2010). Piepenburg et al. (1995) found that over the Barents Sea shelf, as much as 68% of oxygen is attributable to sediment microbes, and that the benthic requirement Cabozantinib for carbon ranges from 10 to 40% of that of local primary production. The carbon requirement of shelf sediments in the Arctic Beaufort Sea was estimated at 60% of new production (Renaud et al. 2007). The importance of the microbial oxidation of organic matter in permeable sediments is emphasized by many authors (e.g. Gihring et al. 2009). In the coarse sediments of the North Sea, the meiofauna responds rapidly

to the organic supply, yet bacteria dominate respiration (Franco et al., 2008 and Franco et al., 2010). In sands, low standing stocks mean a rapid turnover due to advective interfacial flow and microbial populations (Rocha 2008). Respiration and denitrification rates in MAB aerobic denitrifiers (Rao et al. 2008) were 34 times faster than molecular diffusion, and up to 17% of the integrated mid-shelf water column production is recycled annually below the sediment surface there (Jahnke et al. 2005). Algal cells were present to

a depth of 11 cm in MAB sediments and were metabolized as intensely as in coastal waters (Rusch et al. 2003). An estimated volume of 1 m3 m− 2 day− 1 was pumped through the top 10 cm of sands in MAB (Reimers et al. 2004), which was calculated by Rush et al. (2006) as contributing ‘significantly to the cycling of carbon and nutrients in the shelf environment’. Part of the primary production MEK inhibitor side effects Loperamide that falls to the Svalbardbanken seabed goes through the high biomass of large, erect filter feeders (bryozoans, sponges, sea squirts and bivalves) that are able to capture food above the seabed (Idelson 1930). The species composition, distribution and density (present authors, in prep.) was almost identical

to the previous study by Idelson (1930) from this area nearly 80 years ago. That author also noted that the abundance of epifauna and filter feeders on Svalbardbanken was the result of strong currents and the amount of detritus available. In summary we suggest that sediment coarseness and flow intensity most likely create the opportunity for the intensive metabolism of organic carbon within the Svalbardbanken sediments. This particular area (ca 16 000 km2) acts as a huge, three-dimensional converter, probably capable of processing a significant part of the primary production below the seabed surface and enriching the surrounding waters with regenerated nutrients. Direct measurements of flow in local sediments and of metabolic activity in pore waters are needed, although it has to be borne in mind that this may be technically difficult, as no conventional sampler is capable of penetrating the shell/gravel sediment to this depth in order to collect the interstitial water intact. We thank W.