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1.
Trichosporon aquatile sp. n. is described and compared with T. cutaneum and T. inkin, Trichosporon eriense sp. n. is described and compared with T. capitatum and T. penicillatum. A key is presented for all the species in the genus Trichosporon. 相似文献
2.
An overview of the montane and subalpine forests of Abies lasiocarpa, Picea engelmannii, Abies amabilis and Tsuga mertensiana of northwestern North America is provided based on 541 relevés of forest vegetation from coastal and inland British Columbia, Washington and northwestern Montana. A new classification is proposed based on an examination of the floristic patterns across these communities. Owing to their broadscale floristic similarities, coastal subalpine Abies amabilis-Tsuga mertensiana forests and inland forests of Abies lasiocarpa, Picea engelmannii, P. glauca, Thuja plicata and Tsuga heterophylla are combined into a single order, Thujetalia plicatae. The floristic patterns within this order in turn support the recognition of four alliances. These are (1) Tsugion mertensianae, including coastal and inland subalpine forests of Tsuga mertensiana, Abies amabilis, A. lasiocarpa and Picea engelmannii, with deep winter snowpacks and an often luxuriously developed shrub layer; (2) Abieti-Tsugion heterophyllae all. nov., including mesic inland montane Thuja plicata-Tsuga heterophylla and Abies lasiocarpa-Picea engelmannii forests and related southern boreal Abies lasiocarpa-Picea glauca communities; (3) Gymnocarpio-Abietion lasiocarpae, including moist coastal and inland forests dominated by a fern-rich understory and Oplopanax horridus; and (4) Lysichito-Chamaecyparidion nootkatensis, which includes wet coastal subalpine forests with Lysichiton americanum. A total of five new associations are described, bringing the number of recognized associations within the order to twenty-five. An extensive synonymy and crosswalk to other classification systems is provided. 相似文献
3.
The nature of the substratum is a fundamental factor determining the types of organisms and communities found in many terrestrial and benthic habitats. The extent to which this is true in extreme environments was investigated using bryozoan assemblages as model organisms in an Arctic fjord (Kongsfjorden 79°N, 12°E) in summer 2001 using SCUBA. Twenty-seven substrate samples of 0.25 m 2 were taken at 10 m depth from the inner glacial basin to the mouth of the fjord. Multivariate analyses revealed four different bryozoan assemblages. The sea floor of the inner basin of Kongsfjorden near the glacial fronts was characterized by low diversity and dominance of the ctenostome species Alcyonidium disciforme Smitt. Highest richness and diversity occurred on rock substratum with mean size >10 cm 2, on which the most common species was the pioneer Harmeria scutulata Busk (abundance: 15%). On smaller rocks with mean size <2 cm 2, the runner-like pioneer species Electra arctica Borg comprised most individuals of the assemblage (98%). Yet another pioneer, Celleporella hyalina Linnaeus, was the most abundant species (49%) on substratum dominated by algae. Thus, in each habitat type, pioneers dominated but different species and to different extents. There was much variation in species composition and abundance within assemblages of heterogeneous habitats, and this study emphasizes the importance of microhabitats and physical conditions. Heterogeneity was evident at scales of <1 m. 相似文献
4.
Previous studies of fungi in polar environments have revealed a prevalence of basidiomycetous yeasts in soil and in subglacial
environments of polythermal glaciers. Ascomycetous yeasts have rarely been reported from extremely cold natural environments,
even though they are known contaminants of frozen foods. Using media with low water activity, we have isolated various yeast
species from the subglacial ice of four glaciers from the coastal Arctic environment of Kongsfjorden, Spitzbergen, including
Debaryomyces hansenii and Pichia guillermondii, with counts reaching 10 4 CFU L −1. Together with the basidiomycetes Cryptococcus liquefaciens and Rhodotorula mucilaginosa, these yeasts represent the stable core of the subglacial yeast communities. Other glacial ascomycetous species isolated
included Candida parapsilosis and a putative new species that resembles Candida pseudorugosa. The archiascomycete Protomyces inouyei has seldom been detected anywhere in the world but was here recovered from ice in a glacier cave. The glacier meltwater contained
only D. hansenii, whereas the seawater contained D. hansenii, Debaryomyces maramus, Pichia guilliermondii, what appears to represent a novel species resembling Candida galli and Metschnikowia bicuspidata. Only P. guilliermondii was isolated from sea ice, while snow/ice in the fjord tidal zone included C. parapsilosis, D. hansenii, P. guilliermondii and Metschnikowia zobellii. All of these isolated strains were characterized as psychrotolerant and xero/halotolerant, with the exception of P. inouyei. 相似文献
5.
