Incremental coupling of fish and zooplankton model #8
Description
We need a foolproof way of switching an existing Mizer fish model from using its default resource model to using a zooMizer model. As @patricksykes discovered, it is not easy to get the fish model and the zooplankton to be compatible. Mizer knows how to create viable fish communities feeding on its simplistic resource model, and zooMizer knows how to create viable zooplankton communities being predated on by its generic fish species. But when we couple the two together, there will be some adjustment needed in both. The problem is that if we simply couple them together in one step, the result is usually not viable. We need to adjust parameters in both models to make the coupled model work. But how? My proposal is to couple them incrementally rather than in one step.
So we introduce a parameter c that we can vary between 0 and 1. The resource available to the fish will be (c * default resource + (1 - c) zooMizer). The predation mortality on zooMizer will be (c * mortality from zooMizer fish + (1 - c) mortality from Mizer fish). So for c = 0 we have two uncoupled models, for c = 1 we have the fully coupled models. We initially start with a small c, see what changes appear in the fish and zooplankton abundances compared to those we had at c=0, and if any of them are unwanted we make changes to parameters. For example if some fish start growing to fast, we might reduce their gamma. If some fish species become too abundant, we might reduce their reproductive efficiency. And so on. When we are happy, we increase c and make more interventions. And so on until we reach c=1.