Norwegian Basin Research Articles

Water-mass formation and distribution in the Nordic Seas during the 1990s

AbstractHydrographic, oxygen and nutrient data collected in the Nordic Seas during the 1990s are presented. During the decade, deep waters originating from the Arctic Ocean, identified by salinities in excess of 34.9, spread into the Greenland Basin. In 1991, these waters extended westward from the mid-ocean ridge to about 2°E. This process continued over time and by 1993 there was a layer with salinities above 34.9 along the entire section, between 7.6°W and the Barents Sea Slope, and probably across the whole basin. In 2000 the basin had these high salinities at depths greater than 1400 m. At 1500 m in the central basin the salinity increase during the decade was 0.012 units, decreasing to 0.006 at 3000 m, and associated temperatures increased by 0.28 and 0.09°C, respectively. This warming more than compensated for the salinity increase so that the density of the deep water decreased during the decade, σ3 decreasing by 0.027 kg m−3 at 1500 m and by 0.006 kg m−3 at 3000 m. Decreasing oxygen content and increasing concentrations of silicate further indicated the increasing influence of Arctic Ocean Deep Water. Interaction with the atmosphere is decisive for the conditions in the area. In the central Greenland Sea there is close correlation between wind forcing and upper-layer salinity. Significant deep-water formation occurs only during cold winters, or rather, in periods with several succeeding cold winters and the 1960s were the first period in which these conditions occurred since 1920. This is shown by meteorological observations at Jan Mayen since 1921, and at Stykkisholmur, Iceland, since 1823. Relatively high salinities were observed near the bottom over the Iceland Plateau. These waters seem to be derived from Arctic Ocean deep waters that have been diverted from the East Greenland Current, into the East Icelandic Current. While flowing through the Iceland Sea their nutrient concentration increases considerably. This water flows into the Norwegian Basin where it forms a slight salinity maximum around 1500 m, which is associated with a minimum in oxygen content. At greater depths the water masses are from the Greenland Sea. The salinity decreases and the oxygen increases toward approximately 2500 m, from where the trends are reversed toward a slight salinity maximum around 3000 m, where there also is a minimum in oxygen as well as in CFC-11. These characteristics seem to derive from Arctic Ocean Deep Water, floating above waters more characterized by Greenland Sea Bottom water nearest to the bottom as suggested by decreasing salinity and an increase in both oxygen and CFC-11 concentration. This shows that even the very homogeneous Norwegian Sea Deep Water is stratified. There are also slight differences between the deep waters of the basins in the Norwegian Sea. In the Norwegian Basin the deep water has slightly higher salinity, lower dissolved oxygen and higher silicates than the deep water in the Lofoten Basin, and even more so compared with the area west of Bear Island. This shows that the Lofoten Basin and the northern Norwegian Sea are more directly influenced by waters from the Greenland Sea than the Norwegian Basin.

Testing ocean tide models in the Nordic seas with tidal gravity observations

SUMMARY Tidal gravity observations at Ny-Alesund on Spitzbergen, made with a LaCoste & Romberg gravimeter with electrostatic feedback, have been used to assess the accuracy of ocean tide models in the Nordic seas. Eight ocean tide models have been used to compute the ocean tide loading at Ny-Alesund. The station is very close to the coast and therefore experiences a significant direct gravitational attraction of the nearby tidal water mass. For the bay adjacent to the station, the model values have been replaced by the tide gauge values and a special effort has been made to fit the models correctly to the coastline. The ocean tide models for M2 and O1 have also been compared with observations made over 30 years ago at Longyearbyen, Spitzbergen, with Askania gravimeters. The comparisons of the tidal gravity observations with computed ocean tide loading show that for the harmonic M2 the phase lag of the ocean tide model of Schwiderski and the local tide model of Gjevik et al. are wrong by +15 ◦ and −5 ◦ in the Norwegian Basin. For the harmonic S2, the models FES94.1, GOT00.2 and Schwiderski give a poor fit to the observed tidal loading at Ny-Alesund because of phase lags that are too large in the Norwegian Basin by ∼10 ◦ . FES94.1 and GOT00.2 also have S2 amplitudes that are ∼5 cm too large in the Norwegian Basin. For N2, FES94.1, FES95.2, GOT00.2 and Schwiderski have phase lags that are ∼10 ◦ too large in the Norwegian Basin and FES94.1 and 95.2 also have N2 amplitudes that are 2‐4 cm too large in that region. Overall, for these three harmonics the global model FES99 gives the best fit to the tidal gravity observations at Ny-Alesund and this agreement is even closer than that obtained using regional Arctic Ocean tide models.

