Assessment of nitrogen interaction with temperature on the growth and toxin production of mat-forming toxin-producing Anagnostidinema carotinosum

Aims Global warming and eutrophication contribute to the severity of cyanobacteria blooms. However, it is unclear how these factors influence the growth and toxin production of Anagnostidinema carotinosum. Methods and Results Based on morphological and molecular analysis, this is the first time A. carotinosum was identified in South Korea. The interactive effect of temperature (25, 30 or 34 degrees C) and nitrogen (2.5, 3.5 or 4.5 mg NO3-N l(-1)) on A. carotinosum growth and toxin production was studied. Increasing nitrogen limitation reflects reduced growth and chlorophyll-a content at all temperatures. However, the growth was effective under nitrogen limitation when temperatures exceeded 25 degrees C. The maximum growth was found at 30 degrees C, followed by 34 degrees C under higher nitrate levels (3.5 and 4.5 mg l(-1)). In addition, the cell microcystin and anatoxin-a quota increased significantly at 25 degrees C with increasing nitrate limitation, decreasing considerably at 30 degrees C in the same nitrate gradient. Conclusion These results suggested temperatures stimulate A. carotinosum growth at 30 and 34 degrees C and cellular toxin quota at 25 and 34 degrees C with increasing NO3-N levels. Significance and Impact of the Study These findings imply that limiting nitrogen input alone can effectively reduce biomass; however, controlling A. carotinosum and its toxins at higher temperatures under nitrate limitation is necessary for water quality.

Automated summary

Global warming and eutrophication affect the growth and toxin production of Anagnostidinema carotinosum. This study found that temperature stimulates the growth of A. carotinosum at 30 and 34 degrees C and increases cellular toxin content at 25 and 34 degrees C with increasing nitrate levels.