In the latest EOS number there is an interview with Woods Hole Oceanographic Institution's scientist Timothy Shank in which he responds to the question. It seems that we are back to just snapshots and grad samples of the hadal ecosystem.
Eos: What research opportunities have been lost as a result of the loss of Nereus?
Shank: The ability of Nereus to do directed surveys and sample collection is critical for hadal research. Without it, we will be limited to the snapshot views of static instruments that only provide a limited perspective on what is an exceedingly complex ecosystem.
Eos: How much of the science that was planned to be done with Nereus can be done with other methods?
Shank: The capabilities Nereus provided were unique. We will be forced to rely on chance to retrieve sediment samples or macro fauna. Some things are simply not possible—such as near-bottom camera surveys or non-scavenging macro faunal recovery. The big-picture questions that will be affected include how much carbon is being sequestered in hadal sediments, how hadal ecosystems are structured, how human activity is affecting the lower one-third of the ocean’s depth, how much of what type of food is available to life in the deep ocean, and the range of adaptations life has evolved to cope with conditions in the deep ocean. Many of these are fundamental, first-order questions that we are only beginning to address.