For the reasons already mentioned, a psychologist (if properly trained and experienced in such things) is an essential ingredient in efforts to reduce stress levels on such tasks. And I'm referring to both acute reactions to the work and the possibility of long term residual effects.
The inevitably nasty ("gruesome") nature of some of what will occur is of course one (very significant) component of that need. Additionally, if you have ever lived and worked at sea, or worked with a diverse group who may be less than comfortable with each other's roles (especially when you know the world is watching), or worked long long hours both day and night for a few months at a time, then think of the cumulative effect of all those stressors on this group of people.
In this case, I just hope one psychologist is enough...
