Quantitative investigations on the total (living + dead) benthic foraminiferal assemblages were performed on 32 surface-sediment samples (0-2 cm, >63-mu m size fraction) from water depths ranging from 110-600 m ("on-reef") to >2000 m ("off-reef") in the Oslo Fjord (Skagerrak Basin), the mid-Norwegian slope (Sula, Rost, and Traenadjupet reefs), and the northern coral-reef areas in Norway (Korallen, Lopphavet, Stjernsundet, and Sveinsgrunnen reefs). Seven other samples were investigated for their living (stained) and dead (unstained) assemblages. Hierarchical cluster analysis allows the recognition of five benthic species groups linked to foraminiferal microhabitats from on- and off-reef environments as follows: I) shallow "off-reef" areas of the Oslo Fjord, II) deep-sea >1800-m water depth, and III) bathyal between 800-1800 m, and "on-reef" areas of IV) the Skagerrak and V) the shelf and upper continental slope of the mid- and nothern Norwegian margin. The benthic foraminiferal fauna associated with the declining coral reefs in the Oslo Fjord suggests that a low amount of labile organic matter and/or nutrients reach the sea floor making the environment unfavorable for coral growth, reconfirming the previous results on direct measurements of the organic matter. This study indicates that foraminifers can be used as a tool for the characterization of cold-water coral-reef environments.

The Dhaka and Maya mud volcanoes (MVs), located in the Mud Diapir Province in the Western Alboran Basin along the Moroccan Coasts, were cored during the TTR-17, Leg 1 cruise. Cores were taken on the top of the volcanoes at a water depth of 370m on the Dhaka MV (core TTR17-MS411G) and at 410m water depth on the Maya MV (core TTR17-MS419G), respectively. On both mud volcanoes the extruded mud breccia provides the nucleation point for the colonization and development of cold-water corals and associated ecosystems. Two phases of cold-water coral growth are observed: (1) between slightly older than 4175±62years BP and around 2230±59years BP at Dhaka, and (2) between slightly older than 15583±185years BP and around 7613±38years BP at Maya MV. On the top of the Maya MV only a small patch reef and/or isolated corals proliferated, whereas a more extended patch reef colonized the top of the Dhaka MV. At both sites the cold-water coral development was triggered by the availability of a suitable substrate for initial coral settling, provided either as a firm ground or as single clasts. Subsequently coral growth was supported by enhanced nutrient flux possibly related to upwelling and/or strong currents. During the intervals of coral growth planktonic foraminiferal assemblages were dominated by Neogloboquadrina incompta. The decline of coral ecosystems on the mud volcanoes is accompanied at surface by a shift from the N. incompta dominated assemblage to a Globorotalia inflata dominated assemblage, possibly reflecting more oligotrophic conditions. This shift is coeval to the passage from wet to arid conditions at the end of the African Humid Period at Maya MV. It is interpreted as an effect of an early human impact on a fragile environment, which was already stressed by desiccation at the time of the development of complex human society along the Mediterranean coasts, at Dhaka MV.

