to recover or not to recover – the ”laurentius-equation”
DESCRIPTION
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. - PowerPoint PPT PresentationTRANSCRIPT
To recover or not to recover – the ”Laurentius-equation”
Søren Laurentius NielsenRoskilde 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
Established these relationships:
• Nutrients (N, P) → Phytoplankton biomass• Phytoplankton biomass + suspended matter →
Secchi depth• Secchi depth → Eelgrass depth limit• TN → Eelgrass depth limit
N and P vs. Phytoplankton biomass2
2
2
ln( ) 1.072ln( ) 4.959 0.391
ln( ) 0.759ln( ) 1.197 0.277
ln( ) 0.806ln( ) 0.344ln( ) 4.666 0.414
phyto
phyto
phyto
B TN R
B TP R
B TN TP R
2ln( ) 0.367 ln( ) 0.444ln( ) 2.686 0.808sd phytoZ Susp B R
20.787 0.339 0.606c sdZ Z R
2ln( ) 0.755ln( ) 6.039 0.547cZ TN R
• 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
Sediment characteristics suspected
2
0.703 / 12.2
0.703 0.082( / 12.2) / 12.2 0.81c sd
c sd
Z Z C N
Z Z C N C N R
Krause-Jensen et al., Vand & Jord, 2007Krause-Jensen et al., MEPS, 2011
(it might get quite complicated…)
Krause-Jensen et al., MEPS, 2011
Causal links:
N - loading
N - concentration
Phyto-plankton
Light Depth limit
Algal mats
Organic matter
Changes insediment
Anoxia
Resus-pension
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
Kemp et al. 2009
Hysteresis and regime shifts
Duarte et al., Estuaries andCoasts, 2009
Conceptual modelMarkager S., Carstensen J, Krause-Jensen D, Windolf J, Timmermann K. 2010. Technical report from NERI no. 787. http://www.dmu.dk/Pub/FR787.pdf
Reasons for the hysteresisCausal links:
N - loading
N - concentration
Phyto-plankton
Light Depth limit
Algal mats
Organic matter
Changes insediment
Anoxia
Resus-pension
3d dynamic model
Sediment physics
Sediment lability
Benthic fauna
Vegetation
Wave & current energy
Input Output
Hydrodynamic simulation
TD, sediment transport simulation
Ecological simulation
Erosion/deposition
Bio-sedimentation