A poorly implemented runoff would nuke a square km or five of ocean floor with high salinity waste. It would not impact food supply in any discernable way. The ocean is simply too big.

Which ocean? People used to think this about raw sewage discharge. Check the state of UK beaches

That's impacting people who want to swim or surf in the sea. It's not impacting food supplies. Fishing boats operate much farther out.

> poorly implemented runoff would nuke a square km or five of ocean floor with high salinity waste.

So what is the problem then? We only need to lay pipes to ocean floors that are already not that lively?

Well no, that does not describe the local sea life everywhere.