I just checked all of my photos of Fort Worth and yes indeed the gorillas and bonobo/chimp areas have a moat.
Aren't the Ft Worth moats deep and vertical-sided with shallow water at the bottom, similar to DAK and Congo, as opposed to the deep water moats with little or no vertical walls which is the type still often found in Europe? The shallow water acts to discourage the apes from entering the moat, but the real barrier is created by the tall vertical wall on the public side. There is very little danger of drowning in these shallow moats, unlike the real danger of the situations where the water is deep enough to be a true barrier.