Interesting reports according Darwin's Paradox

[Lasse]

so my apoligies since I focus on that

Acropora is a part of this investigation.

Sincerely Lasse

 

[Lasse]

I have parakeets at home and I am thinking of setting up their perch directly over my refugium. Am I over thinking this one?

Un-sincerely,
Kris

You are to late - here

Still Sincerely Lasse

 

[jda]

Indeed, the amount of N available in dissolved inorganic form, mostly nitrate, in reefs close to seabird colonies can be about 90-fold higher than the amount available to corals in the form of zooplankton in reefs elsewhere

No kidding, but there is more to this than just bird poop and zooplankton.

I just want to see the whole picture studied. Inorganic N and P are only a small part of the story. I wish that they would have included the rest as a control. The biologist that I talked to in the coral sea indicated that organics (mostly bacteria) caught in the slime coats offer the most energy and building blocks beside the sun for energy... equivalent in our tanks the fish waste and gut bacteria. Do not confuse this with polyp catching which does not appear as efficient or effective for some coral. That gut bacteria can grow and multiply outside of the fish and provide more food in both organic and inorganic forms.

If seabird waste is important, then fish waste seems doubly important since it can provide organic and inorganic building blocks.

Again, this one study just seems too limited to me, but I am looking forward to something else to corroborate it and study further. We have all been burned by the recency of one study not surviving the test of time - I am not saying that this one will be proven wrong, but that I am not going to be hasty.

 

[danimal1211]

These are all good questions and I feel these studies haven’t just enlarged our knowledge base but also the horizon of what we know we don’t know.

 

[Katrina71]

I have parakeets at home and I am thinking of setting up their perch directly over my refugium. Am I over thinking this one?

Un-sincerely,
Kris

There was a reefer that had a sewage accident over his tank and the coral thrived.

 

[Lasse]

That gut bacteria can grow and multiply outside of the fish and provide more food in both organic and inorganic forms.

Most of them are obligate anaerobic heterotrophs - they can´t survive in aerated water.

If seabird waste is important, then fish waste seems doubly important since it can provide organic and inorganic building blocks.

Not at all. The guano content a lot of nitrogen from the birds pee and phosphorus from the pop. Saltwater fish do not pee so much (of osmotic reasons) - their surplus nitrogen leave the fish mostly through the gills as NH4/NH3 more or less directly after they have eat. In aquarium - if the fish population is large enough - it will contribute (through the NH4/NH3 excreted by the gills) rather much to the nitrogen pool (mostly as NO3 because of nitrification). Most people does not need to add anny N to their aquarium. The people that take away their NO3 and add amino acids trick themselves - IMO. The amino acids will no go directly to the host - they will be taken up by the zooxanthellae along the same channels as the zoox can take up NH4/NH3, hence the animal need to eat the zoox to get it into the animal tissue. And I have always wonder why people dose amino acids. Amino acids are the building blocks for protein - skimmers when they was introduced was named protein skimmers...... If you want to have free amino acids in the water - just turn of the skimmer.......

If seabird waste is important

Is not the seabird waste that is important by itself - it is the run off water that content much inorganic N and P thats matter. Its the extra nutrients that make a reef outside a bird colony grow 4 time faster than a coral reef without a bird colony. This strongly indicate that there is space for more nutrients (and faster growth) in these circumstances (fertilization by nutrient rich run of water) than in the "normal" nutrient poor reefs. IMO - it is also depending on a normal population of grazers - overfishing will lead to an algae explosion in natural waters.

My favorite article mention nutrient concentration of around 0.75 mg/L NO3 and 0,28 ppm PO4 in these high producing reefs. and probably with enough of grazers - the nutrients concentrations can rise further. With all of this in the rearview mirror - both my and @Thales high phosphate aquariums may not be as surprising as they seem to be

Sincerely Lasse

 

[Hans-Werner]

As far as I understand, this cannot be described as a symbiosis any longer - more as slavery and I feed on your offsprings relationship.

I think this is not a correct and not a biological view. It is just normal that the host provides food to its symbionts and then feeds on symbionts. It is the same in the intestines of bovines, with bacteria in the mucus coatings of corals and with zooxanthellae as endosymbionts in corals: The host provides home and nutrients to his symbionts and feeds on excess symbiont biomass. In zooxanthellae in corals the home is also provided with stable and sunny conditions and with shading from excess light.

In contrast to our kids or offsprings of other animals, protists and bacteria usually grow by division which means they form no new and unique individuals but just copies of the parent cells. As long as one copy survives the clone remains alive. This is the (a) difference.

