Dr Angus Lawrie1
1Curtin University, Bentley, Australia
Biography:
Angus Lawrie is a conservation biologist and postdoctoral researcher in the Trace and Environmental DNA laboratory at Curtin University. He is a wetland ecologist who has worked previously in the ecology and evolution of a range of Australian endemic aquatic invertebrates.
Abstract:
Wetlands are in decline globally, yet existing monitoring methods are often system-specific, yield non-comparable results or rely on a limited number of taxa that may not be responsive indicators of environmental stress. We developed the AqWATIC (Aquatic Ecology of Western Australia via Taxon-Independent Classifications) Index, a taxon-independent biotic index built from environmental DNA (eDNA) metabarcoding data, to provide a single comparable measure of freshwater wetland condition. We collected > 1000 water samples from a total of 171 wetlands spanning roughly 357,000 km² of south-western Australia and sequenced across 13 metabarcoding assays. Ecological tolerance values were assigned to individual ASVs through an unsupervised iterative learning model and calibrated against an independent Wetland Pressure Index integrating vegetation loss, trophic status, invasive fish and hydrological disturbance. AqWATIC Index scores correlated strongly with independent measures of anthropogenic pressure, suggesting the index reliably captures cumulative wetland degradation. A parsimonious three-assay panel reproduced this signal and outperformed the full 13-assay model, showing that robust condition assessment is achievable at substantially reduced sequencing cost. This study reinforces that taxon-independent eDNA indices can function as regionally scalable, comparable measures of ecosystem condition, offering a template for next generation biomonitoring beyond the wetlands and region studied here. However, we emphasize the need for careful assessment of eDNA index limitations and appropriate application within the environmental context for which each index was calibrated, so that stakeholders do not extend these tools beyond their valid range and generate misleading assessments of ecosystem condition.