Distribution of Calanus species in Kongsfjorden, a glacial fjord in Svalbard

The distribution of Calanus species was investigated in Kongsfjordenin summer of 1996 and 1997. In both years Calanus finmarchicusand Calanus glacialis dominated, although the boreal C. finmarchicuswas more abundant than the Arctic C. glacialis in 1997. Thiscoincided with a 2°C higher water temperature at 50 m in1997, indicating stronger influence of Atlantic origin waterthat year. Advected Calanus finmarchicus occurred in deep andsubsurface layers of the outer fjord in 1996 (200 ind. m^-3,mainly CIII). A less abundant local population aggregated insurface layers of the inner fjord (100 ind. m^-3). Similarly,advected C. finmarchicus occurred in subsurface layers in 1997(446 ind. m^-3, mainly CIII and CIV) and a local population insurface layers (183 ind. m^-3, mainly CI). Calanus glacialisin 1996 aggregated as CII and CIII in the deep layers of theouter fjord (272 ind. m^-3), whereas CIII–CV were abundant(216 ind. m^-3) in cold surface waters of the inner fjord. In1997 C. glacialis (mostly CIII–CV) was more abundant inthe outer than in the inner part of the fjord (40 and 192 ind.m^-3, respectively). Within Kongsfjorden, Calanus finmarchicusneeds one year to complete its life cycle, whereas Calanus glacialisneeds two. Calanus hyperboreus seems to be an expatriate inthe fjord system.     

Some macrofaunal effects of local pollution and glacier-induced sedimentation,with indicative chemical analyses,in the sediments of two Arctic fjords

Macrofaunal (>1 mm) and chemical sediment sampling was carried out in August 1992 close to the garbage dumping sites of the coal-mining industrialised settlements Longyearbyen (Adventfjord) and Barentsburg (Grønfjord), located in the Isfjord system, Svalbard. Six stations were sampled with respect to chemical parameters and fauna, while three stations were sampled with respect to only chemical parameters that comprised total organic carbon, total nitrogen, heavy metals (Hg, Cd, Pb, Cu), polycyclic aromatic hydrocarbons (PAH) and chlorinated hydrocarbons (5-CB, HCB, γ-HCH, DDT, PCB₇). The concentrations of PCB₇, PAH and HCB were, respectively, up to 5, 16 and 30 times higher than assumed background concentrations, presumably as a result of terrestrial water drainage of coal particles originating from local coal-stores and industrial activities in general. The faunal diversities across the sampled areas were relatively low (e.g. Shannon-Wiener indices between 2.0 and 3.2), probably mainly as a result of glacier-induced fine-particulated inorganic impacts. A relatively high faunal abundance, and a quantitative dominance of the opportunistic polychaete taxaCapitella capitata and Chaetozone/Tharyx sp. in the Adventfjord indicated an additional source of perturbation, which was related to the untreated local sewage effluents and/or drainage water from the garbage dumping sites.     

Composition of bryozoan assemblages related to depth in Svalbard fjords and sounds

Svalbard bryozoan communities were investigated along a depth range from the surface to 296 m between the inner glacial fronts and fjord mouths during 2001 and 2002. The main study area was Kongsfjorden (79°N, 12°E). A total of 137 taxa of bryozoans were identified: 108 to species, 24 to genus, 3 to family, 1 to order and 1 to phylum level. Cluster and multidimensional scaling analyses revealed four distinct assemblages of bryozoans: shallow (0–40 m; 68 taxa), deep (40–296 m; 80 taxa), inner fjordic (three taxa) and an assemblage found on small stones in shallow waters (nine taxa). The inner fjordic assemblage was recorded from the front of tidal glaciers extending about 10 km out into the fjord. In terms of abundance, Celleporella hyalina Linnaeus dominated in shallow areas (18%), Hippothoa arctica Kluge (55%) in deep water, Alcyonidium disciforme Smitt (86%) proximate to glaciers fronts and Electra arctica Borg on small stones (98%). The species were classified according to their depth range as a stenobathic-shallow (46 taxa), stenobathic-deep (57 taxa) and eurybathic-generalist (21 taxa). Mean diversity measures did not show any significant differences between the shallow and deep communities. The bryozoan assemblages seem to be structured primarily by processes related to depth and sediment characteristics.     

