3. Wochenbericht CE0913

Vom 26. Juli bis zum 14. August sind Wissenschaftler vom IFM-GEOMAR auf dem irischen Forschungsschiff Celtic Explorer in der Nordsee unterwegs. Die Expedition CE 0913 unter Fahrtleitung von Dr. Peter Linke findet im Rahmen des Projekts „Fluid- und Gasaustritte in der südlichen deutschen Nordsee“ in Zusammenarbeit mit der Christian-Albrechts-Universität zu Kiel, dem Bundesamt für Seeschifffahrt und Hydrographie und Wintershall statt und dient der Auffindung von Fluid- und Gasaustritten. Die Art und Weise des Austritts und die chemische und isotopische Zusammensetzung der austretenden Gase sollen genauer analysiert werden. Dabei kommen der Tiefseeroboter ROV KIEL 6000, Vibrocorers und Landersysteme zum Einsatz. CELTIC EXPLORER CE 0913: 2. Wochenbericht (10.‐14.08.2009

1. Wochenbericht SO210/1

SO-210: ChiFlux 1. Wochenbericht: 22.09. - 29.09.201

Metabolic adaptations of deep-sea benthic foraminifera to seasonally varying food input

ATP content and metabolic activity of benthic foraminifera were determined from deepsea sediments of the Norwegian-Greenland Sea. Metabolic activity was analysed by measurements of Electron Transport System (ETS] activity and heat production. This, combined with live observations, revealed 2 survival strategies. Ruperlina stabilis, an obligate suspension feeder, is adapted to conditions in which it receives a steady input of particles throughout the year, enabling it to maintain a relatively high ATP content (153 f 23 ng ATP ind.-l) with a reduced ATP turnover rate (0.008 S-'). In contrast Cribrostomoides subglobosum, Pyrgo rotalaria and Rhabdammina abyssorum undergo large (up to 10-fold) fluctuations in seasonal values of ATP and heat production, but retain a high, relatively constant ATP turnover rate (i.e. seconds). Such a rapid turnover allows these foraminifera to take quick advantage of sudden nutrient inputs; this state of readiness, however, is maintained at the cost of the protoplasm, which benthic foraminifera are apparently capable of metabolizing in times of starvation. C. subglobosum and P rotalaria responded to several sedimentation events with an increase in ETS activ~tys;i ngle cells sometimes showed extremely high ATP values (50- to 100-fold increase), reflecting an individual physiological response to food input to the deep-sea

5. Wochenbericht SO210/2

SO-210: ChiFlux 5. Wochenbericht: 20. – 26.10.201

2. Wochenbericht CE0913

Vom 26. Juli bis zum 14. August sind Wissenschaftler vom IFM-GEOMAR auf dem irischen Forschungsschiff Celtic Explorer in der Nordsee unterwegs. Die Expedition CE 0913 unter Fahrtleitung von Dr. Peter Linke findet im Rahmen des Projekts „Fluid- und Gasaustritte in der südlichen deutschen Nordsee“ in Zusammenarbeit mit der Christian-Albrechts-Universität zu Kiel, dem Bundesamt für Seeschifffahrt und Hydrographie und Wintershall statt und dient der Auffindung von Fluid- und Gasaustritten. Die Art und Weise des Austritts und die chemische und isotopische Zusammensetzung der austretenden Gase sollen genauer analysiert werden. Dabei kommen der Tiefseeroboter ROV KIEL 6000, Vibrocorers und Landersysteme zum Einsatz. CELTIC EXPLORER CE 0913: 2. Wochenbericht (4.‐10.08.2009

