Distribution patterns of polychaete fauna in an Arctic fjord (Hornsund, Spitsbergen)

Polychaetes are one of the most important groups of benthic organisms in marine ecosystems. They dominate on the Arctic shelf and play an important role in ecosystem functioning. This study focuses on the polychaete biodiversity and their distribution patterns in Hornsund, an open glacial fjord, in western Spitsbergen and provides important baseline data for future studies of temporal fluctuations in benthic fauna. The main aim of this study was to assess how the polychaete abundance, biomass, diversity, community structure, and function vary along the Hornsund fjord’s axis, in relation to the environmental factors. Eighty-eight polychaete taxa were identified; an average density was 457 ind. m^?2 ± 237.5 SD. Three assemblages were distinguished (INNER, MIDDLE, and OUTER) along the fjord axis, reflecting the intensity of glacial disturbance. A clear division between the highly disturbed inner part of the fjord (Brepollen) and the less impacted middle and outer parts was observed. Continuous gradients in abundance, biomass, and diversity were found with all those values diminishing toward the inner region of the fjord. The polychaete assemblages' indices were significantly correlated with bottom temperature, sediment characteristics (grain size), and distance to the glacier (longitude). No significant correlations were found with depth or total organic carbon content. Carnivore and motile surface deposit feeding polychaete species dominated in the areas close to the glaciers, while the OUTER community was dominated by carnivores and surface sessile and discretely motile species, and had more complex trophic structure, with multiple species representing different functional groups including carnivores, sessile, discretely motile, and motile surface deposit feeders and motile burrowers.     

Meiofaunal (re)colonization of the Arctic intertidal (Hornsund,Spitsbergen) after ice melting: role of wrack deposition

Intertidal meiobenthos of Hornsund—the southernmost fjord of Spitsbergen—was investigated between July and September 2005. Mean total meiofaunal densities ranged between 4.3 and 328 ind. 10 cm⁻². Nematode assemblages were impoverished in terms of the number of genera when compared with those from the western Spitsbergen coast (11 vs. 25–28 genera in total, respectively). It is suggested that severe environmental conditions in the southern part of Spitsbergen overcome the adaptation skills of many nematode species and hamper the establishment of a diverse community. Comparatively high nematode numbers on a beach subject to heavy macroalgal wrack input contrast sharply with numerically poor communities in sparse-wrack beaches (up to 315 vs. 31 ind. 10 cm⁻², respectively). It is suggested that the wrack input to the Arctic beach may substantially influence the richness and composition of the intertidal meiobenthic community. Nematode assemblages were dominated by extreme colonizers: Geomonhystera disjuncta and rhabditids. Their relatively high densities in beach sediments recorded at the beginning of July indicate their ability to recover rapidly after the winter period and to effective (re)colonization of the intertidal habitat just after the ice melt. Average concentration of rhabditids and monhysterids associated with macroalgal wrack deposited on the upper shore was as high as 52 × 10³ individuals per gram of the substrate. It is hypothesized that nematodes can play a substantial role in the wrack decomposition in the Arctic intertidal.     

Assessing species richness of macrofauna associated with macroalgae in Arctic kelp forests (Hornsund,Svalbard)

Kelp beds support diverse and productive benthic coastal ecosystems and are often perceived as cold water analogs of tropical coral reefs, yet the levels of species richness in polar regions have remained largely unexplored. The present study aims to assess the magnitude of macrozoobenthic species richness associated with the macroalgae in an Arctic kelp forest. The study was conducted in Hornsund, a high latitude Arctic fjord off west Spitsbergen (76–77°N). A total of 403 samples (i.e., individual algae) were collected by scuba divers at three sites located along the fjord axis at varying depths (5–10 m). The most common invertebrate species and the sample species richness (mean 11.5 species per sample) were consistent among the most common algal species (Laminaria digitata, Saccharina latissima, Alaria esculenta, Desmarestia aculeta, Odonthalia dentata, Phycodrys rubens). Fauna associated with overstory kelps was concentrated on the holdfasts. A total of 208 species were identified; Bryozoa, Polychaeta and Hydrozoa yielded the highest numbers of species (70, 52 and 37, respectively). The non-parametric Chao2 estimator of true species richness gave an estimate of 259 species (with 95% confidence intervals from 234 to 308). Despite the high sampling effort, the total species richness was not captured. This may stem from the high level of rarity within the fauna associated with kelps; 38% of the species occurred only in one or two samples. The studied fauna was much less diverse than similar assemblages surveyed at lower latitudes. The high numbers of species and the common occurrence of colonial forms (Bryozoa, Hydrozoa) in the current study show that these taxa cannot be omitted in macrobenthic diversity surveys performed within kelp habitats.     

