Marine Topic Of The Week, 1/19-1/26/07

[steelhealr]

One of the thrills of owning a marine tank is the eye-catching vivid colors of our reef and inhabitants. Live rock, per se, doesn't really have color, so, where do those wonderful hues of pink and purple and green come from? They come from living plants called coralline algae. Do you understand what it is?

Your tank looks great

Coralline algae is a plant from the phylum Rhodophyta, or, red algae. It is an encrusting type algae that is found deposited on your live rock (epiphytic) or can actually grow on animals (epizoic). You've probably struggled at one point scraping it off the wall of your tank. That is because it has calcareous deposits within it's cell wall. The color is predominantly pink, but, as we all know, coralline algae can come in blues, greens and purple shades.

There are basicly two types of coralline algae:

• geniculate, or, growing like plant
  
  
  
  
  
  
• non-geniculate, or encrusting, which we see frequently in our tanks

What does that stuff do?

In the natural environment, coralline algae (non-geniculate) helps with the following:

1. helps to cement the reef to together
2. provides calcium/calcareous material to the reef
3. provides the above as calcite, a good reef 'glue'
4. helps prevent shore erosion by forming algal ridges, the strong area of the reef facing the pounding surf
   
   
   
   
   Number 3 is the algal ridge
   
   
   
   
   
   
   
   
5. providing matrix for some preparations of dental implants
6. building stones in construction

But it has needs

Coralline algae, like any living thing, requires several things to survive in your tank. It is a photosynthetic plant that needs light and calcium to survive. Hence, some average requirements include:

• light, moderate
• calcium, 400-440 mg/l
• phophates at 0 and nitrates generally low, 0-10
• Mg2+ 1400 mg/l

Great stuff for my tank, or what?

Well, yes...coralline can be good for your tank but, like many things, can have it's own drawbacks:

Advantages

1. provides beautiful color to the tank
2. can be easily seeded from scrapings from other tanks
3. when encrusting, can outcompete nuisance algaes from taking hold
4. can help to stabilize your aquascaping
5. healthy coralline algae growth usually implies good water parameters
6. provides food for various invertebrates, eg, urchins (however, they can also strip it clean)

Disadvantages

• growth is encrusting and can cover equipment
• encrusting the aquarium walls can reduce vision
  
  
  
  
• scraping is time-consuming and requires elbow grease
• extensive growth can deplete calcium and magnesium levels in the water column requiring expensive calcium dosing equipment and additives; alkalinity can be affected as well
• some claim that extensive encrusting can reduce the biological filter by covering up interstices in the LR

Just a brief note. Hope this helps.

SH

 

[tmreynolds]

Very interesting, thanks

 

[Ter]

I agree interesting..
"some claim that extensive encrusting can reduce the biological filter by covering up interstices in the LR"
I had never thought about that before
Ter

 

[steelhealr]

Yes....coralline algae can be quite encrusting, however, I'm sure a thin layer would have a certain permeability. I don't think there are any studies on this to corroborate this theory though. I can tell you, however, as the owner of a longpsine urchin, they WILL strip your LR of coralline. SH

 

[steelhealr]

Unpinned and released. SH

 

[BigIan]

very interesting thank you good sir....

 

[steelhealr]

I try to keep a topic of the week going in the pinned section. Thanks. SH

 

[steelhealr]

Bump