共查询到20条相似文献,搜索用时 15 毫秒
1.
Sten-Åke Wängberg Kristin I.M. Andreasson Thomas Reinthaler 《Journal of experimental marine biology and ecology》2008,365(2):156-163
The effect of ambient ultraviolet radiation on microplankton communities in an Arctic fjord was measured in mesocosms incubated for 9 days at 2 or 5 meters depth. The mesocosms were either shielded from UV-B radiation by Mylar foil or received full radiation. The parameters measured were: microscopic counts of phytoplankton and micro-zooplankton, photosynthetic capacity, the wavelength-dependent inhibition of photosynthesis, and bacterial biomass and production. The results showed that UV-B radiation increased the photosynthetic capacity of the community but that the overall biomass of the plankton community was reduced. This indicates that UV-B exposure results in a net impairment of the plankton community in that it reduces the potential to allocate the photosynthetic product into new biomass or that the grazing pressure is higher in the UV-B exposed mesocosms. There were no differences in the wavelength dependence between communities exposed to UV-B versus not, but we observed a significantly lower dependence in communities from 2 m depth compared to those from 5 m, indicating that an acclimation of the photosynthetic apparatus to high radiation also reduces the wavelength dependence. A general effect was an increase in nanoflagellate and choanoflagellate biomass and a decreased in the biomass of ciliates and bacteria. The increase nanoflagellates was significantly larger in mesocosms shielded from UV-B, while choanoflagellates increased more in UV-B exposed mesocosms. 相似文献
2.
The benthic infauna and benthic respiration off the Banc d'Arguin (Mauritania,Northwest Africa) 总被引:3,自引:3,他引:0
In May 1988, a study was made of the benthic community structure and benthic respiratory activity along two transects across the Mauritanian shelf off Banc d'Arguin. The main emphasis of the present paper is put on the macrobenthos, but results of a gross analysis of the meibenthos are discussed as well. Macrofaunal and meiofaunal density showed no consistent decrease with distance from the shore. The composition of the macrofauna taxa appeared to be closely correlated with sediment parameters and less so with depth. The highest macrofaunal biomass was found at the northern edge of the Banc d'Arguin, and the lowest biomass along the outer shelf. The biomass levels on the shelf match the ones reported for the northern Cap Blanc area where, in contrast to the seasonal upwelling in the investigated area, upwelling takes place all year round.Benthic respiration rates on the offshore shelf were relatively high at the nearshore stations and low near the shelf break. Experimental evidence suggests that the low O2 levels in the upwelling water covering part of shelf, inhibited benthic respiration. The high respiratory activity at some northern inshore stations coincided with the presence of oxygen-rich coastal water. In this area benthic respiration surpassed the level previously reported for the enriched Cap Blanc area. On the basis of our respiration data, an estimate is made of the total carbon demand of the benthic community on the shelf in May and this quantity is compared with the measurements of daily primary production. 相似文献
3.
Nemova N. N. Pekkoeva S. N. Voronin V. P. Ruokolainen T. R. Falk-Petersen S. Berge J. Murzina S. A. 《Doklady. Biochemistry and biophysics》2021,501(1):429-433
Doklady Biochemistry and Biophysics - A comparative study of lipid profile of the daubed shanny Leptoclinus maculatus postlarvae from fjords of different domains (arctic-boreal Kongsfjord and... 相似文献
4.
