Ecological Outcomes of Invasive Rice Grass ( <scp> <i>Spartina anglica</i> </scp> ) Removal for Restoring Native Saltmarsh Vegetation and Fish Habitat Function

ABSTRACT Rice grass ( Spartina anglica ) is a widespread invasive species in south‐east Australian saltmarshes and has been the target of control programmes since the 1990s, with purported benefits to native saltmarsh vegetation and fish habitat access. Recent large‐scale rice grass control programmes in north‐west Tasmania, funded by the Australian Government, provided an opportunity to monitor changes in vegetation and fish use before and after rice grass treatment. We undertook vegetation and fish surveys at two contrasting locations in Duck Bay, seeking to evaluate the potential benefits of the functional removal of this invasive species on the restoration of native saltmarsh vegetation and fish habitat function. At both sites, rice grass died back almost completely post‐treatment and was replaced by native vegetation dominated by Sarcocornia quinqueflora . Fish surveys using pop nets indicated that the plots where rice grass was removed had a significantly greater number of fish species and abundance. Species richness more than doubled (from 5 to 11 species) 3 years post‐treatment and mean catch per net increased from ~2 to ~45 individuals (~175 fish per 100 m 2 area), matching densities observed in undisturbed saltmarsh. At one site within a seascape formerly dominated by expansive rice grass swards, fish were conspicuously absent from baseline surveys but reached 255 fish per 100 m 2 3 years post‐treatment, with the catch dominated by yellow‐eye mullet ( Aldrichetta forsteri )—a species of commercial and recreational importance. Gut content analyses were done on 21 mullets caught at this site to offer insights into their use of the native marsh as feeding habitats. Results indicate fish have likely fed on the restored native saltmarsh, confirming the recovery of feeding as well as refuge functions. These findings provide novel insights into the nature and extent of saltmarsh ecosystem recovery and fish habitat function, while also highlighting the potential benefits of invasive species control programmes.