Adverse hydrological regimes and secondary salinisation are ubiquitous stressors to wetland plants in southeastern
Australia. To test whether salinity stress interacts with hydrological stress to affect the growth and survival of
aquatic plants,we examined the responses of Melaleuca ericifolia Smith, a shrub favouring drained sites, and the obligately
submerged monocot Vallisneria australis (S.W.L. Jacobs & D.H. Les) to different hydrological regimes under freshwater
and saline conditions. Under freshwater conditions both species recovered from water regimes that were considered prima
facie unsuitable to their growth form: M. ericifolia from 5 and 10 weeks of submersion, and V. australis from a simulated
water-level drawdown and exposure to air. Salinity, however, markedly compromised the survival of M. ericifolia after it
was re-exposed following submersion. Salinity not only reduced the recovery ofV. australis after its release from a period of
drying that desiccated aboveground organs, but prohibited recovery when the soil dried out.We conclude that M. ericifolia
and V. australis can tolerate short periods of submergence and drying, respectively, under freshwater conditions, but that
salinity compromises the ability of both taxa to recover from water regimes that, based on the plant’s growth form, would
be considered unsuitable for long-term survival and growth.