Within the framework of the project “Host-parasite-interactions in freshwater phytoplankton blooms” Ingrid Sassenhagen from Uppsala University is currently sampling the diatom spring bloom in Lake Erken. The project aims to test if parasites preferentially infect highly abundant microalgal species, thereby controlling the diversity of phytoplankton communities. Many environmental sequencing studies recently revealed very high abundance and astonishing diversity of unicellular, eukaryotic parasites in different aquatic habitats. Such parasites might significantly contribute to the termination of the diatom blooms in Lake Erken. Taking advantage of the long-term monitoring data set from Lake Erken, Ingrid will also be able to trace the relative abundance of different parasitic groups through time and identify potential correlations with bloom-forming phytoplankton species. This spring, several fungal infections (Chytrids) were already observed in the diatoms Aulacoseira sp. and Asterionella sp.
The chain-forming diatom Aulacoseira sp. infected by chytrids.