Phytoplankton composition in shallow water ecosystems: influence of environmental gradients and nutrient availability

Environmental gradients caused by hydrological changes, whether natural or maninduced, affect the planktonic taxonomic and functional composition in shallow water ecosystems. In this sense, our aim was to find out the main variables or variable ratios that are the driving forces of the major phytoplankton taxonomic groups in Mediterranean coastal lagoons. For this purpose, 11 waterbodies were choosen, 6 of them in Empordà wetlands and 5 in the Doñana National Park, looking for representative conditions along a gradient of salinity and nutrient content. Two surveys were conducted in each waterbody (January and May 2007), after that the phytoplankton composition (chemotaxonomic composition) and also several physical and chemical environmental variables were analyzed. Two methodological approaches were used and compared: a first approach with a log (x+1) variable transformation and a second one where variables were transformed using the compositional data analysis (CoDa) techniques introduced by Aitchison (1986). When the raw data approach and the CoDa approach analysis (RDA) were compared, the results obtained were similar with regard to explained variance and also interpretation. The CoDa approach was characterized by the introduction of a new environmental driving factor, the bacterial biomass, whose ratio with the peptidase enzyme activity became significant. In this sense, the CoDa approach contributed to improving the biological interpretation of the phytoplankton distribution based on the raw analysis

Influence of grazing on triclosan toxicity to stream periphyton

Interactions between emerging contaminants and other drivers of community structure and function are poorly known. We used laboratory microcosms to investigate the single and combined effects of grazing and triclosan toxicity on the structure and function of stream periphyton. Grazing alone strongly reduced algal biomass, but also reduced oxidative stress and increased periphyton productivity and phosphorus (P) uptake capacity. This suggests that grazed algal communities can compensate for reduced biomass by enhanced growth after being released from grazing. Triclosan exposure (11.6 ± 1.1 μg L−1) reduced the detoxification capacity and P-uptake capacity of periphyton and altered diatom taxonomic composition. This indicates that triclosan at environmentally relevant concentrations affects the capacity of periphyton to remove dissolved nutrients and to cope with toxicant mixtures commonly occurring in streams. Triclosan exposure and grazing pressure had negative synergistic effects on algal size-class distribution and diatom mortality, since the effects of triclosan were higher than expected when periphyton was subject to grazing. Periphyton exposed to toxic substances such as triclosan had a lower capacity to cope with grazing than unexposed communities, because toxicity can limit algal regrowth after release from grazing and promote the loss of less abundant species. This synergism may have important implications because grazing pressure will magnify the negative effects of toxicants on community structure and ecosystem functions such as primary production and nutrient cycling.SCOPUS: cp.jinfo:eu-repo/semantics/publishe

土壤吸附揮發性有機物的實驗研究方法

The aim of EU project MyNewGut is to contribute to future public health-related recommendations supported by new insight in gut microbiome and nutrition-host relationship. In this Opinion Paper, we first revisit the concept of dietary fiber, taking into account their interaction with the gut microbiota. This paper also summarizes the main effects of dietary fibers with prebiotic properties in intervention studies in humans, with a particular emphasis on the effects of arabinoxylans and arabinoxylo-oligosaccharides on metabolic alterations associated with obesity. Based on the existing state of the art and future development, we elaborate the steps required to propose dietary guidelines related to dietary fibers, taking into account their interaction with the gut microbiota.The MyNewGut project is financially supported by a grant from the EU 7th Framework Program under Grant Agreement 613979. MO is a beneficiary of a “MOVE-IN Louvain” grant (incoming Post-Doctoral Fellowship co-funded by the Marie Curie Actions of the European Commission)

A conceptual framework for understanding the biogeochemistry of dry riverbeds through the lens of soil science