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. 相似文献
6.
Marine benthic macrofauna communities are considered a good indicator of subtle environmental long-term changes in an ecosystem.
In 1997/1998 and 2006, soft-bottom fauna of an Arctic glacial fjord Kongsfjorden was extensively sampled and major communities
were identified along the fjord axis, which were related to the diminishing influence of glacial activity. Spatial patterns
in community structure and species diversity were significantly different in the central basin of Kongsfjorden between periods
while there was no change in the inner part of the fjord. In 1997/98, three faunal associations were distinguished with significant
differences in species richness and diversity ( H′) while in 2006 only two faunal associations were identified and there were no differences any more between the two formerly
distinct associations in the central fjord. The increased input of Atlantic water due to a stronger West Spitsbergen Current
may be the reason for unification of previous clear faunal division. The faunal association in the inner, well separated glacial
part of the fjord, characterized by strong glacier influence, was protected from Atlantic water inflow and, hence, the macrobenthic
fauna essentially remained unaffected. Reduced abundance of species typical for glacial bays in the central part of the fjord
in 2006 may result from the decreasing effect of Blomstrandbreen glacier, strong increase of input of Atlantic water into
the fjord and increased temperature of West Spitsbergen Current. Higher values of POC in 2006 than in 1998 are likely the
effect of increased primary production resulting from warmer water temperatures. 相似文献
7.
Algal communities were compared among benthic and net plankton samples from Cape Maclear, Lake Malai. In the cool mixing season (from May to August), rocks were overgrown by Cladophora or Calothrix, accompanied by the diatoms Rhopalodia, Cymbella, and Navicula. These diatoms, together with Epithemia and Cocconeis, were epiphytic on Cladophora and macrophytes. In sandy areas, the common diatoms were Rhopalodia, Fragilaria, Epithemia, Navicula, Surirella, and Melosira.In all phytoplankton samples, taken with a 10 µm mesh net, cyanophyte cells were the most common (70 to 80%), especially those of Oscillatoria. Biomass, however, was dominated by Peridinium from November to April and by Anabaena and Oscillatoria from September to April when the mixolimnion was stratified. Among the chlorophytes, Oedogonium was the most common, especially from May into December when Pleodorina became more common.Diatoms dominated the biomass in the mixing season (May to September): Stephanodiscus in May, followed by Melosira nyassensis and lanceolate Nitzschia species from mid-June through August. For the rest of the year the epilimnion was stratified and these Nitzschia species were virtually the only diatoms present.Benthic and planktonic communities share few taxa: benthic taxa never made up more than 2% of cells in offshore tows. This conclusion contrasts with previous reports, especially regarding Surirella. Consequently, an abundance of benthic taxa in sediment cores may be interpreted as lower lake level if sediment redistribution can be excluded. The seasonality of the planktonic diatoms is compatible with current ecological hypotheses, and therefore increases their value as paleolimnological indicators. 相似文献
8.
Twenty-nine surface sediment samples from Effingham Inlet, a small fjord on the west coast of Vancouver Island, British Columbia, were analyzed for diatoms. This fjord has been selected for paleoceanographic investigation due to the presence of laminated sediments resulting from the dysoxic to anoxic bottom water conditions in the inner and outer basins of the inlet. Distributional patterns of the diatom microflora reflected proximity to littoral regions, phytoplankton production, and marine influence from outside the fjord. Principal components and cluster analyses of the microflora established four diatom assemblages with a clear separation between the inner and outer basin diatom floras. Inner basin stations were characterized by elevated absolute abundance with assemblages dominated by spring–early summer bloom taxa including Skeletonema costatum, Thalassiosira nordenskioeldii, and Thalassiosira pacifica. Chaetoceros spp. resting spores were abundant throughout Effingham Inlet, with the exception of the stations closest to the fjord head. Stations located in the outer basin and towards the fjord mouth had relatively lower absolute abundance yet showed a higher relative and absolute abundance of Thalassionema nitzschioides, Rhizosolenia setigera, Coscinodiscus radiatus, Ditylum brightwellii, Odontella longicruris, and Paralia sulcata in relation to the inner basin. Many of these latter taxa are often associated with late summer and autumn conditions in fjords along coastal British Columbia. Oceanographic data for Effingham Inlet suggest that increased offshore penetration is more likely to occur from summer to early fall, with a more restricted offshore influence in the inner basin. Diatom surface sediment assemblages in Effingham Inlet appear to reflect incursions of offshore waters into the fjord. Absolute abundance estimates and the preservation of lightly silicified taxa suggest excellent preservation of fossil material in the sediments of the predominantly anoxic inner basin. Preservation in the outer basin is reduced, reflecting more frequent recharge by oxygenated waters spilling over the outer sill into the basin. Our findings suggest the inner basin should be an optimal site for reconstruction of diatom production, with records from the outer basin providing more consistent information about offshore influence and coastal upwelling conditions over the Holocene. Estimates of diatom abundance within the inner basin sediment may serve as a good proxy of production, although proxy tracers of bottom water conditions and sedimentological analyses must be coupled to the diatom record to ensure depositional conditions were not influencing valve preservation or abundance. Our results suggest that fjords can serve as good environments for paleoceanographic reconstructions of both inshore and offshore conditions although careful site selection and understanding of processes affecting the microfossil record are essential. 相似文献
9.
