Quantifying the resilience of biogeochemical cycles to environmental change in complex aquatic landscapes

Abstract:

It is well established that aquatic environments such as lakes, rivers and estuaries display complex system properties in response to anthropogenic forcing. Whilst our ability to characterize these dynamics and model them has advanced considerably for ideal systems, it remains difficult to investigate them across more complex aquatic landscapes. New model approaches are required that are able to accommodate spatial heterogeneity, connectivity between both terrestrial and aquatic sub-systems, and that are suited to capture the complex feedback and co-evolution processes that shape the signatures we observe in biogeochemical cycles. A way forward lies in the integration of the diversity of models of ecohydrology and aquatic system dynamics, with environmental sensing data in a way that balances process-driven and data-driven approaches for exploring landscape function, however many challenges remain. Here we report on a strategy being applied for the lower Murray River, Australia, that integrates models of terrestrial landscapes, riparian ecohydrology and surface water hydrodynamic-biogeochemical models in conjunction with sensor network data. The model system is used to quantify biogeochemical budgets and signatures that characterize individual sub-systems within the landscape, but also to quantify how the landscape as a whole responds to environmental change. Whilst such a coupled system is complex and many uncertainties exist, several theoretically relevant metrics of ecosystem function are being used to guide model validation. Further efforts to improve model predictions through assimilation of observed data using Bayesian Hierarchical Modelling are being explored.