Year-to-year variability of the long-range propagation conditions in the Norwegian Sea

On the basis of the experimental data on the sound field formation in the Norwegian Sea, the year-to-year variability of the propagation conditions is estimated. A comparative analysis is performed for the data obtained from two long-range-propagation experiments with explosion-generated signals. The experiments were carried out in summertime (August) on a path crossing the central deep-water part of the Norwegian Sea and were separated in time by a period of four years. Noticeable changes are found to occur in the sound speed fields between the two experiments. These changes are related to a change in the distance between the cores of cold waters (observed in the region of the Norwegian Basin) and warm waters (observed in the region of the Lofoten Basin). According to calculations, the observed changes in the sound speed structure can lead to considerable changes in the propagation anomaly and in the range dependence of the sound field decay. In spite of the noticeable difference in the propagation conditions, the experimental coefficients of low-frequency attenuation differ little for the two experiments.

Late Weichselian depositional processes, fluxes, and sediment volumes on the margins of the Norwegian Sea (62–75°N)

Quaternary continental margin sedimentation in the Norwegian–Greenland Sea has been a response to a combination of tectonic, oceanographic, and glacial activity. Using geophysical survey data (6.5 kHz side-scan sonar and 3.5 kHz penetration echo sounding), in association with bathymetric datasets, the magnitude and frequency of the main forms of margin sedimentation into the Lofoten and Norwegian Basins of the Norwegian Sea during the Late Weichselian and Holocene are estimated. By comparing these geophysically determined estimates of sediment fluxes with numerically modelled ice-sheet sediment delivery, the role of ice-sheets in shaping the processes acting on this margin is assessed. Sediment flux at the shelf edge during the Late Quaternary is dominated by ice-sheet delivery of sediments, focused at the mouths of fast-flowing ice streams formed in bathymetric troughs. Interglacials are, by contrast, characterised by comparatively little sediment accumulation. Submarine fans, at the margins of cross-shelf troughs, are major depocentres on this glacier-influenced margin. However, occasional large-scale failures of the continental slope account for approximately 75% of the basin sediment accumulation during the past 30 000 yr, by eroding substantial quantities of pre-Quaternary deposits. Trough mouth fan and a combination of hemipelagic and glacimarine processes are responsible for the accumulation of the remaining 15% and 7% of basin sediments, respectively.

Possibilities and constraints in the management of the Glomma and Lägen river basin in Norway.

The Glomma-Lagen (G-L) basin is used to analyse the main institutional mechanisms and roles in the present Norwegian river basin operation and management, as well as the development of the conceptual framework for water resource management of large river basins. The main possibilities and constraints of the current river management system is also presented in view of the river basin boarders system proposed in the EU Water-Directive. We will focus especially on important G-L basin management issues such as flood control, fish mitigation and water pollution, to reveal the dilemmas of the current system in accordance to the EU Water-Directive. The most important challenges for a more holistic management of the G-L basin will be to analyse policy development and options, to integrate river basin stakeholder interest and to find long term sustainable solutions accepted by all main stakeholder groups. The achievement will be reduced stakeholder conflicts and a possibility to implement more cost effective flood control, water pollution control and fish mitigation measures. The structures, functions and quality of natural ecosystems will hence improve, and the public interest and the recreational use of the G-L river basin will increase. The development and implementation of a separate River Basin Plan will be a key tool within a more holistic basin management approach. The main constraints include the fragmented structure of the Norwegian 3 level public authority system and the corresponding legislation. A review of the river basin management system and the legislative framework is necessary to increase efficiency, identify cost effective measures, and secure the production of ecosystem products and services, and to comply with the EU Water-Directive.

