eDNA as a holistic measure of pastoral landscape effects on taonga species

Our objective was to increase commitment to action in catchments by demonstrating a new approach of assessing freshwater quality for the agricultural sector. This was done by using traces of genetic material, or environmental DNA (eDNA) as novel indicators which provide a living context for understanding the ecological health of waterways. Currently freshwater quality is measured with key indicators such as faecal indicator bacteria (E. coli), nitrates, phosphates and other physico-chemical parameters for Regional Councils to identify potential health risks to humans. For communities however, such indicators are vague and somewhat abstract.Our case study site area was the upper reaches of the Manawatu River encompassing native bush, a hill country sheep and beef farm, and a dairy farm where freshwater samples were obtained from five separate sites for eDNA analysis. Freshwater sites were sampled for eDNA detection on four occasions December 2022 and February 2023, before Cyclone Gabrielle, and April 2023 and June 2023, after Cyclone Gabrielle. The project used six separate freshwater samples collected from each site on each sample occasion, to maximise eDNA detections for aquatic communities and terrestrial biodiversity, and used a new eDNA based ecological health index score, the taxon-independent community index (TICI) incorporating information across the tree of life.