Establishment of restoration monitoring at Tārerekautuku Yarrs Lagoon: Conservation Biology (ECOL609) project reports

Abstract

Ninety percent of New Zealand’s wetlands have been lost along with the endemic plants, fish, birds, and invertebrates. Those that remain are threatened by choking weeds, suffocating sediment, pollution from livestock and continued drainage and clearance (Hansford, 2010). Therefore, all remaining wetlands, regardless of their ecological state, are precious and need to be restored and managed to maximise the biodiversity within. Tārerekautuku Yarrs Lagoon is a 76.9 ha reserve located along the Ararira/LII River between Lincoln and Te Waihora/Lake Ellesmere. Tārerekautuku is administered by the Selwyn District Council (SDC) who have recognised the wetland’s intrinsic value. The lagoon area was known as a significant mahinga kai (food gathering) site for Ngāi Tahu, and particularly the local hapū of Ngāi Te Ruahikihiki based at Taumutu. Mahinga kai species being gathered at this site include tuna (eel), koareare (the edible rhizome of raupō/bullrush), koukoupara (bullies), mawehe (kōaro), pārera (grey duck), pūtakitaki (paradise duck), pākura (pukeko), whio (blue duck), kaaha (shag) and aruhe (bracken fern root) (Taiaroa 1880). The cultural and biodiversity values of Tārerekautuku are significant and ecological restoration of the lagoon has a huge potential to enhance these (Boffa Miskell, 2017). Selwyn District Council, with the support of the Department of Conservation (mainly Robin Smith), received approximately $800,000 from Ministry for the Environment ‘Freshwater Improvement Fund’ towards achieving five objectives: 1. To control willows and other weeds across approximately 87 ha in the Tārerekautuku Yarrs Lagoon Wetland. 2. To undertake predator control within the wetland and surrounding catchment to target mustelids, rats, and possums 3. To reduce sediment loads through instream works (up to five sediment traps or equivalent) and waterways re-battering work (approximately 2,000 m), including installing two bridges for site access. 4. To plant at least 12,516 native plants and trees across eight ha of Tārerekautuku wetland and connecting waterways. 5. To establish a monitoring programme at the Tārerekautuku wetland for Mātauranga Māori to measure ecological change over time. With Lincoln University’s proximity and MOU (pending) between them and SDC, this project provides a win-win scenario for students to help monitor ecological changes over time (objective 5). The project summaries that follow are an integral part of the ECOL609 (Conservation Biology) course that is undertaken in the first semester of 2022 where students chose a conservation area to monitor. Vegetation quadrat monitoring intended to replicate Stammer (2010); however, access to the site was deemed unsafe to proceed. This work has been added as an Appendix in this report to allow future comparisons.