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Evidence for algae-based nutrient export stunting SPS?


AlanM

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So this article is making the rounds today:

 

http://www.bbc.com/news/science-environment-28880216

 

about how both corals and fish can sense a reef that has been taken over by seaweed, which I assume means macro and micro algae, and isn't healthy.  I assume that there is some kind of chemical battle taking place between the fish, algae, and coral, that prevents the coral from spawning and turns off the fish from the area.

 

Think this would occur in captive tanks which grow lots of algae for nutrient export?  I'm asking because mine is one of those.  I've read a few stories proposing that algae turf scrubbers and such will affect coral growth, but never saw evidence. 

 

What do folks here think?  Maybe I should turn off my fuge light, clean it all out really good and start watching nitrate and phosphate just to see what happens.

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I've seen some algae take hold in places and the coral either recedes or does not encrust the area. You can sometimes even see this on a frag plug. It's also the reason why Coral Reef Foundation used to send volunteer divers out to scrub algae from their coral propagation substrates. I'm sure that there's something going on there. (I'm not sure that the effect goes much further than the interface area, though.)

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Thanks for the link, Alan. It's a very interesting article.

 

Without analyzing the theory too deeply, I am first wondering how the researchers were able to not contaminate the 2 different water samples that the fish supposedly chose from, which assumes they were somehow connected. I don't have an account for the journal but assume it's outlined there...???

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I checked out the research, and it is pretty cool. Taken in collection with a lot of other great conservation work, it provides more data on why it is so hard to restart a coral reef.

 

Alan, I wouldn't shut down your fuge just yet, though.

 

As Tom mentioned, it is known that some algae secrete molecules that irritate corals and prevent growth -- but that is through direct contact. That's why herbivores, urchins, and the like are key supporting elements to a healthy coral reef. The researchers were wondering if there were also chemical cues in the water.

 

Jack -- they used what is known as a Atema Flume (developed by Jella Atema at BU http://people.bu.edu/atema/index_files/page0004.html) this set up has been used in several studies looking for chemical cues in marine systems.

 

The article is great, but it shouldn't change our practices.

 

1) They looked at motile juvenile acropora and fish. It's known that these tiny swimmers are quite selective as to where they settle, but the researchers are trying to learn more about how the choices are made. This research offers nothing for the effect of chemical cues on adult coral and fish.

 

2) The seaweed they looked at were: Padina gymnospora, Sargassum polycystum, and Galaxaura filamentosa. I don't think those are really present in the trade as export macroalgae.

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Cool, thanks for the detailed look at the article.  I didn't get most of it. 

 

I think ousnakebyte was saying in his talk last year that they would get better settling rates of coral larvae if they had coralline algae covering the tiles instead of using bare tiles.  Like the coralline makes a good spot for them because it keeps the green stuff out.

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No prob -- its Friday and I have a subscription to Science so why not.  :-)

 

As for coralline -- yes. In that same article, coral settling increased by 800% in the presence of coralline.

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Kind of a bummer because my chaeto nearly all disappeared in the last fuge cleanout and I was looking for some excuse for someone to tell me to turn off my fuge.  It grows heroic amounts of other algae, so I know it's doing something, but the chaeto is easier to handle.

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I think that it would be naive to discuss this sort of natural phenomenon without taking into consideration that our tanks do not exist in nature. We are lucky enough to be able to create absolutely ideal conditions for algae to grow remotely from our display tanks. We are also luck enough to have protein skimmers at our expense which quite efficiently remove any hydrophilic organic compounds as well as other means to control chemicals which may cause our corals to exhibit stunted growth.

 

I do definitely believe that algae is capable of repelling SPS specifically, enough to prevent encrusting over algae in a battle for space. At the same time, I believe that a healthy, well-maintained tank will prevail. Not long ago, I had some base recession due to an error which I made in my dosing. After correcting it, algae had grown on the base of a few of the corals and the corals have now encrusted outward around the algae and are slowly encompassing it without touching it. Ultimately, I believe that the existence of algae remotely located and controlled in the system will always be beneficial because it  helps to maintain low inorganic nutrient levels which are known to inhibit calcification.

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I think that it would be naive to discuss this sort of natural phenomenon without taking into consideration that our tanks do not exist in nature. We are lucky enough to be able to create absolutely ideal conditions for algae to grow remotely from our display tanks. We are also luck enough to have protein skimmers at our expense which quite efficiently remove any hydrophilic organic compounds as well as other means to control chemicals which may cause our corals to exhibit stunted growth.

 

I do definitely believe that algae is capable of repelling SPS specifically, enough to prevent encrusting over algae in a battle for space. At the same time, I believe that a healthy, well-maintained tank will prevail. Not long ago, I had some base recession due to an error which I made in my dosing. After correcting it, algae had grown on the base of a few of the corals and the corals have now encrusted outward around the algae and are slowly encompassing it without touching it. Ultimately, I believe that the existence of algae remotely located and controlled in the system will always be beneficial because it  helps to maintain low inorganic nutrient levels which are known to inhibit calcification.

+1. Great post.

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