Study shows that corals prefer to grow touching turf

[SantaMonica]

Note: Scrubbers are supposed to grow green hair, which is not covered in this study. But many people still think that scrubbers grow turf, and this study does include the amount of microbes related to turf. Brackets "[ ]" added.


"Microbial to reef scale interactions between the reef-building coral Montastraea annularis and benthic algae", Proceedings of the Royal Society, Biological Sciences, Nov 2011
http://rspb.royalsocietypublishing.org/ ... 2155.short (http://rspb.royalsocietypublishing.org/content/early/2011/11/15/rspb.2011.2155.short)


Page 2, Col 1, (a)

"This study was conducted on the island of Curacao, former Netherlands Antilles"

Page 4, Col 2, (b)...

The [...] coral-associated bacterial communities increased in tissues near [coralline] and [dictyota], but decreased for coral tissue adjacent to [halimeda] or turf algae.

Page 5, Col 1...

We found [anaerobic microbes] present in coral tissue near or at interfaces with three of the four groups of algae: 8.5 percent relative abundance at [coralline] interfaces; 2.2 percent relative abundance near [dictyota] interfaces, 2 percent relative abundance near [halimeda] interfaces; but absent near and at interfaces with turf algae.

Page 5, Col 2, (c)...

Every coral colony observed [on the natural Curacao reef] was interacting with at least one type of alga, with an average of 61 to 80 percent of the coral perimeter involved in any type of algal interaction. Interactions with turf algae were the most abundant, accounting for 32 to 58 percent of the coral edge. [In other words, the corals grew this way, touching the algae, naturally. And more of them grew and reproduced while actually touching turf algae, than grew anywhere else.]

Page 7, Col 1...

This study is the first to identify the types of bacteria present along coral-algal interactions, and we find that bacterial stress response pathways were reduced at coral interfaces with [coralline], [dictyota] and turf algae.

[xerophyte_nyc]

Huh????

Read this article more carefully please. "our observations indicate that the important reef building species of the Caribbean genus Montastraea are directly stressed by neighbouring turf algae despite the fact that Montastraea species were historically characterized as competitively superior species [45]. Turf algae are theorized to negatively influence the growth, reproduction, and feeding efficiency of corals, which would explain the reduction in coral fitness observed in this study







Note: Scrubbers are supposed to grow green hair, which is not covered in this study. But many people still think that scrubbers grow turf, and this study does include the amount of microbes related to turf. Brackets "[ ]" added.


"Microbial to reef scale interactions between the reef-building coral Montastraea annularis and benthic algae", Proceedings of the Royal Society, Biological Sciences, Nov 2011
http://rspb.royalsocietypublishing.org/ ... 2155.short (http://rspb.royalsocietypublishing.org/content/early/2011/11/15/rspb.2011.2155.short)


Page 2, Col 1, (a)

"This study was conducted on the island of Curacao, former Netherlands Antilles"

Page 4, Col 2, (b)...

The [...] coral-associated bacterial communities increased in tissues near [coralline] and [dictyota], but decreased for coral tissue adjacent to [halimeda] or turf algae.

Page 5, Col 1...

We found [anaerobic microbes] present in coral tissue near or at interfaces with three of the four groups of algae: 8.5 percent relative abundance at [coralline] interfaces; 2.2 percent relative abundance near [dictyota] interfaces, 2 percent relative abundance near [halimeda] interfaces; but absent near and at interfaces with turf algae.

Page 5, Col 2, (c)...

Every coral colony observed [on the natural Curacao reef] was interacting with at least one type of alga, with an average of 61 to 80 percent of the coral perimeter involved in any type of algal interaction. Interactions with turf algae were the most abundant, accounting for 32 to 58 percent of the coral edge. [In other words, the corals grew this way, touching the algae, naturally. And more of them grew and reproduced while actually touching turf algae, than grew anywhere else.]

Page 7, Col 1...

This study is the first to identify the types of bacteria present along coral-algal interactions, and we find that bacterial stress response pathways were reduced at coral interfaces with [coralline], [dictyota] and turf algae.

[Garf]

http://i1269.photobucket.com/albums/jj597/Garf1971/3e1488bfbbc5d181e61612cfefc88684.jpg

[SantaMonica]

You are forgetting the fact that the corals grew there in the first place, touching the algae, more (at least) thousands of years. The study is about the increase of algae in the last 20 years or so.

All reefs are like this, with large amounts of algae intermixed within the algae growth.

[Ace25]

I draw a completely different conclusion based on the latest research. In the ocean algae and corals touching is like living with an obnoxious roommate that you can't get rid of. Just because it isn't bad enough to kill the coral unless it gets out of control doesn't mean the coral is happy and healthy. Imagine how much faster the coral would grow without the algae touching it which uses up energy fighting the algae instead of growth. Actually I don't have to imagine that, others have done the research and proven it.

