Overview of the Wairewa Research Project
The catchment area of Wairewa (outlined in yellow) on Banks Peninsula
Te Roto o Wairewa (Lake Forsyth) on Banks Peninsula is a severely degraded lake ecosystem with eutrophication, algal blooms and sedimentation problems. Wairewa Rūnanga have a long term vision of rehabilitation for the lake and its surrounds. The rūnanga have brought together a group of researchers to provide science back up to this vision.
This website is the repository of information from the rehabiltation research work.
Areas of research
It is recognised that rehabilitation of Te Roto o Wairewa (Lake Forsyth) is a long-term multi-generational project. There are many different areas of science that are being brought together in this project. They are described under the following six headings.
History of Wairewa
Wairewa has a long history of human habitation. This work is invetigating that history through archives and oral histories.
Lake sedimentation and previous forms
Te Roto o Wairewa (Lake Forsyth) has not always been a shallow fresh water lake. Changing sea levels, growth of Kaitorete Spit and changing land use in the catchment have all contributed to alterations in the lake form. This research is looking at past forms of the lake and its sedimentation.
State of the catchment
The land cover and land use within Wairewa catchment has changed dramatically over the past 150 years. This strand of research is looking at what state the catchment is in and whether there are management practices that could be implemented to help the lake.
Water quality of the lake
Te Roto o Wairewa (Lake Forsyth) is a highly eutrophied lake with extreme water quality problems. The most severe problem is the summer blooming of blue-green "algae" (actually the Nodularia species of cyano-bacteria) which produce toxic bi-products. The water quality is monitored by Environment Canterbury and various researchers have studied the toxic blooms.
Tuna health and population structure
Tuna (eels) are an important part of the cultural significance of Te Roto o Wairewa to Ngāi Tahu. This research is investigating the age structure of the resident eel population to determine whether it has changed in recent years and how sustainable the tuna heke is.
Feasibility of permanent lake opening
It has been suggested that some of the eutrophication problems in the lake are as a result of an inability of the lake to naturally flush itself. A permanent opening is one way that this could be helped. The opening would also assist in the recruitment of migratory fish species (e.g. tuna, pātiki, kanakana). This research is investigating the feasibility of maintaining a permanent opening for the lake.
Management options
There is a need for land and freshwater management alternatives that actively promote the rehabilitation of degraded ecosystems. Given that significant tracts of land are frequently in multiple ownership, it is important that there be some means of integrating initiatives to improve ecological well-being over whole catchments. This research is investigating alternative management regimes for Wairewa that incorporate multiple values.
