Seagrass tank: substrates to use?

[Samala]

I'm in the midst of planning a seagrass bed only tank, which seems to be a bit of a departure from the way most people use them in their systems (refugia use for nitrate removal). I was wondering if anyone on this board has/is maintained a seagrass tank and had any good tips to give before I got underway with this project.

Species I'd like to keep are paddlegrass/stargrass, manatee grass and eelgrass. I imagine I'll acquire all of these and see which species do best in the aquarium.

Now to the questions - lighting. I see lots of mentions on this board for using CF screw in type bulbs with daylight temperature (5000-6500K) but does anyone have a decent sense of how much light is needed? If we were using a watts per gallon average, how much would we say? 3 or 4 or 5? More?

Temperature. Some of the seagrasses I'm interested in have temperate zone ranges and have marked growing/dormant seasons. Will seagrass kept in a uniform temperature environment go dormant anyway? Do I need to allow for a cool season during the year?

And most importantly, the topic of the thread really, what sort of substrate would we say is best? Most people seem to keep them in deep sand beds which I will certainly follow - somewhere in the range of 5 or 6". In the wild the seagrasses are found in anoxic soil conditions (which is why they have developed an oxygen pumping system to move O2 down to their roots/rhizomes). Do we have any good guesses as to what sort of soil should be used in the tank?

I'm planning on an aragonite fine/coarse blend for the top layer. Could the bottom layer be mud harvested from a local marine mud flat area? Should I sterilize that mud or use it as a live mud addition to spark the tank to cycle and establish itself with filter feeders, bacteria, algaes, etc?

Any thoughts would be fantastic, I really appreciate the help!
Thanks for reading this long post!
>Sarah

 

[biomekanic]

Hi Sarah,
While I have a lack of hands on experience, I've researched this topic somewhat.

I'm not sure about the dormant cycle, billsreef & plantbrain would be the ones to ask.

Mud on the bottom: Man, I wish I had access to mud... *color me jealous*. I'd recommend getting it well away from any industrial/residential area. Being on the east coast and all, have you considered driving down to SC and collecting? I knew someone who collected mud during the summer and got all kinds of good stuff (snails, pods, worms, etc) out of it. The reason I bring up SC is that during the summer you get animals from the tropical Atlantic, hopefully they could better take the conditions in an aquarium (temperature wise).
If you decide to go the covered mud route, I'd recommened slowly covering the mud, say 1/4" inch every few days so the life in it can dig out.
Looking through the threads, Bill mentions that mud mixed in should work well.
If you decide to add LR to the tank, I'd also recommend using a PVC rack to hold it up.
Lighting: You might want to look at MH, seagrass is pretty demanding from what I understand.
There's a thread on here somewhere where Bill (billsreef the moderator) shows his new planted 29g seagrass tank.
Maybe it's time to pester him again to do a 'how I did it' thread...

 

[Samala]

Biomekanic, thanks for the thoughts.. but mud envy?? How very interesting.. dont you have mud in OR? Or have I got my geography all mixed up again. (Sheesh, American schools, eh? ) I really thought northern CA and Washington had eelgrass beds (ie. marine mud flats).

The gradual addition of sand is a fabulous idea, as is making a collection in South Carolina. The area I had in mind in my local area is apart of a major wildlife park (I have special permission to harvest some animals from the mud flat areas and sea grass beds). But, its at the tail end of the Delaware Bay, and we just had a major oil spill back in early December.. or maybe it was late November. Anywho, points along the Delaware River have never been so great for estuary health, being downstream from Philadelphia and Wilmington, DE and the heavily used ports in those areas. However, studies have been going on for this particular mud flat and sea grass bed areas and show that they are in really good health and have been for at least the last decade. I'll be doing some scouting looking for signs of oil impact anyway in those areas so I'll be able to decide if its still a good locality to collect mud from or not.

