I don't understand why this is surprising. The deep ocean gets its carbon and energy from biomaterials that snow from above
The novelty in the research is estimating the speed in which deep sea life absorbs organic matter from the surface. Bomb carbon, C14, is used as a proxy measure.
Let's work on nano tech which we know is toxic to fish but we'll contain it. We promise. We can't stop our economic growth for remote possibilities that will probably never occur.
"Hey kids, the Mariana Garbage Pit used to be an empty trench full of earthlife, and I hear it used to have water in it too..."
Says one alien to another while on a dig on a barren planet in the middle of nowhere.