WaterNotes

First off, lets not imagine I will really be making weekly reports of this tank each week from now on… I was simply going through photos I took of the tank tonight, and upon comparison, noted an amazing amount of growth out of the stargrass. The shoal grass is coming right along as well, manatee seems to need more time to establish itself. New blades on these plants are very easy to see as the blades have no epiphyte growth and are pretty much electric green.

At any rate, note the central area of the two following photos and you’ll see what I mean as far as growth in the star grass. The large brownish blade set fell apart (I’m hoping due to stress from transplanting) so its the major difference in the pictures. But note the blade sets to the left and right of its original position. Sets that existed in the earlier photo opened up considerably, and now
new sets are growing, and the rhizome is extending! Very good news for me! The time lapse between photos is six days – quite amazing I think.

3.13

3.15

3.19

Corner area of stargrass with these two big colonies – both have at least four growing tips comin from them, note the hanging growing tip on the tall colony:

And this the latest full tank shot at the end of week one:

The other notes I have about the stargrass so far are just a few observations about this species, which, as far as I know, has not been kept by other hobbyists. (Email me if you have!) First, the
stargrass obviously has a fantastic growth rate. Much faster than Halodule or Syringodium in my tanks conditions. However the leaves are quite small compared to the size of some of the leaves on the colonies while in the wild. Also, the stem for the leaf sets was much longer.

If I had to guess, I’d imagine that the leaves and stems were longer and bigger in the wild because the grass was limited mostly by light. Halophila species seem to prefer to be in deep water if
you look at all the literature (see seagrass articles). So, under bright light, we get smaller leaf sets,
almost explosive growth (faster than freshwater Hygrophila it seems).

Second, there is a distinct difference in leaf color under my current lighting regime and water conditions. If you take a look at the UVb article I listed in the references pages you may note that the authors concluded that star grass doesnt have any photoprotective adaptations to high light. This isnt so surprising considering their normal habitat conditions deep in the beds. However, they will produce anthocyanins (the same pigmented molecules that makes blueberries blue/purple) if exposed to light stress. Anthocyanin is sort of like the plant version of human melanin pigment – it helps to protect from overexposure to UV rays, in particular the damaging UVb rays. In my tank the leaf sets that were from wild conditions did gradually turn deep red colors. They also eventually fell off under these bright tank conditions.. possibly because the protection from the anthocyanin development wasnt enough.

However, as you can see, new leaf sets are bright green and stay bright green. This suggests that, whil individual Halophila leaves cannot adapt readily to changes in their lighting conditions, new leaf sets can. I need to observe the new blade sets for another week or so to be sure they dont turn to mush, but that doesnt seem likely. The lesson here for Halophila: Stargrass can take a wide range of light levels and leaf physiological characteristics seem to change with lighting intensity, much like other aquatic plants. Stargrass also does not seem to enjoy rapid changes in its lighting regime, and will drop leaves much like the ornamental land plant Ficus but will adapt to these changes through growth.

Otherwise, I’m still waiting for Flourish Excel to arrive so I started a DIY CO2 reactor on the tank. This does drop the pH on the tank some, into the high 7’s and I suggest this to no one. pH stress is a serious buisness in fish, I’m attempting this since I have only two grass shrimp and two horseshoe crabs to lose. Both are not that dear to me – though I do think they’re neat to watch. CO2 supplementation started yesterday evening.

I am dosing fertilizers of a sort to this tank in the form of PMDD – which is known very well in the freshwater planted aquaria circles. It is a homebrew of macro and micro nutrients needed by aquatic
plants – most notably nitrate, phosphorus, potassium, magnesium and iron. I’m not sure if this is really helping things at the moment, but I have noticed that no major nuisance algae has started in
the tank.. just a slight case of diatomaceous algae, to be expected in a young tank.