Recent changes in the nutrient status of a soft-water Lobelia lake, Hampen Sø, Denmark

Nutrient-poor, low-productive (oligotrophic) soft-water lakes in the Atlantic areas of West and North-West Europe – the so-called Lobelia lakes – are of high conservation value as their low nutrient status favours a particular submerged macrophyte flora with isoetids, which are becoming increasingly rare or threatened due to nutrient enrichment (eutrophication) associated with landuse changes and urbanisation. European Union member states have a duty of care, under the Habitats Directive, to protect the biodiversity of oligotrophic to mesotrophic (moderately productive) standing waters.