I´m afraid that you need sooner or later rethink this. Think from an evolutionary standpoint. NO3 is by far the predominant inorganic N species in seawater even over reefs that get N inputs from guano - my bold as usally, According to the background of the natural distribution of NO3 and NH4 in the sea - IMO - uptake of NO3 is normal and that they beneficially absorb NH4/NH3 on the occasions when it is freely available

Are you sure that NO3 is the predominant N species over reef? As far as I know the average molar concentrations are about the same. For a talk I calculated 0.55 µmol/l for NH4+ and 0.6 µmol/l for NO3- average molar concentrations from several publications.

The biologist that I talked to in the coral sea indicated that organics (mostly bacteria) caught in the slime coats offer the most energy and building blocks beside the sun for energy... equivalent in our tanks the fish waste and gut bacteria.

I am not 100 % sure whether this is still up-to-date but there was a "bacteria farming theory" that corals provide their symbiotic bacteria with energy, amino acids and other organic compounds and the dividing bacteria take up phosphate from the water. Bacteria can utilize phosphate form very low concentrations, much better so than the coral host. The coral then feeds on excess bacteria with their utilized phosphate.

The people that take away their NO3 and add amino acids trick themselves - IMO. The amino acids will no go directly to the host - they will be taken up by the zooxanthellae along the same channels as the zoox can take up NH4/NH3, hence the animal need to eat the zoox to get it into the animal tissue.

To my understanding the host can make direct use of amino acids but he cannot make direkt us of nitrate. Why do you think the coral host cannot make direct use of amino acids, only after uptake by zooxanthellae?

The cora host makes poor use of NH3/NH4+ compared to its symbionts.

Another question remains whether the amino acids get to the corals intact at all. A reef tank is not a sterile setup.

 

[Hans-Werner]

Another very interesting publication on the individual and combined effects of nitrate, ammonium and phosphate is the dissertation of Shantz. It should also be interesting to Acropora growers, @jda .

 

[Lasse]

To my understanding the host can make direct use of amino acids but he cannot make direkt us of nitrate. Why do you think the coral host cannot make direct use of amino acids, only after uptake by zooxanthellae?

The cora host makes poor use of NH3/NH4+ compared to its symbionts.

As I understand it - cells use the same channels for uptake of NH4/NH3 and amino acids (I will check it with the person I get the information from.) And if they are bad to take up NH4/NH3 - I suppose its true for amino acids too

I think this is not a correct and not a biological view. It is just normal that the host provides food to its symbionts and then feeds on symbionts. It is the same in the intestines of bovines, with bacteria in the mucus coatings of corals and with zooxanthellae as endosymbionts in corals: The host provides home and nutrients to his symbionts and feeds on excess symbiont biomass. In zooxanthellae in corals the home is also provided with stable and sunny conditions and with shading from excess light.

I think this is a philosophical question but symbiosis to me means mutual benefit - like anemones and clownfish but in this case the zooxanthellae is 100% controlled by the host. It is also questionable whether the animal really normally supplies the zooxanthellae with nutrients - in the current investigation it certainly did not. I would rather liken the relationship between the coral animal and the zooxanthellae to the relationship between me and my greenhouse. Admittedly, I can provide my plants with nutrients from my waste, but I end my care by eating them or the offspring. It's not symbiosis for me.

Are you sure that NO3 is the predominant N species over reef?

It may depend on the reef - if it inside an atoll or a outer reef sloop. But I wrote seawater and the text " even over reefs that get N inputs from guano " referred" to a comment in the base article

My Bold

Indeed, the amount of N available in dissolved inorganic form, mostly nitrate, in reefs close to seabird colonies can be about 90-fold higher than the amount available to corals in the form of zooplankton in reefs elsewhere

Sincerely Lasse

 

[Hans-Werner]

As I understand it - cells use the same channels for uptake of NH4/NH3 and amino acids (I will check it with the person I get the information from.)

To my knowledge there are uptake systems for specific amino acids, even different uptake systems for different amino acids.

I can provide my plants with nutrients from my waste, but I end my care by eating them or the offspring. It's not symbiosis for me.

It is just a matter of view: Without humans eating wheat and corn these cereals wouldn't be the most widespread and numerous plants of the world. You can define this as mutual benefit.

Even if you go further, they are annual grasses anyway, the parent plants will die while ripening their seeds. Although we eat most of their seeds, we use incredible numbers for sowing and in the end again they are the most widespread and numerous plants in the world. Again this is mutual benefit.

