Smith, D., Heenan, P., McCaughan, H., McClellan, R., Patrick, B., Conn, S., Tocher, M., Mazzieri, F., & Shaw, W. (2017, June). Ecological issues and management options for the Avon-Heathcote Estuary/Ihutai. Wildlands.
Commissioned by the Avon-Heathcote Estuary Ihutai Trust in 2017, this report sought to identify and describe the ecology and key management issues of the Ihutai estuary to inform the development of an Estuary Trust Ecological Management Plan. The overarching purposes of the report included guiding the long-term restoration, rehabilitation, protection, and maintenance of ecological processes and estuarine habitats, promoting resilience from coastal hazards through ‘natural engineering’, integrating estuary projects, contributing to evidence-based decision making, and providing an educational resource.
The report identified multiple significant issues affecting the ecological, environmental and cultural values of the estuary, including water contamination and sedimentation from the Ōtākaro and Ōpāwaho rivers, changed hydrodynamics and surface elevation from the 2010-2011 Canterbury earthquakes, and pest animals and plants. Other issues included the loss of the estuary margin and its vegetation from coastal erosion, increased vulnerability to climate change, and significant declines in saltmarsh and native musk herbfields.
To achieve improved ecosystem resilience, water quality, mahinga kai, and recreational values, the report proposed several actions. Such actions included continued advocacy for upstream water quality management by the Estuary Trust, halting development and increasing planting in riparian areas, large-scale ecological restoration, and increased pest management. The report also recommended several research and monitoring projects to gauge restoration effectiveness and address knowledge gaps. Recommendations included ongoing monitoring of sedimentation, fish, shellfish, birds, predator activity, and bird disturbances, and research into the causes of saltmarsh and salt meadow decline.