Over the past 100 years New Zealand’s lowland waterbodies have been modified by streambed lowering, channel straightening and field drainage. Drainage has now occurred to the extent that over 90% of NZ’s wetlands have been lost. While wetland drainage has now largely ceased, lowland waterbodies are subjected to ongoing channel maintenance through mechanical macrophyte clearing, weed spraying and streambank reconstruction. These actions are undertaken to ensure the productivity of surrounding farmland and to protect homes and infrastructure from high water levels. Progressively, many lowland wetland-stream complexes have been replaced by grid-patterned drain networks. Yet, these modified waterbodies are still freshwater habitats that can harbour surprising high, and often overlooked, instream values.
This webinar will explore how drain maintenance practices alter stream habitat and affect instream life—with a focus on freshwater fish and discuss a 10-year fish and habitat monitoring programme in Waituna Creek (Southland), which captured a major stream bank reconstruction initiative and a restoration project that included installing two-stage channels and instream habitat structures. discuss an ambitious project in the Ararira-LII River (Canterbury plains), that aims to reimagine catchment drainage by consolidating and scaling-up various alternative ecosystem friendly drainage management methods to an entire lowland catchment.