i have some friends that live just above tampa i have known since the 90's, i visit them alot. they live in an area that has a number of manmade canals connected to springs which go to the gulf, so the canals are most of the time fresh water. but they get extreme high tides 2, 3 times a year. going to as much as 5ft. or more.
there are many people there growing bananas low enough that, with an extreme high tide, the bananas are under water for some time. and i am one of them.
but not for 12 hrs., 6 or 8 maybe. most of the bananas everybody else has are orinoco or dwarf cavendish, most. anyways the salt does not seem to affect them. i see fruit all the time.
but i will say again, not for 12 hrs. that i know of.