Estimating the minimum salinity level for the control of New Zealand pygmyweed Crassula helmsii in brackish water habitats
Journal: Conservation Evidence
Crassula helmsii is a semi-aquatic, invasive macrophyte, which has become abundant in wetland habitats across Europe. This species is of conservation concern because heavy invasions form dense carpets within which few other plants species occur. C. helmsii is known to be killed by inundation with seawater, but published information on its response to inundation by less saline water is limited. Growth trials were conducted to investigate the levels of salinity required to kill this species. We found a linear negative relationship between growth rate and salinity across the range from 2 - 8 ppt, but that 8 ppt was required to kill C. helmsii. These findings suggest that C. helmsii growth could be controlled by inundation with saline water of 8 ppt. This may present a method for reducing the negative effects of salt water on co-occurring species, and thus the next stage will be to determine the efficacy of this method in field trials.