Sandra Rabow

Blooms like it hot – or not.

The ruling paradigm, blooms like it hot, is that extreme weather events caused by climate change will result in wider spread and more prolific cyanobacterial blooms due in part to higher water temperatures and nutrient inputs. During an extreme hot and dry summer in Sweden 2018 inconsistencies were however observed in this prediction. In Vombsjön, a drinking water supply well known for cyanobacterial blooms, a potentially toxic dinoflagellate bloomed and was dominant throughout the season. The observed shift in community composition was ecologically unexpected and raised new questions about the future management of the affiliated drinking water plant.

During my PhD I will be investigating the driving factors behind the observed community shift in 2018, filling an important knowledge gap in the effect of extreme weather events on future algal blooms as well as the potential implications for managing drinking water supplies. The specific aims include determining how widespread community shifts were in Sweden in 2018, to which extent spring temperatures determine bloom composition, and whether drought reduced nutrient inputs thereby allowing dinoflagellates to outcompete cyanobacteria. To achieve these aims intensive field sampling will be combined with laboratory experiments as well as analyses of existing environmental data.

This project is funded by the Research Council Formas.