URBAN STREAM HABITAT SURVEY

The Urban Stream Habitat Survey is successfully underway in Christchurch for its second summer. Comprising part of the Waterway Enhancement Programme, the survey is an ecological assessment of the city's tributary waterways - its aim is to provide insight into the ecological health and condition of Christchurch's streams and creeks.

The survey, with a focus on life within streams,was designed by the National Institute of Water and Atmospheric Research (NIWA). Christchurch City Council has piloted the survey method over the last over the last two summers with close guidance from NIWA staff. The survey is now finalised and will be used throughout New Zealand as part of a nationwide programme for assessing waterways, including their potential for enhancement and restoration.

Information for the survey is being collected over summer by university students Juliet Milne and Shelley McMurtrie. The survey consists of two parts. The first involves a visual assessment of how the stream looks - whether it is meandering, straight or otherwise - its vegetation - both within the stream and on its banks - and recording any wildlife present. The second and more comprehensive part of the survey includes a detailed analysis of stream hydrology and the collection of invertebrates at various places along the stream. Collected using a "Kick-net" the invertebrates are taken to a laboratory where they are identified and counted. By comparing the composition of the invertebrate community present within a stream with the stream's habitat features, it is possible to ascertain an indication of the state of a stream's ecological health.

Although it is too early yet to draw any conclusions about how Christchurch's tributary waterways are doing, the invertebrate samples collected to date indicate that most are in some state of degradation. Common invertebrates that have been found include: oliogochaetes (worms); nematodes (round worms); chironomids (blood worms); molluscs (snails); and various crustacea.

The data collected from the surveys will be analysed by NIWA and is expected to provide important base-line information for the City council's waterway restoration and enhancement programme. With time, NIWA should be able to give an overview of the state of urban waterways throughout New Zealand.

Rachel Barker
Waterway Enhancement Co-ordinator
Ph: 371-1264