Vernal sedimentation trends in north Norwegian fjords: temporary anomaly in 234Th particulate fluxes related to Phaeocystis pouchetii proliferation

We report data of a naturally occurring radionuclide, ²³⁴Th, an in situ tracer, to investigate vertical export of biogenic matter during a vernal bloom of Phaeocystis pouchetii in the fjords of northern Norway. To optimise sampling of different stages of the bloom, three fjords with increasing oceanic influence (Balsfjord, Malangen fjord and Ullsfjord, respectively) were investigated in April 1997. Contrasting situations were encountered between the three fjords: the proliferation of P. pouchetii in Ullsfjord surface waters coincided with a drastic reduction of particulate ²³⁴Th fluxes in traps, although particulate organic carbon (POC) and dimethylsulphoniopropionate (DMSP) were exported and ²³⁴Th was available in surface waters. When large colonies make up a significant fraction of the vertical flux, as observed in Ullsfjord in April 1997, there may be a large and rapid change in the POC/²³⁴Th ratio, further complicating the use of ²³⁴Th as a tracer for POC export. The results suggest that the proliferation of Phaeocystis pouchetii during vernal bloom could temporary increase OC/²³⁴Th ratio of particles and delay the particulate export of ²³⁴Th, and probably of other particle-reactive species, from surface waters.     

Population dynamics and body composition of the Arctic hyperiid amphipod Themisto libellula in Svalbard fjords

Population structure, growth and body composition (wet-, dry-, ash weight and total lipid) of the Arctic pelagic amphipod Themisto libellula were studied in four fjords on West Spitsbergen, Svalbard, from July to December 2000 and in April 2002. In one of the fjords, Kongsfjorden, growth of T. libellula was calculated as the change in mean length of the 0+ cohort from July to December. The young were released from the brood pouches in early spring (March–April). Summer growth was 3.5 mm month⁻¹, whereas growth during the autumn was only 0.6 mm month⁻¹. The size frequency distributions indicated a 2–2.5 year life-span. The size structure of the population in Hornsund, the southernmost fjord on Spitsbergen, indicated a delayed time of spawning. The storage of lipids in T. libellula occurred during late summer and towards the winter, when the food items contain the maximum amount of stored lipids.     

The biodiversity of macrofaunal organisms in marine sediments

Marine sediments cover most of the ocean bottom, and the organisms that reside in these sediments therefore constitute the largest faunal assemblage on Earth in areal coverage. The biomass in these sediments is dominated by macrofauna, a grouping of invertebrate polychaetes, molluscs, crustaceans and other phyla based on size. Globally, only a small portion of marine habitats have been sampled for macrofauna, but sampled areas have led to global estimates of macrofaunal species number ranging from 500,000 to 10,000,000. Most of these species are undescribed, and global syntheses of patterns of individual taxa and biodiversity are few and based on limited samples. The significance of biodiversity in marine sediments to ecosystem processes is poorly understood, but individual species and functional groups are known to carry out activities that have global importance. Macrofaunal activity impacts global carbon, nitrogen and sulphur cycling, transport, burial and metabolism of pollutants, secondary production including commercial species, and transport of sediments. Documented extinctions of marine macrofauna are few, but the ramifications of species loss through habitat shrinkage and undocumented extinctions are unknown. Limited data suggest there is substantial functional redundancy in macrofauna within trophic groups but whether this redundancy is sufficient to allow species loss without significantly altering ecosystem processes is unknown. Sorely needed are experiments that test specific hypotheses on biodiversity, redundancy, and ecosystem processes as they relate to marine macrofauna.     

