Venice has plans for a new hydraulic flow controlled by levees and a dam during runoff & tidal events as sealevel continues to rise.

This has a brief summary of progress: https://www.citylab.com/life/2016/09/venices-vast-new-flood-barrier-is-almost-here/498935/

[edit] The context of Venice has 3 parts, the freshwater seasonal and episodic flow including groundwater in a relic delta, this with enough fetch to sea allowing winds to pile water for days, and, there are seasonal tides with that.

The almost complete solution deals with sediment compaction separately from defense against high water, those solutions have injection strategies, they're dealing with pore-pressure, flow and having clean water in the canals or they stink.

My view, it's analogous to the high water dam against the North Sea that's closed for storms.

Long-term a dam at Gibraltar Strait, 1200-ft deep has been proposed to save history, otherwise we hit 3mm in a year in 2016 of rise, at 600-ppm Antarctica's land ice begins an unstoppable melt as is going on with submerged valley glaciers.

To the question of littoral habitat that's ok unless there's an oil spill, pollutants in runoff are poisoning it pretty fast being an enclosed sea vs oceanic facing littorals from my reading.