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Numerous ecological problems of continental shelf ecosystems require a refined knowledge of the evolution of suspended sediment concentrations (SSC). The present investigation focuses on the spatial and temporal variabilities of near-surface SSC in coastal waters of the English Channel (western Europe) by exploiting numerical predictions from the Regional Ocean Modeling System ROMS. Extending previous investigations of ROMS performances in the Channel, this analysis refines, with increased spatial and temporal resolutions, the characterization of near-surface SSC patterns revealing areas where concentrations are highly correlated with evolutions of tides and waves. Significant tidal modulations of near-surface concentrations are thus found in the eastern English Channel and the French Dover Strait while a pronounced influence of waves is exhibited in the Channel Islands Gulf. Coastal waters present furthermore strong SSC temporal variations, particularly noticeable during storm events of autumn and winter, with maximum near-surface concentrations exceeding 40 mg l1 and increase by a factor from 10 to 18 in comparison with time-averaged concentrations. This temporal variability strongly depends on the granulometric distribution of suspended sediments characterized by local bimodal contributions of silts and sands off coastal irregularities of the Isle of Wight, the Cotentin Peninsula and the southern Dover Strait.
Full detailed descriptions of the two species of Obtusoecia, one of two planktonic halocyprid ostracod genera that are bipolar, demonstrate that the taxonomic separation of these two forms formerly considered to be conspecific, is valid. The segregation of the genus from Porroecia is also validated. The value of characters of limbs other than the first and second antennae particularly in defining halocyprid genera is emphasised. Zoogeographical distributions of the two species based on comprehensive compilations of both published and unpublished data show that O. obtusata is confined to the North Atlantic, whereas O. antarctica has an Antarctic circumpolar distribution. Detailed bathymetric profiles show that O. obtusata is a shallow mesopelagic species that is overwhelmingly dominant at depths of 50-200 m in subpolar seas, and shows limited ability to submerge at lower depths, so that it is restricted to seas that have a marked seasonal cycle of turn-over and stratification. It is postulated that the bathymetric distributions of the two species are similar, also that O. antarctica is more likely to be ancestral to O. obtusata than vice versa.
This paper discusses the role of glacial shelf topography in the formation of general oceanological and biological mechanisms in the Barents Sea. Analysis of geomorphological data and oceanographic observations obtained on board MMBI research vessels in 2001–08 has shown that: fluxes of Atlantic-origin waters pass along glacial troughs; the inflow of Atlantic waters to the Barents Sea from the west increased from 2001t ill 2007, although this advection began to weaken in 2008; vertical and horizontal thermohaline gradients intensified during the investigated period; a warm period similar to that of the 1930s was observed in the Barents Sea at the beginning of the 21st century.
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