Fungi on speaker! - Help needed

I live right next to the sea and unfortunately cannot keep the room closed and air-conditioned all the time. Of late with the incessant rains in Chennai, the air has gotten really damp and is affecting evrything right from my clothes to the speaker wood. My onkyo ht speakers and sub unfortunately have developed fungi on them and i have to repeatedly brush them off. The worrying thing is that i can keep doing this on the outside but what about the inside?? Does anybody have a solution to this? I'm sure somebody in Mumbai would have encountered something like this. Can anybody suggest a solution?