Keeping track of supplies used, allocating what is needed to what department, checking in and out equipment, knowing what supplies they have when responding to emergency situations, loading/off-loading cargo, safety checks that all supplies are stored correctly, alerting the chain of command when supplies run low and providing an itemised list of what is needed at their next docking, probably also maintenance and operation of cargo transporters and anti-grav sleds, repairing any damaged gear or uniforms, monitoring stock of organic and non-organic replicator matter, and of course the obligatory looking busy by moving cargo containers from one place in the bay to another.