The relationship between a decaying strong turbulence and kinetic instabilities in a slowly expanding plasma is
investigated using two-dimensional (2D) hybrid expanding box simulations. We impose an initial ambient
magnetic field perpendicular to the simulation box, and we start with a spectrum of large-scale, linearly polarized,
random-phase Alfvénic fluctuations that have energy equipartition between kinetic and magnetic fluctuations and
vanishing correlation between the two fields. A turbulent cascade rapidly develops; magnetic field fluctuations
exhibit a power-law spectrum at large scales and a steeper spectrum at ion scales. The turbulent cascade leads to an
overall anisotropic proton heating, protons are heated in the perpendicular direction, and, initially, also in the
parallel direction. The imposed expansion leads to generation of a large parallel proton temperature anisotropy
which is at later stages partly reduced by turbulence. The turbulent heating is not sufficient to overcome the
expansion-driven perpendicular cooling and the system eventually drives the oblique firehose instability in a form
of localized nonlinear wave packets which efficiently reduce the parallel temperature anisotropy. This work
demonstrates that kinetic instabilities may coexist with strong plasma turbulence even in a constrained 2D regime.