First Advective Dispersal Experiment

We connected the Madingley ecosystem model up to ocean current data, and seeded two points (one off the eastern coast of North America, one off the eastern coast of Africa) with thousands of cohorts to see how they would be dispersed. The colours in the video indicate the density of individual cohorts.

Second Advective Dispersal Experiment

The second advective dispersal experiment was much improved in terms of the speed that cohorts get moved by the directed current flow, but still has issues in that the area that they occupy collapses down to a few gyres. This indicated that there were still issues in the balance between advective (directed) and diffusive (random / turbulent) processes.

Third Advective Dispersal Experiment

The third advective dispersal experiment showed a much greater spread of cohorts, with particles reaching all ocean basins. Things are looking up! But of course there are other types of dispersal and biological behaviour sitting on top of these, and this is where we turned our attention next.

Responsive Dispersal Experiment

Adult organisms were given several types of responsive (or 'behavioural') dispersal that are based on their current biological environment. In particular, if there is a lack of food and they are starving, then they will attempt to disperse elsewhere to find something to eat. They may also disperse if their density within a grid cell is very low -- this represents movement to find a mate.

Random Dispersal Experiment

Juvenile mobile organisms disperse from their grid cell of birth using a random walk process, where the probability of a cohort dispersing from a grid cell is dependent on their body mass. We make the assumption that larger, heavier organisms are likely to be more mobile. In this video, we release thousands of juvenile cohorts from a single point and check that their dispersal is random from the point of origin.

June 2012 Early Global Log Biomass Density

We have coupled all the ecological processes within grid cells and the process of dispersal between grid cells and have produced a first simulation of nearly the entire globe*. We are excited to see the model running for all ecosystems, globally and to see some some realistic patterns of and spatial heterogeneity and seasonal biomass fluctuations emerge from a uniform biomass distribution with which the model was initialised.

Adult Juv Body Mass Evolution