Or take fruits. They feed animals and humans to spread and maybe even fertilize their seeds. Again this is mutual benefit. The world is full of mutual benefits, you just have to have an optimistic and benevolent eye on it.

 

[jda]

The Schatz paper echos my experience perfectly.... low nitrate and a trace of phosphate with plenty of ammonia is the best for acropora (growth, color and wide range of happy species), and even coralline (to my bane).

 

[taricha]

I think the farming symbiont algae on NO3 and PO4 is interesting, and though the evidence is not as strong, some sources indicate that the majority of bacteria that corals eat are bacteria they grow on their coral mucus rather than what they "catch" from the water. I don't know if that's true, but the circumstantial picture may be that corals farm almost all of their "prey" in-house - both algae and bacteria, and thus maybe the overwhelming majority of N & P they get is inorganic->farmed algae+bac->coral host.
I'm still going to feed my tank fish food, phyto, pods, aminos etc, but I'm open to the idea that the corals benefit from none of that directly - only as much as those things remineralize N & P to inorganics so the coral's farmed food can munch it.

 

[Subsea]

I think the farming symbiont algae on NO3 and PO4 is interesting, and though the evidence is not as strong, some sources indicate that the majority of bacteria that corals eat are bacteria they grow on their coral mucus rather than what they "catch" from the water. I don't know if that's true, but the circumstantial picture may be that corals farm almost all of their "prey" in-house - both algae and bacteria, and thus maybe the overwhelming majority of N & P they get is inorganic->farmed algae+bac->coral host.
I'm still going to feed my tank fish food, phyto, pods, aminos etc, but I'm open to the idea that the corals benefit from none of that directly - only as much as those things remineralize N & P to inorganics so the coral's farmed food can munch it.

There is scientific research that Cynobacteria in surface slim of coral supply nitrogen to coral; some of these bacteria groups use nitrogen fixation of inorganic nitrogen in water mass, however there are other bactetia in surface film of coral that crosstalk with interior bacteria to adjust gene expression to enhance environmental conditions. Thus the Coral Holibiont.

@Timfish
Help a brother out with a link to a podcast from University of Southern California with Rowler

PS: When I goggled microbes in marine seas, I got this research which is above my pay grade with more degrees than thermometers. Because words have precise meanings, I like using a scientific reference for these details.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4711185/

ACKNOWLEDGMENTS​

We thank Luke E. Ulrich for providing valuable information about the MiST2.2 Database and Rongfang Huang for article style formatting. We also thank the three anonymous reviewers for their valuable comments and suggestions for manuscript improvement.
This work was supported by China NSFC grant 91328209, MOST 973 program grant 2013CB955700, China NSFC grant 91428308, SOA grant GASI-03-01-02-05, and CNOOC grants CNOOC-KJ 125 FZDXM 00TJ 001-2014 and CNOOC-KJ 125 FZDXM 00ZJ 001-2014.
Go to:

BIOGRAPHIES​

•

Hongyue Dang received his Ph.D. in marine science from University of South Carolina in 2001. After postdoctoral studies at SUNY Upstate Medical University and University at Buffalo, The State University of New York, he moved in 2004 to the CAS Key Laboratory of Marine Geology and Environment, Institute of Oceanology, Chinese Academy of Sciences, working on marine geomicrobiology as an Associate Professor. In 2008, he moved to the State Key Laboratory of Heavy Oil Processing, Centre for Bioengineering and Biotechnology, China University of Petroleum (East China), working on marine microbial ecology, biogeochemistry, and biotechnology as a Professor. Since 2013, he has worked as a Chair Professor in the State Key Laboratory of Marine Environmental Science and College of Ocean and Earth Sciences, Xiamen University. His main research interests are marine biocorrosion and surface-associated microbial communities, processes and functions, and marine carbon and nitrogen cycling in response to diverse environmental gradients and anthropogenic perturbations.
•

Charles R. Lovell received his Ph.D. in Biological Sciences from Purdue University in 1984. After postdoctoral studies at the University of Georgia, he accepted appointment as an Assistant Professor in the Department of Biological Sciences at the University of South Carolina in 1987. He was promoted to Associate Professor in 1993 and to Full Professor in 2000. His main research interests are in population and community dynamics of microorganisms, interactions between bacteria and higher organisms, and the physiology and ecology of anaerobic bacteria.
Go to:

APPENDIX​

Definitions​

 

[Subsea]

@Lasse
I think everybody benefits mutually Or it’s not Sustainable.