The invertebrate fauna of High Arctic seabird nests: the microarthropod community inhabiting nests on Spitsbergen,Svalbard

The invertebrate fauna of the nests of three seabird species, black-legged kittiwakes (Rissa tridactyla), common eider (Somateria mollissima) and glaucous gull (Larus hyperboreus), were sampled in Kongsfjorden, Spitsbergen, Svalbard. The invertebrate community was species poor, consisting predominantly of the flea, Mioctenopsylla arctica arctica (Insecta: Siphonaptera), but with six species of oribatid mite (Acari: Oribatida), Diapterobates notatus, Oribatula tibialis, Ameronothrus lineatus, Hermannia reticulata, Trichoribates trimaculatus and Ceratoppia bipilis, plus an occasional mesostigmatid mite. No Collembola or ticks (Acari: Ixodidae) were observed. With the exception of M. arctica arctica, the fauna of seabird nests consisted of opportunistic microarthropod species rather than specialised nest-dwelling or bird parasitic species. Species diversity of soil oribatid mites was greater in nests of the common eider than compared to nests of the black-legged kittiwake, which may be related to the ground nesting behaviour of the common eiders. No rare or unusual microarthropod species for Svalbard were found in the seabird nests. The contentions that nests may facilitate microarthropod colonisation of High Arctic regions via bird phoresy by providing a high-quality habitat at the point of arrival, or that there might be a specialised microarthropod fauna exploiting this habitat, were not supported in this study. These are amongst the first data on the microarthropod community of seabird nests in the High Arctic.     

Comparison of productivity and phytoplankton in a warm (Kongsfjorden) and a cold (Hornsund) Spitsbergen fjord in mid-summer 2002

Kongsfjorden and Hornsund are two glacial fjords without sills on the West Spitsbergen coast. Both sites are under the influence of relatively warm Atlantic-derived water, although Hornsund is more influenced by cold water from the Barents Sea. In this study, we compared the impacts of cold Arctic and warmer Atlantic waters on the pelagic ecosystems of Kongsfjorden and Hornsund. Both fjords were strongly influenced by Atlantic-derived waters during summer (2002). Diatoms were the most substantial contributors to phytoplankton biomass, especially in outer basins of both fjords, whereas the second most important contributors were autotrophic dinoflagellates in Kongsfjorden and nanoflagellates in Hornsund. Total phytoplankton biomass was highest in Hornsund. Primary production rates were an order of magnitude lower in Kongsfjorden than in Hornsund, and increased from inner to outer fjord (from 2.47 to 4.48 mg C m⁻² h⁻¹ in Kongsfjorden and from 14.00 to 86.65 mg C m⁻² h⁻¹ in Hornsund). Chlorophyll-a concentration was also substantially lower in Kongsfjorden. Zooplankton was dominated by omnivorous species in Kongsfjorden and herbivorous in Hornsund. Observed differences between the fjords may originate from (1) advection of different waters into the fjords; (2) differences in freshwater runoff and turbidity, and (3) timing of the phytoplankton bloom. Climate warming will likely increase the Atlantic water influence, and result in reduced production of diatoms and increase in flagellates.     