A new late Katian (Late Ordovician) trilobite association is documented from the Daduhe Formation in Zhenxiong, northeastern Yunnan, including 17 species of 15 genera, among which four species ( Malongullia sinensis, M. zhenxiongensis, Taklamakania paucisegmentatus and Amphitryon constrictus) are new. Lithologic and faunal evidence enables the recognition of a new association with medium diversity, named the Taklamakania Association. It is a typical representative of the Raphiophorid Community that lived in a deep subtidal environment close to the anoxic basin. A total of five trilobite ecological associations were found to occur in South China during the late Katian, in relation to the environmental gradients ranging from shallow subtidal zone, deep subtidal zone, slope to dysoxic shaly basin. 相似文献
10.
Observations were made on the development and distribution of phytoperiphyton communities in 66 lake-river systems in NW Russia
from Lake Ladoga to the Barents Sea. In total, 130 genera and 648 species were identified from different substrates, belonging
to Cyanophyta (19.1%), Bacillariophyta (59.6%), Chlorophyta (18.7%), and algae from other orders (2.6%). In all streams diatoms dominated by species richness, but they were surpassed
by green algae in terms of biomass. The green algae ranged from small planktonic forms to large filamentous species and produced
easily visible algal communities. Among the planktonic forms the desmids were the most diverse group. They occurred in attached
communities of all rivers and, while never abundant, were widespread. The attached community’s biomass was dominated by green
algae. Among these, the filamentous algae Mougeotia sp., Oedogonium sp., Zygnema sp., Spirogyra sp. and Ulothrix zonata exhibited mass development in streams. Their distribution was patchy in the basin, with a total cover varying from less than
1% to 90% of the stream bottom. In some river stretches the diversity and predominance of green algae could be due, in part,
to poorly developed riparian canopies.
The term periphyton adopted here follows the definition of Odum (1971): “Assemblages which include both plant and animal organisms
growing attached to submerged objects”. The prefix phyto- is added to indicate that of the whole biocoenoses only phototrophs
are considered in this study.
Presented at the International Symposium Biology and Taxonomy of Green Algae V, Smolenice, June 26–29, 2007, Slovakia. 相似文献
11.
Arbuscular mycorrhizal (AM) fungi on Japanese semi-natural grasslands were investigated at three adjacent sites with different
vegetation. The predominant grasses at the three sites were 1) Pleioblastus chino, 2) Miscanthus sinensis and Arundinella hirta (M. sinensis/A. hirta), and 3) Zoysia japonica, respectively. The degree of colonization was higher in M. sinensis/A. hirta than in P. chino and Z. japonica. AM fungi were recovered by spore extraction and by pot cultures started from soil inoculum or from transplanting of field
plants. Total spore number obtained by the spore extraction method was highest in the rhizosphere of M. sinensis/A. hirta and lowest in that of P. chino. A Glomus sp. resembling G. geosporum predominated in association with M. sinensis/A. hirta and P. chino. From Z. japonica, three species, Acaulospora gerdemannii, Glomus leptotichum, and a species resembling G. clarum, were isolated by pot culture from soil and two species, A. longula and Scutellospora cerradensis, by pot culture from transplanting of Z. japonica. From M. sinensis/A. hirta, one species, A. longula, was found by pot culture from soil. From P. chino, no AM fungus was detected by either method. Single-spore culture confirmed that G. leptotichum and A. gerdemannii are conspecific. 相似文献
12.
