  Perturbation approaches developed so far for the dark soliton solutions of
the (fully integrable) defocusing nonlinear Schroedinger equation cannot
describe the dynamics resulting from dissipative perturbations of the
Ginzburg-Landau type. Here spatially slowly decaying changes of the background
wavenumber occur which requires the use of matching technics. It is shown how
the perturbation selects a 1 or 2-parameter subfamily from the 3-parameter
family of dark solitons of the nonlinear Schroedinger equation. The dynamics of
the perturbed system can then be described analytically as motion within this
selected subfamily yielding interesting scenarios. Interaction with shocks
occurring in the complex Ginzburg-Landau equation can be included in a straight
forward way.
