What is a refugium?

[firstchevalier]

Okay, and it also doesn't change the fact that the 2 nicest looking reef tanks in the world (IMHO), at Atlantis Marine World and Waikiki Aquarium, are both run with big fat skimmers, hardly a trace of macro, and certainly no dedicated refugium...

 

Double

 

So let me get this straight...you're comparing a home pico tank to a professional swimming-pool sized tank? Isn't that like comparing a blue whale to the krill it eats?

 

Granted your point is well made that awesome professional rref systems don't use refugiums but they do have something the home tank will almost never have and that is a professional, full-time marine biologist monitoring and maintaining it. What we do at home sometimes is out of necessity so we don't have to do other things IMO.

 

Bottom line you can run the tank successfully in either configuration.

[yardboy]

Okay, and it also doesn't change the fact that the 2 nicest looking reef tanks in the world (IMHO), at Atlantis Marine World and Waikiki Aquarium, are both run with big fat skimmers, hardly a trace of macro, and certainly no dedicated refugium...

 

Double

 

At least at one time the Museum of Natural History at the Smithsonian had a refugium, and the Great Barrier Reef Aquarium in Australia used algae scrubbers. The Wakiki Aquarium uses a continuous flow of salt water from an underground aquifer for their tanks, so maybe a refugium isn't needed.

Frankly, I use refugiums on some tanks and skimmers on others, and on some I use both.

[wombat]

Nicest reefs I've seen had macro and no skimmer. Oh wait, sorry, that was the ocean.

 

They didn't have a refugium either.

 

The reefs with the most abundant coral growth are defined by their LACK of macroalgae...

 

http://www.springerlink.com/content/21d3df6lrddy6weh/

 

Abstract  Degradation of coral reefs often involves a “phase shift” from abundant coral to abundant macroalgae. This paper critically reviews the roles of nutrient increases in such phase shifts.

[yardboy]

Read further.

Quote: "unlikely to lead to phase shifts simply by enhancing algal growth rates and hence allowing overgrowth of corals, unless herbivory is unusually or artificially low."

 

A tang in your display with corals and a separate "refuge" from the tang for the macro's could very well keep inorganic nutrients down and corals gowing.

Oh, and there are indeed refugiums in the ocean.

Just a sec, got a pic

[wombat]

So let me get this straight...you're comparing a home pico tank to a professional swimming-pool sized tank? Isn't that like comparing a blue whale to the krill it eats?

 

Yes! They are both closed systems that are pico sized compared to the ocean. The principles of water filtration and husbandry are the same.

 

If we were comparing cellular biology of a mouse and a whale you'd see they have many similarities.

 

Bottom line you can run the tank successfully in either configuration.

 

Agreed.

 

 

At least at one time the Museum of Natural History at the Smithsonian had a refugium, and the Great Barrier Reef Aquarium in Australia used algae scrubbers. The Wakiki Aquarium uses a continuous flow of salt water from an underground aquifer for their tanks, so maybe a refugium isn't needed.

Frankly, I use refugiums on some tanks and skimmers on others, and on some I use both.

 

I don't have pictures of the Smithsonian reef but I don't think it's a great example of the potential of a captive reef system. Same with AustraliaHQ, and they tore out their algae scrubbers from what I understand.

[yardboy]

Okay, here's a pic. Note the mangroves on the left, seagrass and algae in the foreground, and the stake and rocks on the outside mark the edge of an extensive reef. Why tangs don't go into the algae beds I'm not sure; too shallow or not palatable, I don't know, but I didn't ever see any there. As an aside, I did not see any corals in the area where the tide went out, unlike some pics I've seen in Fiji, where many acropora an other reef species are exposed to air during low tide.

[wombat]

Okay, here's a pic. Note the mangroves on the left, seagrass and algae in the foreground, and the stake and rocks on the outside mark the edge of an extensive reef. Why tangs don't go into the algae beds I'm not sure; too shallow or not palatable, I don't know, but I didn't ever see any there. As an aside, I did not see any corals in the area where the tide went out, unlike some pics I've seen in Fiji, where many acropora an other reef species are exposed to air during low tide.[/img]

 

So there were no fish inside that seagrass area, or just no tangs?

[wombat]

Read further.

Quote: "unlikely to lead to phase shifts simply by enhancing algal growth rates and hence allowing overgrowth of corals, unless herbivory is unusually or artificially low."

 

My post was in response to:

 

Nicest reefs I've seen had macro

 

A tang in your display with corals and a separate "refuge" from the tang for the macro's could very well keep inorganic nutrients down and corals gowing.

 

I don't disagree with that at all.

[yardboy]

So there were no fish inside that seagrass area, or just no tangs?

