Responses of riverbank and aquatic vegetation to an instream environmental flow

Environmental flows can help restore rivers by creating conditions that improve recruitment, growth and survival of riverbank and aquatic vegetation. The study aim was to compare responses of riverbank and aquatic vegetation among hydrological zones with different flow regimes. The species richness and cover of riverbank and aquatic vegetation at sixteen sites across four hydrological zones in the Edward-Wakool system in south-eastern Australia were monitored monthly from October 2014 to June 2015. Three zones received an instream environmental flow and one zone did not. The cover of vegetation was significantly different among zones (F=21.548, p<0.000), with higher cover of vegetation in two of the zones that received the environmental flow. There were more taxa in all zones that received the environmental flow than in the zone that did not. The vegetation assemblage was significantly different among zones (ANOSIM R = 0.402, p = 0.001). Potamogeton tricarinatus, Myriophyllum spp. and Azolla spp. occurred only in zones receiving the environmental flow, and Chara spp., Eleocharis acuta and Limosella spp. were in low abundance in the zone with no environmental flow. There has been a gradual improvement in riverbank and aquatic vegetation in this system over the four years since environmental flows commenced.