J. Simons

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 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 Kutz. seem to indicate seepage of groundwater in otherwise nutrient-rich environments.

PHYTOCHELATIN SYNTHESIS IN RESPONSE TO CADMIUM UPTAKE IN VAUCHERIA (XANTHOPHYCEAE)

Production of phytochelatins (PCs) in response to cadmium uptake in the benthic macroalgae Vaucheria compacta and V. debaryana (Xanthophyceae) was investigated. The algae synthesized thiol-containing peptides, identified by means of high-performance liquid chromatography as PC2, PC4 and PC4. In both algal species the level of PCs increased with time of cadmium exposure and was dependent on external cadmium concentration. V. compacta synthesized significantly more PCs than V. debaryana. Exposure of the algae to cadmium at low temperature and in darkness resulted in a significant decrease in PC content over the time interval tested (3 days).

Growth and morphology of Draparnaldia mutabilis (Chlorophyceae, Chaetophorales) in synthetic medium

The development and morphology of Draparnaldia mutabilis under various culture conditions is described. The germination of zoospores is strictly erect. In the first stage of development a primary rhizoid or a small prostrate system is formed, which is generally replaced in a later stage by persistent secondary rhizoids originating from basal cells of the main axis. Optimal growth occurs at about 20°C and at relatively high light intensities. The phenotypic appearance found in field material is maintained best in culture in a dilute modified Woods Hole medium at 8°C under short day conditions. In more nutrient-rich media the typical features of Draparnaldia, especially differentiation of main axes and lateral fascicles, disappear and the plants attain a Stigeoclonium-like habit. Morphological variation has been studied in herbarium material and freshly collected specimens from several localities in The Netherlands. Evidence is presented that in The Netherlands only one, rather polymorphic Draparnaldia spec...

Ecological responses of macro- and microphytic algae to water pollution

In The Netherlands there are many small freshwater habitats where non-planktonic algae represent an important and often dominating biotic community. In recent time extensive blanketing algal mats and closed layers of duckweeds have become very common due to increased contamination by agricultural wastewater and manuring of pastures. Prolific algal growth may outcompete the aquatic macrophytes by reducing irradiance (Phillips et al. 1978) and by directly hindering photosynthesis by increasing pH and reducing the CO2 content of the water (Simpson & Eaton 1986).