We conducted a year-round mesozooplankton study in the Arctic Kongsfjord from August 1998 until July 1999 to investigate seasonal abundance and vertical as well as stage distributions of the prevalent taxa. It is the first investigation in Kongsfjord that covers the Arctic winter season and provides reasonable estimates also of small-sized copepod species. Abundant smaller copepods comprised Oithona similis, Pseudocalanus minutus, Microcalanus spp., Triconia borealis and Acartia longiremis. Among the larger copepods, Calanus finmarchicus, C. glacialis, C. hyperboreus and Metridia longa dominated. The thecosome pteropod Limacina helicina was also an important component. Abundance maxima occurred in November (988,669 ind. m?2) with one to two orders of magnitude higher numbers as compared to all other months (39,832–200,067 ind. m?2). The summers of 1998 and 1999 were characterized by intrusions of Atlantic water, but the community was not entirely dominated by advected boreal species. During winter, the majority of the mesozooplankton occurred below 100 m. Advection is the most likely reason for the accumulation of zooplankton at depth in winter, but local production may also contribute to high overwintering numbers. Much lower abundances of most species in spring suggest high winter mortality and emphasize the importance of sufficient reproductive success during the previous summer to ensure enough winter survivors as seed stock for the coming reproductive season. This study was conducted prior to the recent warming trend in the Arctic. Therefore, it provides valuable baseline data and allows comparing present and future states of the zooplankton community in Kongsfjord. 相似文献
5.
The bottom fauna (16–30 m depth) of Kongsfjord (Svalbard) was investigated by direct observation, a SCUBA-diver operated
suction sampler (quantitative) and underwater photography (semi-quantitative). The fauna on horizontal surfaces showed low
similarity to that on vertical faces and overhangs, and had larger species heterogeneity between sampling sites. This was
due to sedimentation and ice-rafted pebbles and stones creating “soft-bottom habitats” on the rocky bottom. Suction sampling
resulted in collection of 73 taxa, including some species usually regarded as “soft-bottom” inhabitants. Fewer species were
observed on the photographs, demonstrating the selectivity of this technique, but underwater photography may be a useful “non-destructive”
method for obtaining information about conspicuous epifaunal taxa.
Accepted: 18 July 2000 相似文献
6.
In general, biodiversity and species richness follow the latitudinal diversity gradient and decrease from the tropics towards
the poles. Exceptions have however been recorded, as for deep coldwater coral reefs at high latitudes, which comprise biodiversity
hotspots. Here we assess and characterise the high-latitude (69°N) species richness and diversity of a local shallow-water
fauna associated with small calcareous aggregations of a serpulid polychaete. A dense and very species rich fauna was recorded
within aggregations of Filograna implexa Berkeley, 1828. Totally 4663 individuals belonging to 99 species (61 solitary, 38 colonial) were recorded in a total aggregation
volume of only 4.4 l covering an area less than 0.05 m2 of a wreck situated in a tidal stream in North Norway. The number of species within each aggregation was positively related
to its size, indicating that the high species diversity may be due to structural heterogeneity, which increase with aggregation
size and probably creates new microhabitats and protect against predation. We present a species list including abundance and
biomass, pin-point common species and describe a method for sampling such faunas associated with calcareous structures. 相似文献
7.
The composition and ecological role of ciliates and dinoflagellates were investigated at one station in Kongsfjorden, Svalbard,
during six consecutive field campaigns between March and December 2006. Total ciliate and dinoflagellate abundance mirrored
the seasonal progression of phytoplankton, peaking with 5.8 × 104 cells l−1 in April at an average chlorophyll a concentration of 10 μg l−1. Dinoflagellates were more abundant than ciliates, dominated by small athecates. Among ciliates, aloricate oligotrichs dominated
the assemblage. A large fraction (>60%) of ciliates and dinoflagellates contained chloroplasts in spring and summer. The biomass
of the purely heterotrophic fraction of the ciliate and dinoflagellate community (protozooplankton) was with 14 μg C l−1 highest in conjunction with the phytoplankton spring bloom in April. Growth experiments revealed similar specific growth
rates for heterotrophic ciliates and dinoflagellates (<0–0.8 d−1). Food availability may have controlled the protozooplankton assemblage in winter, while copepods may have exerted a strong
control during the post-bloom period. Calculations of the potential grazing rates of the protozooplankton indicated its ability
to control or heavily impact the phytoplankton stocks at most times. The results show that ciliates and dinoflagellates were
an important component of the pelagic food web in Kongsfjorden and need to be taken into account when discussing the fate
of phytoplankton and biogeochemical cycling in Arctic marine ecosystems. 相似文献
8.
