Kilomikedelta,
Tissue gases (CO2, N2, O2) would be forced into solution at the thousands whatever bar pressure at this depth. Biochemically produced gases (CO2), if produced (unlikely), would be similarly solublized. Only when brought to the surface would the expected decomposition processes be operative.
Sorry for being WAAAY off-topic, but...
Wouldn´t this mean that the bottom of the sea at abyssal deeps should be teeming with dead, but conserved, carcasses of the many sea creatures dying for some reason other than being eaten?
[on the other hand maybe not many sea creatures can enjoy a quiet death...]