The Batrachospermeto-Chaetophoretum, A Remarkable Algal Association in the Netherlands

The Batrachospermeto-Chaetophoretum is a very characteristic algal association, widely distributed in oligohalinous as well as in eutrophic and mesotrophic freshwater in the lakes and ponds in the western part of the Netherlands. It prefers shaded stations, sheltered from wave-action and occurs on reeds, Typha stalks and waterplaats, but also on stones and live snails. The association may be found the whole year round; Batrachospermum moniliforme is a perennial species, propagating in spring, Chaetophora incrassata an annual one. Owing to its small light requirement the association is bordered at the upper limit by the photophilous Cladophoretum glomeratae lacustre; the lower limit is determined by competition with sessile animal colonies. Probably the association has a wide distribution in Europe.