The terrestrial small mammal community of the Zakouma National Park (Chad) was assessed by live trapping in various habitats
during the dry season. Nearly 3000 trap-nights yielded 505 captures of nine rodent and two shrew species, making up a representative
small mammal community for the Sudanian savanna biotic zone. Murine rodents of the genus Mastomys dominated, with M. erythroleucus and M. cf. kollmannspergeri occuring at similar abundances. The former was widespread and especially abundant in habitats with high tree cover. The latter
was more localized, predominantly in annually flooded habitats characterized by a clay-rich soil, often with Acacia seyal as the main vegetation. Population structure differed between the two species, suggesting distinct reproductive strategies
possibly linked with habitat preferences: the M. erythroleucus population comprised mainly young, immature individuals, whereas M. cf. kollmannspergeri was represented by older individuals, a significant fraction of which had already reproduced. Taterillus congicus and Tatera kempi (gerbilline rodents), together with Lemniscomys zebra, were mainly found in more open habitats with sand-rich soils. Arvicanthis niloticus, Acomys cf. johannis, Mus mattheyi and Xerus erythropus were the other rodents captured, whereas shrews were represented by Crocidura fulvastra and Suncus sp. 相似文献
13.
The macroalgal communities associated with pneumatophores, basal area of tree trunks and sediment surface in the mangrove forest at Sementa, Selangor consisted of nine main species. Biomass, frequency of occurrence and relative cover of the species along a belt transect, showed two major trends, a decrease in these parameters in the landward direction for Colpomenia sp. Gracilaria blodgettii and Gracilaria crassa and an increase in the landward direction for Dictyota dichotoma, Catenella nipae, Rhizoclonium sp. and Bostrichia radicans. Algal dominance varied with substratum. Pneumatophores were dominated by Caloglossa lepreurii and sediment surface by D. dichotoma. The 40 cm zone at the base of tree trunks was dominated by two algal species. The 0–20 cm region above the sediment surface was colonized by C. nipae, while the 20–40 cm region was dominated by Rhizoclonium sp. The study identified the importance of substrate in macroalgal colonization. 相似文献
14.
Forest communities dominated by Picea jezoensis (Yezo spruce) are described from across their entire distributional range in eastern Asia, including the territories of the Russian Far East and Japan. A total of 476 relevés are used representing the following dominant types of spruce forests: pure P. jezoensis, mixed P. jezoensis and Abies sachalinensis, mixed P. jezoensis and Abies nephrolepis, and pure Picea glehnii communities. The vegetation is classified into 11 associations, 2 community types, 6 subassociations, 25 variants and 8 subvariants. Nine associations, including the Asaro heterotropoidis-Abietetum sachalinensis, Weigelo middendorffianae-Piceetum jezoensis, Lysichito-Piceetum glehnii, Swido albae-Piceetum obovatae, Oplopanaco elati-Piceetum jezoensis, Philadelpho tenuifolii-Piceetum jezoensis, Vaccinio-Piceetum jezoensis, Rhododendro aurei-Piceetum jezoensis, and Moneseto uniflorae-Piceetum jezoensis, are described for the first time. The ecology and structure of all communities are described and their syntaxonomy discussed. The communities are placed in three alliances, Piceion jezoensis, Abieti nephrolepidis-Piceion jezoensis and Pino pumilae-Piceion jezoensis, all. nov. All of the communities described are considered to belong to the order Abieti-Piceetalia of the class Vaccinio-Piceetea. 相似文献
15.
