Author: Kaitlin L Reinl,  PhD Student Researcher (University of Minnesota Duluth)

Designation: 

Description:
Recently emerging cyanobacterial blooms in oligotrophic Lake Superior have been primarily dominated by Dolichospermum lemmermannii with akinetes present. We developed a life cycle model that incorporates this potentially important life stage using field data for temperature and nutrients. We tested 4 sets of akinete germination conditions using combinations of photosynthetically active radiation, total dissolved phosphorus, and temperature, and employed 2 approaches to model growth (minimum and multiplicative) for a total of 8 model runs. We found no difference for the mean and maximum vegetative biomass for all germination conditions, but the contribution of vegetative and akinetes to the total biomass throughout the year was variable. Including akinetes decreased the vegetative peak by 34 and 11% for multiplicative and minimum growth formulas, respectively. We also tested 4 model scenarios including 2x river TDP inputs, increased temperature, no river loading of cyanobacteria, and 2x river loading with 2 growth formulas and 4 germination conditions for a total of 32 model runs. For all runs, inclusion of akinetes resulted in no change or a decrease in vegetative biomass. The effects of model scenarios on vegetative biomass was variable, with doubled TDP loading having the biggest effect. These results indicate that akinetes may provide an important role in survival and establishment of new populations, but not to boost cyanobacterial growth to bloom levels. This work also indicates that nutrient inputs are an important factor in promoting blooms in Lake Superior.

Category: Scientific Program Abstract > Special Sessions > CS18 Harmful blooms