If they must be submerged, you should be good for a few days, but that whole metal + saltwater thing just doesn't go over well in my mind. Have some plastic hose clamps overnited or 2dayed on over.
If it's not submerged, what difference does it make? I use metal hose clamps on my system (I believe they are made of zinc or stainless steel) and I don't worry about them at all. The only thing that might happen is they might get really dusty in my stand, otherwise they get no water exposure at all, and won't ever run the risk of contaminating my water.