Helophyte impacts on the response of hyporheic invertebrate communities to inundation events in intermittent streams

The effects of experimental inundation on invertebrate communities in artificial flumes fed with treated wastewater were investigated. Flumes, designed to simulate intermittent river conditions, were planted with three different species of helophytes widely used in river restoration around the water-stressed regions of Europe. Different species of vegetation had different capabilities to reduce the invertebrates negative reaction on inundation, related mostly to rhizosphere density. Of the three helophyte species tested, only one, Lysimachia vulgaris, showed significant capabilities to reduce invertebrate negative reaction on inundation. Species richness of invertebrates before and after the inundation did not change in any of the flumes, while species density significantly declined in all flumes except one planted with L. vulgaris. This helophyte species was associated with high densities of the Culicidae larvae (common mosquitos) which has severe implications for river restoration and vector management in the region. This study indicates that the selection and establishment of different helophyte species will impact invertebrate communities in restored streams, especially streams experiencing variable inundation conditions.