Model Overview

Model Overview

This page introduces the main concepts behind OSMOSE. It is intended for users who want to understand how the model represents marine ecosystems before working with configuration files, inputs, outputs, or calibration.

OSMOSE is a spatially explicit, size-based, individual-based marine ecosystem model. It represents marine communities through schools of individuals that move, grow, reproduce, die, and interact through opportunistic predation. The model is designed to simulate the dynamics of multiple species and functional groups under the combined effects of trophic interactions, fishing, environmental forcing, and spatial constraints.

At its core, OSMOSE is built around a small number of modelling principles:

• Individuals are grouped into schools.
• Schools are defined by their species, position, abundance, size, age, and other state variables.
• Predation is mainly controlled by body-size compatibility and spatial co-occurrence.
• Population dynamics emerge from the repeated application of growth, mortality, movement, and reproduction processes at the school level.
• Species can be represented with different levels of biological detail, depending on their role in the model and the available data.

The pages below introduce these concepts in more detail.

Pages in this topic

• Main assumptions
  Introduces the main assumptions used by OSMOSE, including its size-based representation of trophic interactions and its individual-based structure.

• Schools
  Explains the concept of a school, which is the elementary simulation unit in OSMOSE.

• Species types
  Describes the different ways species or groups can be represented, including focal species, background species, and resource species.

• Time step
  Explains how time is represented in OSMOSE and how model processes are applied during a simulation step.

• Spatial domain
  Describes the spatial grid, model domain, and spatial constraints used to represent ecosystem dynamics.

• State variables
  Summarises the main variables used to describe the state of schools, populations, and the ecosystem during a simulation.

• Processes
  Introduces the main processes applied during a simulation, including movement, mortality, predation, starvation, fishing, growth, maturation, reproduction, and detritus.

• Modules
  Describes optional or specialised OSMOSE modules, including the bioenergetic, ecogenetic, bioeconomic, fisheries, stable isotopes, and observation modules.