Similar calcareous sediments are also known from Troms district,

Similar calcareous sediments are also known from Troms district, Norway

( Elverhøi and Solheim, 1983 and Freiwald, 1998). The thickness of the permeable layer is not well described in the literature: it is certainly thicker than 1 m and, according to unpublished Russian sources, is more than several metres thick in some places (G. A. Tarasov, Murmansk Marine Biological Institute, personal communication). Below we present for the first time an assessment of the part played by a permeable sediment bank in pelago-benthic coupling in the Barents Sea. Material was collected in August 2009 during a cruise of r/v ‘Oceania’ to Svalbardbanken as part of the BANKMOD project. Hydrographic measurements were performed with a towed Seabird FastCAT SBE49 CTD system. Sediment and benthos samples were collected with a Van Veen grab and a triangular dredge. Table 1 presents the sediment characteristics from two stations where permeability was measured. Navitoclax price The epifaunal wet weight find more exceeded 150 g m− 2 at each site, and sediment organic matter content (loss on

ignition) was < 0.3%. Permeability was measured on sediment samples from the grab, according to the method described in Kluke & Dirksen (1986), on board and then again under laboratory conditions. For comparison, we measured the permeability of Baltic clean quartz sands (fine − 0.1 mm, medium − 0.4 mm and coarse-grained 0.6 mm) on the same equipment. The hydrodynamic benthic boundary flow was modelled on the basis of formulas by Massel (1999) and Massel et al., 2004 and Massel et al., 2005, and was run for assumed permeable layer thicknesses of 5 and 20 m, as well as two grain sizes (0.9 and 20 mm) for a horizontal seabed. The permeability of the sediments was measured (Figure 2); its values (4.28 × 10− 10 m− 2) are well above the permeability of comparable Baltic sands and well-studied Glycogen branching enzyme sands from European waters or the Mid-Atlantic Bight (MAB) (Rush et al. 2006).

The hydrodynamic (Slagstad & McClimans 2005) and tidal (Kowalik & Proshutinsky 1995) models show very intense dynamics and important atmospheric drivers (waves, surface and tidal currents, eddies and oceanic fronts) dominating the top of Svalbardbanken. The circulation over Svalbardbanken was previously modelled by Adlandsvik & Hansen (1998). In situ hydrological measurements taken in August 2009 showed typical settings with warmer, transformed Atlantic Water washing the NW part of Svalbardbanken and cold, Barents Sea Arctic waters on its SE side. On the top, well mixed, relatively warm and less saline local waters predominate (Figure 3), much like the situation known from the literature (e.g. Sakshaug & McClimans 2005). The benthic boundary model shows that during average storms, water percolates through the coarse sediment to a depth of a few metres (depending on the assumed thickness of the permeable layer).

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