mm43,
Organic matter decays or is "recycled". Really no different to being "six feet under".
What we are discussing is precisely the lack of any kind of biological activity at the bottom, so the corpses don´t "decay" or are "recycled".
Razoray,
But the location of AF447 is similar to a barren plain....as we can see by the lifeless bottom....so dead sea life never makes it to the bottom...
I´m not quite sure of what you´re implying here, but...I ´m not referring to life at the bottom, just to the marine life just passing above. THEIR carcasses must fall (per gravity) to the bottom; that´s what I was talking about.
You´re right about the extremophyles living at the hydrotermal vents, but these ecossystems probably constitute only a small percentage of the sea bottom.