Radiolarian faunal provinces in surface sediments of the Greenland, Iceland and Norwegian (GIN) Seas

The overall abundance and species composition of the polycystine and phaeodarian radiolaria have been determined in 63 surface sediment samples from the GIN Seas. These results are compared to chemical and physical properties of the overlying water masses. There are three abundance maxima in the distribution of radiolarian skeletal debris preserved in these surface sediments, centered on the Iceland Plateau, southern Norwegian Basin and northern Norwegian Basin. The most commonly encountered species were: (a) Spumellarida — Actinomma boreale, A. leptoderma, Larcospira minor, and Phorticium clevei, (b) Nassellarida — Amphimelissa setosa, Artobotrys boreale, Lithomelissa setosa, Lithocampe platycephala, Pseudodictyophimus gracilipes, Cycladophora davisiana, and Lithomitra lineata. Based on factor analysis of the core-top assemblages, the radiolarian species were grouped into three associations: Factor 1 —a polar- and arctic water association dominated by Amphimelissa setosa (varimax factor score 5.269), high factor component values are found in the Iceland Plateau area and in a wedge just north of the Iceland–Faeroe Ridge; Factor 2 —an Atlantic water association dominated by Pseudodictyophimus gracilipes (3.247), Lithomelissa setosa (2.731), and Actinomma boreale (1.851), high factor component values are found in the eastern part of the Norwegian Sea, particularly in the area under the influence of the Norwegian Current; and Factor 3 —an Atlantic and arctic water mixed association dominated by Lithocampe platycephala (3.251), Lithomelissa setosa (−2.176), Actinomma leptoderma (1.994) and Artobotrys boreale (1.504), high factor component values are found immediately to the east of the Iceland Plateau in correspondence to the deepest part of the Norwegian Basin. The correlation coefficients obtained between seasonal sea surface temperature and Factors 1 ( R 2=0.835), and 2 ( R 2=0.891) show a good fit, whilst for Factor 3 there was a less marked ( R 2=0.497), but still significant at the 5% confidence level, correlation for fifth-degree polynomial regression functions. The factors correlated better with the summer than the winter sea surface temperatures. However, at 20, 50, 100 and 200 m depth, the correlation became increasingly better, particularly so for the winter situation. The highest species richness for polycystine radiolarians (>28 species) was found in the warm Atlantic domain, the lowest (<24 species) was found in the colder arctic and polar domains, whilst an area approximating the position of the Arctic front had between 24 and 28 species.

Carbon time series in the Norwegian sea

Depth profiles of carbon parameters were obtained monthly from 1991 to 1994 as the first time series from the weathership station M located in the Norwegian Sea at 66°N 2°E. CO 2 was extracted from acidified seawater by a flushing procedure, with nitrogen as the carrier gas. The pure CO 2 gas was measured using a manometric technique, and the gas was further used for 13C and 14C measurements. The precision of the dissolved inorganic carbon (DIC) was better than ±6‰. Satisfactory agreement was obtained with standard seawater from Scripps Institution of Oceanography. The partial pressure of CO 2 (pCO 2) was measured in the atmosphere and surface water, beginning in October 1991. The most visible seasonal variation in DIC, 13C and pCO 2 was due to the plankton bloom in the upper 50–100 m. Typical values for surface water in the winter were: 2.140±0.012 mmol kg -1 for DIC, 1.00±0.04‰ for δ 13 C and 357±15 μatm for pCO 2, and the corresponding values in the summer were as low as 2.04 mmol kg -1, greater than 2.1‰, and as low as 270–300 μatm. The values for deep water are more constant during the year, with DIC values of about 2.17±0.01 mmol kg -1, and δ 13 C values between 0.97 and 1.14‰. A simple one-dimensional biological model was applied in order to investigate possible short-term variability in DIC caused by the phytoplankton growth and depth variations of the wind-mixed layer. The simulated seasonal pattern was in reasonable agreement with the observed data, but there were significant temporal variations with shorter time interval than the monthly measurements. As a supplement to the measurements at station M, some representative profiles of DIC, δ 13 C , Δ 14C, salinity and temperature from other locations in the Nordic Seas and the North Atlantic Ocean are also presented. The results are also compared with some data obtained ( Δ 14 C ) by the TTO expedition in 1981 and the GEOSECS expedition in 1972. The carbon profiles reflect the stable deep water in the Greenland and Norwegian Basins, and the relatively young bottom water just south of Iceland.

