I think it would be very interesting to have an integrated aquaponic system. Maybe it should be called mariponics, since it is more interested in marine plants and seafood than aquatic fish and terrestrial plants.

I think it would be cool to have, say, a tank of salt-water fish, such as tilapia, or dare I say, salmon, if the operation was big enough, and have that waste flow to shellfish and invertebrates like crayfish, crabs, seacucumbers, abalones, and clams and such. That way, the solids are eaten up by those animals before going to the nitrogenous breaking bacteria and then salt-tolerating plants, seaweed, or marine algae. Kelp could be grown hydroponically, right? Maybe have kelp starters and put those on little anchors or upside down floaters in a tank of salt water. The kelp and smaller seafood could maybe even be used for feeding the larger fish!

I also like Moondancer's idea of breeding salt-tolerating strains of terrestrial plants. Maybe over several generations, the plants would be better suited for salt. Imagine, watermelon already salted before you cut it!