Individual-based ModelsThree Examples
Presentation Outline• Individual based models
• Approach • Model Structure • Limitations
• Three examples – Calanus finmarchicus (two examples)– Adelie penguin (Pygoscelis adeliae)
Georges Bank Miller et al. (1998,Fish. Oceanogr.)
• Examine the potential of Gulf of Maine and Scotian shelf as sources of C. finmarchicus • Species is important
component of larval diet of cod, haddock and yellowtail flounder
Model Set Up • Animal life history provides model framework
• Defined particular attributes for each stage – used available data to set up parameterizations for simulating attributes – tracked attributes in space and time
Model Set Up • Characteristics of life history stages
• Each requires data and functionalform
• Each is tracked
Results
Verify that population structure and timing
Results
Spatial distribution of life history stages
Limitations • Assumed that growth and reproduction were
controlled only by temperature • Food quantity and quality important for C.
finmarchicus growth – not included • Assumed light controlled emergence from diapause• No feedbacks between zooplankton and
environment
North Atlantic Carlotti et al. (1998, Fish. Oceanogr.)
• Examine effect of C. finmarchicus on pelagic ecosystem
• Retained the life history structure – different stages have different effects
Model Set Up • Animal life history provides framework
• Defined particular attributes for each stage – • Individual particles – combined to form a population – Lagrangian
ensemble particles • Multiple food sources – varying quality in terms of lipid
Model Set Up • Connections – ingestion, mortality, egestion
• Defined particular attributes for each stage –
Model Set Up • Processes of particles – based on life stage/age
• Equations – testing for different situations (if, then, else)
Results • Ecosystem model, zooplankton particle model,
zooplankton population model
• Estimated grazing control on blooms
Results • Ecosystem model, zooplankton particle model,
zooplankton population model
• Estimated growth, reproduction survival
Results • Ecosystem model, zooplankton particle model,
zooplankton population model
• Estimate biomass distribution
Limitations
• Food quantity and quality important for C. finmarchicus growth – focus only on lipid
• Include carbohydrate, protein – somatic growth • Limitation of numbers via Lagrangian ensemble
particles • Limited role of physical environment in zooplankton
distribution • Analysis of variability
Adelie Penguin Chick Salihoglu et al. (2001, Polar Biology)
• Conceptual model based on life history – chick
Model Set Up • Observed chick fledging weight relatively constant at
2.8 to 3.2 kg in spite of varying environmental conditions and food supply
• Chicks modify energetic and/or metabolic demands to attain an optimal mass that potentially enhances their survival after fledging
• Parent can modify the timing and frequency of food delivery to the chick to compensate for variations in food supply
Model Set Up • Observed chick fledging weight relatively constant at
2.8 to 3.2 kg in spite of varying environmental conditions and food supply
• Chicks modify energetic and/or metabolic demands to attain an optimal mass that potentially enhances their survival after fledging
• Parent can modify the timing and frequency of food delivery to the chick to compensate for variations in food supply
• Modify time of fledging
Model Set Up • Antarctic krill primary food supply for chicks
Food quality varies with krill size
Model Set Up • Relate age determined from culmen length • Growth based on Assimilation – Respiration• Track energy
Results
88/89
89/90
Limitations• Only one prey item – fish possible prey • Thermoregulation effects important • Trade-offs in physiology – imposed• Role of habitat – land and ocean • Project climate change effects need to
understand life history, physiology, ecology and interaction with habitat
Circulation Model(3D and time)
Circulation Model(3D and time)Atmospheric
TidesRiver Discharge
TemperatureSalinity
Larval Growth
Currents
Particle Tracking Module
Larval Behavior
LARVAL MODELLARVAL MODEL
TemperatureSalinity
Settlement 330 um Modified Particle
Tracking Module
Vertical Velocity, Size, Temperature, Salinity
Post-settlementPopulation
Model Framework Genetics ModelGenetics Model
Elephant sealElephant seal
Weddell sealWeddell seal
Crabeater sealCrabeater seal
Animation
2007Slide from D. Costa
Animals and nutrient cycling• Krill release iron from phytoplankton when
they feed.• Krill may feed in the sediments at depth and
then return nutrients to the surface.• Fish and whales have an effect on the ocean
carbon budget • Sperm whales can return significant amounts
to the surface layer.• Vertically migrating animals have access to
nutrients in a deeper layer than phytoplankton.
(Slide from D. Costa)
Concluding Remarks • Model frameworks apply across range of
species • Approaches needed to extend IBM results to
population – genetic variability • Need habitat models – account for variaiblity
in habitat use and foraging – especially important for large vertebrate species
• Approaches for linking food web and biogeochemical models
QUESTIONS?