Wild substrate for Thallasia

[graveyardworm]

The question comes up frequently "Whats a good substrate for my seagrass?" , and the answer is generally any substrate will do, with some detail given to the various substrates we commonly use. So my question is what kind of substrates would Thallasia be found in most often in the wild. The beaches up here wjere I live are primarily a silica type sand, and from memory a brief stay in Florida about 20 years ago on the Gulf side I'm pretty sure I remember it being silica as well.

 

[Samala]

I like this question! This is what I was able to find in my research for the RK article earlier this year:

Soil characteristics for seagrass beds both offshore and in lagoons in the Caribbean are 75-95% sand, 5-15 % mud (silt and clay) with the remainder of the texture made up of coarser shell fragments. In composition they range from 1-2.5% organic material and are mixes of calcium carbonate and silica sand.

I find that more northern Thalassia in the lagoon and between other barrier island systems tends to be more silica sand and oyster shell hash than calcium carbonate from coral and calcerous macroalgae sources. The farther south you progress the more it turns to calcerous aragonite-like sources. I'm not positive its all aragonite at all in the Caribbean. Might be other types of calcium carbonate sand. I'm not sure if that holds true for the Caribbean nations that have Thalassia beds as their geology might mean that the sand is all calcium carbonate.

For what its worth, Syringodium, Halophila, Halodule all do very well in 50/50 and straight mixes of silica and aragonite. They dont seem to show much preference for one over the other.

You'll also notice theres quite a range for silt/clay fractions of the submerged soils in seagrass beds noted above, and the overall organic content wasnt as high at the sampled sites as you might expect.

That also seems to vary. Some spots are super clean and sand from the bed hardly has any detritus out of a 8" core. In other areas right now I'm seeing manatee grass stands (that are almost entirely covered in epiphytic growth) that have oozy muck about 4" down into the substrate before you start to hit sand again. Most of that is probably organic material that is decomposing.

I wonder what else is out there for information that we havent found yet.

Thoughts, anyone?

>Sarah

 

[graveyardworm]

So would you say that the majority of the Thallasia available to use in the US comes from beds which are mostly silica sand?

Anyone keeping Thallasia, could you please describe the substrate you have it in, the age of the bed, and try to describe growth.

 

[Samala]

Mmm.. I'm not sure. I think most Thalassia is coming to us from outside the US, and may be from primarily more calcium carbonate source soils. Someone with better contacts in the industry would know more than I in this area.

Me.. Thalassia.. 50/50 mix silica/arag and 100% silica for seedlings including 10% muck/organic. Growing pretty well right now.

>Sarah

 

[graveyardworm]

Thanks Sarah, mines in 100% arag, no muck, growing okay, but hasnt sent up a new rhizome yet, I've had it about 6 mos.

 

[3D-Reef]

I read an artical this morning that touches on substrate when transplanting. here

 

[graveyardworm]

Thanks 3D, I havent had enough time to read the entire article, but it sound as though new rhizome production is going to be on the order of years rather than months like I thought. Guess I'll just have to wait.