluctuations on many reefs...

bio.biologists.org

[Interestingly, the projected pH decrease for this century is greatly exceeded by the daily pH fluctuation to which Indo-Pacific corals on reef flats and lagoons are exposed, which ranges from 8.7 during the day to 7.8 at night (Ohde and van Woesik, 1999). In addition, the seawater oxygen saturation at these reef locales shows dramatic changes over a diel cycle, with a range of 241% air saturation (or 14.19 mg O2 L−1) at daytime, to 27% saturation (or 1.67 mg O2 L−1) at night (Ohde and van Woesik, 1999).%]

 

[atoll]

In further reading this research paper, pH fluctuation of 8.7 to 7.8 did not effect calcification rates of Acropora millepora, but changes in oxygen concentration drastically effected calcification. Considering this, I see the use of an oxygenator combined with H202 as a superior tool for advanced hobbiest. Ask @atoll

Coral calcification under daily oxygen saturation and pH dynamics reveals the important role of oxygen

ABSTRACT. Coral reefs are essential to many nations, and are currently in global decline. Although climate models predict decreases in seawater pH (∼0.3 units) and oxygen saturation (∼5 percentage points), these are exceeded by the current daily pH and oxygen fluctuations on many reefs...

bio.biologists.org

[Interestingly, the projected pH decrease for this century is greatly exceeded by the daily pH fluctuation to which Indo-Pacific corals on reef flats and lagoons are exposed, which ranges from 8.7 during the day to 7.8 at night (Ohde and van Woesik, 1999). In addition, the seawater oxygen saturation at these reef locales shows dramatic changes over a diel cycle, with a range of 241% air saturation (or 14.19 mg O2 L−1) at daytime, to 27% saturation (or 1.67 mg O2 L−1) at night (Ohde and van Woesik, 1999).%]

I have always had good SPS growth using Oxydators but then I was using Oxydators well before I started with SPS. Having said that LPS growth has always been fine as well but then you have to meet their other needs pf course like calcium and magnesium as examples. Certainly Oxygen depletion has never been an issue. Plenty of people will tell you they don't add oxygen apart from what a skimmer and surface water agitation provide. Personally am not convinced they do in many circumstances. Oxygen levels on the reef can exceed 100% I have read.
When I first started using Oxydators I used a Dupla O2 test to determine my oxygen levels.

 

[wtac]

I remember Oxydators. Used them in a LFS that I worked in the early 90's while doing my undergrad. Owner complained that we (I) was going through so much of the solution that I went to the chem dept storage locker and nicked a few gallons of USP 30% H2O2 and diluted down to 6% so I we (I) didn't get any more grief from the owner.

The planted and marine displays were bloody awesome for the time.

 

[atoll]

I remember Oxydators. Used them in a LFS that I worked in the early 90's while doing my undergrad. Owner complained that we (I) was going through so much of the solution that I went to the chem dept storage locker and nicked a few gallons of USP 30% H2O2 and diluted down to 6% so I we (I) didn't get any more grief from the owner.

The planted and marine displays were bloody awesome for the time.

I recall buy a 10 litre drum I think it was of 70% hydrogen peroxide and sharing it with my friend. It was sold by swimming pool suppliers to kill algae in outdoor ponds. Now you need a licence here in the UK to buy it.

 

[Timfish]

. . . @Timfish posted some information about how coral exudates were proteins & lipids and macro exudates were carbohydrates, which the author compared to junk food. I always thought that carbohydrates were a required building block at the core of body mass and I am sticking to it. . . .

@Subsea : Patrick, you've been using my name in vain again! Obviously carbohydrates (aka sugars, aka DOC) are essential. But research is clearly showing there are different types and they can have very different effects on the microbial processes. Here's some of the links I've come across but first, since you've refferenced Charles Delbeek's comments I thought I'd post a qoute from one of his articles in "Coral" magazine for those interested:

"When I see the colors of some of these low nutrient tanks, I can't help but be reminded of bleached coral reefs. It should therefore not come as a surprise that feeding corals in such systems becomes a very important component in these systems. Though reefs are often catagorized as nutrient "deserts" the influx of nutrients in the form of particulates and plankton is quite high when the total volume of water passing over a reef is taken into consideration.

Our crystal-clear aquaria do not come close to the nutrient loads that swirl around natural reefs. And so when we create low-nutrient water conditions, we still have to deal with the rest of a much more complex puzzle. Much like those who run their aquarium water temperature close to the thermal maximums of corals walk a narrow tight rope, I can't help but think that low-nutrient aquariums may be headed down a similar path." Charles Delbeck, Coral Nov/Dec 2010, pg 127

And an earlier quote from J. E. N. Veron over 25 years ago seems to have been pretty much forgotten or ignored:
"Imported nutrients are usually transported to reefs from rivers; but if there are no rivers, as with reefs remote from land masses, nutrients can only come from surface ocean circulation. Often this supply is poor, and thus the vast ocean expanses have been refered to as "nutrient deserts". The Indo-Pacific has many huge atolls in these supposed deserts which testify to the resilience of reefs, but the corals themselves may lack the lush appearance of those of more fertile waters. Many reefs have another major supply of inorganic nutrients as, under certain conditions, surface currents moving against a reef face may cause deep ocean water to be drawn to the surface. This "upwelled" water is often rich in phosphorus and other essential chemicals." J. E. N. Veron "Corals of Austrailia and the Indo-Pacific" pg 30

So, here's some of the links on DOC or "Exudates" released by corals and algae:

Indirect effects of algae on coral: algae‐mediated, microbe‐induced coral mortality
Coral seperated from algae with a .02 µm filter die. Treatment with aampicillan prevents death.