New species of Echinoderes (Kinorhyncha: Cyclorhagida) from Spitsbergen,with additional information about known Arctic species

The kinorhynch fauna in two Arctic fjords at Spitsbergen was explored and eight species of Echinoderes were recorded, of which three are new to science and described herein. Echinoderes daenerysae sp. nov. is recognized by middorsal spines on segments 6 and 8 only, lateroventral spines on segments 6–9, laterodorsal and ventrolateral tubes on segment 2, lateroventral tubes on segment 5, lateral accessory tubes on segment 8, laterodorsal tubes on segment 9 and small laterodorsal tubes on segment 10. Echinoderes rhaegali sp. nov. has middorsal spines on segments 4, 6 and 8, lateroventral spines on segments 6–9, sublateral and ventrolateral tubes on segment 2, lateroventral tubes on segment 5, lateral accessory tubes on segment 8 and laterodorsal tubes on segment 10 in males. Echinoderes drogoni sp. nov. has middorsal spines on segments 4–8, lateroventral spines on segments 6–9, lateral accessory tubes on segment 5, glandular cell outlets type 2 in subdorsal, laterodorsal, sublateral and ventromedial positions on segments 2, in midlateral positions on segment 5, in sublateral positions on segment 8 and in subdorsal positions on segment 10; segment 11 has divided tergal plates. Moreover, types of other Arctic Echinoderes, including E. angustus, E. aquilonius, E. eximus, E. peterseni, E. svetlanae and E. tubilak, were re-examined and new information on glandular cell outlets type 2 is provided. Our results suggest that Arctic Echinoderes species have a circum-Artic distribution. Morphological analysis indicates that the occurrence of tubes may show intraspecific variation.

http://zoobank.org/urn:lsid:zoobank.org:pub:CBE29FE8-9233-4E3C-9757-FF9576B06C74     

Reproduction and survival of Glaucous Gulls breeding in an Arctic seabird colony

ABSTRACT.   Despite being widespread and easily observed, little is known about the life history of Glaucous Gulls ( Larus hyperboreus ). From 1984 to 2007, we examined their breeding biology and demography at Coats Island, Nunavut, Canada, where they nest alongside a colony of 30,000 pairs of Thick-billed Murres ( Uria lomvia ). The gulls fed mainly on murre eggs and chicks and by scavenging adult carcasses. The median age at first breeding was 5 yr, and the mean age was 4.8 ± 0.9 yr. Adult survival was estimated as 0.84 ± 0.03 (SE). The mean clutch size was 2.56 eggs and the mean number of young reared per year was 1.6 (range = 0.9–2.2). Birds reared at the colony provided 40% of recruits. Assuming that survival of locally reared chicks that emigrated was similar to that of chicks that returned to the colony, about 22% of the young gulls survived to breeding age. The timing of breeding by Glaucous Gulls appeared related to the timing of laying by murres. Although the demographic characteristics of Glaucous Gulls in our study were similar to those of populations of other large gulls, adult survival was at the lower end of the range for populations of large Larus gulls. There is some evidence that Glaucous Gulls exhibit lower survival than large gulls breeding in temperate areas, possibly because of contaminant burdens. In general, however, the demographic characteristics of large gulls show little variation and are probably a product of their common phylogeny.     

Differential sensitivity to natural ultraviolet radiation among phytoplankton species in Arctic lakes (Spitsbergen,Norway)

Incubation experiments demonstrated a differential sensitivity to natural UV-radiation among the dominant phytoplankton species from three Arctic lakes, situated near Ny-Ålesund, Spitsbergen (79° N). The growth of small chlorophytes, diatoms and picocyanobacteria from two oligotrophic lakes was inhibited primarily by the shorter wavelength UV components, while the growth of the larger colony-forming species (cyanobacteria, Planktothrix sp., Woronichinia sp. and the chrysophyte, Uroglena americana Calkins) apparently was stimulated. These colonies (not easily eaten by daphnids) dominated at the end of the experiment in those treatments where the short wavelength UV components were not excluded. For the two oligotrophic localities, 70 and 61%, respectively, of total phytoplankton biovolume were edible in the treatments excluding short wavelength UV, compared to only 13 and 19%, respectively, in the treatments including such radiation. For the third, more productive and less transparent lake, the percentage of edible species in the treatments with and without short wavelength UV radiation did not differ (ca. 75% for both treatments).     

