Macroalgae and phytoplankton as indicators of ... - Naturstyrelsen

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The total score of the Spanish index is calculated by adding the scores obtained for each of the three components: cover, species number and fraction of opportunists. The corresponding EQR value is calculated by division with 100. The final score system has been adjusted upon intercalibration with Portugal (Table 3.4). Table 3.4 The total score of the Spanish index with corresponding EQR-value and status class. Confirmed through intercalibration with Portugal. Total score EQR Status 81-100 0.81-1 High 57-80 0.57-0.80 Good 33-56 0.33-0.55 Moderate 9-32 0.09-0.33 Poor < 9
The variance of a macroalgae indicator (I) is a function of the three variance components and is calculated as V [] I σ = n 2 diver diver σ + n 2 site site + n diver σ ⋅ n 2 residual site ⋅ n samples 2 Where σ denotes the three different variance components, and the sampling is carried out by n diver divers investigating n site sites comprised of n samples point observations, i.e. a total of n ⋅ n ⋅ n observations. diver site samples Power analyses were used to assess how many observations are needed in order to evaluate environmental status based on the various algal variables in so-called 'face value' and 'fail safe' scenarios with a standard power value of 80%. The difference between 'fail safe' and 'face value' corresponds to using a confidence level of 95% and 50%, respectively (Figure 3.4). In the following we will demonstrate power analyses for testing compliance with the good/moderate (G/M) boundary, provided that the true mean is at the H/G boundary. For the face value approach the critical value for testing the indicator equals the G/M boundary, whereas the critical value for the fail safe approach equals the 95% confidence level under the null hypothesis, a distribution with a mean equal to the G/M boundary. Thus, in order to obtain sufficient confidence under the fail safe approach, the indicator value actually has to be better than the G/M boundary with a certain confidence margin. For the face value approach there is no margin, and the uncertainty is equally shared between the 'environment' and 'polluters'. The fail safe approach therefore requires more observations as indicated by the narrower indicator distribution in order to obtain the same power. The power analyses for the transformed macroalgal variables under the normal distribution follow the calculations outlined in Carstensen (2007). We analysed all combinations of 1-3 divers, 1-10 sites and 2-10 point samples per site and chose the combination with the least total number of observations that fulfil the power requirements. Figure 3.4 Two different approaches for classification of ecological status: Face-value classification (left panel) and fail safe classification (right panel), both with a standard power value of 80. The dotted line denotes the critical value for the two approaches for testing compliance with the G/M boundary, provided that the true mean is at the H/G boundary. 29
Page 1 and 2: National Environmental Research Ins
Page 3 and 4: National Environmental Research Ins
Page 5 and 6: Contents Summary 5 Sammenfatning 6
Page 7 and 8: Summary During the implementation o
Page 9 and 10: 1 Introduction This report is part
Page 11 and 12: Figure 2.1 Long-term trends in nitr
Page 13 and 14: Figure 2.2 Surface TN versus salini
Page 15 and 16: 2.2.2 Nitrogen input-TN relationshi
Page 17 and 18: Flensborg Fjord on the ranked scale
Page 19 and 20: Table 2.4 Suggested reference condi
Page 21 and 22: the gradient. These responses have
Page 23 and 24: Table 3.1 Overview of sampling area
Page 25 and 26: We assumed that mean values from th
Page 27 and 28: and 2005), averaged over the months
Page 29: The second component of the Spanish
Page 33 and 34: The levels of mean cumulated algal
Page 35 and 36: Figur 3.5 continued Modelled mean l
Page 37 and 38: while the fraction of opportunists
Page 39 and 40: 3.4.2 Physico-chemical variables Ph
Page 41 and 42: Figure 3.7 continued Mean modelled
Page 43 and 44: 3.4.3 Algal variables in relation t
Page 45 and 46: Figure 3.8 continued Cumulated cove
Page 47 and 48: inputs (Figures 3.9 and 3.10) where
Page 49 and 50: A Total algal cover (%) 100 95 90 8
Page 51 and 52: A 100 B 140 Total algal cover (%) 8
Page 53 and 54: A response to changes in nutrient c
Page 55 and 56: In its present form the Spanish ind
Page 57 and 58: 3.6 Conclusions • All algal varia
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Page 63 and 64: from Randers Fjord and Odense Fjord
Page 65 and 66: moderate boundaries. Reference dept
Page 67 and 68: 4.3 Evaluation of the precision of
Page 69 and 70: The 90-percentile was clearly subst
Page 71 and 72: 5 Conclusions and recommendations R
Page 73 and 74: 6 References Andersen, J., Markager
Page 75: Nielsen, S.L., Sand-Jensen, K., Bor
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78 Appendix 3. Reference levels and
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80 Appendix 5. Reference levels and
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Appendix 7. Modelled mean levels of
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Appendix 9. Modelled mean levels of
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Appendix 11. Modelled mean levels o
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Appendix 13. Results of power analy
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Appendix 18. Results of power analy
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NERI Technical Reports NERI’s web
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of Danish coastal waters 683 Macroa
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Macroalgae and phytoplankton as indicators of ... - Naturstyrelsen

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