  The most energetically favourable arrangement of low-density electrons in an
infinite two-dimensional plane is the ordered triangular Wigner lattice.
However, in most instances of contemporary interest one deals instead with
finite clusters of strongly interacting particles localized in potential traps,
for example, in complex plasmas. In the current contribution we study
distribution of topological defects in two-dimensional Coulomb clusters with
parabolic lateral confinement. The minima hopping algorithm based on molecular
dynamics is used to efficiently locate the ground- and low-energy metastable
states, and their structure is analyzed by means of the Delaunay triangulation.
The size, structure and distribution of geometry-induced lattice imperfections
strongly depends on the system size and the energetic state. Besides isolated
disclinations and dislocations, classification of defect motifs includes defect
compounds --- grain boundaries, rosette defects, vacancies and interstitial
particles. Proliferation of defects in metastable configurations destroys the
orientational order of the Wigner lattice.
