  It is shown that the turbulent dynamo $\alpha$-effect converts magnetic
helicity from the turbulent field to the mean field when the turbulence is
electromagnetic while the magnetic helicity of the mean-field is transported
across space when the turbulence is electrostatic or due to the electron
diamagnetic effect. In all cases, however, the dynamo effect strictly conserves
the total helicity except for resistive effects and a small battery effect.
Implications for astrophysical situations, especially for the solar dynamo, are
discussed.
