Venetians have a term for the constant lapping of the water that surrounds them; I think it might be moto ondoso but I’m not certain. What I do know, from my own experience of living by the sea for many years, is just how corrosive salt water is. The sea defences of my former home were in a constant state of renewal as the saline solution insidiously sought out openings where rusty stains would soon follow.
This (and the extrovert need for spectacle of its former movers and shakers) is why marble is so commonplace as a building material in Venice; it is resistant to the dissolving forces of seawater. Resistant but not impervious. The masonry below the water line clearly shows that changes are taking place. Not surprising then that there is so much scaffolding to be seen within the city.