Arctic rhodolith beds and their environmental controls (Spitsbergen, Norway)

Coralline algae (Corallinales, Rhodophyta) that form rhodoliths are important ecosystem engineers and carbonate producers in many polar coastal habitats. This study deals with rhodolith communities from Floskjeret (78°18′N), Krossfjorden (79°08′N), and Mosselbukta (79°53′N), off Spitsbergen Island, Svalbard Archipelago, Norway. Strong seasonal variations in temperature, salinity, light regime, sea-ice coverage, and turbidity characterize these localities. The coralline algal flora consists of Lithothamnion glaciale and Phymatolithon tenue. Well-developed rhodoliths were recorded between 27 and 47 m water depth, while coralline algal encrustations on lithoclastic cobbles were detected down to 77 m water depth. At all sites, ambient waters were saturated with respect to both aragonite and calcite, and the rhodolith beds were located predominately at dysphotic water depths. The rhodolith-associated macrobenthic fauna included grazing organisms such as chitons and echinoids. With decreasing water depth, the rhodolith pavements were regularly overgrown by non-calcareous Polysiphonia-like red algae. The corallines are thriving and are highly specialized in their adaptations to the physical environment as well as in their interaction with the associated benthic fauna, which is similar to other polar rhodolith communities. The marine environment of Spitsbergen is already affected by a climate-driven ecological regime shift and will lead to an increased borealization in the near future, with presently unpredictable consequences for coralline red algal communities.     

Soft-bottom macrobenthic faunal associations and factors affecting species distributions in an Arctic glacial fjord (Kongsfjord,Spitsbergen)

The Kongsfjord (west Spitsbergen) hosts the most active glacier on the island. Therefore the glacial impact on the marine ecosystem is very pronounced and easily recognisable. The study examines the influence of the steep glacier-derived environmental gradients on dominant macrofaunal species distributions and faunal associations in the fjord. The macrobenthic fauna was sampled by van Veen grab at 30 stations situated throughout the fjord (at depths 38–380 m). Two major communities were recognised. An inner basin receives the outflows from three glaciers and is occupied by a Glacial Bay Community dominated by small, surface detritus-feeders, with Chone paucibranchiata and a set of thyasirid and nuculanid bivalves (Thyasira dunbari, Yoldiella solidula, Y. lenticula) as characteristic species. An outer basin of the fjord is characterised by a common set of dominant species, including Heteromastus filiformis, Maldane sarsi, Levinsenia gracilis, Lumbrineris sp. and Leitoscoloplos sp. Three associations may be distinguished within the Outer Basin Community. Association TRANS is of transitional character, with Nuculoma tenuis and Terebellides stroemi. Association CENTR is the most typical for the community. It is dominated by tube-dwelling Prionospio sp., Clymenura polaris, Galathowenia oculata and Spiochaetopterus typicus. Association ENTR contains shelf benthos elements, e.g. Ophiura robusta and Lepeta caeca. An opportunistic eurytopic Chaetozone group is present throughout the fjord and its density and dominance increase with proximity to the glaciers. Dominant species distribution is discussed in relation to environmental factors, of which sediment stability, inorganic particle concentration, sedimentation rate and amount of organic matter in sediments are considered to be most important in structuring the communities.     

Tardigrada of the Revdalen (Spitsbergen) with the descriptions of two new species: Bryodelphax parvuspolaris (Heterotardigrada) and Isohypsibius coulsoni (Eutardigrada)

Despite a century long history of research, tardigrade fauna of the Svalbard Archipelago remains poorly known. In order to deepen our knowledge of tardigrade biodiversity in the Arctic, we collected forty-one moss and lichen samples from the Revdalen and on the south-east slopes of the Rotjesfjellet (Spitsbergen, Svalbard Archipelago) in June 2010. In these samples, twenty-five tardigrade species were found, including two new for science: Bryodelphax parvuspolaris sp. nov. and Isohypsibius coulsoni sp. nov. B. parvuspolaris sp. nov. belongs to the weglarskae group but differs from all other species of the group by a unique configuration of ventral plates. I. coulsoni sp. nov. differs from the most similar species I. ceciliae Pilato and Binda, 1987 mainly by the absence of ventral sculpture. Two additional species, Milnesium asiaticum Tumanov, 2006 and Diphascon (Adropion) prorsirostre Thulin, 1928, are recorded from the Svalbard Archipelago for the first time.     

