Dormant phytoplankton in shallow lake sediments: cyanobacteria, green algae, diatoms and phytoflagellates are recruited

Abstract Dormant phases, also known as resting stages, are a life-history trait observed in several groups of microalgae. These stages are formed in response to adverse environmental conditions and can remain viable in the sediment for extended periods, germinating and rejoining the photosynthetic community once conditions become favorable. This experimental study investigated how environmental factors (light, temperature and desiccation) influence the recruitment (germination) of microalgal resting stages. The experiment was conducted in two phases. In the first, sediment from a natural shallow lake was subjected to extreme desiccation under three temperature regimes (17, 25 and 34°C). In the second, water was added to the sediment and recruitment was monitored under different light intensities. A total of 35 phytoplankton taxa, including cyanobacteria, diatoms, green algae and phytoflagellates with distinct ecological traits, germinated during the experiment. Analysis of variance (ANOVA) indicated that 34°C reduced the recruitment, while community composition remained stable across treatments. These findings highlight the taxonomic and functional diversity of the recruited microalgae and underscore the ecological importance of resting stages in linking the benthic and planktonic phases of phytoplankton communities.