Removing all those workers, then, would have a huge effect on the industries. Gitis and Varas considered two scenarios to come up with a range for the economic damage.
As a lower-bound scenario, they assumed that any available unemployed native-born or lawful immigrant workers in each industry would pick up as much of the slack as possible and fill in at least some of the jobs vacated by the deported workers. In this scenario, not all the jobs would be filled, as they found that there wouldn't be enough unemployed native or lawful immigrant workers to take over.
As an upper-bound scenario, they instead assumed that these jobs would go unfilled and simply disappear.
They found, using estimates of output per worker in each of those industries, that the cost in lost output would be in the hundreds of billions of dollars (emphasis ours):
"Overall, removing all undocumented immigrants would cause private sector output to decline by between $381.5 billion and $623.2 billion. This translates to a 2.9 percent to 4.7 percent reduction in total annual output from the private sector."