Distribution and diversity of sipunculan fauna in high Arctic fjords (west Svalbard)

Sipuncula is a relatively species poor and generally rarely investigated phylum; nonetheless, it may play a considerable role in the ecosystem. During this study sipunculan species distribution patterns in four fjords of west Spitsbergen (Kongsfjorden, Hornsund, Isfjorden and van Mijenfjorden) were examined. Material was collected during ten cruises undertaken from 1997 to 2006. A total of 381 samples were taken at 132 stations located in the four fjords and, a total number of 920 sipunculans specimens were found in 114 of those samples. The highest sipunculan species richness was observed in Hornsund (six species), followed by Kongsfjorden and Isfjorden (five species in each fjord). Sipunculan fauna in all fjords was strongly dominated by Golfingia vulgaris (80% of all sipunculan individuals in Kongsfjorden), and Golfingia margaritacea (84% in van Mijenfjorden and 40% in Hornsund) or Nephasoma diaphanes (54% in Isfjorden). Locally, sipunculans were found in high densities (max. 62 ind. 0.1 m⁻² and up to 11% of macrobenthic densities) and biomass (max. 110.87 g 0.1 m⁻² and up to 80% of total fauna biomass). At such sites, sipunculans may play an important role in bioturbation of sediments and as a food source for higher trophic levels. Sipunculans did not occur within close proximity of the glacier where they might be eliminated due to high sedimentation rate and low amounts of organic matter. Because of their importance in benthic systems, a need to include sipunculans in routine macrobenthic surveys is emphasized.     

Soft bottom species richness and diversity as a function of depth and iceberg scour in Arctic glacial Kongsfjorden (Svalbard)

Macrozoobenthic soft-sediment communities of central Arctic Kongsfjorden inhabiting six depth zones between 5 and 30 m were sampled using SCUBA-diving during June–August 2003 and analysed comparatively. About 63 taxa were found, nine of which had not been reported for Kongsfjorden and four for Svalbard. Suspension feeding or surface and sub-surface detritivorous polychaetes and deposit-feeding amphipods were dominant. Only 11 of the 63 taxa (45 species and additional 18 families not further identified) inhabited the complete depth range. Biomass ranged from 3.5 to 25.0 g ash free dry mass m⁻² and mean Shannon diversity (Log e) was 2.06. Similarity clustering from abundance and biomass data showed a significant difference between the shallow station (5 m) and the rest. The latter formed two sub-groups (10–20 and 25–30 m). Depth is irrevocably correlated with ice-scouring. Thus the differences in diversity together with the predicted iceberg scour intensity support the ‘intermediate disturbance hypothesis’ indicating that habitats impacted by moderate iceberg scouring enable higher diversity. In contrast, biotopes frequently affected only host pioneer communities, while mature, less diverse assemblages dominate depths of low impact.     

Synoptic patterns of meiofaunal and macrofaunal abundances and specific composition in littoral sediments

During recent years, many investigations on small zoobenthos have been performed at the island of Sylt. As these studies were carried out sporadically over many years and as different extraction methods were used, comparisons of the results have been hampered. Therefore, in August/September 1986, 24 sites were sampled and evaluated using one quantitative method throughout. Sites range from mud to exposed sand and from the sublittoral to the supralittoral. Macrofauna and the taxa Plathelminthes, Polychaeta, and Oligochaeta are determined to species level. Macrofaunal (>0.5 mm) abundance is highest in mud and continuously decreases with increasing exposure to wave action. Meiofaunal (<0.5 mm) abundance is less variable. Nematoda dominate in mud and muddy sand, Copepoda in sheltered and exposed sand, other taxa only intermittently. Related to surface area, no correlation between macro-and meiofaunal abundance is apparent. Plathelminthes and Copepoda reach highest abundance per surface area in sand but their per volume density is higher in mud and muddy sand. Related to sediment volume instead of surface area, the meiofaunal abundance pattern is very similar to the macrofaunal pattern. The faunal composition changes gradually along the tidal gradient without general faunal boundaries. On an averange, the faunal similarity of neighbouring sites is highest in Oligochaeta and lowest in Plathelminthes. Presumably, Oligochaeta tolerate wider ranges of environmental factors. This may explain the low number of oligochaete species. On the other hand, Plathelminthes seem to adapt to relatively narrow ranges of factors and their species richness is highest. Because of macrofaunameiofauna interaction it is suggested that the meiofaunal assemblage will be least stable in mud and muddy sand, and most stable in exposed sand.     

