Calvatia sporocristata sp. nov. (Gasteromycetes) from Costa Rica

Calvatia sporocristata, Gasteromycetes, is described and illustrated as a new species. Its taxonomic characters are discussed and compared with other closely related species of the genus. Few studies have been carried out on tropical Gasteromycetes. The new species here proposed has, as the main features: exoperidium corky, smooth, one-layered, pseudoparenchymatous; endoperidium thin, papyraceous, dextrinoid; subgleba cellular; capillitium septate, dissociated at the septal site, lycoperdon type, without pores, elastic and spores amigdaloid, 4-6 (-7) x 2.5-4.5 microns with spines aligned, forming crests, 0.8 micron high.     

Nitrogen fixation in Arctic vegetation and soils from Svalbard,Norway

Nitrogen fixation was measured by the acetylene reduction method in a high Arctic ecosystem at Kongsfjorden, Spitsbergen (79°N, 12°E). The most important source of biologically fixed nitrogen was found in cyanobacteria either as free living colonies ofNostoc sp. in wet unvegetated or sparsely vegetated grounds or growing as epiphytes on bryophytes. Fixation associated with plant roots or in soil and peat samples had little or no significance for nitrogen input to the ecosystem. The ability to support an epiphytic flora of nitrogen-fixing cyanobacteria varied greatly between bryophyte species.Calliergon richardsonii andSanionia uncinata seemed especially well adapted for harbouring epiphytic cyanobacteria, but the extent of nitrogen fixation varied with the growing location. The rate of nitrogen fixation was greatly influenced by grazing by geese. In a geese-grazing area values were found with a maximum of 693.6±1.5 nmol C₂H₄ h⁻¹ g (dry weight)⁻¹ while the maximum value for ungrazed areas was 65.3±16.6 nmol C₂H₄ h⁻¹ g (dry weight)⁻¹. In the grazed area cyanobacteria were also found fixing nitrogen epiphytically on grass. The high plant productivity, supporting heavy grazing, clearly indicates an effective transfer of fixed nitrogen to the plant community. Under cliffs harbouring colonies of birds, the biological nitrogen fixation was inhibited by bird droppings.     

Observations on diatoms inhabiting natural and artificial substrates in Kongsfjorden,Svalbard, the Arctic

Polar Biology - The most dramatic effects of global climate change are predicted for the Arctic, and there is a raising concern about the lack of baseline information on microalgal biodiversity....     

Summer seawater tolerance of small-sized Arctic charr, Salvelinus alpinus, on Svalbard

Migrating Arctic charr (Salvelinus alpinus) parr (118 ± 34.4 mm) were caught close to the rivermouth of the Dieset river on Spitsbergen (79°10′N), Svalbard. When subjected to a seawater tolerance test (34 ppt at 6°C) their blood plasma osmolality and sodium and magnesium concentrations increased significantly. After 90 h of exposure, average plasma osmolality was 410 (±54.1) mOsmol. Corresponding sodium and magnesium concentrations were 207 (±35.9) mmol l⁻¹ and 2.7 (±1.36) mmol l⁻¹, respectively. Survival at this time was only 12.5%. When smaller fish (96 ± 26.6 mm) were exposed to seawater, mortality was 100% within 72 h. We conclude that small-sized Svalbard charr may survive only short periods in seawater. Therefore, the lack of adequate hypoosmoregulatory capacity limits their access to marine food resources. Received: 29 December 1997 / Accepted: 12 April 1998     

Ploidy determination in Sphagnum samples from Svalbard,Arctic Norway,by DNA image cytometry

Abstract

We measured DNA content of cell nuclei, stained with the Feulgen method, using branch tips of 11 species of Sphagnum from Svalbard, Arctic Norway, as an alternative to chromosome counting. Nine species were haploid and two were diploid, with no intraspecific variation in ploidy level. The results conformed to known chromosome numbers and/or to expectations from isozyme studies. Ploidy levels were determined for the first time in S. tundrae and S. fimbriatum ssp. concinnum (haploid) and S. arcticum and S. olafii (diploid). No mitotic divisions were observed, but unreplicated interphase nuclei still allowed precise ploidy determinations. Basic DNA contents of all Sphagnum species were very similar, and measurement of a few nuclei proved sufficient to ascertain ploidy level despite very low nuclear DNA content. Advantages of the DNA image cytometry method are: mitotic or meiotic cells are not required to be found, and only a small amount of material is required.     

