Didymo predictive maps, quantifying the potential threat from didymo to any river reach in New Zealand, are now in use, thanks to work by NIWA scientists. Potential percentage didymo cover and mat thickness can be mapped, based on models combining what is known about didymo biology with specific river and climate features. The didymo predictive maps (DPMs) are already proving valuable in practical situations.
Scientist Dr Cathy Kilroy cites two recent applications of the DPMs – one where the threat of didymo to an endangered native fish (the Kauru or lowland longjaw galaxias Galaxias cobitinus) in its very localised North Otago habitat needed to be quantified by DOC; another where a South Island local authority wanted an assessment of the potential growth of didymo in all its rivers as it faced the challenge of prioritising freshwater management resources.
The DPMs will be made available to anyone via MAF Biosecurity New Zealand.