Tritium distributions in an isopycnic model of the North Atlantic

An ocean general circulation model with an isopycnic coordinate in the vertical is used to simulate the North Atlantic circulation. Tritium and helium are injected into the model after an initial spin‐up phase to assist our understanding of the model response and to validate the model itself by comparing the model data with available tracer observations. In this paper, the distribution of tritium is presented and compared with observations in 1972 (Geochemical Ocean Sections Study) and 1981 (Transient Tracers in the Ocean (TTO)). The vertical penetration of tritium in the model compares well with observations, reflecting the ventilation patterns in the subtropical and subpolar gyres and the deep overflows from the Greenland and Norwegian basin through the Denmark Strait and across the Iceland‐Faeroes rise. However, the distributions of tritium on various isopycnic layers do show discrepancies with observations, and the magnitude of tritium concentration is too high in the model. It is found that the model produces a pronounced maximum tritium concentration in the interior of the North Atlantic subtropical gyre in 1972, which is not observed. The presence of this maximum suggests that the ratio of diffusion to advection timescales (the Péclet number) is too high in the model. A simple two‐dimensional advection‐diffusion model is used to explore the relationships between the distributions of tritium and the timescales of advection and diffusion processes. These experiments suggest an upper bound on the Péclet number. A further experiment using the Atlantic isopycnic model with a decreased Péclet number shows some improvement to the distribution of tritium on the isopycnic layers. Comparisons of tritium‐helium age in 1981 between the model results and TTO data show that the model has a too rapid circulation. The lack of mixing by eddies in the model is also believed to be partially responsible for the discrepancies between the modeled tritium distributions and the observations. The good correspondence between our tritium simulation with the Atlantic isopycnic model and observations leads us to believe that the model captures the major pathways of deep ocean circulation in the North Atlantic. The model should be useful for other tracer sequestration studies. Combining models of varying complexity has proved useful in identifying and (partially) correcting deficiencies in the model and will be used in future tracer studies.

An Isopycnic Model Study of the North Atlantic. Part I: Model Experiment

This paper describes a 30-yr spinup experiment of the North Atlantic Ocean with the Miami isopycnic-coordinate ocean model, which, when compared with previous experiments, possesses improved horizontal resolution, surface forcing functions, and bathymetry, and is extended to higher latitudes. Overall, there is a conversion of lighter to heavier water masses, and waters of densities 1027.95 and 1028.05 kg m−3 are produced in the Greenland-lceland Norwegian basin, and of density 1027.75 kg m−3 in the Labrador and Irminger basins. These water masses flow primarily southward. The main purpose of this present study, however, is to investigate the ventilation of the subtropical gyre. The role of Ekman pumping and lateral induction in driving the subduction process is examined and the relative importance of the latter is confirmed. The paper also illustrates how the mixed layer waters are drawn southward and westward into the ocean interior in a continuous spectrum of mode waters with densities ranging between 1026.40 and 1027.30 kg m−3. These are organized into a regular fashion by the model from a relatively disorganized initial state. The evolution of the model gyre during spinup is governed by mixed layer cooling in the central North Atlantic, which causes the ventilation patterns to move southwestward, the layers to rise, and surprisingly, to become warmer. This warming is explained by thermodynamic considerations. Finally, it is shown that the rate of change of potential vorticity following a fluid pathway in the subtropical gyre is governed by the diffusion of layer thickness, which represents subgrid-scale mixing processes in the model. This leads to increasing potential vorticity along pathways that ventilate from the thickest outcrop regions as fluid is diffused laterally and to decreasing potential vorticity along neighboring trajectories.