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.     

Epidermal UV-screening in vascular plants from Svalbard (Norwegian Arctic)

Stratospheric ozone depletion is most pronounced at high latitudes, and the concurring increased UV-B radiation might adversely affect plants from polar areas. However, vascular plants may protect themselves against UV-B radiation by UV-absorbing compounds located in the epidermis. In this 3-year study, epidermal UV-B (_max 314 nm) and UV-A (_max 366 nm) screening was assessed using a fluorescence method in 12 vascular species growing in their natural environment at Svalbard. The potential for acclimation to increased radiation was studied with artificially increased UV-B, simulating 11% ozone depletion. Open-top chambers simulated an increase in temperature of 2–3°C in addition to the UV-B manipulation. Adaxial epidermal UV-B transmittance varied between 1.6 and 11.4%. Artificially increased UV-B radiation and temperature did not consistently influence the epidermal UV-B transmittance in any of the measured species, suggesting that they may not have the potential to increase their epidermal screening, or that the screening is already high enough at the applied UV-B level. We propose that environmental factors other than UV-B radiation may influence epidermal UV-B screening.     

Higher phytosociological syntaxa on Svalbard and their use in subdivision of the Arctic

Idealized distributions of phytosociological syntaxa are arranged along topographical gradients on siliceous and carbonaceous substrates in the northern arctic tundra zone of Svalbard. Two alliances (Luzulion arcuatae all. prov. and Papaverion dahliani Hoffm. 68 all. prov. em.) and three associations (Gymnomitrio corallioidis - Luzule-tum arcuatae ass. prov., Cetrario nivalis - Luzuletum arcuatae ass. prov. and Raco-mitrio lanuginosi — Luzuletum arcuatae ass. prov.) are proposed. Luzulion arcticae (Nordh. 36) Gjaerev. 56 and Polytrichion norvegici Gjierev. 49 described from Scandinavia are supposed to be important syntaxa on Svalbard. A subdivision of the Arctic into four zones, arctic polar desert zone, and northern, middle, and southern arctic tundra zones, is proposed. These zones and the transitional hemiarctic zone are defined and mapped in Europe and adjacent areas according to phytosociological criteria. They are also compared with alpine belts of Fennoscandia. The following zonal syntaxa are proposed for Europe and Greenland: Phyllodoco — Vaccinion in the hemiarctic zone, Loiseleurio — Diapension in the southern arctic tundra zone, Kobre-sio — Dryadion (Tetragono — Dryadetum) in the middle arctic tundra zone, Luzulion arcticae in the northern arctic tundra zone, and Papaverion dahliani in the arctic polar desert zone.     

Comparing Norse animal husbandry practices: paleoethnobotanical analyses from Iceland and Greenland

The popular view of the Norse settlement across the North Atlantic describes colonies with similar subsistence practices being established from the Faroe Islands in the west to L'Anse aux Meadows in the east. The importance of plant resources to the Norse animal husbandry strategies implemented by settlers upon arrival are not well established, nor are the changes these strategies underwent, eventually resulting in different cultural solutions to varying environmental and social factors. This paper compares archaeobotanical samples from two Icelandic archaeological sites, Svalbare and Gj?gur, and one Greenlandic site, G?rden Under Sandet (GUS). Results of this comparison suggest that heathland shrubs were an important fodder resource for caprines in both Iceland and Greenland while apophytes ("weedy taxa") were part of the cattle fodder in Greenland. Further, the results indicate that mucking out of cattle barns to provide fertilizer was likely practiced at the GUS site in the Western Norse settlement of Greenland.     

Organic Carbon Degradation in Arctic Marine Sediments,Svalbard: A Comparison of Initial and Terminal Steps