Barbara Urban-Malinga Jozef Wiktor Aleksandra Jabłońska Tom Moens 《Polar Biology》2005,28(12):940-950
Meiofauna communities of four intertidal sites, two sheltered and two more exposed, in Kongsfjorden (Svalbard) were investigated
in summer 2001 at two different tidal levels (i.e. the low-water line and close below the driftline, referred to as mid-water
(MW) level). A total of seven meiofaunal higher taxa were recorded with nematodes, oligochaetes and turbellarians being numerically
dominant. Mean total meiofaunal densities ranged between 50 ind. 10 cm−2 and 903 ind. 10 cm−2. Our data showed a clear decrease in total meiofaunal densities with increasing coarseness of the sediment. Total meiofaunal
biomass varied from 0.2 g dwt m−2 to 2 g dwt m−2 and, in general, was high even at low meiofaunal densities, i.e. larger interstitial spaces in coarser sediments supported
larger meiofauna, especially turbellarians. The results on the vertical distribution of meiofauna contrasted sharply with
typical meiobenthic depth profiles on other beaches, probably in response to ice-scouring and concomitant salinity fluctuations.
Oligochaetes were the most abundant taxon, with a peak density of 641 ind. 10 cm−2 at Breoyane Island. They were mainly comprised of juvenile Enchytraeidae, which prohibited identification to species/genus
level. Nematode densities ranged between 4 ind. 10 cm−2 and 327 ind. 10 cm−2. Nematodes were identified up to genus level and assigned to trophic guilds. In total, 28 nematode genera were identified.
Oncholaimus and Theristus were the most abundant genera. The composition of the nematode community and a dominance of predators and deposit feeders
were in agreement with results from other arctic and temperate beaches. Nematode genus diversity was higher at the more sheltered
beaches than at the more exposed ones. Low-water level stations also tended to harbour a more diverse nematode communities
than stations at the MW level. Differences in nematode community structure between low- and MW stations of single beaches
were more pronounced than community differences between different beaches and were mainly related to resources quality and
availability. 相似文献
9.
The endemic avifauna of Wallacea is of high conservation significance, but remains poorly studied. Identifying priority conservation areas requires a greater understanding of the habitat associations of these bird communities, and of how spatial scale of analysis can influence the interpretation of these associations. This study aims to determine which proxy habitat measures, at which spatial scales of analysis, can provide useful inferential data on the composition of Wallacean forest avifauna. Research was conducted within the Lambusango forest reserve, South-East Sulawesi, using point count surveys to sample avifauna. Habitat properties were characterised in three ways: broad classification of forest type, canopy remotely-sensed response derived from satellite imagery, and in situ measures of vegetation composition and structure. Furthermore, we examined avifauna–habitat relationships at three spatial scales: area (c.400 ha per sample site), transect (c.10 ha) and point (c.0.2 ha). Results demonstrate that broad forest type classifications at an area scale can help to determine conservation value, indicating that primary and old secondary forests are important for supporting many species with lower ecological tolerances, such as large-bodied frugivores. At the transect-scale, significant congruence occurs between bird community composition and several habitat variables derived from vegetation sampling and satellite imagery, particularly tree size, undergrowth density, and Normalised Difference Vegetation Index (NDVI) values; this highlights the importance small scale habitat associations can have on determining α-diversity. Analysis at the point-scale was ineffective in providing proxy indications for avifauna. These findings should be considered when determining future priority conservation areas for Wallacean avifauna. 相似文献
10.