In the tank we can manually control macro algae near corals by interaction, ie. good clean up crew, manual removal, keeping nutrients levels stable and acceptable, keeping and maintaining good bacteria and microfauna levels, etc. While the ocean does have a lot of diversity, in one example of algae winning there are places it can't maintain a balanced nutrient level due to fertilizer run off from farmlands, which makes algae out compete corals in turn smothering and killing them. Raising CO2 levels raise water temperature which leads to coral bleaching. There are so many factors in the ocean, more today than ever, that gives algae an advantage over corals. Corals are a very adaptable animal though, and we are finding that some high light loving corals are moving deeper in the ocean and adapting to less light in order to get out of the warmer waters and away from algae.

http://www.advancedaquarist.com/blog/great-barrier-reef-acropora-found-at-410-feet

[Garf]

I just don't understand that on this thread the response is along the lines of "algae is good for corals and they love growing next to each other" yet on another thread currently active, something along the lines of "algae is bad for corals, which is why we need to grow them in a separate box", is the solution. Clarification would be nice, as I'm sure there must be a reason.

[Amphiprion]

Huh????

Read this article more carefully please. "our observations indicate that the important reef building species of the Caribbean genus Montastraea are directly stressed by neighbouring turf algae despite the fact that Montastraea species were historically characterized as competitively superior species [45]. Turf algae are theorized to negatively influence the growth, reproduction, and feeding efficiency of corals, which would explain the reduction in coral fitness observed in this study



I draw a completely different conclusion based on the latest research. In the ocean algae and corals touching is like living with an obnoxious roommate that you can't get rid of. Just because it isn't bad enough to kill the coral unless it gets out of control doesn't mean the coral is happy and healthy. Imagine how much faster the coral would grow without the algae touching it which uses up energy fighting the algae instead of growth. Actually I don't have to imagine that, others have done the research and proven it.

In the tank we can manually control macro algae near corals by interaction, ie. good clean up crew, manual removal, keeping nutrients levels stable and acceptable, keeping and maintaining good bacteria and microfauna levels, etc. While the ocean does have a lot of diversity, in one example of algae winning there are places it can't maintain a balanced nutrient level due to fertilizer run off from farmlands, which makes algae out compete corals in turn smothering and killing them. Raising CO2 levels raise water temperature which leads to coral bleaching. There are so many factors in the ocean, more today than ever, that gives algae an advantage over corals. Corals are a very adaptable animal though, and we are finding that some high light loving corals are moving deeper in the ocean and adapting to less light in order to get out of the warmer waters and away from algae.

http://www.advancedaquarist.com/blog/great-barrier-reef-acropora-found-at-410-feet

Agreed. It has more to do with the ubiquity of turf algae than anything else, not that corals like it. They are competitors that evolved side-by-side. I don't think corals have to like algae for them to be useful, though. We don't have to grow them next to each other, luckily, otherwise I wouldn't be using a scrubber at all--at least not with corals.

[Ptyochromis]

The findings of the Influence of different algal interactions on corals across multiple spatial scales is clearly represented here:

http://rspb.royalsocietypublishing.org/content/early/2011/11/15/rspb.2011.2155/T1.expansion.html


You are forgetting the fact that the corals grew there in the first place, touching the algae, more (at least) thousands of years.


Where are you getting this information? The study discusses the exact opposite.
"coral reefs around the world are becoming increasingly dominated by benthic algae, resulting in a loss of habitat and biodiversity"

"Micro-scale interactions between benthic algae and the coral holobiont have far-reaching implications for the composition of the reef. [...] On reefs approaching a phase-shift from the coral-dominated to the algae-dominated state, the impacts of fleshy algae on the coral holobiont are worsened by increased fleshy algal cover and more abundant interactions with corals.
"Various disturbances on the reef (herbivore removal via overfishing, eutrophication, elevated sea surface temperature, etc.) undoubtedly influence these micro-scale interactions, affecting benthic composition at the reef scale."

The article provides far more support that the algae conditions are not the norm, and the increase in algae is related to human interaction.

The interaction between coral and turf algae are spelled out clearly:
" The most common coral–algal interactions observed were between corals and turf algae. These interactions were found to negatively affect the physiology of the coral holobiont by eliminating net oxygen production along the interface. While algal removal and coral recovery occurred in situ, DO measurements were taken in an aquarium. [...] The two species of macroalgae examined here also caused DO levels to decrease below ambient, but the magnitudes of their effects differed. Turf algae and many macroalgae have been shown to limit coral growth and negatively impact the bordering coral tissue, lower coral fecundity and inhibit larval settlement, thereby impacting corals on multiple scales in time and space.

Defining "coral holobiont":
"The coral holobiont is a selective environment for bacteria, as evidenced by the variety of stressors that the residents must counteract: host antibiotics, bacteria–bacteria antagonism, and dimethylsulphide (DMS), dimethylsulphoniopropionate (DMSP) and free radicals released by the zooxanthellae."