The construct that one organism must farm the slave is not mutually beneficial. In a different ethos, the ruling class farm the peasants; eventually we have a cultural revolution.

I think the farming symbiont algae on NO3 and PO4 is interesting, and though the evidence is not as strong, some sources indicate that the majority of bacteria that corals eat are bacteria they grow on their coral mucus rather than what they "catch" from the water. I don't know if that's true, but the circumstantial picture may be that corals farm almost all of their "prey" in-house - both algae and bacteria, and thus maybe the overwhelming majority of N & P they get is inorganic->farmed algae+bac->coral host.
I'm still going to feed my tank fish food, phyto, pods, aminos etc, but I'm open to the idea that the corals benefit from none of that directly - only as much as those things remineralize N & P to inorganics so the coral's farmed food can munch it.

Kudos to your post.

 

[Subsea]

Forest Rohwer | SDSU Coastal and Marine Institute

cmi.sdsu.edu

When I find the right pod cast, I will link it.

Forest Rohwer is deep into nutrient recycling and multiples nutrient pathways in coral ecosystems.

Coral reefs worldwide are in decline
The dramatic rise in incidences of coral disease over the last two decades has been instrumental in this process. We have hypothesized that most of these diseases are actually opportunistic infections instigated by anthropogenic stressors. Our research is focused around understanding the interactions between the microbial world and coral reefs, and how these systems change following perturbation.


The Coral Holobiont
Corals are host to a wide diversity of organisms, including endosymbiotic algae, protists, fungi, Bacteria, Archaea, and viruses. Together, these organisms make up the coral holobiont. In our lab, we are interested in understanding the physiological roles of these players in their interaction with the coral animal, and how this relates to coral reef health. Incidences of coral death and disease are highly correlated with human impact, and we propose that anthropogenic stresses induce microbes normally associated with the coral to become opportunistic pathogens. Alternatively, opportunistic or specific pathogens from the water column might attack the weakened coral. To differentiate between these possibilities, my lab has had to determine if healthy corals have characteristic microbiotas. To do this, we have employed a variety of techniques ranging from electron microscopy (e.g., Johnston and Rohwer 2007) to metagenomics (e.g., Wegley et al. 2007).

In order to look at the diversity and specificity of coral microbes, our lab used high-throughput sequencing of bacterial 16S rDNAs associated with three coral species. This culture-independent study of coral-associated Bacteria found 430 (mostly novel) bacterial species in 14 samples from 3 coral species. The coral-associated microbial communities were ecologically structured: different coral species had different bacterial communities, even when physically adjacent, while bacterial communities from the same coral species separated by time (~1 year) or space (3000 km) were similar. We also found that some bacterial species were present only in a subset of spatial niches within individual coral colonies (Rohwer, et al., 2002).

In order to look at the function of microbes on corals, we use metagenomic sequencing (454 Life Sciences) to identify the microbes and their functional genes. Our work found that bacteria associated with corals are primarily heterotrophic. Our metagenomic data showed an abundance of sugar and protein utilization and uptake pathways in the microbial community. These microbes are likely utilizing the complex polysaccharides and peptides from the coral mucus. Several types of cyanobacteria were also found associated with the coral, and may be providing fixed carbon and nitrogen to the coral. In addition, an abundance of fungi were associated with corals, including those involved in nitrogen cycling, indicating that fungi may be fixing nitrogen and making it available to members of the coral holobiont (Wegley et al. 2007).

We have also looked at the viruses associated with healthy and bleaching corals, and find viruses with a wide variety of hosts including many of the various members of the coral holobiont. These viruses include plant and algal viruses, herpes-like viruses, and cyano- and vibriophage, to name a few (Wegley et al. 2007, Marhaver et al. 2008). Due to the abundance of viruses and the wide variety of host ranges they possess, we expect that they play an important role in coral health and structuring of the coral holobiont.

In summary, the associations of the coral animal, prokaryotes, zooxanthellae, viruses, fungi, and other undefined components will define the niche that any coral colony occupies on a reef. This system is almost certainly exemplary of many other interactions between microbes and their higher eukaryotic hosts, and our studies will make predictions that can/will be tested in other complex host-microbial flora systems.