Temporal dynamics of the microbial food web in the Barents Sea and adjacent water masses in the European Arctic are to a large
extent unknown. Seasonal variation in stocks and production rates of heterotrophic bacteria and phototrophic and heterotrophic
picoplankton and nanoflagellates was investigated in the upper 50 m of the high-latitude Kongsfjorden, Svalbard, during six
field campaigns between March and December 2006. Heterotrophic bacteria, picoplankton and nanoflagellates contributed to ecosystem
structure and function in all seasons. Activity within the microbial food web peaked during spring bloom in April, parallel
to low abundances of mesozooplankton. In the nutrient-limited post-bloom scenario, an efficient microbial loop, fuelled by
dissolved organic carbon from abundant mesozooplankton feeding on phytoplankton and protozooplankton, facilitated maximum
integrated primary production rates. A tight microbial food web consisting of heterotrophic bacteria and phototrophic and
heterotrophic picoplankton and nanoflagellates was found in the stratified water masses encountered in July and September.
Microbial stocks and rates were low but persistent under winter conditions. Seasonal comparisons of microbial biomass and
production revealed that structure and function of the microbial food web were fundamentally different during the spring bloom
when compared with other seasons. While the microbial food web was in a regenerative mode most of the time, during the spring
bloom, a microbial transfer mode represented a trophic link for organic carbon in time and space. The microbial food web’s
ability to fill different functional roles in periods dominated by new and regenerated production may enhance the ecological
flexibility of pelagic ecosystems in the present era of climate change. 相似文献
11.
Aim Pockmarks are craters on the sea floor formed by sub‐sea‐floor fluid expulsions, which occur world‐wide at all ocean depths. These habitats potentially host a highly specialized fauna that can exploit the hydrocarbons released. Pockmarks at relatively shallow depths can be easily destroyed by human activities, such as bottom trawling. In the present study, we investigated the combined effects of sea‐floor heterogeneity, rate of fluid emission and trophic conditions of different pockmarks on the biodiversity of the deep‐sea assemblages. Location Continental slope of the Gulf of Lions, western Mediterranean Sea, at water depths from 265 to 434 m. Methods We investigated the biodiversity associated with sea‐floor pockmarks that are both inactive and that have active gas emissions. Control sites were selected on the sea floor outside the influence of the gas seepage, both within and outside the pockmark fields. We examined the combined effects of: (i) sea‐floor heterogeneity; (ii) variable levels of fluid (gas) emissions; and (iii) trophic characteristics of the meiofaunal assemblage structure and nematode diversity. Results Sediments within the pockmark fields had lower meiofaunal abundance and biomass when compared with the surrounding sediments that were not influenced by the gas seepage. Although several higher taxa were absent in the pockmarks (e.g. Turbellaria, Tardigrada, Cumacea, Isopoda, Tanaidacea, Nemertina and Priapulida, which were present in the control areas), the richness of the nematode species within all of these pockmarks was very high. About 25% of the total species encountered in the deep‐sea sediments of the investigated areas was exclusively associated with these pockmarks. Main conclusions We conclude that both active and inactive pockmarks provide significant contributions to the regional (gamma) diversity of the continental slope in the western Mediterranean Sea, and thus the protection of these special and fragile habitats is highly relevant to the conservation of deep‐sea biodiversity. 相似文献
12.
Yihao Ge Chengxing Xia Jun Wang Xiujie Zhang Xufa Ma Qiong Zhou 《Ecology and evolution》2021,11(10):5669
Macroinvertebrates have been recognized as key ecological indicators of aquatic environment and are the most commonly used approaches for water quality assessment. However, species identification of macroinvertebrates (especially of aquatic insects) proves to be very difficult due to the lack of taxonomic expertise in some regions and can become time‐consuming. In this study, we evaluated the feasibility of DNA barcoding for the classification of benthic macroinvertebrates and investigated the genetic differentiation in seven orders (Insecta: Ephemeroptera, Plecoptera, Trichoptera, Diptera, Hemiptera, Coleoptera, and Odonata) from four large transboundary rivers of northwest China and further explored its potential application to biodiversity assessment. A total of 1,144 COI sequences, belonging to 176 species, 112 genera, and 53 families were obtained and analyzed. The barcoding gap analysis showed that COI gene fragment yielded significant intra‐ and interspecific divergences and obvious barcoding gaps. NJ phylogenetic trees showed that all species group into monophyletic species clusters whether from the same population or not, except two species (Polypedilum. laetum and Polypedilum. bullum). The distance‐based (ABGD) and tree‐based (PTP and MPTP) methods were utilized for grouping specimens into Operational Taxonomic Units (OTUs) and delimiting species. The ABGD, PTP, and MPTP analysis were divided into 177 (p = .0599), 197, and 195 OTUs, respectively. The BIN analysis generated 186 different BINs. Overall, our study showed that DNA barcoding offers an effective framework for macroinvertebrate species identification and sheds new light on the biodiversity assessment of local macroinvertebrates. Also, the construction of DNA barcode reference library of benthic macroinvertebrates in Eurasian transboundary rivers provides a solid backup for bioassessment studies of freshwater habitats using modern high‐throughput technologies in the near future. 相似文献
13.