Patterns of carbon and nitrogen uptake during blooms of Emiliania huxleyi in two Norwegian fjords

Blooms of the coccolithophorid Emiliania huxleyi were monitoredin two land-locked fjords, Fauskangerpollen and Nordåsvannet(Western Norway), in May 1993. The chemical composition of particulatematter, size-fractionated photosynthesis, calcification, nitrogenuptake rates and the patterns of macromolecular synthesis wereexamined during the peak and decline of E.huxleyi blooms. Thetemporal evolution of the bloom in Fauskangerpollen was definedby a gradual decrease in cell abundance and cell-specific calcificationrates, and by increasing numbers of empty coccospheres and theratio detached coccoliths/living cells. A large proportion ofthe nitrogen required for microplankton growth was suppliedby aminonium and dissolved organic compounds such as urea and,as a consequence, the f-ratios were low (0.2). In general, nitrogenuptake patterns were consistent with ambient concentrationsof nitrogenous species. The photosynthetic carbon metabolismof E.huxleyi dominated phytoplankton assemblages was characterizedby high carbon allocation into lipids and relatively low carbonincorporation into protein as compared with diatom-dominatedassemblages. Consequently, the organic C/nitrogen uptake ratiodetermined stoichiometrically was significantly higher (up to10.8) when coccolithophorids were dominant than in diatom-basedor mixed-phyto-plankton assemblages. These carbon incorporationpatterns were reflected in differences in the chemical compositionof particulate matter.     

A reaction diffusion model of C-N-S-O species in some arctic sediments

Abstract A reaction diffusion model was used to simulate the mineralization processes in an Arctic sediment. The simulation and the actual sediment were compared in relation to profiles of O₂, NO₃ and NH₄⁺. The site of particulate organic matter (POM) degradation was the single most important factor in fitting the simulation profiles to those of the sediment. It was deduced that most POM degradation occurred close to the sediment surface. When a reasonably good simulation had been obtained, the sensitivity of the model to changes in other parameters was investigated. Increases in POM degradation in the upper sediment resulted in increases in concentration of NH₄⁺ and NO₃⁻, but further increases in POM degradation created anoxic conditions below 3 mm, resulting in decreases in NO₃⁻ concentrations. The model was relatively intensive to changes in POM degradation in the lower sediment layers; increases led to more anoxic conditions and to less NO₃⁻. Increases in the C/N ratio of the POM in the lower sediment layers had little effect; increases in C/N in the upper layers led to a decrease in NH₄⁺ and NO₃⁻. The model was sensitive to changes in the first order rate constant for nitrification, but not for denitrification. Decreases in the K _m for O₂ of the nitrifying bacteria had no effect on the profiles.     

The effect of wrack composition and diversity on macrofaunal assemblages in intertidal marine sediments

