A922 Sequential measurement of 1 hour creatinine clearance (1-CRCL) in critically ill patients at risk of acute kidney injury (AKI)

Meeting abstrac

Biological soil crusts increase the resistance of soil nitrogen dynamics to changes in temperatures in a semi-arid ecosystem

Aims: Biological soil crusts (BSCs), composed of mosses, lichens, liverworts and cyanobacteria, are a key component of arid and semi-arid ecosystems worldwide, and play key roles modulating several aspects of the nitrogen (N) cycle, such as N fixation and mineralization. While the performance of its constituent organisms largely depends on moisture and rainfall conditions, the influence of these environmental factors on N transformations under BSC soils has not been evaluated before. Methods: The study was done using soils collected from areas devoid of vascular plants with and without lichen-dominated BSCs from a semi-arid Stipa tenacissima grassland. Soil samples were incubated under different temperature (T) and soil water content (SWC) conditions, and changes in microbial biomass-N, dissolved organic nitrogen (DON), amino acids, ammonium, nitrate and both inorganic N were monitored. To evaluate how BSCs modulate the resistance of the soil to changes in T and SWC, we estimated the Orwin and Wardle Resistance index. Results: The different variables studied were more affected by changes in T than by variations in SWC at both BSC-dominated and bare ground soils. However, under BSCs, a change in the dominance of N processes from a net nitrification to a net ammonification was observed at the highest SWC, regardless of T. Conclusions: Our results suggest that the N cycle is more resistant to changes in T in BSC-dominated than in bare ground areas. They also indicate that BSCs could play a key role in minimizing the likely impacts of climate change on the dynamics of N in semi-arid environments, given the prevalence and cover of these organisms worldwide

Vertical boundary mixing events during stratification govern heat and nutrient dynamics in a windy tropical reservoir lake with important water-level fluctuations: A long-term (2001–2021) study

Physical processes play important roles in controlling eutrophication and oligotrophication. In stratified lakes, internal waves can cause vertical transport of heat and nutrients without breaking the stratification, through boundary mixing events. Such is the case in tropical Valle de Bravo (VB) reservoir lake, where strong diurnal winds drive internal waves, boundary mixing, and hypolimnetic warming during stratification periods. We monitored VB during 21 years (2001–2021) when important water-level fluctuations occurred, affecting mixing and nutrient flux. Stability also varied as a function of water level. Hypolimnetic warming (0.009–0.028◦ C day−1) occurred in all the stratifications monitored. We analyzed temperature distributions and modeled the hypolimnion heat budget to assess vertical mixing between layers (0.639–3.515 × 10−6 m3 day−1), vertical diffusivity coefficient KZ (2.5 × 10−6 –13.6 × 10−6 m2 s−1), and vertical nutrient transport to the epilimnion. Nutrient flux from the metalimnion to the epilimnion ranged 0.42–5.99 mg P m−2 day−1 for soluble reactive phosphorus (SRP) and 5.8–101.7 mg N m−2 day−1 for dissolved inorganic nitrogen (DIN). Vertical mixing and the associated nutrient fluxes increase evidently as the water level decreases 8 m below capacity, and they can increase up to fivefold if the water level drops over 12 m. The observed changes related to water level affect nutrient recycling, ecosystemic metabolic balance, and planktonic composition of VB

The proportion of soil-borne pathogens increases with warming at the global scale

Understanding the present and future distribution of soil-borne plant pathogens is critical to supporting food and fibre production in a warmer world. Using data from a global field survey and a nine-year field experiment, we show that warmer temperatures increase the relative abundance of soil-borne potential fungal plant pathogens. Moreover, we provide a global atlas of these organisms along with future distribution projections under different climate change and land-use scenarios. These projections show an overall increase in the relative abundance of potential plant pathogens worldwide. This work advances our understanding of the global distribution of potential fungal plant pathogens and their sensitivity to ongoing climate and land-use changes, which is fundamental to reduce their incidence and impacts on terrestrial ecosystems globally.This project received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 702057 and the European Research Council (ERC) grant agreements no. 242658 (BIOCOM) and no. 647038 (BIODESERT). M.D.-B. is supported by a Ramón y Cajal grant from the Spanish Government (agreement no. RYC2018-025483-I) and a MUSGONET grant (LRA17\1193) from the British Ecological Society. F.T.M. also acknowledges funding from Generalitat Valenciana (CIDEGENT/2018/041) and from sDiv, the synthesis centre of the German Centre for Integrative Biodiversity Research Halle–Jena–Leipzig (iDiv). Work on microbial distribution and colonization in the B.K.S. laboratory is funded by the Australian Research Council (DP190103714). B.K.S. also acknowledges a research award by the Humboldt Foundation. C.A.G. and N.E. acknowledge support from iDiv, funded by the German Research Foundation (DFG FZT118) through flexpool proposals 34600850 and 34600844. N.E. also acknowledges support from the ERC under the European Union’s Horizon 2020 research and innovation programme (grant agreement no. 677232)

Improved appreciation of the functioning and importance of biological soil crusts in Europe – the Soil Crust International project (SCIN)

Here we report details of the European research initiative "Soil Crust International" (SCIN) focusing on the biodiversity of biological soil crusts (BSC, composed of bacteria, algae, lichens, and bryophytes) and on functional aspects in their specific environment. Known as the so-called "colored soil lichen community" (Bunte Erdflechtengesellschaft), these BSCs occur all over Europe, extending into subtropical and arid regions. Our goal is to study the uniqueness of these BSCs on the regional scale and investigate how this community can cope with large macroclimatic differences. One of the major aims of this project is to develop biodiversity conservation and sustainable management strategies for European BSCs. To achieve this, we established a latitudinal transect from the Great Alvar of A-land, Sweden in the north over Gossenheim, Central Germany and Hochtor in the Hohe Tauern National Park, Austria down to the badlands of Tabernas, Spain in the south. The transect stretches over 20A degrees latitude and 2,300 m in altitude, including natural (Hochtor, Tabernas) and semi-natural sites that require maintenance such as by grazing activities (A-land, Gossenheim). At all four sites BSC coverage exceeded 30 % of the referring landscape, with the alpine site (Hochtor) reaching the highest cyanobacterial cover and the two semi-natural sites (A-land, Gossenheim) the highest bryophyte cover. Although BSCs of the four European sites share a common set of bacteria, algae (including cyanobacteria) lichens and bryophytes, first results indicate not only climate specific additions of species, but also genetic/phenotypic uniqueness of species between the four sites. While macroclimatic conditions are rather different, microclimatic conditions and partly soil properties seem fairly homogeneous between the four sites, with the exception of water availability. Continuous activity monitoring of photosystem II revealed the BSCs of the Spanish site as the least active in terms of photosynthetic active periods