Cold-water coral reef ecosystems occur worldwide and are especially developed along the European margin, from northern Norway to the Gulf of Cadiz and into the Western Mediterranean Sea. The dominant reef builder in these areas is the scleractinian coral Lophelia pertusa, often associated with the scleractinian coral Madrepora oculata. These species settle on suitable hard substrates, in environments characterized by elevated currents and high food availability. Along the European margin cold-water coral reefs developed during different times and with different morphologies. In particular, on the Norwegian shelf and upper slope, extended active/living reefs have developed on elevated hard substrata. Along the Irish margin on the Rockall Bank, on the Porcupine Bank, and in the Porcupine Seabight, L. pertusa has built large fossil and/or active carbonate mounds. In the Gulf of Cadiz and in the Alboran Sea buried reefs and patch reefs with often strongly fragmented coral rubble are generally found in association with mud volcanoes below a (hemi-) pelagic sediment cover. Cold-water corals have been known since the eighteenth century but the development of new technologies has resulted in the discovery of huge cold-water coral ecosystems and carbonate mounds during the last few decades. Their widespread occurrence presents a challenge to understand their development, preservation and possible importance in the geologic record. In modern oceans, they provide important ecological niches for the marine benthic fauna in the deep-sea. In comparison to the macrofauna the microfauna, particularly the foraminifera associated with these systems, are poorly known. The present study focuses on the foraminiferal assemblages associated with cold-water coral ecosystems from the European continental margin. Samples were collected in three key regions: surface sediments along the Norwegian margin and in the Porcupine-Rockall region, gravity cores were taken on the top of two mud volcanoes in the Alboran Sea. Planktonic and benthic foraminiferal assemblages were quantitatively analyzed. Since patterns of community structures are often not readily apparent, hierarchical cluster analysis, multidimensional scaling (nMDS), and diversity analysis were applied to emphasize differences in the foraminiferal assemblages. Planktonic foraminiferal assemblages provide information about the conditions in surface waters. The assemblage of planktonic foraminifera in the coral-rich layer of two sediment cores in the Alboran Sea and in surface sediments from the Norwegian margin indicate similar conditions in the uppermost waters of both regions: nutrient-rich with enhanced phytoplankton blooms. At the transition from the coral-rich layer to the overlying (hemi-)pelagic sediments in the Alboran Sea a main shift in the planktonic foraminiferal assemblage indicate a reorganization of water masses towards more oligotrophic conditions. Low food availability could be the main reason for the decline of the cold-water coral reefs in this area. The benthic foraminiferal assemblages in the Porcupine/ Rockall region on the Irish margin are strictly related to the distribution of different sedimentary facies. On the Norwegian margin, benthic foraminiferal assemblages show a clear separation of cold-water coral reef associated fauna and off-reef associated fauna. However, different assemblages for each facies are only weakly defined and grade one into the other preventing a strict facies attribution as that observed along the Irish margin. The benthic assemblages from coral-rich layers in the Alboran Sea and those from cold-water coral reefs associated to carbonate mounds in the Porcupine/Rockall and cold-water coral reefs along the Norwegian margin also show remarkable similarities. In particular, the assemblages are dominated by epifaunal-attached species such as Discanomalina coronata, Cibicides refulgens, and Lobatula lobatula but also infaunal foraminifera such as Globocassidulina spp., Epistominella spp., Cassidulina spp. are highly abundant. The benthic fauna provide information on currents, oxygenation and organic matter content. In particular, the benthic fauna associated with cold-water coral ecosystems indicates an environment characterized by high energy, well oxygenated waters and high organic matter supply derived from phytoplankton blooms and reaching the sea floor. In the investigated areas D. coronata is restricted to living cold-water coral reefs facies only and/or in co-occurrence with coral fragments. Based on these observations D. coronata is interpreted to require similar ecological conditions to cold-water corals and, therefore, proposed as an indicator species for healthy cold-water coral ecosystems on the European continental margin. In conclusion, our data suggest that although cold-water coral ecosystems occur at different latitudes, the associated foraminiferal assemblages are consistent from Norway to the Western Mediterranean. Thus they can be used to identify these ecosystems even in the geologic record, when the corals are often strongly dissolved like in the Alboran Sea.

The understanding of the paleoenvironment during initiation and early development of deep cold-water coral carbonate mounds in the NE Atlantic is currently a focus of international research. The Integrated Ocean Drilling Program (IODP) Expedition 307 drilled the 155 m high Challenger Mound in the Porcupine Seabight (SW off Ireland) in order to investigate for the first time sediments from the base of a giant carbonate mound. In this study we focus in high resolution on 12 m of sediments from Site 1317 encompassing the mound base. The mound initiation and start-up phase coincide with the intensification of the Northern Hemisphere Glaciation (INHG) at around 2.7 Ma. Further carbonate mound development seems to be strongly dependent on rapid changes in paleoceanographic and climatic conditions at the Pliocene-Pleistocene boundary, especially characterized and caused by the interaction of intermediate water masses, the Mediterranean Outflow Water (MOW), the Eastern North Atlantic Water (ENAW) and the influence of Southern Component Water (SCW).This study is based on well-established proxies such as delta O-18 and delta C-13 of planktonic (Globigerina bulloides) and benthic foraminifera (Fontbotia wuellerstorfi, Discanomalina coronata, Lobatula lobatula, Lobatula antarctica, and Planulina ariminensis) as well as grain size parameters to identify the paleoenvironmental and paleoecological setting favourable for the initial coral colonization on the mound. Stable oxygen and carbon isotope records of benthic foraminiferal species indicate that L lobatula provides a reliable isotopic signature for paleoenvironmental reconstructions. In particular, delta O-18 values of L lobatula indicate that initial mound growth started in a glacial mode with moderate excursions in delta O-18 values. Carbon isotope values of D. coronata are significantly offset compared to other epibenthic species. This offset may be related to vital effects. Bottom water temperatures, calculated using standard equations based on delta O-18 of foraminiferal tests, range between 7 and 11 degrees C. consistent with the known temperature range conducive for cold-water coral growth and development.Bottom currents transporting intermediate water masses of southern origin (Mediterranean and Bay of Biscay) enhanced at 2.6 Ma supporting first coral settlements with the INHG. The benthic delta C-13 and the sortable silt records indicate that the early Pleistocene hydrodynamic regime was characterized by weaker current intensities associated with vertical movements of MOW or its replacement by SCW at intermediate depth. After these sluggish phases enhanced MOW flow dominated again and led to stronger current intensities and most probably sediment erosion on Challenger Mound. Erosion in combination with early diagenetic (oxidation) processes overprinted the sediment layers as indicated by dissolved coral skeletons, the increase in Ca-content and sediment density, minimum delta C-13(planktonic) values, as well as the occurrence of gypsum and pyrite, implying a careful evaluation of original and overprinted geochemical signals. We conclude that the Challenger Mound development was already influenced by short-term variability of water masses from southern origin and possible erosional events comparable to the late Pleistocene setting. (C) 2010 Elsevier B.V. All rights reserved.

