# Uncovering Putative Bacterial Pathogens in Lakes in Aotearoa New Zealand Using Environmental DNA

## TL;DR

A study used environmental DNA to find potential bacterial pathogens in 287 New Zealand lakes, revealing widespread presence even in remote areas.

## Contribution

The study introduces a broad-spectrum eDNA screening method for detecting bacterial pathogens in freshwater ecosystems.

## Key findings

- 412 potentially pathogenic bacterial taxa were detected across 287 lakes.
- Putative pathogens were found even in remote alpine lakes with minimal human impact.
- Pathogen presence was linked to high-productivity grasslands and elevated nutrient levels.

## Abstract

The emergence of aquatic diseases poses significant risks to ecological, social, cultural and economic values. Aquatic environments are intricately linked to human and animal health, as water can facilitate the spread and transmission of pathogens and waterborne diseases. We conducted an environmental DNA survey of 287 lakes across Aotearoa New Zealand, spanning a broad gradient of natural and human‐influenced conditions. Using a curated bacterial pathogens database, we detected 412 potentially pathogenic taxa—250 detected only in water and 162 found in both water and sediment; none were exclusive to sediment. Dominant groups included Pseudomonas, Acinetobacter, Clostridium, Afipia and Burkholderiaceae. Putative pathogens were ubiquitous in all lakes, including remote alpine sites with minimal human impact. Pathogen communities were associated with the extent of high‐productivity exotic grassland in the catchment and elevated nutrient levels, although richness was not linked to environmental drivers. Our findings show that eDNA can be a cost‐effective, broad‐spectrum screening tool that complements targeted diagnostics. The widespread occurrence of potential pathogens in lakes underscores the need for improved understanding of their ecological dynamics and the environmental conditions that promote disease outbreaks, supporting freshwater biosecurity, ecosystem management and public and animal health.

Aquatic diseases threaten ecological, social, cultural and economic values. An eDNA survey of 287 lakes in Aotearoa New Zealand detected 412 potential pathogens. Key drivers of putative pathogen presence included high‐productivity exotic grassland and elevated nutrient levels.