Stressors Alter Microbial Dynamics on Corals
An important implication of the coral holobiont model is that disrupting any one of these components may cause the whole community to collapse and lead to coral death. In order to test this hypothesis, we have performed several experiments exposing corals to different stressors and then looked at the changes in microbial dynamics and diversity, as well as coral pathology. In collaboration with Dr. Nancy Knowlton and Davey Kline at the Scripps Institution of Oceanography, we applied stresses to different coral species in the presence and absence of antibiotics. Our data showed that of the many commonly cited stressors of corals, organic carbon (OC) loading is the most problematic. Coral death induced by OC can be delayed with antibiotics. Additionally, OC loading causes the coral-associated microbial communities to grow much faster then normal. This strongly suggests that changes in the bacterial community, and not the stresses themselves, are responsible for coral mortality. (Kline et al. 2006, Kuntz et al. 2005). Additionally, when corals are placed next to algae with a filter impervious to viruses and bacteria, corals mortality is high. This mortality is also inhibited by antibiotics (Smith et al. 2006).

In a separate experiment, corals were exposed to one of four types of stressors currently threatening coral reefs: elevated nutrients, temperature, and organic carbon, and lowered pH. We then isolated the microbial and viral communities and performed whole-genome sequencing (pyrosequencing, 454 Life Sciences) to look at how the diversity and function of these organisms changed following stress. Our data showed that stress led to a shift towards a more pathogenic microbial community in all cases, with pathogen-associated genes also increasing in abundance (e.g. motility, virulence, and secondary metabolite genes) (Vega Thurber et al. Env Micro 2009). The viral assemblages also changed on the coral, with viruses related to the Herpesviridae family greatly increasing in abundance (Vega Thurber et al. PNAS 2008). We found that one herpes-like virus was undetectable by quantitative PCR (qPCR) prior to stress, but then increased dramatically within 1 hr of stress exposure, indicating an increase in production of the virus under stress.

Coral Reef Microbiology in Pristine and Human-impacted Reefs
In 2005, we visited the Northern Line Islands with a group of coral reef experts to look at coral reef health across a gradient of human disturbance. The islands ranged from uninhabited to serving as a home for over 9000 residents. Surveys found that uninhabited islands had high coral cover and fish biomass (Sandin et al. 2008). The microbial community on healthy reefs was evenly split between autotrophs and heterotrophs, while on Kiritimati, the most inhabited island, the microbial community was primarily heterotrophs. Microbes were also ~10 times more abundant on these inhabited reefs, while coral cover decreased and disease was much more prevalent (Dinsdale et al. 2008).

In April 2009, we participated in a cruise to the Southern Line Islands to characterize pristine coral reefs. The group included most of the collaborators from the NLI trip, as well as a group from National Geographic to photo-document the reefs (http://ocean.nationalgeographic.com/). The islands visited on this trip lie just south of the equator, and have been uninhabited for 100 years or more. As such, they are home to some of the last remaining pristine coral reefs on the planet. We are again characterizing microbial and viral communities at these islands.

We are also trying to use metabolic theory to link performance of individual organisms to the whole community ecology of coral reefs, using data collected across the Pacific. We are interested in how fishing-related alterations in trophic structure affect community-level energy use and biomass production. Allometric power laws provide the basis for assessing the relative importance of fish vs. microbial components across coral reefs of varying degrees of health. Metabolic theory predicts that rates of energy and nutrient use should be approximately equal for all size categories within a restricted taxonomic group. However, when both fish and microbes are considered, we want to know if the flow of energy and materials through coral reef ecosystems is dominated by small or large organisms (i.e., microbes or fish).
Collaborators: Dr. Jennifer Smith, Dr. Stuart Sandin

 

[Timfish]

Here you go Pat,

. . .

@Timfish
Help a brother out with a link to a podcast from University of Southern California with Rowler

PS: When I goggled microbes in marine seas, I got this research which is above my pay grade with more degrees than thermometers. Because words have precise meanings, I like using a scientific reference for these details.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4711185/

. . .

"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


Here's a couple more videos by scientists studying corals.

Changing Seas - Mysterious Microbes


Microbial view of Coral Decline



As far as corals being bacteriavores that makes as much sense to me as saying mammals are bacteriavores. Certianly bacteria are consumed when particulate stuff is taken in but the coral microbiome is very complex. And the food webs on reefs are also very complex. The carbon and nitrogen (non redfieldian ratios) enriched detritus sloughed off by sponges and makes it's way into the food webs within hours is one example. Since many of the microbial stuff are essential components of a coral's immunity the roles of some microbes in protecting corals from pathogenic microbes has to be taken into account (1) (2) (3). If corals are indeed bacteriavores and feeding off the bacteria in their surface mucus, what is the mechanism corals use to distinguish beneficial microbial stuff from non beneficial microbial stuff?

