Fluvial Meta-Ecosystem Functioning: Unravelling Regional Ecological Controls Behind Fluvial Carbon Fluxes

PI: Gabriel Singer

Fluvial ecosystems are an important element in the global carbon cycle metabolizing large amounts of terrigenous organic matter (tOM). This contributes to CO2 evasion fluxes that are under continuous reevaluation at the global scale. In contrast, research on the underlying processes is concentrated at the local ecosystem scale. This scale-gap seriously hampers process understanding across scales, limits upscaling accuracy, and reduces our scope of reaction strategies.

FLUFLUX suggests ground-breaking research on ecological processes at the intermediate ‘regional’ scale of the ‘fluvial network‘ to create a deeper mechanistic understanding of biogeochemically relevant carbon fluxes. The starting point is trifold: (1) detrital tOM has extremely high molecular-level diversity that requires consumers of equally high biodiversity for efficient respiration; (2) exactly this biodiversity of heterotrophic microbes, fungi and insects is constrained by metacommunity dynamics unfolding at a larger regional scale; and (3) the rules by which the conspicuously dendritic structure of the fluvial network shapes a metacommunity differ fundamentally from those governing regional diversity patterns of tOM resources.

The main hypothesis is that regional carbon dissimilation in ‘fluvial metaecosystems’ is the interactive product of spatially partitioned resource and consumer diversities. This coupling of metacommunity structure to metaecosystem function is supposedly influenced by fluvial network topology, anthropogenic network fragmentation, and terrestrial matrix variation. Research will combine experiments in innovative lab-scale metaecosystems, spatially explicit modelling using cellular automata, and field studies spanning gradients of regional anthropogenic impact in real fluvial networks. We expect this cross-disciplinary research at the crucial landscape scale to generate novel mechanistic process understanding behind fluvial carbon fluxes in a world changing at ever faster pace.


PI: Dr. Edurne Estévez

Rivers were recently recognised as important contributors to the global carbon cycle as they actively cycle terrestrial organic matter (OM) during transport to the oceans. The mechanisms behind this efficient OM processing are poorly understood, particularly at the river network scale and for Particulate OM (POM). River network hierarchical dendritic nature and the diversity of land cover types in its terrestrial matrix result in the formation of gradients of chemically and physically varied POM and, expectedly, of POM diversity. The efficient degradation of diverse POM likely requires an alignment between traits of POM and those of its – mostly macroinvertebrate – consumers. However, at the river network scale, the diversity of POM and the diversity of macroinvertebrates are controlled by different mechanisms. Thus, their distribution patterns may not spatially conform, with unresolved consequences for POM degradation and, ultimately, for carbon cycling.

DiverCycle will investigate how land cover shapes (bio)diversity of both POM and its consumers to understand ensuing implications for carbon cycling at the regional scale of river networks. The project will combine novel molecular methodologies to characterize (bio)diversity such as Particle size will be characterised by flow cytometry combined with microscopic imaging to characterize POM particle size, infrared spectroscopy and microscopy to characterize POM composition, and molecular techniques (i.e., for COI-based metabarcoding ) to characterize macroinvertebrate diversity; field experimentation to measure POM degradation (e.g. leaf litter decomposition experiment); and river network-scale spatial modelling.

DiverCycle will be carried out between the Fluvial Ecosystem Ecology group at the University of Innsbruck (Supervised by Prof. Gabriel Singer) and the Stream Ecology group at the University of the Basque Country (Supervised by Dr. Aitor Larrañaga), in collaboration with Prof. Florian Leese (University of Duisburg-Essen). This project will highly benefit from the complementarity with Prof. Gabriel Singer’s European Research Council-Starting Grant (ERC-STG) FLUFLUX.


Contacts: Gabriel Singer, Thibault Datry

Climate change and biodiversity in river networks: Launch of the H2020 DRYvER project

Rivers, streams, lakes, wetlands and other aquatic environments are among the world’s most biodiverse ecosystems. They are also those most threatened by human activities. River networks also provide essential ecosystem services – such as drinking water, food and climate regulation – that enhance society’s well-being. But climate change and humans’ growing water needs cause river networks to dry up around the world. The effects on biodiversity, the networks’ ecological integrity and the ecosystem services they provide are devastating. Today, scientists estimate that more than half of the world’s river networks are going dry, a phenomenon that is worsening dramatically around the planet. And yet, so far the scientific community, natural resource managers and legislators have devoted little attention to drying river networks, which are often not even on the public’s radar. As a result, no comprehensive biodiversity conservation or resource management strategies are in place for these Anthropocene environments.

A multidisciplinary consortium of 25 experts from 11 countries (in Europe and South America, as well as China and the United States) will explore for a four-year period how the drying effects of climate change alter the biodiversity, functional integrity and ecosystem services of drying river networks. The consortium is coordinated by Dr. Thibault Datry at INRAE in Lyon, France. At the University of Innsbruck, Prof. Dr. Gabriel Singer from the Department of Ecology leads the work package on ecosystem functions. The aim of DRYvER (Securing biodiversity, functional integrity and ecosystem services in DRYing riVER networks) is to collect, analyse and model data from nine case studies in Europe and South America to create a novel global meta-system approach that incorporates hydrology, socio-economics, ecology and biogeochemistry. Another goal of DRYvER is to craft strategies, tools and recommendations for adaptive management of river networks. Working in collaboration with resource managers and citizens, the DRYvER team plans to co-develop new strategies to mitigate and adapt to the effects of climate change on these networks by integrating quantitative and qualitative perspectives, including nature-based solutions with a strong socio-economic and legislative component. DRYvER’s findings, which should be available in 2024, will contribute to meeting the objectives of the Paris agreement and put Europe at the forefront of climate change research.

DRYvER is supported by the Horizon 2020 program funded by the European Commission.

Dry Riverbed

A dry riverbed with accumulated leaf litter.

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