• European Marine Science
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The transfer of Microcystis aeruginosa from freshwater to estuaries has been described worldwide and salinity is reported as the main factor controlling the expansion of M. aeruginosa to coastal environments. Analyzing the expression levels of targeted genes and employing both targeted and non-targeted metabolomic approaches, this study investigated the effect of a sudden salt increase on the physiological and metabolic responses of two toxic M. aeruginosa strains separately isolated from fresh and brackish waters, respectively, PCC 7820 and 7806. Supported by differences in gene expressions and metabolic profiles, salt tolerance was found to be strain specific. An increase in salinity decreased the growth of M. aeruginosa with a lesser impact on the brackish strain. The production of intracellular microcystin variants in response to salt stress correlated well to the growth rate for both strains. Furthermore, the release of microcystins into the surrounding medium only occurred at the highest salinity treatment when cell lysis occurred. This study suggests that the physiological responses of M. aeruginosa involve the accumulation of common metabolites but that the intraspecific salt tolerance is based on the accumulation of specific metabolites. While one of these was determined to be sucrose, many others remain to be identified. Taken together, these results provide evidence that M. aeruginosa is relatively salt tolerant in the mesohaline zone and microcystin (MC) release only occurs when the capacity of the cells to deal with salt increase is exceeded. Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe; 1130

Summary Data‐rich restoration experiments offer opportunities to test the ability of bioassessment tools, such as those currently used to assess the ‘ecological status’ of waterbodies targeted by the European Water Framework Directive, to detect observed ecological changes. Minimum flow increases in four regulated reaches of the French Rhône River modified the invertebrate and fish communities in a predictable way, as detailed in other articles of this Special Issue. We tested the ability of several fish and macroinvertebrate metrics currently used in bioassessment to detect these changes. In addition, we considered changes in metrics that are expected to respond specifically to flow increase. These metrics were related to the habitat requirements of species, the ecological specialisation of communities and the abundance of macroinvertebrate functional groups (seen as surrogates for ecosystem attributes). For invertebrate communities, bioassessment metrics based on richness had equivocal responses to restoration and the Potamon‐Type Index demonstrated no or contradictory responses to restoration. The French biotic index was not sensitive to restoration and instead depicted spatial differences in biological quality. For fish communities, the French fish index was marginally sensitive in the reach with the largest minimum flow increase and some of its metrics were sensitive in other reaches. Contrasting with commonly used bioassessment indices and metrics, several metrics related to habitat requirements appropriately indicated the observed changes in community structure. Large flow changes increased the proportion of fish and macroinvertebrate individuals with preferences for midstream habitats, fast currents, deep waters and/or coarse substrates. However, these changes did not translate into the expected increase in ecological specialisation. In addition, functional metrics indicated that restoration led to higher proportions of grazers and higher availability of suspended food for filtering collectors, suggesting a return to the ecological conditions of a large river. The mixed and potentially contradictory responses of the different metrics confirm the difficulty of establishing benchmarks for ecological indicators in large‐regulated rivers and the need to design appropriate bioassessment metrics.

