the models could change if convection is properly taken into account [@Klapp2005].

Thus, the issue of whether very massive stars could be vibrationally unstable to pulsation and induce pulsationally driven mass loss is still open. The contribution of pulsation to mass loss remains uncertain.

Other mechanisms
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[@Smith2006] suggested that the mass loss during the evolution of Population III stars may be dominated by optically thick, continuum-driven outbursts or hydrodynamical explosions, similarly as in the very massive Luminous Blue Variable (LBV) stars and $\eta$ Car in particular. Unlike the steady line-driven winds, this mechanism, investigated also, e.g., by [@vanMarle2008a; @vanMarle2008b], is insensitive to metallicity but requires a high, nearly Eddington luminosity, close to which the mass loss rates of the wind highly increase [@Kudritzki2002; @Grafener2008; @Vink2011]. This condition is well satisfied by the first stars owing to their high masses and luminosities.

The role of magnetic fields in activity of late-type stars and their winds is generally known. The growing observational evidence of magnetic fields in early-type stars (e.g. Be-stars) suggests that they could also be present in the first stars and consequently influence their winds or mass loss via their decretion disks [cf., e.g., @Puls2008; @udDoula2008 and references therein]. 