Spirogyra species and accompanying algae from pools and ditches in The Netherlands

Abstract

In ditches and moorland pools zygnematacean algae, especially Spirogyra, make up an important and often dominant component of floating algae. Of the total number of 60 Spirogyra species as yet recorded in The Netherlands, 47 species were recorded in ditches and pools. Sirogonium was represented by only one species, S. sticticum (Engl. Bot.) Wille, and Mougeotia and Zygnema by seven and six species, respectively. In hardwater ditches, especially at sites with relatively low pollution, Spirogyra forms a richly diversified component with up to ∼ 20 species per site. At hardwater sites with appreciable pollution, Spirogyra is suppressed or replaced by massive growths of algae such as Cladophora, Vaucheria, Enteromorpha or Hydrodictyon. At low alkaline and slightly acid sites, the number of species per site is considerably lower. Under conditions with pH values < 5, Spirogyra does not occur and is replaced by Mougeotia, Zygnema, Klebsormidium, Microspora and some others. The periodicity of Spirogyra species was studied. A peak in spore production occurs in the second half of May and the first half of June. Spores were more frequently observed in hardwater habitats than in low-alkaline environments. Most species have wide ranges of occurrence; 22 species were found in low alkaline and slightly acid habitats, but most of these species are not restricted to such environments. Presumably they are adapted to nutrient-poor conditions. In eutrophic hardwater ditches, Spirogyra granulata Jao and S. singularis Nordst. appeared to be very tolerant to pollution. Species such as Spirogyra nitida (Dillw.) Link and S. majuscula Kütz. seem to indicate seepage of groundwater in otherwise nutrient-rich environments.