  The thesis focuses on processes on symplectic Gelfand-Tsetlin patterns. In
chapter 4, a process with dynamics inspired by the Berele correspondence
[Ber86] is presented. It is proved that the shape of the pattern is a Doob
$h$-transform of independent random walks with $h$ given by the symplectic
Schur function. This is followed by an extension to a $q$-weighted version.
This randomised version has itself a branching structure and is related to a
$q$-deformation of the $so_{2n+1}$-Whittaker functions. In chapter 5, we
present a fully randomised process. This process $q$-deforms a process proposed
in [WW09]. In chapter 7 we prove the convergence of the $q$-deformation of the
$so_{2n+1}$-Whittaker functions to the classical $so_{2n+1}$-Whittaker
functions when $q \to 1$. Finally, in chapter 8 we turn our interest to the
continuous setting and construct a process on patterns which contains a
positive temperature analogue of the Dyson's Brownian motion of type $B/C$. The
processes obtained are $h$-transforms of Brownian motions killed at a
continuous rate that depends on their distance from the boundary of the Weyl
chamber of type $B/C$, with $h$ related with the $so_{2n+1}$-Whittaker
functions.
