On the trophic fate of Phaeocystis pouchetii: VII. Sterols and fatty acids reveal sedimentation of Phaocystis-derived organic matter via krill fecal strings

As part of a joint project on the fate of phytoplankton in Balsfjorden in Northern Norway, we investigated the trophic fate and sedimentation potential of Phaeocystis pouchetii by tracing the transition of biomarker patterns from a phytoplankton bloom to sediment traps and during a gut passage experiment. The phytoplankton biomass during the spring bloom 1996 was dominated by colonial P. pouchetii (ca. 85 %) and four members of the diatom family Thalassiosiraceae (ca. 10%). Particulate organic carbon in sediment traps largely consisted of fecal material from the Arctic krill Thysanoessa sp.. Sterol and fatty acid biomarker patterns in the phytoplankton bloom could be reproduced by combining the individual biomarker patterns of the isolated phytoplankters P. pouchetii and Thalassiosira decipiens in a ratio of ca. 75:25. In a laboratory experiment, Arctic krill (Thysanoessa raschii) fed with similar efficiency on Phaeocystis colonies and the Thalassiosiraceae. During gut passage, the abundance of Thalassiosiraceae biomarkers in fecal strings increased relative to Phaeocystis biomarkers, while biomarkers from krill became dominant. This transition of biomarker patterns due to gut passage in T. raschii closely resembled the biomarker transition from the surface bloom to material in sediment traps at 40-170 m depth, which was mainly composed of krill fecal strings. We conclude that krill grazed efficiently on Phaeocystis colonies in Balsfjorden, and caused sedimentation of Phaeocystis-derived organic matter below the euphotic zone via fecal strings. Hence, both transfer to higher trophic levels and sedimentation of Phaeocystis-derived organic matter can be more effective than commonly believed

Climate-smart Rice Production for Combining Adaptation and Mitigation: Technological Options within the Context of Southeast Asia

Adaptation to changing climatic condition is imperative to forestall dramatic threats to food security, but agriculture is also a source of greenhouse gases (GHG). For most countries in Southeast Asia, rice farming represents a major component in their national GHG budget which is attributed to the emission of methane from (predominantly flooded) rice fields. ASEAN member states have committed, as one community, to improve their capacity to reduce emissions in their respective countries. Climate-smart agriculture denotes a concept to merge adaptation (adjusting to climate change) and mitigation (reducing emissions) into one comprehensive approach. In the case of rice production, improved varieties are the key for coping with climatic stresses such as floods and droughts. In addition to more resilient rice plants, short-maturing varieties can be used to avoid climate stresses by adjusted cropping calendars and also reduce methane emissions due to shorter flooding periods. Crop and water management practices offer many options for CSA. “Alternate Wetting and Drying (AWD)” is an irrigation technique originally developed for saving water and coping with water scarcity, e.g., in El Nino years. This practice also reduces emissions by 30%–70% as has been shown in several field studies in the Philippines and other countries in Southeast Asia. Mechanization has several climate-smart components such as laser leveling and direct seeding that reduce water needs and emissions. This illustrates that the principles of climate-smart agriculture can be aligned with socio-economic drivers

Essays on the consequences of the European eastern integration process on border regions in the EU-15

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Greenhouse gas emissions from Indian rice fields: calibration and upscaling using the DNDC model

International audienceThe Denitrification and Decomposition (DNDC) model was evaluated for its ability to simulate methane (CH4), nitrous oxide (N2O) and carbon dioxide (CO2) emissions from Indian rice fields with various management practices. The model was calibrated and validated for field experiments in New Delhi, India. The observed yield, N uptake and greenhouse gas (GHG) emissions were in good agreement with the values predicted by the model. The model was then applied for estimation of GHG emissions from rice fields in India using a newly compiled soil/climate/land use database. Continuous flooding of rice fields (42.25 million ha) resulted in annual net emissions of 1.07-1.10, 0.04-0.05 and 21.16-60.96 Tg of CH4-C, N2O-N and CO2-C, respectively, with a cumulated global warming potential (GWP) of 130.93-272.83 Tg CO2 equivalent. Intermittent flooding of rice fields reduced annual net emissions to 0.12-0.13 Tg CH4-C and 16.66-48.80 Tg CO2-C while N2O emission increased to 0.05-0.06 Tg N2O-N. The GWP, however, reduced to 91.73-211.80 Tg CO2 equivalent. The study suggested that the model could be applied for estimating the GHG emissions and the influences of agronomic management, soil and climatic parameters on the GHG emissions from rice fields in India

