I was interning at Exxon when the Deepwater Horizon oil spill happened. The mood really changed as soon as BP threw a binding agent into the oil spill, coagulating the oil and sinking it below the surface (a recommendation that Exxon's upstream research arm was proud to have recommended).

I also lived near the Alabama gulf coast and had friends that lived on the coast. Those globs of oil washed up on shore for a long time, years if I'm not mistaken. I don't know if there was any good research done to see if the environmental impact was better or worse but it would be interesting to see how it would have compared.

The PR value was huge though. Its amazing how quickly the popular sentiment can chill out when the problem is no longer easily visible.

The UK government, as well as others, is currently funding research into the ecology of the target areas and the impacts of mining (https://blogs.noc.ac.uk/blogs/SMARTEX)

I'm not sure it will be 'hidden' (the research projects are not going away) so much as yet another case of competing interests within governments, where the environment gets sidelined for the sake of an hypothetical future magic money tree.

Are these particular ecosystems all that sensitive? The places where you find nodules are mostly just empty "deserts", right? The seabed isn't continuous brightly colored coral reef.