Individual-based Models Three Examples. Presentation Outline Individual based models Approach Model...

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?