I am concerned about having temperate zone animals though, just as you mentioned. For instance one of the main critters I will be purposely avoiding on the flats is a very common snail, the eastern mud snail, Ilyanassa obsoleta. Some people use them in reefs and they do well at the high temperatures for a while, but this particular species has a dormancy period (going on right now) that just can't be avoided. Even when kept in constant temperature and constant photoperiod aquaria for a full six months following collection from very warm mud flats in the summer they seem to 'remember' winter and go dormant. Its very perplexing and makes them hard to work with in our labs!

Anywho my parents live in Titusville, FL right on the Indian River Lagoon so I think I will be having some mud from the Delaware Bay seagrass area and some from the Lagoon's sea grass beds. I'm still working on a provisional license for harvesting some mud and perhaps a few species of seagrass and possibly some horseshoe crabs (its a different genetic population from our Delaware ones). We'll see what they will let me do. If they let me collect in FL that should give me some tropical animals to work with.. :-D

I am still fiddling with lighting needs.. I may go MH but I really would rather stick to PC.. hmm. Decisions decisions!

Thanks again for the tips!
>Sarah

 

[piercho]

Hi Sarah, please go to the stickied thread at the top of the Marine Plants forum for Marine plants links. Then follow the thread I linked to the Indian River Lagoon (IRL) Seagrass community page. Go to the bottom of that page and follow the links to the descriptions of individual specie of seagrass. You should be able to derive quite a bit of seagrass information from there. Usefull print sources that have some information on seagrass communities are Adey, "Dynamic Aquaria"; and Micheal, "Reef Fishes Volume 1".

I was wondering if anyone on this board has/is maintained a seagrass tank

Yes, currently manatee grass, shoal grass, and some associated sandbed alga.

paddlegrass/stargrass, manatee grass and eelgrass. I imagine I'll acquire all of these and see which species do best in the aquarium

Turtle grass is the grass most commonly offered by dealers. Manatee grass, occasionally. Eelgrass (Zostera) and paddlegrass/stargrass are not collected for resale, as far as I know. I have seen shoal grass and widgeongrass (Ruppia) offered for sale. I'd recommend manatee grass, its the easiest IME.

does anyone have a decent sense of how much light is needed? If we were using a watts per gallon average, how much would we say? 3 or 4 or 5? More?

I use a single 250W 6500K for a 65G volume (36LX18WX25D). I do an average job (spider reflector and gloss white hood interior) of getting the light from the bulb into the tank. For tanks less than 16" (water surface to sandbed), I think PC or 150/175W single ended MH bulbs should be adequate. For deeper I'd recommend 250W MH. That is assuming you are using decent reflectors. For fixtures casting very tight light patterns, like the 150W double-ended MH, a 150W bulb may get adequate intensity as deep as a single-ended 250W bulb does. My opinion is that bulbs with a decent spread spectra, like the EYE 6500K, are the best choice.

Do I need to allow for a cool season during the year?

For turtle, shoal, paddle, and manatee grass; no. These have tropical distribution. Eel and widgeon grass are temperate, so may demand a dormant cycle, I don't know.

what sort of substrate would we say is best?

I used 5" of a very fine, heavily sedimented silica substrate taken from a local eelgrass bed. Other people have used fine carbonate sands sold as "aragonite" and/or "oolitic" with success. I have no experience with gravels, like would be used over a Jaubert plenum. I have no experience using substrates that are iron-rich, like would be used for a FW planted tank. My opinion is that the substrate needs to be allowed time to become sedimented. My observation is that sandbed alga grow toward sand/solid surface interfaces, while grass grows towards the deepest, most heavily sedimented sand. 4 or 5 inches is adequate, IME, but deeper may be better. IMO, there is no reason to try to layer grades of sand. The smallest stuff will work its way toward the bottom, eventually.

Seagrass takes some patience, IME. The only other advice I have is to avoid Diadema urchins in the tank until the grass growth is very robust. Fish like rabbitfish may nibble the tenderest growth, but in general grazers (except urchins) serve a useful function by cleaning the epiphytes off the blades.

