River ecosystems are superlatives in many respects. Their networks represent the largest biogeochemical nexus between the continents, oceans and atmosphere. River networks span multiple catchments, even biomes, and are highly dynamic in space and time. The world’s rivers contribute relatively little by areal extent, but their CO₂ emissions are of the same magnitude as the CO₂ sequestration flux by the world’s oceans. Rivers figure among the most heterotrophic ecosystems on Earth, metabolizing terrestrial organic carbon. Owing to their dendritic structure, the biodiversity that river networks host is exceptionally high. Finally, needless to emphasize how critical the ecosystem services are that rivers provide. Central to many of these river superlatives are microbial biofilms that abundantly coat the sedimentary surfaces of the river beds. A microbiome, encompassing all three domains of life, shapes, in conjunction with the turbulent nature of water flow, intriguing biofilm architectures. Biofilms, a hidden beauty emanating from the interactions between biology, physics and chemistry, regulate ecosystem energetics and are therefore an important linchpin between river biodiversity and biogeochemistry.

In my lecture, I will attempt to provide the state-of-the-art of global river carbon biogeochemistry and biofilm ecology. An emphasis will be given on the rivers that literally drain the roof of our planet, now at risk because of climate change. It is my hope, that soon we will appreciate the world’s river networks as we do appreciate the oceans and various terrestrial ecosystems.

How to cite: Battin, T. J.: River ecosystems: A tale of superlatives and hidden beauty, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8898, https://doi.org/10.5194/egusphere-egu23-8898, 2023.

Study of past carbon cycle perturbation events is fundamental for assessing Earth’s climatic and ecological sensitivities, and our planet’s overall biogeochemical functioning and responses. Major hindrance to our understanding is the lack of reliable CO₂ estimates from Earth’s ‘deeper’ geologic past. I will summarize my work on CO₂ reconstruction from the rock record and make the case that boron isotope values of brachiopod shells serve as a robust CO₂ proxy. I will first present evidence from culturing experiments and natural marine settings demonstrating that the boron isotope composition of recent brachiopod shells responds predictably to the coupled ocean pH and CO₂ system, and provide a calibration that enables its accurate quantification. Next, I will showcase ocean pH and CO₂ records for some of most crucial yet enigmatic events in Earth’s evolutionary history, including the Permian-Triassic mass extinction, and discuss the causes and consequences of CO₂ change and its biogeochemical impacts during extinctions and events of abrupt environmental change. Finally, I will highlight recent progress and new capabilities to lay out a roadmap towards robust record of Phanerozoic CO₂.

How to cite: Jurikova, H.: Causes and consequences of environmental perturbations through the Phanerozoic, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9859, https://doi.org/10.5194/egusphere-egu23-9859, 2023.