Marine Fauna Audio/Visual

I think adding some subtle marine life to the game would do wonders for the atmosphere of the game, and could even potentially offer some greater visual indicator of pollution effects (though that is largely secondary in my mind for this suggestion). I want to see a pod of dolphins rarely pass by, a whale or two, some seagulls by the coast. I would recommend any audio elements to be subtle or only able to be heard when zoomed in, but the game can currently be eerily quiet, in my opinion.