Delbeek and Veron's observations add an additional layer of complexity, and also help explain Darwin's Paradox.

"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

"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


What puzzles me, looking at the distribution of phosphate in the ocean, is where the idea corals needed to be kept in super low phosphate levels. There's a clear diffusion gradient of phosphate in the oceans - highest in deep water, lower at the surface away from reefs where phytoplankton use it and lowest on coral reefs. That seems to indicate a pretty heavy demand for phosphate, not that the ideal phosphate level is super low.

 

[Randy Holmes-Farley]

What puzzles me, looking at the distribution of phosphate in the ocean, is where the idea corals needed to be kept in super low phosphate levels. There's a clear diffusion gradient of phosphate in the oceans - highest in deep water, lower at the surface away from reefs where phytoplankton use it and lowest on coral reefs. That seems to indicate a pretty heavy demand for phosphate, not that the ideal phosphate level is super low.

IMO, our incomplete and divergent views on nutrient effects on hard corals is because the whole field still has a poor understanding, and there are likely to be additional complexities yet to be understood:

Calcification response of reef corals to seasonal upwelling in the northern Arabian Sea (Masirah Island, Oman)

Abstract. Tropical shallow-water reefs are the most diverse ecosystems in the ocean. Their persistence rests upon adequate calcification rates of the reef building biota, such as reef corals. Coral calcification is favoured in oligotrophic environments with high seawater saturation states of...

bg.copernicus.org

"In general, reef corals are highly adapted to oligotrophic waters with micro-algae symbionts to allow an efficient use of essential nutrients (Muscatine and Porter, 1977). This enables outcompeting other fast-growing biota on a reef whose growth is inhibited by the undersupply of nutrients (Vermeij et al., 2010; Barott and Rohwer, 2012). Strong eutrophication disturbs this adaptive advantage, leading to harmful algal blooms followed by reef coral mass mortality and reef destruction due to the increasing abundance of bioeroders (Al Shehhi et al., 2014; Hallock, 1988). However, moderate increases in certain nutrients such as ortho-phosphate () have been shown to promote the linear extension rate (Bucher and Harrison, 2001; Dunn et al., 2012; Koop et al., 2001). The opposite effect is reported for nitrate () even though the calcification response is less pronounced compared to (Koop et al., 2001). In general, increasing eutrophy is considered to cause reef corals to sacrifice skeletal density for increased extension rate (“stretching modulation of skeletal growth”), which can either lead to enhanced, constant or reduced rates of calcification (Carricart-Ganivet and Merino, 2001; Carricart-Ganivet, 2004; D'Olivo et al., 2013; Manzello et al., 2015)."

 

[jda]

I would like to see any of these tests reconcile the many forms that phosphorus is available and not just orthophosphate.

In my tanks there is 8x10x more P available through Hach Total P test kit than with ortho only. I asked some researchers in Florida and the same was about 25-30x more in the reefs that they study.

Ortho is just such a small part, it appears.

Some of the divergent views are also on the approach, IMO. Some just look at ortho in the wild and ignore the other forms and then only dose ortho in captivity - no wonder they need more ortho since they did not include the others. There is some research that looks at total P and they are less divergent than other subsets of studies.

 

[Randy Holmes-Farley]

Ortho is just such a small part, it appears.

I think there's a bit of a chicken vs egg issue here. If orthophosphate is what organisms most want, and can take up, they will take it up preferentially and drive down its concentration relative to things they do not want or cannot take up as easily.

not sure if you have seen this, but there's a lot of discussion here:

https://esajournals.onlinelibrary.wiley.com/doi/full/10.1002/ecm.1217

 

[Lasse]

I would like to see any of these tests reconcile the many forms that phosphorus is available and not just orthophosphate.

In my tanks there is 8x10x more P available through Hach Total P test kit than with ortho only. I asked some researchers in Florida and the same was about 25-30x more in the reefs that they study.

IMO - orthophosphate is the only P form that can be taken up by a primary producer as the zooxanthellae. Even on cases ther the coral animal transport P waste to the zooxanthellae. However in that case the host have on prey on organisms that contain organic P and the host will release orthophosphate internal to the algae. In this study - that P source was blocked

not sure if you have seen this, but there's a lot of discussion here:

I´m sorry - it is behind a paywall - it had been very interesting to see that article because it is basically the same scientist group that have produce the article we discuss here.

Sincerely Lasse