RESUMO
Harmful algal blooms impair the aesthetic quality and healthy performance of in-situ water. Worse yet, dramatic temperature variability arises additional difficulty in algal-induced risk assessment, which is so far poorly explored. Microcystis aeruginosa (FACHB 905), was selected to explore the odor-producing pattern (ß-cyclocitral, the major odorant of the test alga) under several temperature-varying scenarios. Significant differences were observed in total ß-cyclocitral yield between these scenarios, e.g., a rapid yield response as a result of acute temperature variation. Yield response was not only dependent on absolute temperature, but influenced by temperature variability stress. Acute increase (AI) or sequential increase (SI) in temperature caused extra production response, while the opposite was observed in groups with acute decrease (AD) and sequential decrease (SD) in temperature. Cell growth in AD group showed severe inhibition, with the specific growth rates fluctuating around half of that in 16-control. Whereas, SD could relieve such detrimental growth effects. Cell quota of ß-cyclocitral yield was sensitive to temperature variation, with notable increase in AI and SI. Further, peaks in cell quota for SI group (79.3 %) were higher than for AI group (57.9 %). Cell quota variations in temperature-varying conditions contributed to the total yield response (R2 = 0.566-0.980) more than cell intensity variations (R2 = 0.0397-0.548). Further, it was also found that the internal mechanism by reactive oxygen species and pigments varied in various thermal scenarios. Overall, it was demonstrated that more than absolute value differences, temperature varying patterns across time influence algal behavior and related hazards, which should be noted in resource water quality management.