A wide-angle reflection profile across the Iceland-Faeroe Ridge

Abstract A wide-angle reflection profiling (WARP) survey was carried out in July 1993 across the Iceland-Faeroe Ridge in the North Atlantic. Sleeve guns were employed as energy source and ocean bottom seismometers (OBS) used to observe the seismic energy. Results of the first evaluation show that the crust below the Iceland-Faeroe Ridge is stretched continental, with an average thickness of 23 km at its central part. Towards the NE end of the profile, the transition to oceanic crust of the Norwegian Basin has been identified. The upper crust has P -wave velocity ( V p ) values which range between 5.8 and 6.3 km/s, while the lower crust is more homogeneous with V p values between 6.7 and 7.0 km/s. The upper crust, excluding sediments and volcanics, is about 6 km thick at the crest of the ridge and thins with increasing water depths to the northeast and southwest. The lower crust can be separated from the upper part by a first order discontinuity, a P i P reflector, that has been identified in several travel-time sections. P -wave velocities below the Moho have values of approximately 7.9 km/s.

EARLY HOLOCENE DIATOM PULSE IN THE NORWEGIAN SEA AND ITS PALEOCEANOGRAPHIC SIGNIFICANCE

A time synchronous mass abundance of sedimented marine planktonic diatom valves occurs in four cores from the western slopes of the Norwegian Basin and from the extinct Aegir Ridge in the middle of the Norwegian Basin. This mass abundance occurs shortly after the Saksunarvatn ash layer (9,000 to 9,100 y B.P.). Contrary to previous investigations we interpret the diatom pulse to represent a time synchronous event in the wider Norwegian Sea that has no direct relationship to a polar front movement but is related to “unique” oceanographic conditions favoring immense diatom production in the photic zone leading to the deposition of a sediment rich in diatom valves. The “unique” oceanographic condition may be related to a “switch on” of the Broecker conveyor belt coupled with an influx of surface and subsurface Atlantic waters rich in dissolved nutrients. Other Late Pleistocene and Holocene diatom peak abundances from the Skagerrak, from the Norwegian continental margin, from the western Barents Sea slope and ...

The morphology of deep-sea Thyasiridae (Mollusca: Bivalvia) from the Atlantic Ocean

Twenty-five species and three subspecies of the family Thyasiridae (Bivalvia: Lucinacea) are described from the deep Atlantic. They belong to two genera and five subgenera. Eleven of the species and all of the subspecies are described for the first time. The number of demibranchs in the gill and shape of the lobes of the lateral body pouches are characteristic features which are additionally used to clarify taxonomic divisions that have been previously based on shell features alone. One species,Axinus grandisVerrill &amp; Bush (1898), is thought to be the sole living representative of the predominantly Tertiary fossil genusAxinusSowerby (1821). This genus has been regarded by most previous authors as a synonym ofThyasiraLeach (1818).Axinus grandis, as here defined, is morphologically distinct from all other thyasirids and possesses primitive characters. It shows affinities to the lucinacean family Ungulinidae, suggesting that the Thyasiridae may have an origin close to the ungulinid stem. The morphology of the species described here is extremely conservative, all sharing a number of key features. The most important of these is the form of the lateral body pouches. Shell shape and morphology relate in part to different life habits. Some species which have vertically elongate shape are probably immobile deep-burrowers, while others, principally the smallest species, which are horizontally elongate are adapted for a more active existence. All are infaunal. The deep-water species are thought to be pre-adapted to life at depth through their ability to inhabit impoverished deoxygenated habitats. Few morphological differences could be detected between the populations of species that occur in both shallow and deep waters. The small size of all but a few species may be one of their greatest adaptive features. The greatest reduction in size and greatest simplification of morphology are seen in species of the subgeneraThyasiraandParathyasira. The subgeneraAxinulusandMendiculashow the greatest radiation in deep water. The latter subgenera are thought to have arisen from the larger subgenera by neoteny. The thyasirids, unlike the deep-sea protobranch and septibranch bivalves, are predominantly inhabitants of slope depths. Very few are truly abyssal. Many have very wide depth distributions extending from shelf to abyssal depths. This, together with the production of planktotrophic larvae, has ensured that most thyasirid species, unlike other deep-sea bivalves, are very widely distributed. Thus species extend into Arctic waters, including the Norwegian Basin and into the Pacific and are truly cosmopolitan.