In Draghi we trust: how unorthodox monetary policy weakened the anti-austerity movement in Europe

Soon after the sovereign debt crisis started taking a toll on European economies, several strikes and mass protests spread acoss the continent. Yet, while the crisis continued lingering on in some European countries, the mobilisation quickly ebbed away. Federica Genovese, Gerald Schneider and Pia Wassmann argue that one reason why people stopped going to the streets is that the Europan Central Bank decided to adopt a new unconventional policy to ease the problems in Europe’s economies and reduce public discontent

Revisiting the footprints of climate change in Arctic marine food webs: An assessment of knowledge gained since 2010

In 2011, a first comprehensive assessment of the footprints of climate change on Arctic marine ecosystems (such as altered distribution ranges, abundances, growth and body conditions, behaviours and phenologies, as well as community and regime shifts) was published. Here, we re-assess the climate-driven impacts reported since then, to elucidate to which extent and how observed ecological footprints have changed in the following decade (2011 to 2021). In total, 98 footprints have been described and analysed. Most of those impacts reported in the 2011 assessment are reconfirmed and can, hence, be assumed as continuing trends. In addition, novel footprints (behavioural changes, diet changes, altered competition and pathogen load) are described. As in 2011, most reported footprints are related to changes in distribution ranges, abundances, biomass and production. Range shifts have mostly been observed for fish species, while behavioural changes have mainly been reported for mammals. Primary production has been observed to further increase in Arctic seas. The footprints on pelagic herbivores, particularly the key species Calanus spp., are less clear. In comparison to 2011, more complex, cascading effects of climate change, such as increased bowhead whale body conditions due to increased primary production, have been reported. The observed footprints, and the trends that they indicate, strongly suggest that due to further northward range shifts of sub-Arctic and boreal species Arctic seas are likely to experience increasing species richness in the future. However, a tipping point may be reached, characterized by subsequent biodiversity decline, when Arctic-endemic species will go extinct as ocean warming and/or acidification will exceed their physiological adaptation capacity.Overall, the future Arctic Ocean will very likely experience increasing numbers and intensities of climate-change footprints

Yield gap analysis and assessment of climate-induced yield trends of irrigated rice in selected provinces of the Philippines

This study describes a combined empirical/modeling approach to assess the possible impact of climate variability on rice production in the Philippines. We collated climate data of the last two decades (1985-2002) as well as yield statistics of six provinces of the Philippines, selected along a North-South gradient. Data from the climate information system of NASA were used as input parameters of the model ORYZA2000 to determine potential yields and, in the next steps, the yield gaps defined as the difference between potential and actual yields. Both simulated and actual yields of irrigated rice varied strongly between years. However, no climate-driven trends were apparent and the variability in actual yields showed no correlation with climatic parameters. The observed variation in simulated yields was attributable to seasonal variations in climate (dry/wet season) and to climatic differences between provinces and agro-ecological zones. The actual yield variation between provinces was not related to differences in the climatic yield potential but rather to soil and management factors. The resulting yield gap was largest in remote and infrastructurally disfavored provinces (low external input use) with a high production potential (high solar radiation and day-night temperature differences). In turn, the yield gap was lowest in central provinces with good market access but with a relatively low climatic yield potential. We conclude that neither long-term trends nor the variability of the climate can explain current rice yield trends and that agroecological, seasonal, and management effects are over-riding any possible climatic variations. On the other hand the lack of a climate-driven trend in the present situation may be superseded by ongoing climate change in the future

Detection of Separase activity using a cleavage sensor in live mouse oocytes Detection of Separase activity using a cleavage sensor in live mouse oocytes.

International audienceSeparase proteolytically removes Cohesin complexes from sister chromatid arms, which is essential for chromosome segregation. Regulation of Separase activity is essential for proper cell cycle progression and correct chromosome segregation. Onset of Separase activity has not yet been observed in live oocytes. We describe here a method for detecting Separase activity in mouse oocytes in vivo. This method utilizes a previously described cleavage sensor made up of H2B-mCherry fused with Scc1(107-268 aa)-YFP. The cleavage sensor is loaded on the chromosomes through its H2B tag, and the signal from both mCherry and YFP is visible. Upon Separase activation the Scc1 fragment is cleaved and YFP dissociates from the chromosomes. The change in the ratio between mCherry and YFP fluorescence intensity is a readout of Separase activity