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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

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

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.
Starch and sugars (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

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

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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

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

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

Diverse microbial communities associate with coral tissues and mucus, providing important protective and nutritional services, but once disturbed, the microbial equilibrium may shift from a beneficial state to one that is detrimental or pathogenic. Macroalgae (e.g., seaweeds) can physically and...

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

Because sponges are essential players in the carbon, nitrogen and phosphorus cycle(s) on reefs here's some links to research done with them.

Element cycling on tropical coral reefs.
This is Jasper de Geoij's ground breaking research on reef sponges. (The introduction is in Dutch but the content is in English.)

https://www.rug.nl/research/portal/files/14555035/13completethesis.pdf

Sponge symbionts and the marine P cycle

Sponge symbionts and the marine P cycle

Marine sponges are ubiquitous colonizers of shallow, clear-water environments in the oceans (1, 2). Sponges have emerged as significant mediators of biogeochemical fluxes in coastal zones by virtue of respiring organic matter and facilitating both the consumption and release of nutrients (3, 4)...

www.pnas.org

Phosphorus sequestration in the form of polyphosphate by microbial symbionts in marine sponges
(Chris Kenndall had a problem with low PO4 and had problems raising it with Neophos. Samples sent off showed phosphorus crystals developing in some of the sponges in his system accounting for at least some of his systems consumption.)

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

Coral reefs are highly productive ecosystems that raise a conundrum called “Darwin’s paradox”: How can high production flourish in low-nutrient conditions? We show here that in three abundant Caribbean sponges, the granules that have been commonly observed in sponge tissue for decades are...

www.pnas.org

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

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besjournals.onlinelibrary.wiley.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

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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

Aura-biomes are present in the water layer above coral reef benthic macro-organisms - PubMed

As coral reef habitats decline worldwide, some reefs are transitioning from coral- to algal-dominated benthos with the exact cause for this shift remaining elusive. Increases in the abundance of microbes in the water column has been correlated with an increase in coral disease and reduction in...

www.ncbi.nlm.nih.gov

 

[Subsea]

Thank you for the links.
That is a lot to digest and I did not use your name in vain, because you are here. @Timfish

I will not address the advantages of coral exudates over macro exudates. When Julian Sprung was asked about that research, he indicated he would enjoy an in-depth conversation with those authors because it did not agree with his experience and research. So, we will agree to disagree.

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

In reading abstract to this link, it focus on corals creating autotrophic conditions as opposed to algae shifting toward heterophic microbial communities.

[Our results highlight the variability of the influence of different benthic primary producers on microbial metabolism in reef ecosystems and the potential implications for energy transfer to higher trophic levels during shifts from coral to algal dominance on reefs.]

Coral reefs are not dominated by coral, they are dominated by algae, kept in check by herbivores.

Tim,
We will get into the “Sponge Loop”, which merits much attention for biofiltration and nutrient recycling.

 

[Subsea]

Eureka, I have found it!

[Archimedes was so thrilled and excited with this discovery that he immediately hopped out of the bath and ran onto the streets to tell the king, shouting loudly 'Eureka! Eureka!' (I have found it!) ]

https://www.researchgate.net/profile/D-Oevelen/publication/279061640_2013_deGoeij_Science_Sponge_loop/links/5589c0b108ae273b2876d7b8/2013-deGoeij-Science-Sponge-loop.pdf?origin=publication_detail

[Ever since Darwin’s early descriptions of coral reefs, scientists have debated how one of the world’s most productive and diverse ecosystems can thrive in the marine equivalent of a desert. It is an enigma how the flux of dissolved organic matter (DOM), the largest resource produced on reefs, is transferred to higher trophic levels. Here we show that sponges make DOM available to fauna by rapidly expelling filter cells as detritus that is subsequently consumed by reef fauna. This “sponge loop” was confirmed in aquarium and in situ food web experiments, using 13C- and 15N-enriched DOM. The DOM-sponge-fauna pathway explains why biological hot spots such as coral reefs persist in oligotrophic seas—the reef’s paradox—and has implications for reef ecosystem functioning and conservation strategies.]

 

[tripdad]

I am not, will never be, and am just too plain hardheaded to ever be in a league to enter this debate on any level. That said, as a reef hobbyist this quote that Timfish used is , in my opinion, the single most important thing we can learn from.

since you've refferenced Charles Delbeek's comments I thought I'd post a qoute from one of his articles in "Coral" magazine for those interested:

"When I see the colors of some of these low nutrient tanks, I can't help but be reminded of bleached coral reefs. It should therefore not come as a surprise that feeding corals in such systems becomes a very important component in these systems. Though reefs are often catagorized as nutrient "deserts" the influx of nutrients in the form of particulates and plankton is quite high when the total volume of water passing over a reef is taken into consideration.

Our crystal-clear aquaria do not come close to the nutrient loads that swirl around natural reefs. And so when we create low-nutrient water conditions, we still have to deal with the rest of a much more complex puzzle.

In my opinion, when we see the very successful reefers, over a span of years, they all seem to embrace lots of food input and lots of waste extraction. I have argued for years that coral reefs are anything but nutrient poor. Instead they are very low in residual nutrients in such that anything that flows into the system is utilized by some life form almost instantly. Also that any excess in nutrients will be met by an increase in an organism that utilizes that nutrient source. In other words, balance of in and out. Sorry to derail but that quote is awesome.

 

[Nano sapiens]

Having read through many of these very interesting studies, and looking at the bigger picture, the overarching theme that comes to mind is that these various macro fauna and microbial mediated processes must all be in a continuous state of dynamic equilibrium to produce what we deem a 'heathy reef environment'. Altering a bit too far in one direction or the other, the system becomes unstable. Go too far and it shifts to something entirely different.

As was known way back in the early days of reef keeping; 'The more major elements from the natural reef environment that we can incorporate into our systems, the more likely we are to have a positive outcome'.