Degradation of marine organic matter under anoxic conditions involves microbial communities working in concert to remineralize complex substrates to CO ₂ . In order to investigate the coupling between the initial and terminal steps of this sequence in permanently cold sediments, rates of extracellular enzymatic hydrolysis and sulfate reduction were measured in parallel cores collected from 5 fjords on the west and northwest coast of Svalbard, in the high Arctic. Inventories of total dissolved carbohydrates were also measured in order to evaluate their potential role in carbon turnover. Polysaccharide hydrolysis rates exhibited substrate-related and, to a lesser extent, depth-related differences (p < 0.0001); laminarin hydrolysis was consistently most rapid at nearly all depths and sites, and fucoidan hydrolysis was least rapid. Although there was a high degree of variability in parallel cores, sulfate reduction rates also exhibited statistically significant depth-and station-related differences. A comparison with data from previous investigations in Svalbard sediments suggests that this variability is linked to substrate availability rather than to organism distribution. Total dissolved carbohydrate concentrations were comparable to those measured in more temperate sediments, and likely comprise a considerable fraction of porewater dissolved organic carbon. A comparison of dissolved carbohydrate inventories with hydrolysis and sulfate reduction rates suggests that the turnover of carbon through the dissolved pool occurs quite rapidly, on the order of a few days to weeks. The transformation of particulate to dissolved organic matter must also be sufficiently rapid to maintain the measured rates of terminal remineralization.     

Segregation in spawning and early life history among polymorphic Arctic charr, Salvelinus alpinus, in Thingvallavatn, Iceland

The relationships among time of spawning, incubation temperature, timing of first feeding and early growth were examined in four sympatric morphs of Arctic charr in Thingvallavatn, Iceland. Large benthivorous charr spawn in July-August at sites with cold ground-water flow. Planktivorous and piscivorous charr spawn in September-November and are not confined to ground-water sites. The spawning of small benthivorous charr overlaps with that of other morphs. Progeny of large benthivorous charr start feeding 2-3 months earlier than the progeny of autumn spawners. This results in differential size distribution and growth rates of young in the spring.     

Ecological parasitology of polymorphic Arctic charr, Salvelinus alpinus (L.), in Thingvallavatn, Iceland

The helminth endoparasite fauna in four Arctic charr morphs, Salvelinus alpinus (L.), small benthivorous (SB), large benthivorous (LB), planktivorous (PL) and piscivorous (PI) charr, from Thingvallavatn, Iceland consisted of: Crepidostomum farionis (Trematoda: Allocreadiidae); Diplosttomum sp. (Trematoda: Diplostomatidae); Eubothrium salvelini; Diphyllobothrium dendriticum; D. ditremum (Cestoda: Pseudophyllidae); Proteocephalus longicollis (Cestoda: Proteocepha-lidae): and Philonema oncorhynchi (Nematoda: Filariidae). The morphs exhibited distinctive patterns in prevalences and parasite burdens (mean intensity and mean relative density of parasites). SB charr had high prevalence and parasite burden of the eye fluke Diplostomum sp. and none to very light infections of the other parasite species. LB charr had relatively high prevalence and parasite burden of the intestinal fluke C. farionis , whereas infections of the remaining parasite species were light to moderate. PL and PI charr had high prevalences and worm burdens of Diphyllobothrium spp. and P. longicollis . PL charr differed from PI charr in higher worm burden off P. longicollis and lighter burden of £. salvelini . Prevalences of P. oncorhynchi were high in PL and PI charr. Association of parasite intensities and age and length offish were investigated. The different infection patterns among the morphs agree well with their partitioning in food and habitat utilization, and confirm that there is a high degree of ecological segregation between the morphs. The results demonstrate the importance of ecological factors influencing transmission efficiency of parasites to the fish host.     

Phytochemical profiles and antioxidant potential of four Arctic vascular plants from Svalbard

Environmental stress in the Arctic region leads to damage in plant membranes as a result of oxidation processes. To withstand these stress conditions, plants are expected to produce antioxidants that differ from phenolics. Here, we investigated the chemical composition and antioxidative activities of four Arctic flowering plant species (Dryas octopetala, Carex rupestris, Silene uralensis and Deschampsia alpina.) through in vitro measurements of the free radical scavenging activities (FRS), inhibition of lipid peroxidation (ILP) and trolox equivalent antioxidant capacities (TEAC). D. octopetala exhibited the highest ILP (76.45?%) and FRS (86.58?%) activities. The TEAC values were higher than those of the Trolox vitamin E standard in all four species. Overall, the antioxidative activity was highest in D. octopetala, followed by C. rupestris, S. uralensis and D. alpina. Electrospray ionization tandem mass spectrometric (ESI–MS/MS) analysis of methanolic extracts of these plants revealed the presence of organoselenides, linear alkylbenzenesulfonates (LAS) and oligosaccharides, some of which are reported as antioxidants in the literature. Hence, it is likely that the antioxidant activities exhibited by these plants are not only related to the production of phenolics. This is the first report of the antioxidant potential of four Arctic flowering plants and the presence of selenides in D. octopetala and S. uralensis, and the production of LAS in C. rupestris. Our findings suggest that these plants can be used as nutraceutical sources of selenium and as biomarkers for environmental pollution.     

