Linda May Centre for Ecology & Hydrology The importance of long-term data: An example from Loch Leven

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1 Presentation given at: 2 Years of ECN Research & Monitoring May 214 Lancaster Linda May Centre for Ecology & Hydrology The importance of long-term data: An example from Loch Leven Event organized by Sponsors: and supported by ECN s sponsors and research partners Research partners: Note: This presentation may differ slightly from that given at the symposium

2 IMPORTANCE OF LONG-TERM DATA An example from Loch Leven Linda May 1 (Loch Leven Project Manager) Laurence Carvalho, Bryan Spears, Iain Gunn, Ian Winfield, Bernard Dudley, Dave Carss, Helen Woods, Alanna Moore Contact: lmay@ceh.ac.uk;

3 Overview of Loch Leven A shallow lake Surrounded by farmland Polluted by runoff and effluent discharges Home of world famous trout fishery High conservation & tourism value Supplies water to industry

4 Historical data and information CEH 45 years at weekly/fortnightly intervals 5 in-lake physical, chemical and biological variables weekly nutrient (P, N, Si) input data at 1-year intervals Other sources loch level & outflow since 185 (Tullis Russell) lake chemistry (Freshwater Lab, Pitlochry) aquatic plants (Various) fish catches since 19 (Kinross Estates) birds since 1967 (SNH) visitor numbers since 24 3 TP concentration (µg L -1 )

5 Water quality problems Serious algal blooms developed in the late 198s/early 199s A particularly bad event in 1992 hit the headlines with: Toxic bloom turns loch into shallow grave The cost to the local community was about 1 million over the following 3 months, alone The event became known locally as Scum Saturday

6 Understanding cause and effect Eutrophication causes water quality problems. Mean annual chlorophyll conc. (mg m -3 ) y = 1.6x R 2 =.82 These include: toxic algal blooms. reduced amenity value increased water treatment costs Mean annual TP conc. (mg m -3 ) Long term monitoring data ( ) showed P availability to be the main problem.

7 Identifying catchment sources Rainfall 2% Wildfowl 2% Sewage 26% Runoff 39% Woollen mill 31% P input measured every 8 days for 1 year, 1985: 2.5 tonnes per year Bailey-Watts & Kirika, 1987

8 Setting restoration targets Indicators Target values Actual values Annual mean P conc. (mg m -3 ) 4 75 Annual mean chlorophyll conc. (mg m -3 ) Annual mean water clarity (m) Max. macrophyte depth (m) Estimated P loading capacity = 1.5 t y -1 Actual P loading = 2.5 t y -1

9 Reducing P inputs Campaign to stop loch going septic

10 External P input reduced by 6% P input (t/y) Diffuse + Point Point Diffuse P input measured every 8 days during 1985, 1995 & 25 Bailey-Watts & Kirika, 1987, 1999; Defew 28

11 Recovery: phosphorus concentrations Water column TP conc. (µg l -1 ) 3 25 Recovery delayed by internal recycling of legacy P In-lake P conc. (mg m -3 ) Cost of scum Saturday : 1M P input 6% P input reduced by 6% LLCMP Target Spears et al., 212

12 Change in chlorophylla vs P concs 12 y = 1.6x R 2 = Mean annual chlorophyll conc. (mg m -3 ) Mean annual Chl (µg/l) Annual mean chlorophyll a concentrations (mg m -3 ) Mean annual TP conc. (mg m -3 ) Mean Annual annual mean TP (µg/l) TP concentrations (mg m -3 ) Carvalho et al., 212

13 Recovery: aquatic plants in deeper water Macrophyte max. rooting depth (m) R 2 =.873 Aquatic plant growing depth (m) Annual P input to lake (tonnes) Phosphorus load (t y -1 ) May & Carvalho, 21

14 Recovery: Improved habitat for wildlife Mallard Mallard Scotland Pochard Pochard Scotland Carss et al., 212

15 Moving forward... Lakes provide many ecosystem services, including: Provisioning services such as food (fish) & water supply Regulating services such as waste management & water purification Supporting services such as nutrient cycling & primary production Cultural services such as inspiration, recreation & conservation Managing the delivery of multiple services effectively is a key challenge for the future.

16 Promoting sustainable use

17 Linking social and environmental data algal-dominated state Habitat Quality WFD status (phytoplankton macrophytes) Bad, Moderate, Good plant-dominated state Rainbow trout (presence/absence) Abundance of all brown trout Abundance of large brown trout Reputation Fishing Quality (Catch Per Unit Effort) State Transition BBN Model Number of fishermen (service - benefit)

18 Conclusions Managing lakes to provide multiple ecosystem services is a major challenge Understanding the role of good water quality and biodiversity in service delivery is essential Long term data are key to identifying ecosystem responses to environmental change Lessons learned can improve management of natural capital and ecosystem elsewhere Combining data from different lakes improves understanding and transferability of results Incorporating socio-economic data is key to achieving sustainable management

19 Acknowledgements Many thanks to: Kinross Estates for access to the loch & historical records SNH & SEPA for co-funding & data provision Tony Bailey-Watts and Alex Kirika for establishing long term monitoring at Loch Leven more than 4 years ago More than 15 people for their contributions to this project since 1967

20 ... and a wide range of stakeholders And many others