Biology subjects

Palacin-Lizarbe, C.

Publications and source records attributed to Palacin-Lizarbe, C..

4 recordsLinked to original sources

bioRxiv2026

Soil nitrogen dynamics in riparian zones of two Arctic rivers

Riparian zones act as protective buffers, filtering land-to-river nutrient inputs through retention and nitrogen (N) gas losses. While rapid Arctic warming and permafrost thaw may enhance terrestrial nutrient inputs to aquatic systems, comprehensive assessments of N cycling in Arctic riparian soils are lacking. Conventionally, these zones are considered inactive due to N limitation of Arctic soils and low temperatures, leaving their N cycling unexplored. To address this, we investigated N pools and turnover processes in riparian zones of two Arctic rivers in Finland and Greenland. We combined measurements of the extractable N pool and in-situ nitrous oxide (N2O) flux with 15N-labeling techniques to quantify gross mineralization, nitrification, potential denitrification, and potential dissimilatory nitrate reduction to ammonium (DNRA). Our findings reveal that mineral N cycling in high-latitude riparian zones is more active than previously assumed. Despite low temperatures and low to intermediate soil organic carbon content, we found high gross N mineralization rates, alongside detectable rates of gross nitrification and potential DNRA. We attribute the unexpectedly high N activity in C-poor soils to low C/N ratios, which create a stoichiometric imbalance, thereby enhancing N mineralization. The presence or absence of vegetation largely determined the dominance and magnitude of these pathways. While dense vascular plant cover was associated with higher extractable N pools and gross mineralization rate, low nitrification rates and elevated DNRA potential indicated a tight N cycle. Conversely, sparsely vegetated patches with cryptogamic biocrusts acted as N2O hotspots. In bare sandy soils adjacent to the river, we found high gross nitrification rate and detectable N2O losses, possibly driven by riverine organic N inputs. Taken together, this research shows that Arctic riparian zones may play an important role in reducing terrestrial N inputs to the rivers, which should be considered when studying the fate of N in the rapidly changing Arctic.

ecology↗

bioRxiv2026

Vegetation increases CH4 emissions and methanotroph diversity in marine sediments

Seagrass meadows are key blue carbon (C) ecosystems, storing large amounts of organic C over centuries. Their climate benefits may be reduced by methane (CH) emissions, whose microbial and environmental descriptors in Zostera noltei meadows, dominant seagrass in North-Western Europe, remain poorly understood. We studied CH fluxes, CH-producing and consuming microbial communities and sediment physico-chemical parameters in Z. noltei meadows and adjacent bare sediments across seven sites in Arcachon Bay, France. In situ CH fluxes were measured at low tide and microbial communities were characterised using targeted metagenomics of three functional genes (mcrA, mmoX, pmoA) and quantitative PCR. CH fluxes were higher in vegetated than bare sediments (24.4 {+/-} 2.6 vs. 9.4 {+/-} 0.7 {micro}mol m-{superscript 2} d-{superscript 1}). Mixed linear models and random forest analyses identified C accumulation rate and CO2 flux as the strongest positive descriptors of CH fluxes. Vegetated sediments hosted more diverse methanotrophs, while methanogens showed no habitat differences. Four genera (mcrA-Methanolobus, mmoX-Methylocella, pmoA-Methylococcus, Methyloglobulus) emerged as abundant, seagrass-associated, correlated with CH fluxes, and highlighted by models. Functional diversity, especially pmoA richness, was a stronger microbial descriptor of CH fluxes than gene abundance or a specific genus. Findings indicate Z. noltei meadows enhance C burial and CH emission, with methanotroph diversity potentially mitigating CH emissions. Our results provide the first integrated assessment of CH fluxes and their descriptors in Z. noltei meadows, highlighting the intertwined nature of C burial and CH emissions and the need to account for both in blue C climate assessments.

ecology↗

bioRxiv2023

Activity and abundance of nitrous oxide consuming bacteria in Platismatia glauca cryptogamic lichen in boreal Finnish spruce forest.

The boreal spruce forest soil can assimilate atmospheric N2O through symbiotic relationships with mycorrhizae or with bacteria, especially during spring and autumn, when aerobic microsites to soil can form. In cold soils with large field capacity (FCD), high humidity and absence of fertilisation, a balance between absorption and emission of nitrous oxide and dinitrogen was observed to be close to zero, and even to assume negative values in some cases, thus suggesting that forest soils absorb more N2O than they emit. Furthermore, in the presence of cryptogamic coverings of mosses and lichens, the absorption value was observed to be greater than in forests with less coverage; although the main role in N2O absorption is played by soil and root system. However, the role played by epiphytic organisms in N2O absorption in the boreal forests has not been uncovered yet. We studied, N2O dynamics of the lichen, Platismatia glauca, showing that N2O is consumed especially at lower incubation temperatures. The quantitative analysis with real-time PCR of nitrous oxide reductase gene fragment nosZ, showed that enzyme is present in the lichen and the gene is more transcribed under lower incubation temperature. The presented results unveil that cryptogamic covers consume nitrous oxide (with values between 0.1 and 0.4 ng N2O-C/g (ww)/h) at the atmospheric concentration via complete dissimilatory denitrification when nitrogen is limited.

microbiology↗

bioRxiv2019

Early-Career Coordinated Distributed Experiments: Empowerment Through Collaboration

Coordinated distributed experiments (CDEs) enable the study of large-scale ecological patterns in geographically dispersed areas, while simultaneously providing broad academic and personal benefits for the participants. However, the effective involvement of early-career researchers (ECRs) presents major challenges. Here, we analyze the benefits and challenges of the first CDE exclusively led and conducted by ECRs (i.e. ECR-CDE), which sets a baseline for similar CDEs, and we provide recommendations for successful CDE execution. ECR-CDEs achieve most of the outcomes identified in conventional CDEs as well as extensive benefits for the young cohort of researchers, including: (i) receiving scientific credit, (ii) peer-training in new concepts and methods, (iii) developing leadership and communication skills, (iv) promoting a peer network among ECRs, and (v) building on individual engagement and independence. We also discuss the challenges of ECR-CDEs, which are mainly derived from the lack of independence and instability of the participants, and we suggest mechanisms to address them, such as resource re-allocation and communication strategies.

scientific communication and education↗