Individual-based Models Three Examples

Presentation Outline Individual based models Three examples 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 functional form 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

Carlotti et al. (1998, Fish. Oceanogr.) 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

Salihoglu et al. (2001, Polar Biology) 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

Vertical Velocity, Size, Model Framework Genetics Model Circulation Model (3D and time) LARVAL MODEL Atmospheric Tides River Discharge Temperature Salinity Currents Temperature Salinity Larval Growth Particle Tracking Module Larval Behavior Settlement 330 um Modified Particle Tracking Module Vertical Velocity, Size, Temperature, Salinity Post-settlement Population

Slide from D. Costa 2007 Elephant seal Crabeater seal Weddell seal Animation

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

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