Correlation of paleogene dinoflagellate assemblages to standard nannofossil zonation in North Atlantic DSDP sites

Abundant and diverse dinoflagellate assemblages characterized Palaeogene sections in eightten DSDP coreholes from the North Atlantic Oceans basins. Zonation of the coreholes (located in the Gulf of Mexico, Sohm Abyssal Plain, Newfoundland Basin, Rockall Plateau and Norwegian Basin) has been almost exclusively on planktonic foraminifera and nannoplankton. The following zones contain diagnostic dinoflagellate assemblages: nannoplankton zones NP 9–11, NP 12, NP 13, NP 16–17, NP 19/20, NP 24 and NP 25. Preliminary occurrence data for more than fifty species of dinflagellates aer presented for these NP zones. Our goal is to produce a dinoflagellate zonation comparable in precision to the two standard planktonic microfossil zonations, allowing correlation across the entire spectrum of marine environments using a single group of microfossils.

Surface sediment diatom distribution and Holocene paleotemperature variations in the Greenland, Iceland and Norwegian Sea

One hundred and four surface sediment samples and two piston cores from the Greenland, Iceland and the Norwegian (GIN) Sea (Hopkins, 1988) were analyzed. Diatoms were common to abundant in most surface sediment samples and throughout the Holocene. Q mode factor analysis allowed the definition of six significantly different floral assemblages which explained 91.7% of the total variance. Mapping of the six factors showed their close affinity to hydrographic regimes. These are the Norwegian‐Atlantic Current assemblage (Thalassionema nitzschioides, Paralia sulcata, Proboscia alata), Arctic Water assemblage (Thalassiosira gravidaspores), Sea Ice assemblage (Nitzschia grunowii, Nitzschia cylindra, Thalassiosira hyalina), Arctic‐Norwegian Waters Mixing assemblage (Rhizosolenia hebetata f. semispina, Rhizosolenia borealis), Atlantic assemblage (Thalassiosira oestrupii), and Norwegian‐Arctic Waters Mixing assemblage (Thalassiosira gravidavegetative cells). Transfer functions (GINT2) relating factor distributions to winter (February) and summer (August) surface water temperatures were generated. The transfer functions have a standard error of estimate of ±1.5°C (August) and ±1.0°C (February). Downcore studies of core 52–43 from the Norwegian Basin and core 57–5 from the Iceland Plateau revealed diatom abundance and sea surface paleotemperature trends in the area during the Holocene. The first appearance of diatoms in cores 52–43 and 57–5 occurs within the Vedde ash layer (10,600 years B.P.) and the Saksunarvatn ash layer (9100 years B.P.), respectively. Diatom abundances increase steadily throughout the Pre‐Boreal‐Atlantic time to 25 and 35 million valves per gram dry sediment in the Norwegian Basin and Iceland Plateau cores, respectively. Application of the temperature transfer functions (GINT2) to the two Holocene records revealed higher than present sea surface temperatures during the Boreal‐Atlantic chronozones for the Iceland Plateau and during the middle Younger Dryas‐Sub Boreal chronozones for the Norwegian Basin core. Temperatures decreased steadily since then with a slight increase to the present values. Both the Iceland and the Norwegian seas experienced a strong influx of temperate Atlantic surface waters in the beginning of the Holocene. Sea surface temperatures dropped steadily in the latter part of the Holocene as the influx of the Atlantic surface waters diminished.