Twenty‐seven species of well‐preserved and abundant Early Cretaceous non‐marine ostracod crustaceans were recovered from the North Falkland Basin. The assemblage is unusually diverse for a non‐marine palaeoenvironment and is sourced from cuttings samples collected during 2011 drilling of wells by Desire and Rockhopper Exploration, in the northern and southern areas of the basin. Ostracoda are entirely undocumented in published accounts from this basin, and all but one species appear to be new to science. For the new taxa, one new family (Alloiocyprideidae; type genus Hourcqia) is proposed and includes Hourcqia woodi sp. nov. Four new genera are erected: Falklandicypris gen. nov.; type species F. petrasaltata sp. nov., Gangamoncythere gen. nov.; type species G. colini sp. nov., Paraplesiocypridea gen. nov.; type species P. alloios sp. nov., and Musacchiocythere gen nov.; type species M. sarunata (Musacchio, 1978 ). Nine other species are described as new and are Falklandicypris desiderata, Clinocypris epacrus, Cypria poietes, Ilhasina? leiodermatus, Looneyellopsis tuberculatus, Theriosynoecum petasmathylacus, Theriosynoecum ballentae, Timiriasevia fluitans, and Vecticypris samesi. The remainder are left in open nomenclature due to paucity of material. The ostracod assemblage is largely restricted to the southern part of the basin (wells 25/5‐1 and 26/6‐1). In the northern part of the basin only four species, dominated by Vecticypris samesi, are present and with one possible exception are restricted there. There appears to have been little or no interchange of species suggesting that a barrier probably existed between the northern and southern regions. The more diverse southern assemblage indicates that more favourable conditions existed to the south. Stratigraphically, a distinct change in faunal composition recorded in both southern wells is likely to be an isochronous event correlatable across the southern area, and of an age no younger than Hauterivian. 相似文献
16.
The arbuscular mycorrhizal (AM) status of two plant communities on a calamine spoil mound (rich in cadmium, lead and zinc)
in southern Poland was surveyed: an undisturbed grassland community and an early succession community that developed after
complete removal of the surface layer of the calamine substrate about 10 years earlier. The undisturbed site harbored 40 herbaceous
species making up 87% of the absolute cover. AM colonization was recorded in 25 species accounting for 77% of the relative
cover. Species with 51–75% AM root colonization such as Festuca ovina and Leontodon hispidus dominated the undisturbed turf, contributing 45% to the relative cover. Carex ssp. were the most abundant nonmycorrhizal plants and accounted for 9% of the relative cover. Spores of Glomus aggregatum, G. constrictum, G. fasciculatum, G. pansihalos, Glomus sp. and Entrophospora sp. averaged 25 per 100 g dry substrate at the undisturbed site. The disturbed site was colonized by 25 species accounting
for 17% of the absolute cover. Among the AM plants, most abundant were the species with up to 20% AM root colonization, such
as Agrostis stolonifera and Thymus pulegioides, wich accounted for 24% of the relative cover. Nonmycorrhizal species, such as Biscutella laevigata,
Cardaminopsis arenosa, Gypsophila fastigiata and Silene vulgaris, dominated the early succession community and contributed 64% to the relative cover. Spores of G. fasciculatum and Entrophospora sp. averaged 20 per 100 g dry substrate at the disturbed site.
Accepted: 29 November 1996 相似文献
17.
A study was conducted to determine whether colonization of legume roots and nodulation by Rhizobium meliloti and Bradyrhizobium japonicum could be enhanced by using inocula containing microorganisms that produce antibiotics suppressing soil or rhizosphere inhabitants
but not the root-nodule bacteria. An antibiotic-producing strain of Pseudomonas and one of Bacillus were isolated, and mutants
of R. meliloti and B. japonicum sp. resistant to the antibiotics were used. The colonization of the alfalfa rhizosphere and nodulation by R. meliloti were enhanced by inoculation of soil with Pseudomonas sp. in soil initially containing 2.7×10 5
R. meliloti per g. The colonization of soybean roots by B. japonicum was enhanced by inoculating soil with three cell densities of Bacillus sp., and nodulation was stimulated by Bacillus sp. added at two cell densities. In some tests, the dry weights of soybeans and seed yield increased as a result of these
treatments, and co-inoculation with Bacillus also increased pod formation. Inoculation of seeds with Bacillus sp. and the root-nodule bacterium enhanced nodulation of soybeans and alfalfa, but colonization by B. japonicum and R. meliloti was stimulated only during the early period of plant growth.
Studies were also conducted with Streptomyces griseus and isolates of R. meliloti and B. japonicum resistant to products of the actinomycete. Nodulation of alfalfa by R. meliloti was little or not affected by the actinomycete alone; however, both nodulation and colonization were enhanced if the soil
was initially amended with chitin and S. griseus was also added. Chitin itself did not affect R. meliloti. Treatments of seeds with chitin or S. griseus alone did not enhance colonization of alfalfa roots by R. meliloti or soybean roots by B. japonicum, but the early colonization of the roots by both bacterial species was promoted if the seeds received both chitin and S. griseus; this treatment also increased nodulation and dry weights of alfalfa and soybeans and the N content of alfalfa. It is suggested
that co-inoculation of legumes with antibiotic-producing microorganisms and root-nodule bacteria resistant to those antibiotics
is a promising means of promoting nodulation and possibly nitrogen fixation. 相似文献
18.
