Long-term variation and regulation of internal phosphorus loading in Loch Leven
- 818 Downloads
Long-term monitoring data (1968–2008) were used to investigate internal phosphorus (P) loading following external P loading reduction in shallow Loch Leven, Scotland. A whole-lake sediment P inventory (upper 3 cm of sediment; 2005) suggested a release-potential of 29.7 tonnes (t) from the release sensitive sediment P pools. 18.5 t was contained within shallow water sediments (<4.5 m water depth) with 7.6 t in deeper water sediments below the photic zone (>5 m water depth). The “observed” release (<5.1 t), estimated using a water column P mass balance approach (1989–2008), was <5.1 t, indicating the presence of regulating mechanisms. Observed P release declined between 1989 and 2008, with the exception of 2003–2006. Observed P release estimates were positively correlated with annual average water column P concentration after 1989, highlighting the role of internal loading in maintaining poor water quality conditions after management intervention. Multiple regression analysis suggested that internal loading was driven by the wave mixed depth in spring (positive driver), summer water temperature (positive driver) and spring water clarity transparency (negative driver). The potential importance of biological and physico-chemical feedback mechanisms in the regulation of benthic–pelagic coupling and water quality in Loch Leven are discussed.
KeywordsSediment Phosphorus Internal loading Weather Water quality Recovery Eutrophication
We would like to acknowledge Mr. Jamie Montgomery and, his father, Sir David Montgomery for their continued support, enthusiasm and assistance throughout the project. We would also like to thank Willie Wilson, of Loch Leven Fisheries, for his invaluable advice and support during the project and for the provision of weather data. Finally, we wish to thank Dr. Martin Søndergaard (NERI, Denmark) and Dr. Andrea Kelly (the Broads Authority, UK) for useful comments that led to the improvement of the manuscript. This project was funded by the Natural Environment Research Council, UK.
- Calvert, S. E., 1974. The distribution of bottom sediments in Loch Leven, Kinross. Proceedings of the Royal Society of Edinburgh B 74: 69–80.Google Scholar
- Canfield, D. E. Jr., K. A. Langeland, S. B. Linda & W. T. Haller, 1985. Relations between water transparency and maximum depth of macrophyte colonization in lakes. Journal of Aquatic Plant Management 23: 25–28.Google Scholar
- Carvalho, L., C. Ferguson, I. Gunn, H. Bennion, B. Spears, A. Kirika & L. May, 2011. Water quality of Loch Leven: responses to enrichment, restoration and climate change. Hydrobiologia. doi: 10.1007/s10750-011-0923-x.
- D’Arcy, B. J., L. May, J. Long, I. R. Fozzard, S. Greig & A. Brachet, 2006. The restoration of Loch Leven, Scotland. Water Science and Technology 53: 181–191.Google Scholar
- Holden, A. V. & L. A. Caines, 1974. Nutrient chemistry of Loch Leven, Kinross. Proceedings of the Royal Society of Edinburgh B 74: 101–121.Google Scholar
- Jeppesen, E., M. Søndergaard, J. P. Jensen, K. Havens, O. Anneville, L. Carvalho, M. F. Coveney, R. Deneke, M. T. Dokulil, B. Foy, D. Gerdeaux, S. E. Hampton, S. Hilt, K. Kangur, J. Kohler, E. H. H. R. Lammens, T. L. Lauridsen, M. Manca, M. R. Miracle, B. Moss, P. Noges, G. Persson, G. Phillips, R. Portielje, S. Romo, C. L. Schelske, D. Straile, I. Tatrai, E. Willen & M. Winder, 2005. Lake responses to reduced nutrient loading – an analysis of contemporary long-term data from 35 case studies. Freshwater Biology 50: 1747–1771.CrossRefGoogle Scholar
- LLAMAG, 1993. Loch Leven: the report of the Loch Leven area management advisory group. Forth River Purification Board, Edinburgh.Google Scholar
- May, L., L. H. Defew, H. Bennion & A. Kirika, 2011. Historical changes (1905–2005) in external phosphorus loads to Loch Leven, Scotland, UK. Hydrobiologia. doi: 10.1007/s10750-011-0922-y.
- Rip, W., 2007. Cyclic state shifts in a restored shallow lake. Thesis, Wageningen University. ISBN 978-90-8504-706-3.Google Scholar
- Scheffer, M., 2001. Ecology of shallow lakes. Kluwer Academic Press, London.Google Scholar
- Sas, H., 1989. Lake restoration by reduction of nutrient loading. Academic Verlag Richarz, St. Augustin.Google Scholar
- Smith, I. R., 1974. The structure and physical environment of Loch Leven, Scotland. Proceedings of the Royal Society of Edinburgh B 74: 81–100.Google Scholar
- Søndergaard, M., 1989. Phosphorus release from a hypertrophic lake sediment: experiments with intact sediment cores in a continuous flow system. Archive für Hydrobiologie 116: 45–59.Google Scholar
- Søndergaard, M., 2007. Nutrient dynamics in lakes – with emphasis on phosphorus, sediment and lake restorations. DSc. Thesis. National Environmental Research Institute, University of Aarhus, Denmark: 276 pp.Google Scholar
- Spears, B. M., 2007. Benthic–pelagic nutrient cycling in shallow lakes: investigating the functional role of benthic microalgae. PhD Thesis, University of St Andrews.Google Scholar
- Townend, J., 2004. Practical statistics for environmental and biological scientists. Wiley, West Sussex.Google Scholar
- Wetzel, R. G. & G. E. Likens, 2000. Limnological analyses, 3rd ed. Springer-Verlag, New York.Google Scholar