Wrack (dead, washed-up seaweed and seagrass) buried in soft substrata may increase the organic content and alter the physical structure of sediments. These effects may influence the composition and structure of macrofaunal assemblages in the sediment. Such influences can be expected to vary according to the type and amount of wrack as well as the presence of invasive seaweeds in the wrack. In this study, we deliberately buried different amounts of the invasive species Sargassum muticum in isolation or mixed to the native species Ulva sp. and Fucus vesiculosus, in two intertidal sandflats to test some hypotheses about the response of macrofaunal assemblages. We tested whether (1) diversity of detritus (i.e. different mixtures), and (2) the amount of detritus of S. muticum influenced the composition and the relative abundance of macrofaunal assemblages. We also assessed whether the sediment organic carbon and the biomass of benthic microalgae varied depending on the diversity of detritus and the amount of detritus of S. muticum. Finally, we tested if these effects of wrack were consistent across sites. Results indicated that buried wrack affected the composition and structure of macrofaunal assemblages in short-term (i.e. 4 weeks), but there were no differences depending on detritus diversity or the amount of S. muticum. In addition, sediment organic matter and microalgal biomass were not affected by the addition of wrack. They instead varied greatly among small spatial scales (i.e. plots). Wrack composition or abundance of the invasive species S. muticum played thus a small role in shaping the structure of macrofaunal assemblages or the biomass of benthic microalgae in these intertidal sediments, probably because these sediments are frequently affected by various inputs of organic matter and benthic assemblages are already adapted to organically enriched sediments.     

Annual growth of the cockle Clinocardium ciliatum in the Norwegian Arctic (Svalbard area)

The Svalbard Islands are influenced by warm Atlantic water in the south and west, and cold Arctic water in the east. Ice cover, and hence the location of the highly productive marginal ice zone, varies both intra and interannually. Part of the primary production accumulates on the bottom and is utilized by the benthos. In this study, the annual growth of the cockle Clinocardium ciliatum (Fabricius, 1780) from three sites in Svalbard waters is reported. Moffen, the site in the north (80° 01 N, 13° 48 E) is located in the northernmost areas influenced by Atlantic water. The Storfjorden site (77° 10 N, 20° 09 E) is situated in cold Arctic water masses, and the Bear Island site (74° 50 N, 18° 54 E) is in the Polar front area where Atlantic and Arctic water masses meet. Annual growth of cockles was analysed retrospectively by measuring external growth increments, which gave annual growth records from the 1970s to 1996. Shell height for age for different year classes was highest at the Storfjorden site, and lowest at Bear Island. Periods of high growth occurred at Storfjorden and Bear Island during the 1980s while the beginning of 1990s was characterized by low growth. At Moffen, growth was more variable between single years. Several factors are influencing the growth of C. ciliatum in the Svalbard area and growth cannot be coupled to only one environmental factor like ice cover.     

Population genetics of drifting (Calanus spp.) and resident (Acartia clausi) plankton in Norwegian fjords

Kaartvedt distinguished between drifting and resident planktonand hypothesized that the latter were distinguished by theirability to maintain their horizontal position in desired habitats(Kaartvedt, 1993). In this study, we examined the populationgenetic consequences of these two lifestyles for copepods infour fjords of western Norway (Lurefjorden, Masfjorden, Sognefjordenand Sørfjorden) and one fjord in eastern Norway (Oslofjorden).Based on DNA sequence variation of a region of mitochondrial16S rRNA, we contrasted population genetic diversity and structurein drifting populations of Calanus spp. with that of residentpopulations of Acartia clausi. With the exception of Sørfjorden(where Calanus spp. were rare), two or three species of Calanusco-occurred in significantly different proportions in the fjords.Based on a 350 base-pair region of mitochondrial 16S rRNA, Calanusspp. varied in molecular genetic diversity, with the highestvalues for C.helgolandicus. There was no evidence of significantgenetic structure of fjord populations for either C.finmarchicusor C.helgolandicus; the population structure of C.glacialiscould not be evaluated as the species was only abundant in Lurefjorden.Acartia clausi was abundant in all five fjords sampled for thisstudy. Molecular genetic diversity of A.clausi, based on a 220bp region of mt 16S rRNA, was within the range of Calanus spp.values. Populations of A.clausi showed significant genetic structure(i.e. haplotype frequencies differed markedly) among the fjords.The results of this study indicated that little exchange (geneflow) occurs between populations of A.clausi in different fjords,and suggested that the populations are long-term residents ofa fjord. In contrast, most Calanus spp. fjord populations maybe replaced periodically, as they drift with currents flowingto and from coastal and fjord environments.     