The yeast communities from necrotic tissues, decaying flowers and fruits, and from larval feeding sites of the moth Sigelgaita sp. in the cactus Pilosocereus arrabidae were surveyed in three restinga ecosystems in Southeastern Brazil. Insects associated with these substrates were sampled to verify the vectoring of yeasts. The cactus Pilosocereus arrabidae was shown to have four different yeast communities associated with it. Necrotic stems had a diverse yeast community with the prevalent species Pichia barkeri, Candida sonorensis, Pichia cactophila, Geotrichum sp., Myxozyma mucilagina and Sporopachydermia sp. A, representing about 80% of the total isolates. Pichia sp. A and a Candida domercqii-like species represented more than 90% of the yeast isolates from decaying flowers. Fruits had a heterogeneous yeast community with typical fruit yeasts of the genus Kloeckera, basidiomicetous anamorphs of the genus Cryptococcus, the black yeast Aureobasidium pullulans, Pichia sp. A, a Candida domercqii-like species, and some cactophilic yeasts, especially Clavispora opuntiae. The feeding site of Sigelgaita sp. larvae had Clavispora opuntiae as the prevalent species. Insect vectors are suggested as one the most important factors influencing the composition of these yeast communities. 相似文献
19.
Summary This study presents sedimentological and micropaleontological data on ostracods from a cold-temperate inner shelf setting
in the Troms District, northern Norway. The coarse fraction analyses carried out on sediment surface samples from coastal
platforms and adjacent outer fjord troughs reveal a considerable contribution from ostracods to the accumulation of skeletal
carbonates in distinct depositional settings. Ostracod accumulation is highest along wave-sheltered areas of coastal platforms
where fleshy seaweed and coralline algal communities thrive in 10 to 30 m water depth. Current-exposed slopes of outer fjord
troughs show a highly mixed ostracod assemblage consisting of imported species from the shallow coastal platform which is
mixed with the trough assemblage. The hydrodynamic transport of ostracods into deeper areas results from the strong tidal
current regime. Because of this mixing process, only the end members, the coastal platform and the fjord trough assemblages
can be defined. The former is characterized by Baffinicythere emarginata, Cythere lutea, Finmarchinella angulata, Hemicytherura clathrata, Robertsonites tuberculatus, Sclerochilus
rudjakovi, Semicytherura undata and Xestoleberis cf. depressa. The outer fjord trough assemblage is characterized by Cluthia cluthae, Cytherella abyssorum, Cytheropteron alatum, Krithe cf. adelspergi, Muellerina abyssicola, Cytherella cf. vulgatella and Cytheropteron testudo. Members of the northern Norwegian trough assemblage are known to occur in deeper open shelf environments of the NE-Atlantic. 相似文献
20.
Sedimentary environments in the Arctic are known to harbor diverse microbial communities playing a crucial role in the remineralization of organic matter and associated biogeochemical cycles. In this study, we used a combination of culture-dependent and culture-independent approaches to understanding the bacterial community composition associated with the sediments of a terrestrial versus fjord system in the Svalbard Arctic. Community-level metabolic profiling and growth response of retrieved bacterial isolates towards different carbon substrates at varying temperatures were also studied to assess the metabolic response of communities and isolates in the system. Bacterial species belonging to Cryobacterium and Psychrobacter dominated the terrestrial and fjord sediment retrievable fraction. Amplicon sequencing analysis revealed higher bacterial diversity in the terrestrial sediments (Shannon index; 8.135 and 7.935) as compared to the fjord sediments (4.5–5.37). Phylum Proteobacteria and Bacteroidetes dominated both terrestrial and fjord sediments. Phylum Verrucomicrobia and Cyanobacteria were abundant in terrestrial sediments while Epsilonbacteraeota and Fusobacteriia dominated the fjord sediments. Significant differences were observed in the carbon substrate utilization profiles between the terrestrial and fjord sediments at both 4 °C and 20 °C incubations (p?<?0.005). Utilization of N-acetyl-D-glucosamine, D-mannitol and Tween-80 by the sediment communities and bacterial isolates from both systems, irrespective of their temperature incubations implies the affinity of bacteria for such substrates as energy sources and for their survival in cold environments. Our results suggest the ability of sediment bacterial communities to adjust their substrate utilization profiles according to condition changes in the ecosystems and are found to be less influenced by their phylogenetic relatedness. 相似文献
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