While dolphins lack the communication methods available to humans, I believe that they have the same methods available to them that whales possess. Whales have a pretty sophisticated "culture" that is encapsulated in the variying songs of different species and among the various geographic and tribal groupings within a particular species.
Yes, I know about that. I just doubt that it's as effective at expressing precise meanings as methods available for humans ("area within 100km radius from 33.593316 135.943022 is to be considered unsafe," and let's not get started on bordering the area with 3 meter high fences topped with barbed wire).