Temporal patterns of benthic community development in an Arctic fjord (Kongsfjorden, Svalbard): results of a 24-year manipulation study 总被引:1,自引:1,他引:0
We investigated temporal patterns of recolonisation and disturbance in a benthic hard bottom community in high-arctic Kongsfjorden
from 1980 to 2003 through annual photographic surveys. A manipulative sampling design was applied, where half of the study
area (treatment areas) was cleared at the beginning of the study. Twenty-three different taxa and groups of benthic epifauna
were found in the photographs. The benthic community structures of treatments and controls converged within the first decade,
but significant differences prevailed until ≤13 years after the start of the study. We could distinguish between three different
time intervals with increased inter-annual changes. While the observed differences during the first two intervals could be
attributed to recolonisation and succession, the changes in interval 3 were mostly due to increased external forcing and characterised
by low inter-group and high inter-annual differences. During this interval, brown algae (mainly Desmarestia) and the sea urchin Strongylocentrotus droebachiensis emerged in high densities, while sea anemone populations declined. Different recolonisation patterns for individual species
were related to life span, rate of maturity, predators and larval settlement. We could not find a climax stage in the succession
for the benthic community at Kvadehuken, presumably due to the constant level of disturbances at the site. 相似文献
14.
Benthic macroinvertebrates collected in biomonitoring programs are a potentially valuable source of biodiversity information
for conservation planning in river ecosystems. Biomonitoring samples often focus on riffles; however, we have only partially
assessed the extent to which riffle biodiversity patterns reflect those of other river habitats, particularly riverine wetlands.
Using a standard biomonitoring protocol, we assessed the richness, composition and magnitude of variation of macroinvertebrate
assemblages in riffles across 18 sites in the Nashwaak river catchment, and compared these to samples from adjacent riverine
wetlands. Despite containing on average fewer taxa per site than riffles, riverine wetlands demonstrated similar levels of
taxon richness at the catchment scale. There was strong assemblage separation between habitat types, and riverine wetlands
displayed significantly greater assemblage variation than riffles. Riffles and riverine wetlands did not demonstrate significant
correlations in terms of taxon richness or assemblage variation, though this may be partially due to the scale at which we
collected observations. Principal component analysis with vector fitting suggested that (log) sub-catchment area was an important
factor structuring riffle assemblages, while depth was potentially important for riverine wetland assemblages. We discuss
the implications of these results for the use of biomonitoring data in systematic conservation planning, and identify future
research that will improve our understanding of the role riverine wetlands play in maintaining catchment biodiversity and
ecosystem processes. 相似文献
15.