Variability of protistan and bacterial communities in two Arctic fjords (Spitsbergen)

Krossfjorden and Kongsfjorden are Arctic fjords on the western side of Spitsbergen. These fjords share a common mouth to the open sea, and both are influenced by the input of sediment-rich glacial meltwater leading to decreased surface salinity, increased turbidity and decreased light penetration during summer. Earlier classical taxonomic studies had described the pelagic protistan composition of the Kongsfjorden during summer, revealing the dominance of flagellates of often unresolved taxonomic origin. Only little information existed on microbial eukaryote composition of the Krossfjorden as well as the bacterial composition of both fjords. The aim of the present study was to analyze and compare surface summertime protistan and bacterial communities in both fjords, using molecular approaches (16S and 18S rRNA DGGE, sequencing). Samples were collected three times a week from the central Kongsfjorden over a 1-month period. Additionally, 10 marine and 2 freshwater sites were sampled within a 1-week period in both Kongsfjorden and Krossfjorden. The central Kongsfjorden revealed a relatively stable protistan community over time with dinoflagellates, chlorophytes and small heterotrophs dominating. In contrast, the bacterial community varied over time and appeared to be correlated with the inflow of glacial meltwater. The Kongsfjorden and Krossfjorden were found to harbor distinctive bacterial and eukaryotic communities. We speculate that differences in glacial meltwater composition and fjord bathymetry affect the surface water properties and therefore the observed spatial variability in the community fingerprints.     

Viability, diversity and composition of the bacterial community in a high Arctic permafrost soil from Spitsbergen, Northern Norway

The viable and non-viable fractions of the bacterial community in a 2347-year-old permafrost soil from Spitsbergen were subjected to a comprehensive investigation using culture-independent and culture-dependent methods. LIVE/DEAD BacLight staining revealed that 26% of the total number of bacterial cells were viable. Quantitatively, aerobic microcolonies, aerobic colony-forming units and culturable anaerobic bacteria comprised a minor fraction of the total number of viable bacteria, which underlines the necessity for alternative cultivation approaches in bacterial cryobiology. Sulfate reduction was detected at temperatures between -2 degrees C and 29 degrees C while methanogenesis was not detected. Bacterial diversity was high with 162 operational taxonomic units observed from 800 16S rDNA clone sequences. The 158 pure cultures isolated from the permafrost soil affiliated with 29 different bacterial genera, the majority of which have not previously been isolated from permafrost habitats. Most of the strains isolated were affiliated to the genera Cellulomonas and Arthrobacter and several of the pure cultures were closely related to bacteria reported from other cryohabitats. Characterization of viable bacterial communities in permafrost soils is important as it will enable identification of functionally important groups together with the as yet undescribed adaptations that bacteria have evolved for surviving subzero temperatures for millennia.     

The influence of water transparency on the distribution and abundance of macrophytes among lakes of the Mackenzie Delta, Western Canadian Arctic

