Ecosystem Health in Wellington City urban streams
Greater Wellington Regional Council and Wellington City Council joined forces to carry out a four-year monitoring programme of the city’s streams.
Greater Wellington Senior Environmental Scientist Dr Evan Harrison says there is an extensive network of streams across the city, many of which have been piped and historically there has been minimal information on their ecological health.
“What we have been looking at, since monitoring began in 2016, is the streams’ habitat condition, invertebrate community health, and fish populations.
“We have worked together with Wellington City Council to better understand the ecological health of both the piped and open portions of streams in Wellington,” Dr Harrison says.
Fifty-one survey sites were spread across a range of urban streams throughout the city area, including sites upstream of urban areas and stream sections within the current urban footprint.
“The data collected during this survey indicates invertebrate communities were generally in better condition in streams with less urban land use in the upstream catchment.
“We found that fish communities within urban streams were generally in fair to poor condition. However, there is greater fish diversity in sections of stream with direct connection to the sea. This is important because many of our native fish species migrate between rivers and the sea.”
Banded kokopu and eel species were the most abundant fish species present across the majority of sites surveyed. Native fish species present included at risk and declining species such as koaro, inanga, redfin bully, longfin eel and giant kokopu.
“Barriers to fish movement are likely to be one of the major pressures influencing fish communities in urban streams. The only fish species found upstream of piped sections of stream were climbing species.
“The monitoring highlights the need for a whole of catchment approach for improving ecosystem health of Wellington’s streams. The improvement in ecosystem health of our streams will need to include modifying and removing fish barriers, as well as reducing the stormwater contaminants flowing into the streams,” Dr Harrison says.
Wellington City Council Urban Ecology Manager Michelle Frank says it is exciting to see a report as comprehensive as this, developed in partnership by the two councils.
“Though findings highlight a great need to improve the health of our streams, it shows us that there are still many diverse species living in them. The report really does show Wellingtonians that there is quite literally ‘fish under their feet’.”
Greater Wellington Councillor and member of the Te Whanganui a Tara Whaitua Committee, Roger Blakeley says regional council is working closely with iwi and the community to encourage urban design, which helps to improve our marine and freshwater ecosystems.
“We are working to reduce contaminated run-off from roads, and maintain or restore open, well-vegetated stream margins. Upgrades to aging and damaged sewerage infrastructure, particularly where sewage overflows into stormwater and our urban streams, is also a key component of these discussions and planning,” Cr Blakeley says.
If residents have would like to share their ideas on the future of water in the Wellington region, they can visit the Have Your Say page.