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Understanding the impacts of multiple pressures with MARS experiments, catchment models and pan-European analyses Stefan Schmutz & Laurence Carvalho What we will cover Introduction – concepts Literature review Lakes River Basins (incl. transitional waters) Synthesising understanding for tools/apps How do pressures interact? Dominant? Additive? Synergistic? Antagonistic? Concepts in ecology Concepts in ecology Concepts in ecology Two gradients of pressure Review of the Literature Evidence item (EI) - effect of combined pressures described in a quantitative way Nõges et al. 2016. Science Total Environment: 540:43-52 Pressure groups Nõges et al. 2016. Science Total Environment: 540:43-52 Types of pressure interaction Types of interactions are seldom specified Nõges et al. 2016. Science Total Environment: 540:43-52 Response of BQEs (all water categories) Number of pressures Fish response better explained by multiple pressures Number of pressures Benthic flora sensitive to one dominant pressure Nõges et al. 2016. Science Total Environment: 540:43-52 Common questions being studied in MARS What is the response of BQEs (and related services) to: 1. Extreme temperature and nutrient stress? What are the consequences for water supply and recreation? 2. Extreme rainfall (drought) and nutrient stress? What are the implications for abstraction & eFlows? 3. Extreme rainfall (floods) and nutrient stress? What are the consequences for water supply? 4. Changes in morphology & nutrient stress? What are the consequences for flood management? Temperature & nutrients in lakes + Temperature & Nutrients in lakes Knowledge from experiments, time-series and pan-European studies Does climate change act synergistically with eutrophication to exacerbate problems of algal blooms? What are the consequences for water supply and recreation? Lake mesocosm experiment Control (P) + Phosphorus Heated Control (Temp) • Nutrient reductions need to continue to be the focus of management • Warming increases risk at lower nutrient conditions Jess Richardson, NERC Cyanobacteria abundance Lake time series • Significant effects of nutrients • No significant effect of temperature extremes • Significant interaction Year Carvalho and 15 others (4 external) % lakes exceeding health threshold European Lake Data 20 µg L-‐1 TP 10% exceed low risk 50 µg L-‐1 TP 40% exceed low risk 80 µg L-‐1 TP 50% exceed low risk Data from 1300 lakes used to establish management targets to reduce risks to water supply and recreation services Carvalho et al. 2013. Journal of Applied Ecology, 50: 315-323 Had Pro Ref Had Worst probability (%) (e) Had Best Ref Had 0 Ref Application to Lake Vansjø (Bayesian Model) Best ef Ref Had Climate scenario 0 Ref Management scenario Best Worst 80 60 60 40 40 20 20 0 0 - Had Worst Ref Had Climate scenario Had Ref Ref Management scenario Cyanobacteria most sensitive to management scenarios Had Best Ref Ref Had Climate R Climate scenario Worst Ref R Management scenario Manageme Phytop 100 80 Ref Had (f) Cyanobacteria 100 Ref Poor-Bad Moderate High-Good Ref Had Worst Ref Climate R Manageme (g) ity (%) ef 0 20 100 80 Jannicke Moe, NIVA 60 La Drought & Nutrients + Extreme rainfall (drought) & nutrients: concepts Before Water level fluctuations After + = Eutrophication Extreme rainfall (drought) and nutrient stress Case-study: Lake Beyşehir • Largest freshwater lake in Turkey (650 km2) • Pressure of water abstraction for irrigation & drinking water • Climate change adds additional pressure • Model simulation of scenarios to derive optimum water use & nutrients * * Extreme rainfall (drought) and nutrients Future water levels of Lake Beyşehir Climate scenarios: 2 GCMs Land use & abstraction scenarios Default : Current land use & abstraction LC1 : Sugarbeet farming increase LC2 : Forest to shrubland LC3 : Agricultural land to shrubland LC4 : Shrubland to agricultural area OUT10 : 10% increase in abstraction OUT20 : 20% increase in abstraction • Minor effect of land use change on water levels • Abstraction pressure dominant • MPI model suggests lake may dry out by 2040 How can we synthesise this understanding for useful RBM tools? Synthesis will: - identify indicators (species, metrics) that are sensitive or tolerant to multiple pressures to aid diagnosis - identify water-body types that are sensitive or tolerant to multiple pressures to aid risk and resilience management