Reporting on Tomahawk Lagoon

Ecotago scientist Andrew Innes wades out into the shallow waters of Tomahawk Lagoon with Tahuna...
Ecotago scientist Andrew Innes wades out into the shallow waters of Tomahawk Lagoon with Tahuna Intermediate pupils Elise Chrystal, left, 12, and Faith Abbott,12, to count fish and invertebrates during a citizen science session earlier this year. PHOTO: BRENDA HARWOOD
The latest results from ongoing citizen science monitoring at Tomahawk Lagoon and plans for future efforts at the site will be discussed during a public reporting day this weekend.

The Tomahawk Lagoon Citizen Science Reporting Day will be held this Sunday, November 3, from 9am-noon, at the new venue of Grants Braes Football Club rooms, 1 Domain Ave. Morning tea and barbecue food will be provided.

Ecotago chairman and project leader Andrew Innes said the event had to be transferred to the football club after the original venue, Ocean Grove Domain Hall, was yellow-stickered by Dunedin City Council due to the effects of the recent heavy rain event. This restricted access due to safety concerns.

Mr Innes said Tomahawk Lagoon had "filled right up" in the rain and overflowed in places, resulting in the hall being inundated by 10-15cm of water. This had been cleaned up by local volunteers in the aftermath of the flooding.

"So, now we will be holding our reporting day nearby at the football club, but otherwise things will remain the same," he said.

Mr Innes said Sunday’s reporting day would be a chance for some of the keen student-citizen scientists of Bayfield High School, Tahuna Normal Intermediate School, Otago Girls’ High School, Queen’s and King’s High Schools to share what they have learned with friends, family and interested members of the local community.

The young people had met monthly throughout the year to monitor the biodiversity, as well as the chemical and physical patterns of Tomahawk Lagoon and its catchment.

Also giving presentations on Sunday will be University of Otago freshwater scientist Assoc Prof Marc Schallenberg, Tomahawk Smaills BeachCare Trust plant nursery manager Dr Nicole Bezemer, and possibly a representative from NZ Bird.

Mr Innes said, after eight years of monitoring by local school pupils and with the Otago Regional Council now conducting its own water quality monitoring, now was a good time to ask the question "where to next?" for the project.

"We have embarked on a project of restorative work around the lagoon, mainly involving riparian planting of Lagoon Creek, which is an important part of the catchment, supplying the upper lagoon."

Landowner Warren Matheson had been very supportive, agreeing to build fencing along the creek and supporting the riparian planting [along the banks of the creek] managed by the Tomahawk Smaills BeachCare Trust plant nursery team.

"Now that the first phase of planting is done, we will monitor what impact it has on the site — although it could take two to three years before that can be measured," Mr Innes said.

"The plan is to carry on with planting in another part of the catchment next year, so it will be good to discuss this at the reporting day."

The Tomahawk Lagoon Project started in 2016, led by citizen scientist group Ecotago Charitable Trust, with support from local schools.

Two years ago, the regional council completed a detailed catchment management plan for the area to help improve water quality, meet national standards, and support a healthy ecosystem. An active local community group has also been formed.