 

[biomekanic]

re mud: the water here is cold, very, very cold. I don't think that the animals there would do very well unless I had a temperate setup. Alas, I don't have the money for that.

 

[Samala]

Piercho - Thanks so much for all the advice and info. I have been all over the Smithsonian's pages and read up in Dynamic Aquaria.. what an awesome book. Mostly I've been relying on academic papers and journals for source info for the tank. I got lucky and found sources for eelgrass, shoal, turtle, paddle and star.. but I'll be starting out with manatee grass (good to see you also recommend to start with it) and eelgrass.

Biomekanic - ahhh I forgot the water temperature issue. I remember a giant octopus tank and its side by side cold water anemone tank... brrr! I cant remember how low they kept them.. 54F? All I know is that you couldn't keep your hand in the water much longer than a minute.. must be close to your water since that's their home range. If this all pans out and I get a nice assortment of temperate/tropical animals and mud I'll send you some!

>Sarah

 

[piercho]

I'll trade pretty much anything for paddle and/or star grass. Bonus points if you can get it as "plugs" with roots in sediment. I have a variety of stony coral and zoanthids that may be of interest to you and should do well in a lagoonal tank. PM me and I'll send you a list of stuff I can trade. Or if your collector is willing I will pay them for their trouble. I can also ship Zostera marina, with roots in sediment, but IME that is a difficult grass. Late spring to early summer is a good time to ship as more economical shipment methods can be use due to the warmer temperatures.

 

[Samala]

Piercho I will definitely keep that in mind as far as the paddle/star grass and see what I can do. I am serving as my own collector, but its my grandfather who does all the scouting. Twenty years on the Intercoastal waterway and the IRL, he knows where to go for all things aquatic... I just have to educate him a bit on some things. For instance he used to call the various grasses "useless crap that gets on my line" and the horseshoe crabs "useless crap that eats my bait" and seahorses he would pull while seining for bait "stupid fish that no game fish will eat"... he's rather colorful.

I was out in the Delaware bay yesterday and found lined seahorses in some eelgrass beds and pulled a few plants, left the seahorses in the sea. There was literally pounds of gracillaria washing up on shore and ulva too.. at least it looked like gracillaria, I'm pretty sure about the ulva ID.

I'll let ya know! Thanks again for all the help.
>Sarah

 

[Fredfish]

The only other advice I have is to avoid Diadema urchins in the tank until the grass growth is very robust.

Hmmm. Define robust growth. I thought Diadema urchins were a no no in a seagrass tank, but I have no direct ecperience.

Sounds like a risky venture either way. What if your robust growth turns not-so-robust?

Samala. Can you give us a list of the papers you found?

Fred.

 

[piercho]

Fred, IME with one Diadema, it was an occasional grazer of seagrass, and prefered red and green alga. It became an occasional grazer or stony coral as it grew large, which is one of the things that led to it being removed. When it did graze the grass, it grazed the grass to below the level of the sandbed. Newly planted grass seemed to have trouble recovering from that. So its a function of proportions, I guess. The grass has to put up new shoots faster than the old blades are grazed. The urchin has to be small enough in relation to the tank that it has plenty of preferred graze, and does not single out the grass. IME Diademas will outgrow a tank the size of mine fairly quickly. A small import less than 3" got to more than 6" inches in less than a year I'd estimate. The fast growth rate is unfortunate because IMO these really are good and thorough grazers of rock surfaces.

 

[Samala]

Fredfish - here are some links to the papers I pulled up that I thought were most useful. There should be a 56k warning though, as most of these links are to pdf files that are pretty big. Here we go:

Zimmerman, Kohrs, Steller and Alberte. 1997. Impacts of CO2 enrichment on productivity and light requirements of Eelgrass. Plant Phys. 115: 599 - 607
http://www.pubmedcentral.nih.gov/picrender.fcgi?artid=158520&blobtype=pdf

Hammill and Sumby. 2002. In vitro culture of Heterozostera tasmanica and Zostera muelleri. Presented at Western Port Sea Grass Seminar in Hastings, Victoria, AUS.
http://www.seagrass.com.au/pdfs/monashseagrass.pdf

