NZARM Conference 2025: Reducing Sediment Loss to Restore Ecological and Cultural Health on Streams

Описание: Dr Merrin Whatley presented on 'Reducing Sediment Loss to Restore Ecological and Cultural Health on Streams' at the NZARM Conference in Marlborough.

This presentation outlines an integrated cultural–scientific monitoring programme in the Mahurangi catchment, led through a partnership between Auckland Council and Ngāti Manuhiri and supported by central government funding. It matters because increasing erosion, sedimentation, and climate-driven extreme rainfall are placing growing pressure on freshwater systems, requiring more resilient, place-based approaches to land and water management.

The project builds on two decades of restoration activity and focuses on whether riparian retirement and planting in small headwater streams are delivering measurable improvements in sediment reduction, ecological health, and mauri. Monitoring was deliberately designed to integrate western scientific methods with Ngāti Manuhiri kaitiaki-led cultural monitoring, recognising that both knowledge systems provide complementary insight into catchment condition and change. Cultural monitoring centres on sensory observation, place-based judgement, and seasonal context, while scientific monitoring measures sediment, habitat, and ecological indicators. Both teams work together in the field, sharing observations and interpretation.

Early results indicate strong alignment between cultural assessments of stream health and scientific indicators. Streams with mature riparian vegetation and stock exclusion consistently show better habitat quality, higher abundance of sediment-sensitive invertebrates, and stronger cultural indicators of vitality, while unmitigated sites show greater variability and signs of stress. The work also highlights the importance of upstream land use and forest cover in influencing downstream outcomes.

Key implications are that integrated monitoring deepens understanding of restoration outcomes, supports more confident decision-making, and reinforces the value of long-term, collaborative approaches