Over verspreiding en periodiciteit van de zoetwaterwieren in Drentsche heideplassen : bijdrage voor het samenstellen eener Nederlandsche wierenflora

The pools were all situated in the diluvium of the Dutch northern province of Drente. From the macroflora 3 main types of pools were distinguished which paralleled 3 clearly distinguishable associations of the algal flora. Several algae may serve as type species. In plankton collected and isolated by centrifuging from open water, Flagellatae usually predominated, Desmidiaceae were few and Bacillariaceae and Cyanophyceae were almost absent. Protococcaceae and Desmidiaceae may temporarily predominate in the plankton of some pools.
The periodic fluctuation of the whole algal vegetation (comprising plankton and benthos) was traced in six places, of which two dried up sometimes in the summer of 1925. The association of algae in a pool fluctuated over the year. Seasonal development was parallel in the different pools for only a few of the species. Heat and light were important factors for the development of the algae. Which of them was decisive in a particular case was difficult to establish. Their influence on reproduction could not be explained.