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To recover or not to recover – the ”Laurentius-equation”

To recover or not to recover – the ”Laurentius-equation”. Søren Laurentius Nielsen Roskilde University. Original dataset based on:. 162 transects /stations 23 areas Data from years 1980 – 1991 Data from the then Danish counties. Spearman- Rank Correlation Coefficients – all significant.

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To recover or not to recover – the ”Laurentius-equation”

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  1. To recover or not to recover – the ”Laurentius-equation” Søren Laurentius Nielsen Roskilde University

  2. Original dataset based on: • 162 transects /stations • 23 areas • Data from years 1980 – 1991 • Data from the then Danish counties

  3. Spearman- Rank Correlation Coefficients – all significant

  4. Established these relationships: • Nutrients (N, P) → Phytoplankton biomass • Phytoplankton biomass + suspended matter → Secchi depth • Secchi depth → Eelgrass depth limit • TN → Eelgrass depth limit

  5. N and P vs. Phytoplankton biomass

  6. The equations reflect a comparison between locations • Not a development over time • Later uses imply a place for time substitution • Variation caused by differences among locations in other factors

  7. Sediment characteristics suspected Krause-Jensen et al., Vand & Jord, 2007 Krause-Jensen et al., MEPS, 2011

  8. (it might get quite complicated…) Krause-Jensen et al., MEPS, 2011

  9. Causal links: N - loading N - concentration Light Depth limit Phyto-plankton Algal mats Resus-pension Organic matter Changes in sediment Anoxia

  10. Markager S., Carstensen J, Krause-Jensen D, Windolf J, Timmermann K. 2010. Technical report from NERI no. 787. http://www.dmu.dk/Pub/FR787.pdf Based on empirical analyses of data from Skive Fjord, Horsens Fjord and Odense Fjord

  11. Hysteresis and regime shifts Duarte et al., Estuaries and Coasts, 2009 Kemp et al. 2009

  12. Markager S., Carstensen J, Krause-Jensen D, Windolf J, Timmermann K. 2010. Technical report from NERI no. 787. http://www.dmu.dk/Pub/FR787.pdf Conceptual model

  13. Reasons for the hysteresis Causal links: N - loading N - concentration Light Depth limit Phyto-plankton Algal mats Resus-pension Organic matter Changes in sediment Anoxia

  14. Output Input Vegetation Benthic fauna Sediment lability Sediment physics Ecological simulation Bio-sedimentation TD, sediment transport simulation Erosion/deposition Hydrodynamic simulation Wave & current energy 3d dynamic model

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