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| Guillermic, Maxence; Cameron, Louise P.; De Corte, Ilian; Misra, Sambuddha; Bijma, Jelle; De Beer, Dirk; Reymond, Claire E.; Westphal, Hildegard; Ries, Justin B.; Eagle, Robert A.. |
| The combination of thermal stress and ocean acidification (OA) can more negatively affect coral calcification than an individual stressors, but the mechanism behind this interaction is unknown. We used two independent methods (microelectrode and boron geochemistry) to measure calcifying fluid pH (pH(cf)) and carbonate chemistry of the corals Pocillopora damicornis and Stylophora pistillata grown under various temperature and pCO(2) conditions. Although these approaches demonstrate that they record pH(cf) over different time scales, they reveal that both species can cope with OA under optimal temperatures (28 degrees C) by elevating pH(cf) and aragonite saturation state (Omega(cf)) in support of calcification. At 31 degrees C, neither species elevated these... |
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| Ano: 2021 |
URL: https://archimer.ifremer.fr/doc/00686/79846/82675.pdf |
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| Feseker, Tomas; Boetius, Antje; Wenzhofer, Frank; Blandin, Jerome; Olu, Karine; Yoerger, Dana R.; Camilli, Richard; German, Christopher R.; De Beer, Dirk. |
| Submarine mud volcanoes are important sources of methane to the water column. However, the temporal variability of their mud and methane emissions is unknown. Methane emissions were previously proposed to result from a dynamic equilibrium between upward migration and consumption at the seabed by methane-consuming microbes. Here we show non-steady-state situations of vigorous mud movement that are revealed through variations in fluid flow, seabed temperature and seafloor bathymetry. Time series data for pressure, temperature, pH and seafloor photography were collected over 431 days using a benthic observatory at the active Hakon Mosby Mud Volcano. We documented 25 pulses of hot subsurface fluids, accompanied by eruptions that changed the landscape of the... |
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| Ano: 2014 |
URL: https://archimer.ifremer.fr/doc/00245/35601/34137.pdf |
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| Chennu, Arjun; Faerber, Paul; Volkenborn, Nils; Al-najjar, Mohammad A. A.; Janssen, F; De Beer, Dirk; Polerecky, Lubos. |
| We describe a novel, field-deployable hyperspectral imaging system, called Hypersub, that allows noninvasive in situ mapping of the microphytobenthos (MPB) biomass distribution with a high spatial (sub-millimeter) and temporal (minutes) resolution over areas of 1 x 1 m. The biomass is derived from a log-transformed and near-infrared corrected reflectance hyperspectral index, which exhibits a linear relationship (R-2 > 0.97) with the chlorophyll a (Ch1 a) concentration in the euphotic zone of the sediment and depends on the sediment grain size. Deployments of the system revealed that due to factors such as sediment topography, bioturbation, and grazing, the distribution of MPB in intertidal sediments is remarkably heterogeneous, with Ch1 a concentrations... |
| Tipo: Text |
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| Ano: 2013 |
URL: https://archimer.ifremer.fr/doc/00176/28762/27229.pdf |
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