Catchment METAbolism of Blue and Green fluxes

Objective

Catchments are key regulators of carbon (C) and nutrient fluxes across terrestrial and aquatic domains, sustaining biodiversity, water quality, and the global carbon cycle. They involve two main sources of metabolic activity, defined as the fixation and dissipation of energy by all organisms: blue metabolism, arising from biogeochemical processes in flowing waters shaped by light, flow regimes, nutrient concentrations, and organic matter supply, and green metabolism, associated with terrestrial primary production driven by the uptake of light, energy, and water by vegetation. Aquatic and terrestrial metabolism contribute simultaneously to the land-atmosphere carbon fluxes, but, despite coexisting and interacting within catchments, their intertwined dynamics remain largely unaccounted for, leaving major uncertainties in how carbon is partitioned and routed along the land-water continuum. This represents a major challenge for predicting the response of catchment carbon dynamics to climate and land-use change, with profound implications for water quality, ecosystem resilience, and carbon-climate feedbacks. The C-METABnG project will develop the first coupled framework of whole-catchment metabolism, explicitly linking blue and green metabolic activities and embedding the spatio-temporal variability of key resources such as hydroclimatic fluctuations. This addresses persistent uncertainties in the global carbon cycle, and the urgent need to improve predictability of catchment processes under climate change. To this end, the project will compile and harmonize a global dataset of blue and green metabolic observations, extend a process-based model to couple terrestrial fluxes with in-stream C processing, and advance a deterministic-probabilistic framework that captures resource variability. The ultimate goal is to provide the first predictive system for whole-catchment metabolism, directly responding to the call for integrated land-water carbon research.