Session 1d Selecting appropriate thresholds Introduce Shiny app Link is in Guidance Manual Participants to have a go Run through values Summarise results using Fig 2-1

Making life easier for ourselves: the Shiny app http://phytoplanktonfg.okologia.mta.hu:3838/Tkit_nutrient/ http://varbirog.shinyapps.io/Tkit_nutrient Start by clicking on “Import and Preprocess”

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Possible boundary values for L-CB1 You have generated a number of possible boundary values Differences between methods Decisions regarding outliers Decisions regarding linear range

Possible boundary values for L-CB1 Output from regression methods: Output from categorical methods: Output from mismatch method (GM only):

Potential boundary values for L-CB1 (summarised as g L-1 TP) Method Lower Centre Upper OLS1 57 87 RMA 50 73 OLS2 36 53 Average medians Average quartiles 54 75th quartile mismatch 51 Logistic regression 56 79 Range of national boundary values (Table 4-4 from CIS Guidance Manual) 25th percentile 33 Median 60 75th percentile 62

Regulation options (a) intersection with best-fit line (b) upper confidence line (c) lower confidence line Horizontal line shows the biological good/moderate boundary (0.7 in this example); vertical lines show intersection with regression line ± confidence intervals marking potential good/moderate boundary values for total phosphorus . Triangles mark areas where classification mismatches occur, green (biology good but phosphorus moderate) and yellow (biology moderate or worse but phosphorus good) using three different approaches to interpretation.

Regulation options Action (e.g. programme of measures) is triggered as soon as the nutrient boundary is exceeded (“one out, all out”). a higher boundary value may be appropriate, to minimise the instances in which elevated nutrient concentrations trigger measures despite biology being at good status (i.e. Figure 2‑1b). Additional considerations that should be made before measures are implemented include current proximity to the good/moderate (G/M) boundary for sensitive BQEs, likely trends in nutrient concentrations if no action is taken and whether there are other factors that might reduce the sensitivity to nutrients (e.g. shade, high flow, grazing, toxic substances). Exceedance of the nutrient boundary is one of a number of strands of evidence that are considered before a programme of measures is triggered. A more precautionary (lower-concentration) boundary value may be selected (e.g. Figure 2‑1c); however, the regulator would then check that that a nutrient-sensitive BQE was also failing in the water body under consideration prior to taking action, or that there was evidence that it might do so in the future (e.g. if there was a trend of increasing nutrient concentrations, or the likelihood of an increased sensitivity to nutrients due to climate change, removal of shade, lower flow or reduced grazing pressures).

Potential boundary values for L-CB1 (summarised as g L-1 TP) Method Lower Centre Upper OLS1 57 87 RMA 50 73 OLS2 36 53 Average medians Average quartiles 54 75th quartile mismatch 51 Logistic regression 56 79 Range of national boundary values (Table 4-4 from CIS Guidance Manual) 25th percentile 33 Median 60 75th percentile 62