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Processes Movement
Movement determines how schools are redistributed across the spatial domain during a simulation. In OSMOSE, movement is applied at each time step and affects where schools are located before mortality, growth, and reproduction processes are updated.
Movement can be represented in different ways depending on the species, life stage, available spatial data, and ecological assumptions of the model configuration. Some movement rules are based on externally provided spatial distributions, while others describe local or directed displacement across the model grid.
The main movement approaches documented in this wiki are listed below.
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Gradient-based movements
Describes directed movement based on gradients of habitat suitability or other spatial drivers. This approach can be used when schools are assumed to move preferentially towards more suitable areas. -
Map distribution
Describes movement or spatial redistribution based on externally provided distribution maps. This approach is useful when species distributions are forced or constrained by spatial maps. -
Random distribution
Describes random redistribution of schools across suitable or accessible areas. This approach can be used when detailed movement mechanisms are not represented explicitly.
Movement often depends on spatial inputs such as species distribution maps, environmental drivers, or habitat suitability fields. These inputs can describe realised distributions, suitable habitat, or spatial constraints used to determine where schools can occur or move.
The interpretation of these spatial inputs depends on the movement approach selected. For example, a map may be used as a realised biomass distribution in one configuration, or as a suitability field guiding movement in another.
Movement is closely connected to other OSMOSE processes:
- it affects predation by changing spatial overlap between predators and prey;
- it affects starvation by changing access to prey and resource fields;
- it affects fishing by changing the overlap between schools and fishing effort;
- it can interact with environmental drivers when habitat suitability or movement rules depend on environmental conditions.