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The benthic microbial mat community of the only permanent hypersaline natural inland lake of Western Europe, 'La Salada de Chiprana', northeastern Spain, was structurally and functionally analyzed. The ionic composition of the lake water is characterized by high concentrations of magnesium and sulfate, which were respectively 0.35 and 0.5 M at the time of(More)
 Extracellular polysaccharides (EPS) were quantified in dense granules and loose flocs by chemical analysis of the uronic acid content. Their distribution within the aggregates was determined by microscopic staining. Granules contained a higher amount of EPS (1–1.6 mg/g volatile suspended solids, VSS) than flocs (0.3 mg/g VSS). In granules approximately 50%(More)
From the Hå kon Mosby Mud Volcano (HMMV) on the southwest Barents Sea shelf, gas and fluids are expelled by active mud volcanism. We studied the mass transfer phenomena and microbial conversions in the surface layers using in situ microsensor measurements and on retrieved cores. The HMMV consists of three concentric habitats: a central area with gray mud, a(More)
The sulfate-reducing bacterium strain SRB D2 isolated from the photic zone of a hypersaline microbial mat, from Lake Chiprana, NE Spain, respired pyruvate, alanine, and α-ketoglutarate but not formate, lactate, malate, succinate, and serine at significant rates under fully oxic conditions. Dehydrogenase enzymes of only the former substrates are likely(More)
In this study the degradation of hydrophobic petroleum model compounds (phenanthrene, pristane, octadecane and dibenzothiophene) added to a submersed hypersaline microbial mat was investigated. Montmorillonite with an artificially altered, hydrophobic surface was used as carrier material, forming an organo-clay complex (OCC) with the attached mixture of(More)
A new CO, microelectrode with a tip diameter of 10 pm and a response time (t,,) of-10 s is presented. The sensor allows CO, measurements with a detection limit of <3 PM. The microsensor was tested in experimental systems of increasing complexity. A diffusion-reaction simulation model was used to calculate CO, profiles in order to check the reliability of(More)
The effect of sediment-dwelling macrofauna on nitrifying bacteria was investigated by direct probing in their overlapping habitat, i.e., the upper few millimeters of freshwater sediments. Microsensors (O 2 , NH þ 4 , NO 2 3 , and diffusivity) were used at the sediment surface and inside animal burrows to record steady-state and dynamic distributions of(More)
Aerobic respiration plays an important role in the degradation of carbon and is typically estimated to account for 25% to 50% of carbon mineralization in coastal sediments. Two established methods have been used for the determination of areal oxygen consumption rates (OCR) in sediments, namely the dif-fusive oxygen uptake and the benthic-chamber total(More)
Sediment-reworking macrofauna can stimulate nitrification by increasing the O2 penetration into sediments or it can reduce nitrification by grazing on nitrifying bacteria. We investigated the influence of Chironomus riparius larvae (Insecta: Diptera) on the in situ activity, abundance, and distribution of NH 4 + -oxidizing (AOB) and NO 2 − -oxidizing(More)