speaker grills and rusty speakers?

Does anyone else have a problem with their speaker housings (maybe the speakers themselves) rusting? I have four Titan speakers and they are beginning to rust at the bottom. The rust is dripping onto my bimini top and hopefully the discoloring will continue to come out and not stain.

Also, one of the speaker grills came off last night and I'm looking for a suggestion as to what to use to repair. I need something that is strong enough to hold the grill in place but not too strong in the event repair needs to be done.