Targeted isolation approaches combined with environmental sequencing unveil ecological interactions and seasonality of chytrid fungi

Environmental sequencing surveys often focus on spatial diversity and less on temporal, i.e. seasonal dynamics, within a system. Many parasitic chytrids are considered to be host specific and their occurrence is coupled with the seasonal population dynamics of their host phytoplankton. It is therefore assumed that they show a strong seasonality and short, distinct temporal dynamics. To test our hypothesis, we performed a field study combining high-throughput environmental sequencing with several targeted approaches, i.e. cultivation, single cell isolation and in situ baiting, during a full seasonal cycle in the pelagic zone of the mesotrophic, temperate Lake Stechlin (North-East Germany).