Biomarker hydrocarbons in Lower Proterozoic sediments of north Eurasia

Geochemical characteristics of Lower Proterozoic organic matter of the Baltic and Aldan shields have been studied. Particular emphasis has been placed on biomarker hydrocarbons which carry information on lipid complexes of Lower Proterozoic living organisms and their postmortem evolution.     

The macroinvertebrate communities of two contrasting Norwegian glacial rivers in relation to environmental variables

1. Macroinvertebrate communities in two Norwegian glacial rivers, one in the western fjords (Dalelva) and one in the eastern mountains (Leirungsåi), were investigated during three time periods in 1996 and 1997.
2. Channel stability variables (substratum heterogeneity/Pfankuch index/hydraulic stress) and water temperature accounted for 54% of the total inertia in the principal components analysis (PCA) ordination of environmental variables. The importance of these variables was confirmed by cluster analysis.
3. The two rivers were well separated in the ordinations, with Leirungsåi showing much greater heterogeneity. This is explained by differences in altitudinal range, terrestrial vegetation and the importance and nature of tributary inputs.
4. Channel stability and temperature were also important in determining faunal communities in the two glacial rivers, supporting the main determining variables in the conceptual model of glacial streams ( Milner & Petts, 1994 ). However, clear temporal differences were apparent in the data, the two rivers being more similar during the summer period of high discharge dominated by glacial meltwater. During spring and especially during autumn environmental conditions and the macroinvertebrate fauna differed both within and between rivers.
5. Diamesinae dominated in the upper reaches of both rivers, with Orthocladiinae becoming more common downstream. The dominance of Diamesinae persisted further down Dalelva because of the continued influence of glacial tributaries, whereas in Leirungsåi the influence of non-glacial tributaries led to a change towards a greater proportion of Orthocladiinae. Lakes modified macroinvertebrate communities in both river systems.     

Application of in situ cage cultures of phytoplankton for monitoring heavy metal pollution in two Norwegian fjords

A simple apparatus for in situ use of the cage culture technique for growing planktonic algae has been developed and used to follow growth and metal uptake of three diatoms in two Norwegian fjords polluted by heavy metals. Continuous pumping of sea water through a chelating resin and continuous water sampling was used to obtain average values for dissolved and particulate heavy metal content at the various test sites. The metals investigated (zinc, copper, lead, cadmium, and mercury) showed differences in the proportion of dissolved to particulate fractions.The three species of diatoms tested gave systematic growth responses to heavy metal pollution in the moderately polluted fjord; one alga died, one showed reduced growth rate at the more contaminated site compared with those at less polluted sites, while the most tolerant alga was apparently not affected. In the heavily polluted fjord only the most tolerant alga survived, showing decreasing growth rate with increasing pollution.Uptake of heavy metals increased generally with increasing heavy metal content in the sea water. The contents in the algae grown in the most polluted fjord were much higher than those obtained in the less polluted fjord, which were higher than the contents reported for algae from non-contaminated areas.     

Distribution of the twenty seven dominant species of shelf benthic foraminifers on the continental shelf, north of Dakar (Senegal)

One hundred and thirty-one samples were collected on the shelf and on the uppermost slope (down to 180 m) off Northern Senegal, between 14 °50′ and 16 °20′ N latitude.Two hundred and three species of benthic foraminifers were recognized. Most of them were reported in previous works, along the coast of Africa. Twenty seven species are selected for detailed analysis and distribution maps are given for each of them. Q mode and R mode statistical analyses were performed on these selected species. The distribution is mainly related to depth; the second factor of distribution is the nature of the sediments: about 30% of the study area is covered by the muddy sediments of the pro-delta of the Senegal river. Hierarchical analysis shows that the main limit in the pattern of change of these 27 species with depth is about 60–65 m.A depth index Di, calculated on the basis of twelve selected species, gives a depth indication with a precision of about 40 m over the shelf. It is possible to envisage a possible use of this index for the investigation of Quaternary sea-level changes.