Deep-sea ecosystems represent the largest biome of the global biosphere, but knowledge of their biodiversity is still scant. The Mediterranean basin has been proposed as a hot spot of terrestrial and coastal marine biodiversity but has been supposed to be impoverished of deep-sea species richness. We summarized all available information on benthic biodiversity (Prokaryotes, Foraminifera, Meiofauna, Macrofauna, and Megafauna) in different deep-sea ecosystems of the Mediterranean Sea (200 to more than 4,000 m depth), including open slopes, deep basins, canyons, cold seeps, seamounts, deep-water corals and deep-hypersaline anoxic basins and analyzed overall longitudinal and bathymetric patterns. We show that in contrast to what was expected from the sharp decrease in organic carbon fluxes and reduced faunal abundance, the deep-sea biodiversity of both the eastern and the western basins of the Mediterranean Sea is similarly high. All of the biodiversity components, except Bacteria and Archaea, displayed a decreasing pattern with increasing water depth, but to a different extent for each component. Unlike patterns observed for faunal abundance, highest negative values of the slopes of the biodiversity patterns were observed for Meiofauna, followed by Macrofauna and Megafauna. Comparison of the biodiversity associated with open slopes, deep basins, canyons, and deep-water corals showed that the deep basins were the least diverse. Rarefaction curves allowed us to estimate the expected number of species for each benthic component in different bathymetric ranges. A large fraction of exclusive species was associated with each specific habitat or ecosystem. Thus, each deep-sea ecosystem contributes significantly to overall biodiversity. From theoretical extrapolations we estimate that the overall deep-sea Mediterranean biodiversity (excluding prokaryotes) reaches approximately 2805 species of which about 66% is still undiscovered. Among the biotic components investigated (Prokaryotes excluded), most of the unknown species are within the phylum Nematoda, followed by Foraminifera, but an important fraction of macrofaunal and megafaunal species also remains unknown. Data reported here provide new insights into the patterns of biodiversity in the deep-sea Mediterranean and new clues for future investigations aimed at identifying the factors controlling and threatening deep-sea biodiversity.

Most environmental bio-monitoring methods using the species composition of marine faunas define the Ecological Quality Status of soft bottom ecosystems based on the relative proportions of species assigned to a limited number of ecological categories. In this study we analyse the distribution patterns of benthic foraminifera in the Mediterranean as a function of organic carbon gradients on the basis of 15 publications and assign the individual species to five ecological categories. Our categories (of sensitive, indifferent and 3rd, 2nd and 1st order opportunists) are very similar to the ecological categories commonly used for macrofauna, but show some minor differences. In the 15 analysed publications, we considered the numerical data of 493 taxa, of which 199 could be assigned. In all 79 taxa were classified as sensitive, 60 as indifferent, 46 as 3rd order, 12 as 2nd order and 2 as 1st order opportunists. The remaining 294 taxa are all accessory, and will only marginally contribute to biotic indices based on relative species proportions. In this paper we wanted also to explain the methodology we used for these species assignments, paying particular attention to all complications and problems encountered. We think that the species list proposed here will constitute a highly useful tool for foraminiferal bio-monitoring of soft bottoms in the Mediterranean Sea, which can be used in different ecological indices (Foram-AMBI and similar methods). With additional information becoming available in the next few years, it will be possible to expand the list, and, if necessary, to apply some minor corrections. As a next step, we intend to test this species list using several biotic indices, in a number of independent data sets, as soon as these will become available.

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The depositional history of the Storfjorden and Kveithola trough-mouth fans (TMFs) in the northwestern Barents\ud Sea has been investigatedwithin two coordinated Spanish and Italian projects in the framework of the International\ud Polar Year (IPY) Activity 367, NICE STREAMS. The investigation has been conducted using a multidisciplinary approach\ud to the study of sediment cores positioned on high-resolution multibeam bathymetry and TOPAS/CHIRP\ud sub-bottom profiles.\ud Core correlation and the age model were based on 27AMS 14C samples, rock magnetic parameters, lithofacies sequences,\ud and the presence of marker beds including two oxidized layers marking the post Last GlacialMaximum\ud (LGM) inception of deglaciation (OX-2) and the Younger Dryas cold climatic event (OX-1).\ud Sediment facies analysis allowed the distinction of a number of depositional processes whose onset appears\ud closely related to ice stream dynamics and oceanographic patterns in response to climate change. The glacigenic\ud diamictonwith lowwater content, high density, and high shear strength, deposited during glacial maxima, indicates\ud ice streams grounded at the shelf edge. Massive release of IRD occurred at the inception of deglaciation in\ud response to increased calving rates with possible outer ice streams lift off and collapse. The presence of a severalmeter-\ud thick sequence of interlaminated sediments deposited by subglacial outbursts of turbid meltwater\ud (plumites) indicates rapid ice streams' melting and retreat. Crudely-layered and heavily-bioturbated sediments\ud were deposited by contour currents under climatic/environmental conditions favorable to bioproductivity.\ud The extreme sedimentation rate of 3.4 cm a−1 calculated for the plumites from the upper-slope area indicates a\ud massive, nearly instantaneous (less than 150 years), terrigenous input corresponding to an outstanding meltwater\ud event.Wepropose these interlaminated sediments to represent the high-latitudemarine record ofMeltWater\ud Pulse 1a (MWP-1a). Different bathymetric and oceanographic conditions controlled locally the mode of glacial\ud retreat, resulting in different thickness of plumites on the upper continental slope of the Storfjorden and\ud Kveithola TMFs. It is possible that the southern part of Storfjorden TMF received additional sediments from the\ud deglaciation of the neighboring Kveithola ice stream