Abstract
The aim of this Urgent Grant application is to document nutrient dynamics during an recent change in dominance among plant growth forms in Lake Tåkern, Southern Sweden. The lake has a historical record of repeated structural regime shifts between clear and turbid states and the present situation may precede a regime shift. In August, floating filamentous algae and high biomass of phytoplankton were noted in the open water. Interactions between submerged macrophytes and nutrients, particularly phosphorus, are central to the lake system structure and resilience to perturbations. The present situation provides a unique opportunity to collect data that, together with previous monitoring and experimental studies, are of high scientific and applied value. Much of the information that is available now will be lost during autumn senescence of macrophytes and filamentous algae. The project aim is therefore to document the nutrient level in the water and stored in plants (submerged vegetation, filamentous algae and phytoplankton), and phosphorus fractions in surface sediments in different vegetation stands across the lake, in September-October. We assume that the collected data will be useful to the understanding of non-linear responses to eutrophication and regime shifts in aquatic systems, but also for the understanding and management ecosystems in general.
Sweden