  Conservation laws in ideal gas dynamics and magnetohydrodynamics (MHD)
associated with fluid relabelling symmetries are derived using Noether's first
and second theorems. Lie dragged invariants are discussed in terms of the MHD
Casimirs. A nonlocal conservation law for fluid helicity applicable for a
non-barotropic fluid involving Clebsch variables is derived using Noether's
theorem, in conjunction with a fluid relabelling symmetry and a gauge
transformation. A nonlocal cross helicity conservation law involving Clebsch
potentials, and the MHD energy conservation law are derived by the same method.
An Euler Poincar\'e variational approach is also used to derive conservation
laws associated with fluid relabelling symmetries using Noether's second
theorem.