More on the bacteria, the study does find an increase in virulence with turf algae-
"[W]e find that bacterial stress response pathways were reduced at coral interfaces with CCA, D. bartayresiana and turf algae. Type III and IV secretion pathways, hallmarks of pathogenesis but important for some symbiotic interactions , were also lower at these three interface types, potentially indicating a breakdown of symbiosis."

"The coral–turf interface was the only one to show increased bacterial virulence pathways, suggesting that coral–bacterial symbiosis may be breaking down further here and shifting towards a more pathogenic state compared with the other coral–algal interfaces."

CCA (Coralline), correlated positively with benthic cover:
"Previous studies have also demonstrated that CCA are generally less detrimental to the health, growth and photosynthetic efficiency of adjacent coral tissue than turf algae. Because some species of CCA also promote coral settlement [30,31], their influence on corals is counter to that of turf algae examined here across multiple spatial scales."

While there is ample evidence in this study that direct contact with the algae is the most detrimental, there is strong evidence that DOCs released by algae are just as deleterious to coral.
"In contrast, DOC is a water-soluble product of photosynthesis that is potentially released by many algae [51,63] and does not require contact to affect the coral holobiont. Various forms of DOC released by algae have been shown to kill corals and increase microbial growth rates."

As much as I love using algae for filtration, this is something that should not be overlooked. It would be wise to take steps to mitigate the DOCs. The use of GAC and a protein skimmer can be highly effective.

[SantaMonica]

Page 5, Col 2, (c)...

Every coral colony observed [on the natural undisturbed Curacao reef] was interacting with at least one type of alga, with an average of 61 to 80 percent of the coral perimeter involved in any type of algal interaction. Interactions with turf algae were the most abundant, accounting for 32 to 58 percent of the coral edge. [In other words, the corals grew this way, touching the algae, naturally. And more of them grew and reproduced while actually touching turf algae, than grew anywhere else.]


The article provides far more support that the algae conditions are not the norm, and the increase in algae is related to human interaction.

More algae now with pollution etc, yes, but lots of algae always did. And... the more extra algae is absorbing the extra nutrients that are being added to the water. In other words, the new extra algae is reducing the effects of pollution etc; not causing it.

Yes of course if new algae grows on top of corals, they will die. But they grew side by side, touching, for ages. Some reef areas have 10 kg wet weight of benthic algae per square meter. And this does not include the phyto in the column.

Of course extra new coralline does not harm corals, because it does not grow over them.

DOC's do not build up; the water is DOC limited, consumed by bacteria faster than it can be produced. Besides, the DOC (vitamins, amino's, glucose etc) is what you buy and dose anyway, and, is what is put into natural reefs by the algae there.

[Ptyochromis]

Page 5, Col 2, (c)...
More algae now with pollution etc, yes, but lots of algae always did. And... the more extra algae is absorbing the extra nutrients that are being added to the water. In other words, the new extra algae is reducing the effects of pollution etc; not causing it.



Page 5, Col 2, (c)...


Yes of course if new algae grows on top of corals, they will die. But they grew side by side, touching, for ages. Some reef areas have 10 kg wet weight of benthic algae per square meter. And this does not include the phyto in the column.



Yes, alage would be sequestering the extra nutrients in the water. This would only accelerate the growth of algae. Algae is in direct competition with corals for space. Humans have altered the environment, giving algae a competitive advantage. This is not the normal state of things. Some benthic algae have even developed alleochemicals that are toxic to corals.


Instead of addressing the rest of your arguments one by one , I have transcribed the table from the article. Even if you don't want to read the article, you can see the findings in a nice low word format.




Measured attribute
Encrusting Coralline
Halimeda spp.
Turf algae
Fleshy Macroalgae


reef scale
Interactions on healthy reef
increase
decrease
decrease
decrease



Coral recruitment
promotes
inhibits
none/inhibits
inhibits



Coral fecundity
no data
no data
inhibits
inhibits


colony scale
shading and abrasion
absent
present
absent
present



tissue damage
absent/present
absent/present
present
present



bleaching
absent
present
present
present



photosynthesis inhibition (experiment)
no data
med
no data
low-high



Photosynthetic inhibition (natural)
none
no data
low
no data


Microbial scale
number of over represented bacterial taxa at interface
20
12
14
19



predicted bacterial metabolic subsystems enriched at interface
cell wall, cofactors, nucleotides, photosynthesis, respiration
membrane transport, aromatics, motility, stress response
virulence, potassium
carbohydrates


molecular scale
allelochemical impact on coral
no data
high
no data
high



DOC release
med
none-low
high
med-high



Oxygen change at interface
hyperoxic
[higher than normal oxygen]
below ambient
below ambient
below ambient