Exponential decline of deep-sea ecosystem functioning linked to benthic biodiversity loss 总被引:7,自引:0,他引:7
Danovaro R Gambi C Dell'Anno A Corinaldesi C Fraschetti S Vanreusel A Vincx M Gooday AJ 《Current biology : CB》2008,18(1):1-8
BACKGROUND: Recent investigations suggest that biodiversity loss might impair the functioning and sustainability of ecosystems. Although deep-sea ecosystems are the most extensive on Earth, represent the largest reservoir of biomass, and host a large proportion of undiscovered biodiversity, the data needed to evaluate the consequences of biodiversity loss on the ocean floor are completely lacking. RESULTS: Here, we present a global-scale study based on 116 deep-sea sites that relates benthic biodiversity to several independent indicators of ecosystem functioning and efficiency. We show that deep-sea ecosystem functioning is exponentially related to deep-sea biodiversity and that ecosystem efficiency is also exponentially linked to functional biodiversity. These results suggest that a higher biodiversity supports higher rates of ecosystem processes and an increased efficiency with which these processes are performed. The exponential relationships presented here, being consistent across a wide range of deep-sea ecosystems, suggest that mutually positive functional interactions (ecological facilitation) can be common in the largest biome of our biosphere. CONCLUSIONS: Our results suggest that a biodiversity loss in deep-sea ecosystems might be associated with exponential reductions of their functions. Because the deep sea plays a key role in ecological and biogeochemical processes at a global scale, this study provides scientific evidence that the conservation of deep-sea biodiversity is a priority for a sustainable functioning of the worlds' oceans. 相似文献
16.
This paper focuses on the difference between the value of some commonly used diversity indices (Simpson, Shannon, abundance, richness) calculated from benthic grab samples and their value in the population or region from which the samples are taken. The ability of the sample indices, as well as a recently derived relative Shannon index, to reflect change in biodiversity is examined in a short simulation study based on changing one of the diversity parameters (abundance, richness and evenness) in the population, whilst keeping the other two components constant. Our results suggest that, whilst their population equivalents do not always reflect biodiversity changes, the sample Simpson, Shannon and Richness indices perform well. We note that this will be true for any surveys where the sampling programme fails to detect many species in a population, and hence will be applicable for most benthic surveys. The use of sample indices to detect changes in biodiversity from long-running time series in the Thames and Tyne estuaries is illustrated. 相似文献
17.
Spatial patterns and ecology of benthic communities on a high-latitude South Florida (Broward County,USA) reef system 总被引:1,自引:0,他引:1
High-latitude reef communities consisting of typical Caribbean fauna of variable composition and density exist on four parallel ridges at varying depths along the Broward County (Florida, USA) coast. Two of these ridges, at 7–13 and 15–30 m in depth, are drowned early Holocene coral reefs of 5 and 7 ky uncorrected radiocarbon age. In this study, community data were collected on each reef using 50-m, line-intercept transects. Using multivariate non-metric statistics, the data show distinct differences in benthic community structure across several spatial gradients. Diversity indices revealed that while all values were low, species diversity (H) was consistent throughout the county, and species richness (d) and evenness (J) increased along a north-south gradient. Scleractinian coral (27 species) cover was low (<6%) in all areas, and Montastrea cavernosa dominated as the major hermatypic scleractinian. Notably absent was the major Caribbean reef-builder Acropora palmata. A rich alcyonacean fauna was present on all studied reefs, and these were typically the most important faunal group determining community structure. Although during the 2-year period 2000–2002 mean water temperatures never fell below 20 °C, scleractinia were small in size. 相似文献
18.
álvaro Luis Pe?a Cantero 《Polar Biology》2012,35(6):851-865
The Bellingshausen Sea constitutes the third largest sea in the Southern Ocean, though it is widely recognized as one of the
less-studied Antarctic areas. To reduce this lack of knowledge, a survey to study the biodiversity of its marine benthic communities
was carried out during the Bentart 2003 and Bentart 2006 Spanish Antarctic expeditions. The study of the hydroid collection has provided 27 species, belonging to ten families and
15 genera. Twenty-one out of the 27 species constitute new records for the Bellingshausen Sea, raising the total number of
known species to 37, as also do nine out of the 15 genera. Candelabrum penola, Lafoea annulata, and Staurotheca juncea are recorded for the second time. Most species belong to Leptothecata. Sertulariidae with 13 species (48%) is by far the
most speciose family, and Symplectoscyphus with seven species (26%), including S. bellingshauseni sp. nov. and S. hesperides sp. nov., the most diverse genus. Considering the whole benthic hydroid fauna of the Bellingshausen Sea, 18 species (69%)
are endemic to Antarctic waters, either with a circum-Antarctic (12 species, 46%) or West Antarctic (6 species, 23%) distribution,
23 (88%) are restricted to Antarctic or Antarctic/sub-Antarctic waters, and only three species have a wider distribution.
