Sediment-based investigation of naturally or historically eutrophic lakes—implications for lake management

• Published in: Journal of environmental management Vol. 79; no. 3; pp. 253 - 265
• Main Authors: Räsänen, Johanna, Kauppila, Tommi, Salonen, Veli-Pekka
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.05.2006; Elsevier; Academic Press Ltd
• Subjects: Animal and plant ecology; Animal, plant and microbial ecology; Applied ecology; Bacillariophyceae; Bacillariophyta; Biological and medical sciences; Conservation, protection and management of environment and wildlife; core samplers; diatom assemblages; Diatoms; Environmental management; Environmental monitoring; Environmental policy; European Union; European Union Water Framework Directive; European water framework directive; eutrophication; Fresh Water; Fresh water ecosystems; Freshwater; Freshwater resources; Fundamental and applied biological sciences. Psychology; General aspects; Geologic Sediments - chemistry; Lakes; Paleolimnology; phosphorus; Reference conditions; sediments; soil sampling; Synecology; water management; water quality; Finland; European water framework directive; Diatoms; Reference conditions; Paleolimnology; Water Framework Directive; Algae; Trophic status; Sediments; Environmental management; Eutrophication; Freshwater environment; Heterokontophyta; Aquatic environment; Bacillariophyta; European directive; Lakes; Thallophyta
• ISSN: 0301-4797; 1095-8630
• DOI: 10.1016/j.jenvman.2005.08.001

Implementation of the EU Water Framework Directive will call for new lake monitoring and management strategies. Therefore, different methods need to be tested in order to achieve reliable assessment of lake background conditions and water quality. Sediment-based techniques provide one such tool for lake management. In this work, 10 lakes, presumed to be naturally eutrophic, were investigated with a paleolimnological short core study. The aim of the study was to examine the composition of the diatom assemblages in their natural state, estimate their change over time and assess the background nutrient levels. One sediment profile from each lake was divided into six sub-samples that were analyzed for diatoms (60 samples). Diatom-based inference models were applied to reconstruct the past total phosphorus concentration and assess the eutrophication. The results indicated that all the lakes studied had already been nutrient-rich before the impact of modern agriculture. However, diatom assemblages have changed remarkably over time and total phosphorus concentrations have generally increased, so at present only two of the study lakes are close to their natural status. This suggests that naturally eutrophic lakes will probably require management actions to fulfill the new directive requirements in the future.