  It is shown that the Clebsch parameterization, upon canonizing the
Hamiltonian system of ideal fluid or plasma dynamics, converts the Casimir
invariants (mass and helicities) in the original noncanonical formulation into
the Noether charges pertinent to the gauge symmetries of the parameterization.
The problem is addressed in the context of magnetohydrodynamics. The concrete
forms of the gauge symmetries of Clebsch parameterization are worked out.