SUMMARY 1. Macrophyte abundance and distribution was assessed in a chain of six interconnected lakes (all with the same flooding frequency) in the Arctic, where increasing distance from the Mackenzie River channel resulted in a gradient of water transparency (‘chain‐set’ lakes), and in a group of 26 spatially discrete lakes where increasing frequency and duration of lake flooding with river water (controlled by sill height) also resulted in a transparency gradient (‘sill‐set’ lakes). 2. Among the chain‐set lakes, above‐ground macrophyte biomass increased from 0 to 1000 g m^?2 with increasing water transparency. Among the sill‐set lakes, the transparency gradient among the lakes was less well defined and the relations with biomass were more varied. A decrease in flooding was associated with increasing water transparency and an increasing biomass of macrophytes from about 0 to over 2000 g m^?2. For a specific flood frequency, however, the effect of flooding was much greater when lakes were directly connected to a river channel than when floodwaters flowed first through an intervening lake. Among infrequently flooded lakes the effect of flooding on water transparency and biomass was negligible. 3. Among relatively clear lakes in both sets of lakes, biomass increased with increasing water transparency and decreasing lake depth. Among relatively turbid lakes, however, biomass increased with the combined effect of increasing water colour (decreasing water transparency) and increasing lake water depth. The increases in biomass with increasing water colour (coloured dissolved organic matter) and increasing depth, which together result in reduced light at the bed, may be explained by reduced exposure to ultra violet light. 4. An average light attenuation of 1.3 m^?1 (Secchi depth about 1 m) over the growing season appears to represent a threshold water transparency which, in combination with water depths early in the growing season, is consistent with a light supply on the bed required for growth of the common macrophytes in lakes of the Mackenzie Delta. However, a comparison with other systems indicates that macrophytes among lakes of the Mackenzie Delta grow deeper, for a given level of transparency, than is reported in lakes at lower latitude, despite the lower sun angles and increased reflectivity of water surfaces in the arctic. 5. A complete accounting of water transparency (at PAR and UV wavelengths), lake depth, summer sun angle and duration of sunlight may be necessary to explain patterns of macrophyte growth among lakes across a full range of latitudes.     

Arctic seabird food chains explored by fatty acid composition and stable isotopes in Kongsfjorden, Svalbard

Marine birds are important predators in the marine ecosystem, and dietary studies can give useful information about their feeding ecology, food webs and oceanographic variability. The aim of this study was to increase our understanding of the diet and trophic level of the seabirds breeding in Kongsfjorden, Svalbard. We have used fatty acids and stable isotopes, both of which integrate diet information over space and time, to determine trophic relationships in marine food webs. Fatty acid compositions of muscle from Little auk (Alle alle), Brünnich’s guillemot (Uria lomvia), Black-legged kittiwake (Rissa tridactyla), Northern fulmar (Fulmarus glacialis) and Glaucous gull (Larus hyperboreus) were determined and compared with their prey species. Canonical analysis (CA) showed that fatty acid composition differed among the five seabird species. Little auk, Black-legged kittiwake and Northern fulmar had high levels of the Calanus markers 20:1n9 and 22:1, indicating that these seabirds are a part of the Calanus food chain. Brünnich’s guillemot differed from the other species with much lower levels of 20:1n9 and 22:1. Brünnich’s guillemot is a pursuit diver feeding on fish and amphipods deeper in the water column, below 30 m. Glaucous gull also differed from the other seabird species, with a larger variation in the fatty acid composition indicating a more diverse diet. Trophic level analysis placed Little auk at the lowest trophic level, Brünnich’s guillemot and Black-legged kittiwake at intermediate levels and Glaucous gull and Northern fulmar at the highest trophic level.     

Elasmobranch species richness,fisheries, abundance and size composition in the Azores archipelago (NE Atlantic)

ABSTRACT

Elasmobranchs are a vulnerable resource, more susceptible to overfishing than most teleosts, and their assessment is complicated due to a general lack of information about their fisheries, biology and ecology. This study aimed to analyse all fishery and survey data available for elasmobranchs caught over the past c. 25 years around the Azores (NE Atlantic) to provide a baseline information, which can be used to inform stock assessment and management strategies. Elasmobranch species covered pelagic, benthopelagic and demersal habitats, from shallow to deep-water strata in areas around the islands and seamounts. These species are taken accidentally as by-catch of three main fisheries: swordfish fishery, black scabbardfish fishery and demersal bottom longline fishery. The latter represents one of the most important fishing activities in the Azores, and frequent elasmobranch by-catches include Raja clavata, Galeorhinus galeus, Deania calcea, D. profundorum, Etmopterus pusillus and E. spinax. A slight reduction in the abundance indices of these species was observed, despite the implemented technical measures (e.g. minimum size, zero catch). Little is known about resource dynamics for the Azorean region and no analytical assessments have been conducted. This study highlights the vulnerability to overfishing of these resources and the urgent need to develop management strategies.