Sound velocity, density, and related properties along a transect across the Bay of Bengal

Physical properties, sound velocity and density of 95 core samples from ten locations along a transect (parallel to 15°N latitude) across the Bay of Bengal were measured. Results indicate that sound velocities range from 1,482 to 1,679 m/s (av: 1,583 m/s) and densities from 1,338 to 1,757 kg/m3 (av: 1,527 kg/m3). It has been observed that dark colored clays and sandy clays show higher values of sound velocity and density than the average values. A comparative study of the same with that of the sediment cores collected from the Norwegian basin, Mediterranean Sea, and Hatteras, Nares Abyssal plains, western North Atlantic Ocean was done.

A multicalorimeter for the study of biological activity in marine sediments

A multicalorimeter is described which allows the measurement of heat production of up to 10 sediment samples simultaneously. System regulation a s well as data processing and evaluation are performed by personal computer. The instrument performs well even a t non-controlled room temperature down to -0.5C on board a research vessel. First results from tests employing pressure chambers are presented. An example for a deep-sea heat-production proflle 1s given from the Norwegian Basin, depichng subsurface maxlma in benthic activity. Direct microcalorimetry has been widely used in biological sciences (Wadso 1975, Ljungholm et al. 1980, Gnaiger 1983, Lock & Ford 1985). In biological oceanography the technique has been used for the investigation of anaerobic metabolism of benthic invertebrates (Pamatmat 1978, Famme & Knudsen 1983, Shick 1981, Hammen 1983) and of soft bottom community metabolism (Pamatmat 1982). The method measures simultaneously all types of metabolism in a community; thus the rate of heat loss is enthalpy change and the last step of energy flow through the system. The combustion value of metabolized organic matter is equivalent to the released heat. The method has been used to calculate carbon budgets (Graf et al. 1982, 1983). Recently, the reliability of these budgets was demonstrated by direct calorimetry of a predominantly anaerobic sediment (Graf 1987). By comparison, oxygen consumption, also called indirect calorimetry, only accounted for the topmost few milhmeters of sediment activity and greatly underestimated the amount of metabolized organic matter in the lower layers. Most calorimeters used are of the heat conduction type. These work isothermically and need long equilibration times (Calvet 1956), making direct calorimetry Q Inter-Research/Pnnted In F. R. Germanv a relatively slow method. To overcome this problem, it is desirable to increase the number of devices in use simultaneously. An example is given by the Pamatmat double twin calorimeter (Pamatmat 1978). In the present article we present a multicalorimeter which can measure 10 samples simultaneously, thus enabling the measurement of a sediment heat flow profile in one run. Other features of the instrument for calorimetry of sediments have been improved. The multicalorimeter works at low temperature on board shlp and accomodates larger samples than commercially available instruments. Furthermore the chambers can be compressed to simulate in situ pressure up to 310 bar. Description of the instrument. The calorimeter block is placed inside a PVC-covered aluminium container (90 cm diameter) and fixed inside a well-insulated constant-temperature bath (Fig. 1). The aluminium container is completely submersed exept for PVC shafts through which samples are inserted into the instrument. Temperature is regulated by an external cooler (Braun, Frigomix 1497 and Thermomix 1480E), which is connected to a copper coil surroundng the container, and an internal heater (Braun Thermomix, 1480E), creating a accuracy of & 0.005 Co. A mixer increases turbulence in the water bath. It is possible to run the instrument at -0.5 C at unregulated ambient room temperature. The calorimeter block is constructed from about 200 kg of aluminium and has the shape of a 10-armed star (Fig. 2). Fig. 3 shows 2 sections of this construction. The left side depicts a tangential section through 2 arms including the PVC shaft for sample insertion and removal (8). The left arm holds a V4A-steel chamber (6 cm external diameter) containing the sediment sam202 Mar. Ecol. Prog. Ser. 45: 201-204. 1988 Fig. 1. Temperature-regulating scheme of the m~~lticalorimeter External cooler (1) and internal heater (2) keep the calorimeter at constant temperature. Samples are introduced via the shafts (10) '0 2

