When you say maturing roosters, are they young cockerels or actual roosters? They might have tensed up due to the addition of something new and that alerts them.
It sounds like you are going to do an integration with a look no touch set up? I would just make it so that the roosters cannot "bust in". I would make sure to do a full integration of 2 weeks and then allow the ducklings brief moments supervised with the chickens. Chickens can kill ducklings by pecking them to death - as they can with any new addition.
However, my grown ducks always pick on the chickens. Eventually, a rooster is more apt to fight a drake - a drake will most likely win due to adult size and strength.
Hopefully you have enough room for the 2 species to live harmoniously and to keep each as happy as can be. Ducks need & love water. They also love to make mud. Whereas, chickens need dry areas and dust baths.
I have both species, but mostly they are sectioned off into their own area with their own housing in a very large run.