Harper, Ashleigh R.Santin, CristinaDoerr, Stefan H.Froyd, Cynthia A.Albini, DaniaOtero Pérez, Xosé LoisViñas, LucíaPérez Fernández, Begoña2020-04-012020-04-012019Harper Ashleigh R., Santin Cristina, Doerr Stefan H., Froyd Cynthia A., Albini Dania, Otero Xose Luis, Viñas Lucia, Pérez-Fernández Begoña (2019) Chemical composition of wildfire ash produced in contrasting ecosystems and its toxicity to Daphnia magna. International Journal of Wildland Fire 28, 726-737. https://doi.org/10.1071/WF182001049-8001http://hdl.handle.net/10347/21052It is well established in the world’s fire-prone regions that wildfires can considerably change the hydrological dynamics of freshwater catchments. Limited research, however, has focused on the potential impacts of wildfire ash toxicity on aquatic biota. Here, we assess the chemical composition and toxicity of ash generated from wildfires in six contrasting vegetation types distributed globally (UK grassland, Spanish pine forest, Spanish heathland, USA chaparral, Australian eucalypt forest and Canadian spruce forest). Acute (48 h) immobilisation tests were conducted on the extensively studied aquatic macroinvertebrate Daphnia magna, a sensitive indicator of aquatic contaminants. We found significant differences between the chemical composition and toxicity of these ash types. The UK and Spanish ash had no detectable toxicity to Daphnia magna, whereas the Australian eucalypt, USA chaparral and Canadian spruce ash all caused significant toxicity (immobilisation). The principal characteristics of the latter ash types were their high pH, and NO3, Cl and conductivity levels. Elevated water-soluble and total concentrations of metals (e.g. Mn, Fe, Zn, Pb, Cu and As) and total polycyclic aromatic hydrocarbons (PAHs) were not linked to toxicityeng© IAWF 2019 Open Access CC BY-NC-NDhttps://creativecommons.org/licenses/by-nc-nd/4.0/BioassaysEcotoxicologyPolycyclic aromatic hydrocarbons (PAH)Wildfire impactsjournal article10.1071/WF182001448-5516open access