  We investigate the effects of varying the intensity of the primordial
magnetic seed field on the global properties of the galaxy population in ideal
magnetohydrodynamic cosmological simulations performed with the moving-mesh
code AREPO. We vary the seed field in our calculations in a range of values
still compatible with the current cosmological upper limits. We show that above
a critical intensity of $\simeq 10^{-9}\,{\rm G}$, the additional pressure
arising from the field strongly affects the evolution of gaseous structures,
leading to a suppression of the cosmic star formation history, \rev{which is
stronger for larger seed fields. This directly reflects into a lower total
galaxy count above a fixed stellar mass threshold at all redshifts, and} a
lower galaxy number density at fixed stellar mass and a less massive stellar
component at fixed virial mass at all mass scales. These signatures may be
used, in addition to the existing methods, to derive tighter constraints on
primordial magnetic seed field intensities.
