The Effect of Fertilizer Regime on Soil Fauna

Soil fauna activity in agricultural soil is a key factor to maintain soil fertility and to assure soil ecosystem services. It is now accepted that agricultural practices like tillage and pesticide use can harm soil organisms including earthworms and springtails. Other practices like the use of green manure or animal manure have been considered as being beneficial to these soil invertebrates. To deepen our knowledge on the effect of fertilizers (mineral and organic) on earthworms (Aporrectodea caliginosa and Lumbricus terrestris) and springtails  (Folsomia candida) 56 microcosm experiments were made with two soil types and two hydric regimes. The microcosms were amended with four fertilizers: ammonium nitrate, mustard as green manure, cow manure and slurry. The results emphasize that mustard use had beneficial effect on Folsomia candida abundance and Aporrectodea caliginosa biomass, while mineral fertilizer had negative effects for all species used in the experiment

Priming Effect Induced by the Use of Different Fertilizers on Soil Functional Diversity

Agricultural practices, such as the use of fertilizers, can change the structure and function of soil microbial community. Monitoring and assessing the soil microbiota and its dynamics related to different factors can be a powerful tool for understanding basic and applied ecological contexts. The main objective of this paper was to assess the changes of carbon turnover rate and the microbial metabolic activity, when different types of fertilizers were used, process called priming effect. A microcosm experiment was designed and performed under controlled temperature and humidity and the soil samples were analyzed using the MicroResp technique. Results show that the integration in soil of different carbon sources, such as green manure, can lead to a positive priming effect and integration of mineral fertilizers can lead to negative priming effect. The carbon sources with the highest respiratory activity were α-ketoglutaric acid, malic acid, oxalic acid, citric acid, while the lowest respiratory activity was obtained in case of arginine

Searching for cold-adapted microorganisms in the underground glacier of Scarisoara Ice Cave, Romania

Scarisoara Ice Cave (Romania) hosts one of world’s largest and oldest underground glacier. While no studies were carried out on the existence of microorganisms in this cave’s ice block, our interest is to investigate the presence of microorganisms and their chronological distribution in the cave’s subterranean ice in relationship with past climatic changes. Samples were collected from ice layers of different age (from present to ~900 cal. yrs. BP), and the diversity of embedded microbial communities was assessed by classical cultivation and molecular techniques. The microorganisms from icesediments were cultivated at 4 °C and 15 °C, in the presence and absence of light. Epifluorescence microscopy analysis indicates the presence of autotrophic prokaryotes and eukaryotes in sunlightexposed ice and water samples. Total DNA was isolated from each ice sample and the bacterial and eukaryotic SSU-rRNA genes were amplified by PCR. The chemical composition and organic content of both deeply buried (>10 m inside the ice block) and surface (supra- glacial pond water) habitats were analyzed in relation to their age and organic composition. This study is the first to report on the presence of both prokaryotic and eukaryotic microorganisms in the subterranean ice block of Scarisoara Ice Cave, thriving in both organic-rich ice and clear ice layers. Phototrophic prokaryotes and eukaryotes were identified in sun-exposed recent ice. The composition of cold-adapted ice embedded microbiota varied with the habitat age and organic content, as resulting from dissimilarities in growth curve profiles at two different temperatures. The presence of bacteria and eukaryotes in all the analyzed samples was asserted by PCR amplification of SSU-rRNA gene fragments. These findings can be further used to reconstruct changes in the microbial diversity over the past approximately 5000 years, in correlation with climatic and environmental changes recorded by the ice block

Groundwater is a hidden global keystone ecosystem

Groundwater is a vital ecosystem of the global water cycle, hosting unique biodiversity and providing essential services to societies. Despite being the largest unfrozen freshwater resource, in a period of depletion by extraction and pollution, groundwater environments have been repeatedly overlooked in global biodiversity conservation agendas. Disregarding the importance of groundwater as an ecosystem ignores its critical role in preserving surface biomes. To foster timely global conservation of groundwater, we propose elevating the concept of keystone species into the realm of ecosystems, claiming groundwater as a keystone ecosystem that influences the integrity of many dependent ecosystems. Our global analysis shows that over half of land surface areas (52.6%) has a medium‐to‐high interaction with groundwater, reaching up to 74.9% when deserts and high mountains are excluded. We postulate that the intrinsic transboundary features of groundwater are critical for shifting perspectives towards more holistic approaches in aquatic ecology and beyond. Furthermore, we propose eight key themes to develop a science‐policy integrated groundwater conservation agenda. Given ecosystems above and below the ground intersect at many levels, considering groundwater as an essential component of planetary health is pivotal to reduce biodiversity loss and buffer against climate change

Search for dark matter produced in association with bottom or top quarks in √s = 13 TeV pp collisions with the ATLAS detector

A search for weakly interacting massive particle dark matter produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and miss- ing transverse momentum are considered. The analysis uses 36.1 fb−1 of proton–proton collision data recorded by the ATLAS experiment at √s = 13 TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are in- terpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour- neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark-matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross- section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour- charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements