Freshwater and marine projects

The Aquatic Ecology and Rare Species Survey (ACERSS) project was set up to study the plants and animals living in selected coastal water bodies along South Canterbury. The survey took place in summer 2024 and covered 15 water bodies between the Ōrari and Waihao catchments.

Survey findings: Using both environmental DNA (eDNA) sampling and conventional fish trapping methods, the project identified 295 species across six groups, including macroinvertebrates, fish, birds, algae, and amphibians.

Many of the surveyed sites showed signs of disrupted flow connectivity due to human activities such as farming, water abstraction, flood control, and gravel buildup, which have altered natural hydrological patterns and isolated water bodies from the sea.

Despite these pressures, the survey revealed a diverse fish community, including 21 species such as lamprey, eels, galaxiids, bullies, triplefins, and flounders. Several rare species, including giant kōkopu, redfin bully, and bluegill bully, were found at fewer than 20 per cent of sites, highlighting the importance of ongoing monitoring and habitat protection.

Waterways in the Mackenzie Basin host a variety of native fish species, many of which are threatened with extinction. However, populations of small galaxiids are under pressure from predation by introduced brown trout.

Worke done: We funded the installation of a perched culvert trout barrier at Waterwheel Wetland, in partnership with DOC. This proven design, implemented under a global consent held by us, prevents trout from accessing upstream habitats. Paired with trout removal upstream of the barrier the project will provide a refuge for threatened non-migratory native fish species such as the big nose galaxias.

The newly protected habitat may also support future translocations of the critically endangered lowland longjaw galaxias to help ensure its long-term survival.

Seagrass (Zostera muelleri) is nationally classified as at risk - declining, and its status in Waitaha remains unknown.

Seagrass provides vital ecosystem services including nursery habitat for marine invertebrates and fishes, foraging grounds for shorebirds, stabilisation of marine sediments reducing coastal erosion, improved water quality, and carbon isolation in the dense, subterranean root mat. 

Work done: In the first stage of a multi-year project funded through the Christchurch and Banks Peninsula biodiversity targeted rate, NIWA mapped seagrass beds in Duvauchelles, Takamatua, Robinsons, and Childrens Bays in Akaroa harbour and Pūrau Bay in Whakaraupō/Lyttelton Harbour.

Next actions: These maps form the first stage of a multi-year project that aims to protect and restore existing seagrass meadows across Banks Peninsula through effective management on a catchment scale.

These maps establish a baseline to monitor the impact of catchment-scale management interventions, such as reducing land-based pollution and recreational abrasion, and will guide future restoration efforts, including seagrass propagation and transplantation, where protection proves effective.

As part of our commitment to protecting marine biodiversity and the annual Regional Marine Pest Surveillance programme, we undertake marine biosecurity surveillance to target invasive species like Mediterranean fanworm (Sabella spallanzanii) across four key harbours — Lyttelton, Timaru, Kaikōura, and Akaroa. In partnership with the Lyttelton Port Company (LPC), a large-scale removal operation was carried out in Lyttelton’s inner harbour, focusing on high-risk areas such as Te Ana Marina and LPC Wharfs 1–3.

Work done: NIWA conducted a remote survey of the Z-berth using a BoxFish ROV, successfully trialling fanworm removal in areas unsafe for divers. To support public awareness, we also developed a fanworm identification guide, now widely shared across the marine biosecurity sector.

Community action on marine pests: Community engagement was also a key focus, with the first Boaties Biosecurity BBQ held at Te Ana Marina in March 2025, bringing together vessel owners, iwi, and industry partners to raise awareness of marine pests and promote best practices. These efforts are part of a broader strategy to safeguard Aotearoa’s unique marine ecosystems from invasive threats.