Intermittent rivers and ephemeral streams (IRES) encompass fluvial ecosystems that eventually stop flowing and run dry at some point in space and time. During the dry phase, channels of IRES consist mainly of dry riverbeds (DRBs), prevalent yet widely unexplored ecotones between dry and wet phases that can strongly influence the biogeochemistry of fluvial networks. DRBs are often overlooked because they do not strictly belong to either domain of soil or freshwater science. Due to this dual character of DRBs, we suggest that concepts and knowledge from soil science can be used to expand the understanding of IRES biogeochemistry. Based on this idea, we propose that DRBs can be conceptually understood as early stage soils exhibiting many similarities with soils through two main forces: i) time since last sediment transport event, and ii) the development status of stabilizing structures (e.g. soil crusts and/or vascular plants). Our analysis suggests that while DRBs and soils may differ in master physical attributes (e.g. soil horizons vs fluvial sedimentary facies), they become rapidly comparable in terms of microbial communities and biogeochemical processes. We further propose that drivers of DRBs biogeochemistry are similar to those of soils and, hence, concepts and methods used in soil science are transferable to DRBs research. Finally, our paper presents future research directions to advance the knowledge of DRBs and to understand their role in the biogeochemistry of intermittent fluvial networks. © 2018 The AuthorsThis paper resulted from discussions conducted as part of working group 3 “Coupled Aquatic-terrestrial Biogeochemistry in IRES” based upon work from COST Action CA15113 (SMIRES, Science and Management of Intermittent rivers and Ephemeral streams; www.smires.eu ) supported by COST (European Cooperation in Science and Technology). Additional support was provided for MIA by an Alexander von Humboldt Grant (Ref: 1162886 ) and a Juan de la Cierva Grant (Ref: FJCI-2015-26192 ), for CM-L by an Early Career Fellowship from the Graduate Research School (GRS) at BTU Cottbus-Senftenberg and by the French Agency for Biodiversity (ONEMA-AFB, Action 13, Colmatage, échange snappe-rivière et processus biogéochimiques), for MA by the Spanish Government (Ref: DISECO CGL-2014-55-405-R ) and by a Juan de la Cierva Grant (Ref: IJCI-2015-23500 ), for NC by a Juan de la Cierva Grant (Ref: FJCI-2014-23064 ), for SB by Spanish Government (Ref: NICUS CGL-2014-55234-JIN ), for RG by the Science and Technology Agency of Murcia Region (SENECA Foundation, Ref: 19525/PI/14 ), for OS by the SMART joint Doctorate Programme (Science for the MAnagement of Rivers and their Tidal systems, funded by the Erasmus Mundus programme of the European Union ) and for DvS by the Spanish Government (Ref: CGL2016-77487-R ) and Basque Government (Ref: IT951-16 )

On the tectonic origin of Iberian topography

The present-day topography of the Iberian peninsula can be considered as the result of the MesozoicCenozo–ic tectonic evolution of the Iberian plate (including rifting and basin formation during the Mesozoic and compression and mountain building processes at the borders and inner part of the plate, during the Tertiary, followed by Neogene rifting on the Mediterranean side) and surface processes acting during the Quaternary. The northern-central part of Iberia (corresponding to the geological units of the Duero Basin, the Iberian Chain, and the Central System) shows a mean elevation close to one thousand meters above sea level in average, some hundreds of meters higher than the southern half of the Iberian plate. This elevated area corresponds to (i) the top of sedimentation in Tertiary terrestrial endorheic sedimentary basins (Paleogene and Neogene) and (ii) planation surfaces developed on Paleozoic and Mesozoic rocks of the mountain chains surrounding the Tertiary sedimentary basins. Both types of surfaces can be found in continuity along the margins of some of the Tertiary basins. The Bouguer anomaly map of the Iberian peninsula indicates negative anomalies related to thickening of the continental crust. Correlations of elevation to crustal thickness and elevation to Bouguer anomalies indicate that the dierent landscape units within the Iberian plate can be ascribed to dierent patterns: (1) The negative Bouguer anomaly in the Iberian plate shows a rough correlation with elevation, the most important gravity anomalies being linked to the Iberian Chain. (2) Most part of the so-called Iberian Meseta is linked to intermediate-elevation areas with crustal thickening; this pattern can be applied to the two main intraplate mountain chains (Iberian Chain and Central System) (3) The main mountain chains (Pyrenees and Betics) show a direct correlation between crustal thickness and elevation, with higher elevation/crustal thickness ratio for the Central Systemvs. the Betics and the Pyrenees. Other features of the Iberian topography, namely the longitudinal pro le of the main rivers in the Iberian peninsula and the distribution of present-day endorheic areas, are consistent with the Tertiary tectonic evolution and the change from an endorheic to an exorheic regime during the Late Neogene and the Quaternary. Some of the problems involving the timing and development of the Iberian Meseta can be analysed considering the youngest reference level, constituted by the shallow marine Upper Cretaceous limestones, that indicates strong dierences induced by (i) the overall Tertiary and recent compression in the Iberian plate, responsible for dierences in elevation of the reference level of more than 6 km between the mountain chains and the endorheic basins and (ii) the eect of Neogene extension in the Mediterranean margin, responsible for lowering several thousands of meters toward the East and uplift of rift shoulders. A part of the recent uplift within the Iberian plate can be attributed o sostatic uplift in zones of crustal thickening

Exopolymeric substances (EPS) from Salmonella enterica: polymers, proteins and their interactions with plants and abiotic surfaces

When Salmonella enterica is not in a planktonic state, it persists in organised communities encased in extracellular polymeric substances (EPS), defined as biofilms. Environmental conditions ultimately dictate the key properties of the biofilms such as porosity, density, water content, charge, sorption and ion exchange properties, hydrophobicity and mechanical stability. S. enterica has been extensively studied due to its ability to infect the gastrointestinal environment. However, only during the last decades studies on its persistence and replication in soil, plant and abiotic surfaces have been proposed. S. enterica is an environmental bacterium able to effectively persist outside the human host. It does so by using EPS as tools to cope with environmental fluctuations. We therefore address this mini-review to classify those EPS that are produced by Salmonella with focus on the environment (plant, soil, and abiotic surfaces) by using a classification of EPS proposed by Flemming and collaborators in 2007. The EPS are therefore classified as structural, sorptive, surface-active, active, and informative