Cold-water coral ecosystems dominated by the species Lophelia pertusa and Madrepora oculata, as well as cold-water coral carbonate mounds (fossils and/or active) occur worldwide and are especially developed along the European margin, from northern Norway to the Gulf of Cadiz and into the Alboran Sea. Their discovery is a major achievement of the last few decades and their widespread occurrence presents a challenge to understand their development, preservation and possible importance in the geologic record. On the Norwegian shelf active/living reefs are developed on elevated hard substrata. Along the Irish margin L. pertusa builds large fossil and/or active carbonate mounds. In the Gulf of Cadiz and in the Alboran Sea buried reefs and patch reefs are generally found in association with mud volcanoes. In modern oceans, they provide important ecological niches for the marine benthic fauna in the deep-sea. In comparison to the macrofauna the microfauna, particularly the foraminifera associated to these systems, are poorly known. We present here a detailed study based on quantitative analyses of benthic and planktonic foraminifera together with the statistical treatment of assemblage data collected along the Norwegian margin, in the Porcupine-Rockall region and in the Alboran Sea. The three regions were and/or are site of cold-water coral ecosystems settlements. Our study reveals that in the Porcupine/Rockall region benthic foraminiferal assemblages are strictly related to the distribution of facies. On the Norwegian margin, benthic foraminiferal habitats are weakly defined and grade one into the other preventing the sharp facies separation observed along the Irish margin (Margreth et al., 2009). In the Alboran Sea cold-water coral ecosystems and cold-water carbonate mounds are presently buried and corals are generally fragmented. However, benthic assemblages from coral-rich layers in the Alboran Sea and those from Porcupine/Rockall and Norway show remarkable similarities. In particular, epifaunal-attached species such as Discanomalina coronata, Cibicides refulgens, and Lobatula lobatula dominate the assemblages with D. coronata restricted to living cold-water coral reefs facies only and/or in co-occurrence with coral fragments. In conclusion, our data suggest that although cold-water coral ecosystems occur at different latitudes, the associated foraminiferal assemblages are consistent from Norway to the Western Mediterranean. Thus they can be used to identify these ecosystems even in the geologic record, when the corals are often strongly dissolved like in the Alboran Sea.

Cold-water coral ecosystems building cold-water carbonate mounds occur worldwide and are especially developed along the European margin, from northern Norway to the Gulf of Cadiz. A remarkable mound province is documented southwest of Ireland along the Porcupine and Rockall Banks. In this area carbonate mounds are formed in water depths between 500 and 1200m and are often densely settled by cold-water coral ecosystems offering many ecological niches for benthic foraminifera. We investigated total (unstained) benthic foraminiferal assemblages from surface sediments (0–1cm, >63μm size fraction) of this region with the aim to trace their distribution patterns and to test if they can be used as bioindicators for facies characterization in different parts of carbonate mound systems. Our quantitative data were further statistically treated with non-metric multidimensional scaling (nMDS) based on Bray–Curtis similarity matrix to highlight community patterns that were not readily apparent. Our results indicate that different benthic foraminiferal assemblages characterize different facies along cold-water carbonate mounds and are related to the environmental conditions and available substrates. The following facies can be described: (1) the Off-Mound Facies is dominated by uvigerinids and other infaunal species; (2) the Dropstone Facies is characterized by infaunal Globocassidulina subglobosa and attached-epifaunal Cibicidoides sp.; (3) the Dead Coral Facies is characterised by epifaunal species (e.g., Planulina ariminensis, Hanzawaia boueana) and infaunal species (Spiroplectinella wrightii, Angulogerina angulosa, Epistominella vitrea); (4) the Living Coral Facies includes both infaunal and epifaunal species, but is dominated by the epifaunal Discanomalina coronata; and (5) the Sandwave Facies contains high abundances of epifaunal species including D. coronata. Based on this distribution, we propose D. coronata, as an indicator species to identify active mounds and/or living cold-water coral ecosystems. Our results also emphasise the importance of studying the small size fractions that yield many infaunal species. A causal link exists between distribution patterns of benthic foraminifera and cold-water coral facies, thus providing an independent tool to identify and describe the different facies in this setting.