Conference 2003


Conference 2003
Greening the City:
Bringing Biodiversity Back
into the Urban Environment

Abstract:

Restoring In-stream Values and Habitat for Canterbury Mudfish in Okeover Stream, Christchurch

Leanne O'Brien (Department of Zoology, University of Canterbury) & Rachel Barker (Parks & Waterways Unit, Christchurch City Council)

Since the 1990s there has been a changed approach to managing streams throughout Christchurch city.  The focus has moved away from managing drainage channels to restoring streams for the plants, fish, invertebrates and birds they support — and to make streams an enjoyable part of our daily lives. At the Okeover Stream, Christchurch City Council and the University of Canterbury have gone a step further and created a special project that is the first of its kind in Christchurch.

The Okeover Stream has changed considerably over the past few years; this project is the latest in a series of focused habitat restorations.  Previously, the upper section of the stream was often dry, due to reduced flow from the ground water springs that once fed this stream. This reach was looking doomed until the Maths and Computer Science building was constructed.  This building is air-conditioned using aquifer water which is pumped round the building and the piped into the stream at its upper end.  This produces an adequate flow of good quality water.  However, the air-conditioning is not always on, and when it is turned off, such as in University holidays, little water is left.  This restoration project was designed to mediate the impacts of these fluctuating water levels on the aquatic community.

One species which thrives in such fluctuating spring-fed streams is the Canterbury mudfish.  Mudfish habitats often dry up, but mudfish are quite amphibious, if pools go stagnant they can breathe air at the water surface, or leave the water.  If the whole area dries they can survive for months, as long as they are moist.  So mudfish appear perfectly suited to this type of waterway.  When establishing a species it is important to consider food resources and habitat requirements, particularly for vulnerable stages of development.  Extensive habitat development has been conducted with the site excavated to construct deep pools to retain water during low flow.  An innovative feature of this restoration is the creative use of engineering structures such as gabions (wire baskets filled with river stones) to line pools and direct flow, creating refuge and backwaters within the stream.  Backwater areas are important for mudfish as they provide a still habitat for the vulnerable fry stages.   Native aquatic vegetation, which is important to mudfish for spawning, will also be established in these backwaters.  Our vision is to have a thriving population of Canterbury Mudfish located here on the University campus, where their progress can be monitored and researched over the long-term.  We hope that lessons learned from establishing this population can be used to direct conservation initiative in other habitats where mudfish could gain a stronghold.

Conference sponsored by:

British Council NZ
CCC
The Community Trust
Landcare Research
ECan
PGG

Follow this link to view other organisations supportive of the conference

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