Epidemiology of Renibacterium salmoninarum in wild Arctic charr and brown trout in Iceland

Renibacterium salmoninarum (Rs) is common in wild Arctic charr Salvelinus alpinus and brown trout Salmo trutta in Iceland. Of 22 charr and nine trout populations none were free of Rs antigens. In two charr populations only one fish exceeded the Rs antigen detection limit and in one of these cases the ELISA value was within uncertainty limits of the infection criterion. Mean prevalence of infection was 46% for Arctic charr (range: 3–100%) and 35% for brown trout (range: 6–81%). No infected fish showed gross pathological signs of bacterial kidney disease (BKD). The ubiquity and high prevalences of infection indicated that the bacterium has been endemic for a long time, and is probably a normal, low density resident in the fish. A lack of correlation in mean intensity of Rs antigen and prevalence of infection between sympatricpopulations of Arctic charr and brown trout suggests that the dynamics of infection and internal proliferation of bacteria can be quite independent in the two species even if they live in the same lake. Rs intensity and its coefficient of variation decreased with age in older fish, suggesting a connection between Rs intensity and host mortality. However, this can be caused by other ecological factors that decrease survival, especially low food availability, which simultaneously increase the susceptibility to Rs infection and internal proliferation.     

Verrucomicrobia Are Candidates for Polysaccharide-Degrading Bacterioplankton in an Arctic Fjord of Svalbard

In Arctic marine bacterial communities, members of the phylum Verrucomicrobia are consistently detected, although not typically abundant, in 16S rRNA gene clone libraries and pyrotag surveys of the marine water column and in sediments. In an Arctic fjord (Smeerenburgfjord) of Svalbard, members of the Verrucomicrobia, together with Flavobacteria and smaller proportions of Alpha- and Gammaproteobacteria, constituted the most frequently detected bacterioplankton community members in 16S rRNA gene-based clone library analyses of the water column. Parallel measurements in the water column of the activities of six endo-acting polysaccharide hydrolases showed that chondroitin sulfate, laminarin, and xylan hydrolysis accounted for most of the activity. Several Verrucomicrobia water column phylotypes were affiliated with previously sequenced, glycoside hydrolase-rich genomes of individual Verrucomicrobia cells that bound fluorescently labeled laminarin and xylan and therefore constituted candidates for laminarin and xylan hydrolysis. In sediments, the bacterial community was dominated by different lineages of Verrucomicrobia, Bacteroidetes, and Proteobacteria but also included members of multiple phylum-level lineages not observed in the water column. This community hydrolyzed laminarin, xylan, chondroitin sulfate, and three additional polysaccharide substrates at high rates. Comparisons with data from the same fjord in the previous summer showed that the bacterial community in Smeerenburgfjord changed in composition, most conspicuously in the changing detection frequency of Verrucomicrobia in the water column. Nonetheless, in both years the community hydrolyzed the same polysaccharide substrates.     

Seasonal occurrence of picocyanobacteria in the Greenland Sea and central Arctic Ocean

The seasonal occurrence of picocyanobacteria in the Greenland Sea and Arctic Ocean was investigated during four expeditions in May–June 1987 and 1988, August–October 1991, and November–December 1988 by epifluorescence microscopy. In early summer, the abundance of picocyanobacteria was related to water masses: they were nearly absent in polar water, whereas they occurred in high concentrations (up to 5470 cells ml^–1) in Atlantic Water. During autumn and beginning of winter, the abundances of picocyanobacteria remained around 10³ cells ml^–1. Their relative contribution to total picoplanktonic algal abundance increased from 0% during spring/summer to 70–80% in late autumn, as a result of a decrease in the abundance of eucaryotic picoalgae. Consequently, the impact of picocyanobacteria on Arctic epipelagic carbon and energy flow is of minor importance, and the strong contribution of picoplankton algae to biomass and primary productivity in Arctic seas has to be attributed to eucaryotic species.