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Despite considerable research examining the environmental controls on toxin-producing cyanobacteria, it remains unclear which factor(s) regulate toxin release, thereby limiting management strategies to mitigate harmful algal blooms (HABs). Toxic blooms often occur in eutrophic ecosystems during warm months and are anticipated to increase in frequency and duration with rising surface-water temperatures. Here we present evidence that temperature regulates microcystin release by toxin-producing cyanobacteria (Planktothrix agardhii). In particular, we have found that cyanobacteria can be present at bloom levels across a wide range of temperatures (5-30°C), but toxins are most elevated (on a biomass basis) at temperatures between 20-25°C, decreasing rapidly thereafter. We have observed this trend in both laboratory and in-situ studies examining the relationship between temperature and toxin release. These findings suggest that there is a temperature-dependent threshold between 20-25°C where cyanobacteria release a greater proportion of their toxins into the water column. Given the ubiquity of this cyanobacteria in eutrophic freshwater ecosystems globally, these data could aid managers in predicting instances of greater HAB toxicity to reduce human health risk.


Rober, A. R., Ball State University, USA,

Walls, J. T., Ball State University, USA,

Rubenstein, E. M., Ball State University, USA,

Wyatt, K. H., Ball State University, USA,


Oral presentation

Session #:021
Date: 03/03/2017
Time: 10:45
Location: 323 B

Presentation is given by student: No