In recent decades, the presence of micropollutants in the environment has been extensively studied due to their high frequency of occurrence, persistence and possible adverse effects to exposed organisms. Concerning chiral micropollutants in the environment, enantiomers are frequently ignored and enantiomeric composition often neglected. However, enantioselective toxicity is well recognized, highlighting the need to include enantioselectivity in environmental risk assessment. Additionally, the information about enantiomeric fraction (EF) is crucial since it gives insights about: (i) environmental fate (i.e., occurrence, distribution, removal processes and (bio)degradation); (ii) illicit discharges; (iii) consumption pattern (e.g., illicit drugs, pharmaceuticals used as recreational drugs, illicit use of pesticides); and (iv) enantioselective toxicological effects. Thus, the purpose of this paper is to provide a comprehensive review about the enantioselective occurrence of chiral bioactive compounds in aquatic environmental matrices. These include pharmaceuticals, illicit drugs, pesticides, polychlorinated biphenyls (PCBs) and polycyclic musks (PCMs). Most frequently analytical methods used for separation of enantiomers were liquid chromatography and gas chromatography methodologies using both indirect (enantiomerically pure derivatizing reagents) and direct methods (chiral stationary phases). The occurrence of these chiral micropollutants in the environment is reviewed and future challenges are outlined. © 2017 by the authors. This work was developed at Laboratory of Environmental Research area/Environmental and Applied Chemistry research line of the IINFACTS-CESPU. The authors acknowledge the financial support from PARMADRUGS-CESPU-2014 and ChiralDrugs_CESPU_2017. This research was partially supported through national funds provided by FCT/MCTES: Foundation for Science and Technology from the Minister of Science, Technology and Higher Education (PIDDAC) and European Regional Development Fund (ERDF) through the COMPETE: Programa Operacional Factores de Competitividade (POFC) programme, under the Strategic Funding UID/Multi/04423/2013, in the framework of the programme PT2020. ARR and MSM acknowledge Fundação para a Ciência e Tecnologia (FCT) for their grants, SFRH/BD/86939/2012 and SFRH/BPD/101703/2014, respectively

Near-shore and direct groundwater inputs are frequently omitted from nutrient budgets of coastal lagoons. This study investigated groundwater-driven dissolved inorganic nitrogen (DIN) inputs from an alluvial aquifer to the hypertrophic Or lagoon, with a focus on the Salaison River. Piezometric contours revealed that the Salaison hydrogeological catchment is 42% bigger than the surface watershed and hydraulic gradients suggest significant groundwater discharge all along the stream. Hydrograph separation of the water flow at a gauging station located 3 km upstream from the Or lagoon combined with DIN historical data enabled to estimate that groundwater-driven DIN inputs account for 81–87% of the annual total DIN inputs to the stream upstream from the gauging station. A radon mass balance was performed for the hydrological cycle 2017–2018 to estimate groundwater inflow into the downstream part of the stream. Results showed that (1) DIN fluxes increased by a factor 1.1 to 2.3 between the gauging station and the Salaison outlet, (2) the increase in DIN was due to two groundwater-fed canals and to groundwater discharge along the stream, the latter represented 63–78% of the water flow. This study thus highlights the significance of groundwater driven DIN inputs into the Salaison River, which account for 90% of the annual DIN inputs. This is particularly true in the downstream part of the river, which, on averages, supplies 48% of total DIN inputs to the river. These downstream DIN inputs into the Or lagoon were previously not taken into account in the management of this and other Mediterranean lagoons. The inputs will probably affect restoration processes for many years due to their residence time in the aquifer. This study throws light on a rarely documented source of ‘very-nearshore’ groundwater discharge to coastal streams in water and nutrient budgets of coastal zone ecosystems. International audience

The seasonal and spatial variability of dissolved Barium (Ba) in the Amundsen Gulf, southeastern Beaufort Sea, was monitored over a full year from September 2007 to September 2008. Dissolved Ba displays a nutrient-type behavior: the maximum water column concentration is located below the surface layer. The highest Ba concentrations are typically observed at river mouths, the lowest concentrations are found in water masses of Atlantic origin. Barium concentrations decrease eastward through the Canadian Arctic Archipelago. Barite (BaSO4) saturation is reached at the maximum dissolved Ba concentrations in the subsurface layer, whereas the rest of the water column is undersaturated. A three end-member mixing model comprising freshwater from sea-ice melt and rivers, as well as upper halocline water, is used to establish their relative contributions to the Ba concentrations in the upper water column of the Amundsen Gulf. Based on water column and riverine Ba contributions, we assess the depletion of dissolved Ba by formation and sinking of biologically bound Ba (bio-Ba), from which we derive an estimate of the carbon export production. In the upper 50 m of the water column of the Amundsen Gulf, riverine Ba accounts for up to 15% of the available dissolved Ba inventory, of which up to 20% is depleted by bio-Ba formation and export. Since riverine inputs and Ba export occur concurrently, the seasonal variability of dissolved Ba in the upper water column is moderate. Assuming a fixed organic carbon to bio-Ba flux ratio, carbon export out of the surface layer is estimated at 1.8 ± 0.45 mol C m‑2 yr‑1. Finally, we propose a climatological carbon budget for the Amundsen Gulf based on recent literature data and our findings, the latter bridging the surface and subsurface water carbon cycles. International audience

