Mini-review of process-based food web models and their application in aquatic-terrestrial meta-ecosystems

In a meta-ecosystem, spatially separated ecosystems are linked by biotic and abiotic cross-ecosystem flows. Hence, food webs in a meta-ecosystem are functionally linked. They are susceptible to multiple stressors threatening ecosystem functions and associated services. Although empirical studies can help understand stressor effects on meta-ecosystem food webs, they are often limited by their narrow spatial and temporal scales. This limitation may be overcome by process-based food web models, which allow variable spatial and temporal scales. We reviewed process-based food web models and their application to aquatic-terrestrial and theoretical meta-ecosystems. We refer to theoretical models as food web models based on theoretical considerations rather than describing a particular natural system. We found nineteen aquatic-terrestrial models that represented aquatic food webs with flows from terrestrial to aquatic ecosystems. Most of the aquatic-terrestrial models can be applied to study the environmental stressors of eutrophication (15 models) and climate change (10 models). Eight theoretical models were found that study ecosystem stability, trophic cascades, source-sink dynamics, co-nutrient limitation and co-existence of primary consumers. The theoretical models are more similar in terms of types of state variables and model complexity (i.e., number of state variables) than the aquatic-terrestrial models. Generally, the applications of the models have shown that environmental changes cause cross-scale effects on food webs in aquatic-terrestrial and theoretical meta-ecosystems. Finally, we outline major research gaps regarding the directionality of cross-ecosystem flows, anthropogenic stressors, and accessibility of models’ codes.