Tmetonyx norbiensissp.n. andTryphosella abyssalis(Stephensen, 1925), two deep-sea lysianassids from the Norwegian sea (Crustacea, Amphipoda)

Abstract Two deep-sea species of the Lysianassidae collected in the Norwegian Basin by the French-Swedish expedition (NORBI) in 1975 are fully described. Of these, Tmetonyx norbiensis is new to science, while Tryphosella abyssalis (STEPHENSEN) has previously been found in the Norwegian Sea. In addition to these two species other North Atlantic species within the Tmetonyx-Tryphosella group have been studied at the generic level. Provisional diagnoses of Tmetonyx and Tryphosella given and discussed herein indicate distinct boundaries between the two genera with respect to the North Atlantic fauna. Two variants of the first coxal shape, a rectangular and a weakly tapering one, are manifested in Tmetonyx. The close relationship between Tmetonyx and Tryphosella is reflected in their mouthparts which, on the other hand, clearly show the difference between the two genera, and in this case features like armature and fine structures have proved to be significant. The aberrant Tmetonyx caeculus, which should be rem...

Deep-water Sipuncula from the eastern Atlantic Ocean

Abstract Over 9000 recently collected sipunculans from the deeper waters of the eastern Atlantic Ocean from 80° N to 34° S are discussed. Brief notes on their morphology and a key to the 31 species are presented. The existence of zoogeographical barriers at slope depths between the Norwegian and European Basins, within the Cape Verde Basin (a diffuse one), and between the Angolan and Cape Basins are noted. Most species (17) are very widely distributed (north of 40° N and south of 15° N). Most of those with wide latitudinal ranges also have wide vertical ranges. Two slope species occur on the shelf in upwelling areas off West Africa. These analyses are based on just these recent collections, i.e. disregarding earlier records.

Nephrospyris knutheierisp.n., an extant trissocyclid radiolarian (Polycystinea: Nassellarida) from the Norwegian-Greenland Sea

Abstract Skeletons produced by the trissocyclid Polycystinea are rare or absent in surface sediments of the boreal Atlantic and the Norwegian-Greenland Sea, and the few species that have been observed are cosmopolitan in distribution. Examination of Polycystine a in 268 sediment core tops and six plankton tows from the Norwegian-Greenland Sea indicates that a new species, Nephrospyris knutheieri, is restricted to the Icelandic Current. This species may also occupy the East Greenland Current north of Jan Mayen, where the underlying sediments are largely unfossiliferous. High salinities (≥ 35%) of the warm waters flowing north through the Shetland-Faroe Channel and the Denmark Strait may impede the eastward and southward penetration of N. knutheieri into the Norwegian Basin and Labrador Sea, respectively. The species is easily distinguishable from warm-water and Antarctic trissocyclids. There is a homeomorph in the Subarctic Province of the North Pacific, Nephrospyris ?pervia, which appears to have similar ...

Geochemical evidence of a massive slide in the southern Norwegian Sea

During the 1981 cruise of the MS Tyro to the southern Norwegian Basin several piston-cores were collected for sedimentological research. Some of these were available for geochemical study (Fig. 1). In laboratory analyses the pore water composition of one of these cores showed evidence of input of non-saline water, whereas pore water in other cores from the same Basin did not give any indication of dilution with fresh water. Careful examination of the chemical constituents of the pore water and some parameters of the sediment, gives convincing evidence for the origin of the fresh water. The presence of non-saline water can be attributed to a massive slide of a coastal fresh-to-brackish sediment ‘slab’, with preservation of structural and pore water composition. This sliding is thought to have taken place about 12,000 to 15,000 years BP.