The common process of low energy geothermal exploitation is the doublet of production- and reinjection borehole. The quality of water reinjected into a elastic reservoir is essential for the reliability of an injection well. In order to estimate precipitation reactions it is necessary to obtain extensive reliable analysis data of the water for the use of thermodynamic modelling. For thermal anoxic brines, the analysis of major and especially minor ion content is difficult because of matrix effects and possible iron precipitation. A selection of analysing methods were applied to two anoxic thermal brines of deep sandstone aquifers of Northern Germany. Detection limits and measured data of the major constituents are presented of Na+, K+, NH4+, Ca2+, Mg2+, Ba2+, Sr2+, Fe-total, Mn2+, SiO44-, B(OH)(3), Zn2+, Pb2+, Cd2+, F-, Cl-, Br-, I-, SO42-, SO32-, S2-, PO43-, NO3-, NO2- and DOC. The measurements were done with ICP-OES, ionselective electrodes, photometry, polarography, titration methods, ion chromatography and TOC-analyzer. Except for SO(4)(2-)and Cl-, the anion analysis was done on-site, since the high iron content in the anoxic water requires acidification in order to prevent iron hydroxide precipitation. The minor constituents Zn2+, Pb2+, Cu2+, Cd2+, Cr3+, Sc3+, Co2+, Y3+, La3+, Ce3+, Al3+, were enriched by trace matrix separation using the cation exchange resin Chelex((R))100. The element concentrations in the acidic eluates of the Chelex((R))100 columns were measured using ICP-MS. The pH dependency of the exchange equilibrium at pH values of 4, 5 and 6 (buffered and unbuffered) as well as the relation to the salt content between 35 and 250 gl(-1) total dissolved solids of Na-K-Ca-Mg-Cl-SO4 were evaluated by sensitivity analysis.

The abundance of both heterotrophic nanoflagellates (HNAN) and bacterioplankton in a large (9km2) ultraoligotrophic Antarctic lake (Crooked Lake) were investigated from December 1992 until November 1993. HNAN abundance peaked in spring, summer and autumn, falling to lowest numbers during the winter. Numbers ranged between 0 and 50.9×104 l−1. Bacterioplankton abundance was highest during the late summer and then fell progressively towards winter and autumn (range 1.19–4.46×106 l−1) In contrast to numbers, mean cell volumes (MCV) of the bacteria reached their highest in spring, and consequently highest bacterial biomass occurred at this time. MCV ranged between 0.052 and 0.224μm3. Bacterial production measurements following the incorporation of [3H] thymidine into DNA and [14C] leucine into protein using a doubling-labelling procedure were undertaken in January, June, August, October and November. Rates varied between 2.8 and 52 ng C l1 h1. On occasions, a significant difference in production rates based on the uptake of leucine and thymidine was observed, suggesting unbalanced growth. Highest rates of production coincided with times of high dissolved organic carbon levels in the water column and lowest production with low levels of DOC. HNAN grazing rates were measured by following the uptake of fluorescently labelled bacteria and averaged 4.8 bacterial cells individual1 day1 at 2 and 4°C. Specific growth rates (h1) ranged around 0.00070–0.00077 in both the field and laboratory, giving doubling times of 37.3 and 41.0 days, respectively. These low rates of grazing and growth indicate that there is no adaptation to low temperatures in these freshwater protists. Based on these data, the gross production efficiency is 24%. HNAN removed between 0.1 and 9.7% of bacterial production per day.