Modelling of Aquatic Ecosystems

1
Modelling of Aquatic Ecosystems

• Exercise 2
• 04.03.2009

2
Introduction to ECOSIM
V
3
Introduction to ECOSIM

• Computer programme functions that can be used
  (ecosim.r)
• Uses ode.r for solution of ordinary differential
  equations (source(ode.r))
• Offers templates for modelling of system
  consisting of reactor(s),
  with links
  between reactors and processes
  within them
• Executes simulations and plots results

4
Introduction to ECOSIM
5
Introduction to ECOSIM
6
Introduction to ECOSIM
7
Introduction to ECOSIM

• ? methods calc.res, plot.res

8
Model exercise 2.1
9
Model exercise 2.1

• State variables concentration of algae (C.ALG),
  zooplankton (C.ZOO) and phosphate (C.HPO4)
• Considered processes growth of ALG on HPO4,
  growth of ZOO on ALG, death of ALG and ZOO
• Implementation change the script exercise02.r by
  means of the example of growth of ALG and copy
  the commands to R

10
Model exercise 2.1

• Stoichiometric coefficients according to process
  table 8.4
• Rate expressions according to table 8.5
• e.g.

11
Model exercise 2.1

• ? Differential equation (generally)
• ? Differential equation (change of phosphate
  concentration)

12
Sensitivity analysis exercise 2.2

• Change in model results as an effect of changes
  in model inputs
• Change the parameters, plot the results and
  interpret the (magnitude of) changes in the
  simulation results (reset parameters
  system_at_paramlt-param)

13
Model extension exercise 2.3

• Growth ALG temperature dependency, light
  limitation
• Environmental conditions temperature, light
  intensity

14
Discussion results

• Example halved growth rate of algae