| Autor: |
Stone S; CSIRO Environment, Tharawal Country, Lucas Heights 2234, Australia.; School of Life Sciences, University of Technology Sydney, Gadigal Country, Ultimo 2007, Australia., Koppel DJ; Australian Institute of Marine Science, Noongar Country, Perth 6009, Australia., Binet MT; CSIRO Environment, Tharawal Country, Lucas Heights 2234, Australia., Jolley DF; CSIRO Environment, Ecosciences Precinct, Jagera and Turrbal Country, Brisbane 4001, Australia., Simpson SL; CSIRO Environment, Ecosciences Precinct, Jagera and Turrbal Country, Brisbane 4001, Australia. |
| Abstrakt: |
Aquatic organisms may frequently be exposed to short-term discharges of contaminants, including those from pesticide use, stormwater runoff, or industrial effluents entering waterways. Here, a new microalgal multispecies flow cytometry-based bioassay is used to assess knowledge gaps in risk assessments posed by the short-term exposure of organisms to contaminants. The toxicities of atrazine, metolachlor, and copper were assessed using four exposure scenarios, a 72 h exposure (continuous), an 18 h pulse exposure, and two 3 h pulse exposures (light and dark conditions), that assessed chronotoxicity. The influence of duration on toxicity explored the utility of two expressions of chemical-exposure dose: pulse-exposure concentration (PeC) and time-weighted average concentrations (TACs). The three coexisting microalgae ( Monoraphidium arcuatum , Nannochloropsis -like sp., and Pediastrum duplex ) tolerated higher concentrations for shorter 3 and 18 h pulses compared to continuous 72 h exposures. Toxicity estimates calculated on a TAC basis were effective for predicting the toxicity of the pulses of atrazine, metolachlor, and copper. Fluorescence data collected using flow cytometry were linked to physiological diel changes for each species. Chronotoxicity was observed for copper with two species. While continuous contaminant exposures provide a conservative estimate of toxicity compared to pulses, the duration and time of exposure are critical factors to consider when assessing the toxicity of contaminants to microalgae. |
