The response of freshwater plants to salinity pulses

To test whether a pulse of saline water affects the growth and survival of aquatic plants, the response of four common freshwater macrophytes; Triglochin procerum, Myriophyllum simulans, Cotula coronopifolia and Baumea arthrophylla was examined. Plants established in freshwater were exposed to a pulse of diluted sea water of <1000, 4000, or 8000 mg L⁻¹ for either three or six weeks followed by four weeks in water of <1000 mg L⁻¹. All four species survived exposure to salinity pulses. At the end of the recovery period all species had a positive relative growth rate of between 0.01 and 0.06 g g⁻¹ day⁻¹. It can be concluded that all four species can tolerate short periods of exposure to saline conditions and this gives some flexibility to managers when deciding the best way to utilise and dispose of saline groundwater.