Ruminal and Plasma Responses in Dairy Cows to Drenching or Feeding Glycerol

Four Holstein dairy cows (137 DIM, 60 kg milk/d) were used in a Latin square with 1-wk periods to evaluate the effect of methods of oral delivery of glycerol on ruminal VFA and plasma concentrations of glucose, 6-hydroxybutyrate (BHBA), nonesterified fatty acids (NEFA), and insulin. All cows were fed only grass hay for ad libitum consumption during 12 h before the experiment. At the start of the experiment, time 0, all cows were fed 5 kg of cracked corn. Treatments administered at time 0 were: 1) control (C), no glycerol; 2) fed glycerol (F), 1 kg of glycerol solution (80% glycerol) added to the com; 3) drench glycerol (D), 1 kg of glycerol solution in 1 L of water and delivered as oral drench; and 4) tube delivery of glycerol (T), 1 kg of glycerol solution in 9 L of water and delivered into the rumen via an esophageal tube. Blood samples were collected at -1, -0.5, 0, 0.25, 0.5, 0.75, 1, 1.5, 2, 4, 6, 8, 12, and 24 h after administering glycerol. Rumen samples were collected at 0, 2, 4, and 6 h. After administration of glycerol, concentrations of acetate decreased in rumens of cows while propionate and butyrate were increased by glycerol with peak concentrations at 4 h. Concentrations of glucose were increased in plasma of D and T compared with C, reaching peak concentrations at 1.5 and 3 h for D and T, respectively. Glucose response expressed as area under the curve (AUC) over baseline for 6 h was greater for D and T compared with C. Insulin concentrations in plasma were increased for D and T reaching peak concentrations at 1.4 and 1.1 h for D and T respectively. The 6-hAUCfor insulin concentrations were greater for D and T than for F and C. The BHBA was increased in plasma of D, T, and F compared with C, reaching peak concentrations at 2.5, 2.4, and 1.6h for D, T, and F, respectively. These data demonstrate that the ability of glycerol to increase plasma concentrations of glucose and insulin is dependent upon rapid delivery

An Algorithm for Dynamic Load Balancing of Synchronous Monte Carlo Simulations on Multiprocessor Systems

We describe an algorithm for dynamic load balancing of geometrically parallelized synchronous Monte Carlo simulations of physical models. This algorithm is designed for a (heterogeneous) multiprocessor system of the MIMD type with distributed memory. The algorithm is based on a dynamic partitioning of the domain of the algorithm, taking into account the actual processor resources of the various processors of the multiprocessor system.Comment: 12 pages, uuencoded figures included, 75.93.0

In situ benthic fluxes from an intermittently active mud volcano at the Costa Rica convergent margin

Along the erosive convergent margin off Costa Rica a large number of mound-shaped structures exist built by mud diapirism or mud volcanism. One of these, Mound 12, an intermittently active mud volcano, currently emits large amounts of aqueous dissolved species and water. Chemosynthetic vent communities, authigenic carbonates, and methane plumes in the water column are manifestations of that activity. Benthic flux measurements were obtained by a video-guided Benthic Chamber Lander (BCL) deployed at a vent site located in the most active part of Mound 12. The lander was equipped with 4 independent chambers covering adjacent areas of the seafloor. Benthic fluxes were recorded by repeated sampling of the enclosed bottom waters while the underlying surface sediments were recovered with the lander after a deployment time of one day. One of the chambers was placed directly in the centre of an active vent marked by the occurrence of a bacterial mat while the other chambers were located at the fringe of the same vent system at a lateral distance of only 40 cm. A transport-reaction model was developed and applied to describe the concentration profiles in the pore water of the recovered surface sediments and the temporal evolution of the enclosed bottom water. Repeated model runs revealed that the best fit to the pore water and benthic chamber data is obtained with a flow velocity of 10 cm yr− 1 at the centre of the vent. The flux rates to the bottom water are strongly modified by the benthic turnover (benthic filter). The methane flux from below at the bacterial mat site is as high as 1032 μmol cm− 2 yr− 1, out of which 588 μmol cm− 2 yr− 1 is oxidised in the surface sediments by microbial consortia using sulphate as terminal electron acceptor and 440 μmol cm− 2 yr− 1 are seeping into the overlaying bottom water. Sulphide is transported to the surface by ascending fluids (238 μmol cm− 2 yr− 1) and is formed within the surface sediment by the anaerobic oxidation of methane (AOM, 588 μmol cm− 2 yr− 1). However, sulphide is not released into the bottom water but completely oxidized by oxygen and nitrate at the sediment/water interface. The oxygen and nitrate fluxes into the sediment are high (781 and 700 μmol cm− 2 yr− 1, respectively) and are mainly driven by the microbial oxidation of sulphide. Benthic fluxes were much lower in the other chambers placed in the fringe of the vent system. Thus, methane and oxygen fluxes of only 28 and 89 μmol cm− 2 yr− 1, respectively were recorded in one of these chambers. Our study shows that the aerobic oxidation of methane is much less efficient than the anaerobic oxidation of methane so that methane which is not oxidized within the sediment by AOM is almost completely released into the bottom water. Hence, anaerobic rather than aerobic methane oxidation plays the major role in the regulation of benthic methane fluxes. Moreover, we demonstrate that methane and oxygen fluxes at cold vent sites may vary up to 3 orders of magnitude over a lateral distance of only 40 cm indicating an extreme focussing of fluid flow and methane release at the seafloor