The sensitivity of phytoplankton in Loch Leven (U.K.) to changes in nutrient load and water temperature

Elliott, J. Alex; May, Linda. 2008 The sensitivity of phytoplankton in Loch Leven (U.K.) to changes in nutrient load and water temperature. Freshwater Biology, 53 (1). 32-41.

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1. Loch Leven is a shallow, eutrophic lake in Scotland, U.K. It has experienced much change over the 30 years that it has been studied; this has primarily been due to reduced nutrient loads to the lake through active catchment management. Its recovery has been slow and, therefore, we used a phytoplankton community model (PROTECH) to test its sensitivity to changing nutrient loads and water temperature. 2. PROTECH was initialized to simulate the observed phytoplankton community in 1995 and was then repeatedly run through a combination of step-wise changes in water temperature and nutrient load (two treatments were simulated for nutrient load: one changing both nitrate and phosphorus, and one changing just phosphorus). The effect on total chlorophyll-a concentration, cyanobacteria abundance and phytoplankton diversity was examined. 3. Whilst changes in temperature had little effect, variations in the nutrient load produced a range of responses. Increasing only the phosphorus load caused a large increase in Anabaena abundance and total chlorophyll-a concentration. However, the opposite response was recorded when nitrate load was changed as well, with Anabaena increasing its biomass under reduced nutrient load scenarios. 4. The key factor determining the type of response appeared to be nitrogen availability. Anabaena, a nitrogen fixer, could exploit the phosphorus resource of Loch Leven under limiting nitrogen conditions, allowing it to dominate under most of the scenarios tested apart from those supplying extra nitrogen to the lake. The model predictions agree with the observed data, which show that Anabaena continues to dominate the summer phytoplankton bloom in Loch Leven despite the considerable reduction in phosphorus supply from the catchment. This research provides a possible explanation for this.

Item Type: Publication - Article
Digital Object Identifier (DOI):
Programmes: CEH Programmes pre-2009 publications > Water > CC01A Detection and Attribution of Change in UK and European Ecosystems > CC01.2 Lake Ecosystems
CEH Programmes pre-2009 publications > Water > WA02 Quantifying processes that link water quality and quantity, biota and physical environment > WA02.3 Physico-chemical processes and effects on freshwater biot
UKCEH and CEH Sections/Science Areas: Watt
ISSN: 0046-5070
Additional Keywords: Anabaena, blue-green algae, cyanobacteria, phytoplankton phytoplankton responses to environmental change, Loch Leven
NORA Subject Terms: Biology and Microbiology
Ecology and Environment
Date made live: 18 Jan 2008 11:25 +0 (UTC)

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