This reminds be of the book Hyperion in which there was this paradise ocean world planet, Maui-Covenant. Maui-Covenant had motile isles, giant plant/animal moving islands. They were herded by dolphins. Humans made a device that could translate and talk to the dolphins.
All the dolphins committed suicide when the hegemony of man (some sort of capitalistic state) arrived and ruined the planet to extract all the oil.