Re:Turtle Grass

     >I am researching growing a Turtle Grass saltwater Tank as a 
     >semi-natural environment for Seahorses.  I plan to set this up in a 
     >greenhouse.  That should  handle most of the light requirements.  Can 
     >anyone tell me where to start?  Montana is a long way from any 
     >saltwater and university libraries are 2-4.5 hours down the road.
     I am a marine biologist with the Texas Parks and Wildlife Department.  
     We have five species of seagrasses in Texas--Thalassia testudinum 
     (turtle grass), Syringodium filiformae (manatee grass), Halodule 
     wrightii (shoal grass), Halophila engelmannii (no common name), and 
     Ruppia maritima (widgeon grass).  All grow in shallow, clear water 
     (except Halophila, which can grow in deeper water and needs less 
     light).  All grow in sandy soil with a very low organic content (1-4% 
     organics), except Ruppia, which I have seen growing in mud.  Ruppia 
     can also tolerate low salinities; the other grasses do best at 
     salinitites from 20-40 parts per thousand.
     Eel grass, Zostera marina, is not native to the Gulf, but is common in 
     the Chesapeake Bay.  It can tolerate lower temperatures than the Gulf 
     species; perhaps you should check into it.  I have a greenhouse, and 
     it is hard to keep a fairly constant temperature; daytime temperatures 
     can easily break 100 F inside, even in January, and I have to use a 
     heater to keep my greenhouse over 50 F on a cold winter night (our 
     idea of "cold" is +40 F).  Your seahorses probably wouldn't like 50 
     degree temperature swings, either.
     The Smithsonian keeps a living reef aquarium, with turtle grass 
     planted in the fore reef.  Maybe one of Walter Adey's books will 
     describe their setup.  They have a complicated system, and use banks 
     of metal halides for lighting.
     Another good general reference is "The ecology of the seagrass meadows 
     of the west coast of Florida:  A community profile"  by Zieman and 
     Zieman, 1989.  This is published by the U.S. Fish & Wildlife Service, 
     Biological Report 85(7.25).  It does not cover cultivation, but it has 
     a lot of good information on their physical environment.
     There has been a lot of work here in Texas on seagrass cultivation, 
     but it is mostly concerned with replanting them in the wild, not 
     aquarium cultivation.
     In my experience, marine macroalgae such as Caulerpa are much easier 
     to grow, and the seahorses will do just as well.  There are also more 
     species to choose from, need less light, and would be easier for you 
     to get in Montana (even mail order).  You could grow these indoor, 
     under flourescent lights.  I recommend them.