 

Well, duh. I was thinking strictly of tangs as herbivores, but of course there were many fish there, and certainly some of them were herbivores. Sorry about that. The difference would be that in a closed system like a tank, the foraging area is much more limited for anything,so they could easily eat every nub of macroalgae, while the pictured environment would be much more extensive, limiting the possibility of completely foraging an area clean.

For that matter, the level of macroalgae, or at least stuff like algae that a tang would eat, must have been extensive even on the reef, because there were many of them, constantly foraging all throughout the reef area. I can easily imagine that it wouldn't take long at all for algae to take over the reef if the herbivores, like tangs, were removed.

[wombat]

At least at one time the Museum of Natural History at the Smithsonian had a refugium, and the Great Barrier Reef Aquarium in Australia used algae scrubbers. The Wakiki Aquarium uses a continuous flow of salt water from an underground aquifer for their tanks, so maybe a refugium isn't needed.

Frankly, I use refugiums on some tanks and skimmers on others, and on some I use both.

 

More on this:

 

http://en.microcosmaquariumexplorer.com/wi...r_Reef_Aquarium

 

Adopting Adey's designs, the GBR Aquarium was equipped with 72 separate algae-scrubbers as the aquarium’s only filtration. The scrubbers were placed on the roof, and exposed to natural sunlight and artificial illumination. The idea was to circulate the aquarium's water constantly over the beds of growing green turf and let the natural bio-chemical processes of algae growth absorb nutrients and maintain a natural biological balance in the system.

 

A report in Australian Science Magazine was optimistic: “Algae are the key to keeping the water clean. They remove wastes from the water and put oxygen back in.” (Eager and Peterson, 1988).

 

It was a fine theory.

 

Lessons Learned

Unfortunately time has shown that this does not work. In fact, the opposite seems to have happened! The algae filtration impoverished the system, the corals grew poorly and there was very little microfauna life surviving in the sand or in the live rock.

 

Today the Reef HQ team, under the supervision of Dr. Kirsten Michalek-Wagner, now works to improve the aquarium and bring back coral growth and keep microlife thriving in the system.

 

They experiment with the addition of calcium and have modified the aquarium to be a partial open system taking in water from Ross Creek just outside the wharf where the facility is situated. 17 years after opening the GBR-Aquarium and after much trouble, the algal scrubbers have finally been removed and replaced with protein skimmers. The Reef HQ biologists believe that the skimmers do a much better job of removing dissolved organics than the old algal turf systems.

[Biotoper]

A "refugium" with sand, lr rubble, and macroalgae is quite different than a algal or turf scrubber consisting of screen(s) with microalgae growing on it. I have no experience with turf scrubbers, but it seems to me they would need to be harvested almost on a daily basis to not end up just exuding as much nutrients as they take up (and more importantly for me - they're ugly to look at). In tanks with lots of fish and lots of big fish, like most public aquariums, I agree that a skimmer and lack of anywhere like a refugium or DSB where lots of waste can collect is the much safer route.

[Mordoff]

wow over a thousand views

[Mr. Fosi]

It doesn't surprise me that they would be getting better results without the microalgae. Anyone who advocates using such a system is lacking in basic knowledge about microalgae ecology and physiology.

 

Microalgae produce quite a bit of dissolved organic matter when they are photosynthesizing. Not all algae are equal in the production of these exopolysacharride (EPS) compounds but there is quite a bit known about diatoms in the literature. There was work being done on this back into the 50's so it isn't like it is new info.

[wombat]

It doesn't surprise me that they would be getting better results without the microalgae. Anyone who advocates using such a system is lacking in basic knowledge about microalgae ecology and physiology.

 

Hehe, have you read SantaMonica's posts?

 

Microalgae produce quite a bit of dissolved organic matter when they are photosynthesizing. Not all algae are equal in the production of these exopolysacharride (EPS) compounds but there is quite a bit known about diatoms in the literature.

 

There's a new word to learn for the day.

 

Any info in this respect on some of the specific macro/microalgaes that are common in reef aquaria? It would be interesting to compare them. Off to do some searching...

[Mr. Fosi]

From what I have read (since it plays a largeish role in my dissertation), EPS is a thing of bacteria and microalage not macroalgae. I have plenty of EPS papers but none of them on specifically aquarium species. Most of the studies have been done in estuaries either here in the USA or in northern Europe.

 

It doesn't really matter where the studies were done or in what system they were done because the production of EPS is a key part of many microalgae's physiology.

 

I am sure that species info would be interesting but you will find such detailed info lacking since IDing microalgae, even things as easy to see as diatoms, isn't easy. You will more easily find information about different algae classes: Dinophyta, Prymnesiophyta, etc...