[this one is big] Evaluating Indicators of Seagrass Stress to Light. http://www.marine.unc.edu/Paerllab/research/seagrass/Biberetal_Seagrass.pdf

This was a helpful page on TheKrib by Steve Pushak on lighting terminology and PAR: http://www.thekrib.com/Plants/Tech/intensorama.html

There are a number of very good articles that I can find abstracts or references for that I can't find in my university's library or available free online. Still looking though, I'll post any others that I come across. Nearly all the papers published by RC Zimmerman in the past 10-15 years are worth reading, I just need to find them. He seems to be a big expert on Zostera in particular. Some of the articles above are very helpful, some not so helpful.

Oh, and there's also this one that's not a paper:

Quick reference on "Light and Seagrass"
http://www.marine.uq.edu.au/marbot/publications/pdffiles/seagrass2.pdf

 

[Samala]

Oh I also thought these two were cool.. but only because I am becoming a big nerd with seagrass..

Zimmerman, RC, Kohrs, Steller, Alberte. 1995. Carbon partitioning in Eelgrass. Plant Phys. 108: 1665 - 1671
http://www.pubmedcentral.gov/picrender.fcgi?tool=pmcentrez&blobtype=pdf&artid=157548

Alberte, Suba, Procaccini, Zimmerman, Fain. 1994. Assessment of genetic diversity in seagrass populations using DNA fingerprinting. Proc. Natl. Acad. Sci. USA. 91: 1049-1053.
http://www.pubmedcentral.gov/picrender.fcgi?tool=pmcentrez&blobtype=pdf&artid=521451

>Sarah

 

[Fredfish]

Thanks for the links Sarah. They should keep me busy for a while.

Thanks for the info on the Diedemas piercho. I had no idea they grow so fast. I was planning on setting up a 130 to 150 gallon tank. Even a 150 is probably very marginal for a full grown urchin unless I am commited to growing macros for it.

No, back to those links.


Fred

 

[Samala]

Collection trip - requests anyone?

Collection trip - requests anyone?

Well my collection permits through FWS and Merritt Island came through earlier this week so my trip is all set to go. I'll be pulling manatee grass, shoal grass, and star grass from the IRL this weekend while I visit my family in FL. (The star grass we found a good location for in a large mixed species bed, hopefully I will still be able to pull plant plugs.)

I'll also be collecting fun mangrove/seagrass bed mud.

Was anyone looking for something particular in this area that they would like me to see if I can find while I'm there? I was planning on bringing back some extra plants of all three types, and possibly turtle grass if we make a day trip to Sebastian Inlet, just in case someone was interested. PM me any requests and I'll see what can be done.

Oh yes, the FWS people laughed quite hard on the telephone when I told them I wanted to know if there were protective measures on mangrove mud.. but hey, a girl has got to ask or she'll never know!

>Sarah

 

[piercho]

Samala,

Dibs! Dibs! Dibs! Will PM you a list of potential trades and HAPPY to pay shipping from FL to WA. IMHO should ship best damp. Keeping it warm while shipped may be tough this time of year, though. Roots in plugs, or with some sediment from near the roots are IMHO a big bonus; brings in the associated sand community with the seagrass. You are doing what I've wanted to do for the last 2 years, good luck.

 

[Fredfish]

I wish I could call dibs, but I live in the wrong country.

Fred.

 

[mygreengoldfish]

I have gone SCUBA diving in the Bahamas and there are quite a few places with sea grass beds. In every case, the substrate was a fine aragonite just like that "oolictic" stuff they sell. The beds were about 20 feet from the surface of the water so the lighting was very bright and also more yellowish colored like a 6500K metal halide. As for what was living there were some giant bahama stars and blacks sea cucumbers. There weren't any fish except near the few patches of corals. Also there were clustered pink feather dusters on the few rocks in the sea grass beds. Hope this helps.