It is shown that the turbulent-dynamo alpha effect converts magnetic helici
ty from the turbulent field to the mean field when the turbulence is electr
omagnetic, while the magnetic helicity of the mean field is transported acr
oss space when the turbulence is electrostatic or due to the electron diama
gnetic 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.