Bellingshausen Sea hydroid fauna is composed of a relatively high diversity of typical representatives of the Antarctic benthic
hydroid fauna, though with a surprisingly low representation of some of the most diverse and widespread Antarctic genera (Oswaldella and Schizotricha), what could be related to the fact that its shelf-inhabiting hydroid fauna remains practically unknown. 相似文献
19.
We assessed whether tributaries in upland catchments (=watersheds) affected assemblages of benthic macroinvertebrates in mainstems,
as has been reported in northern hemisphere systems. Eight confluences of small to medium streams (stream orders 1–4, 2.2–10.8 m
wide) were studied in the Acheron River basin in Victoria, Australia. For each confluence, two transects were sampled at each
of five zones relative to the confluence: two zones upstream in the mainstem, one zone upstream in the tributary, one zone
at the confluence and one zone downstream in the mainstem. Surveys were conducted in both high-flow and low-flow conditions.
In mainstems, there was no change in macroinvertebrate density, taxonomic richness or functional feeding group composition
downstream relative to upstream of the confluences. While tributaries statistically had distinctive benthic macroinvertebrate
assemblages compared to mainstems, these distinctions were small. In low flows, densities in tributaries were substantially
lower than in mainstems, but densities during high flows were more similar (albeit only about one-third as high as in low
flow) in tributaries and mainstems. An inverse pattern was evident for taxonomic richness, where richness in tributaries and
mainstems was similar in low flows but was greater in mainstems than in tributaries in high flows. We found little evidence
of tributary effects in macroinvertebrate assemblages in this basin, which is at odds with some previous results from other
continents. To explain this divergence, we suggest a conceptual model outlining factors that control variation in effects
of tributaries on assemblages of benthic macroinvertebrates in mainstems. 相似文献
20.
Ngoc-Loi Nguyen Joanna Pawłowska Inès Barrenechea Angeles Marek Zajaczkowski Jan Pawłowski 《Geobiology》2023,21(1):133-150
Arctic marine biodiversity is undergoing rapid changes due to global warming and modifications of oceanic water masses circulation. These changes have been demonstrated in the case of mega- and macrofauna, but much less is known about their impact on the biodiversity of smaller size organisms, such as foraminifera that represent a main component of meiofauna in the Arctic. Several studies analyzed the distribution and diversity of Arctic foraminifera. However, all these studies are based exclusively on the morphological identification of specimens sorted from sediment samples. Here, we present the first assessment of Arctic foraminifera diversity based on metabarcoding of sediment DNA samples collected in fjords and open sea areas in the Svalbard Archipelago. We obtained a total of 5,968,786 reads that represented 1384 amplicon sequence variants (ASVs). More than half of the ASVs (51.7%) could not be assigned to any group in the reference database suggesting a high genetic novelty of Svalbard foraminifera. The sieved and unsieved samples resolved comparable communities, sharing 1023 ASVs, comprising over 97% of reads. Our analyses show that the foraminiferal assemblage differs between the localities, with communities distinctly separated between fjord and open sea stations. Each locality was characterized by a specific assemblage, with only a small overlap in the case of open sea areas. Our study demonstrates a clear pattern of the influence of water masses on the structure of foraminiferal communities. The stations situated on the western coast of Svalbard that are strongly influenced by warm and salty Atlantic water (AW) are characterized by much higher diversity than stations in the northern and eastern part, where the impact of AW is less pronounced. This high diversity and specificity of Svalbard foraminifera associated with water mass distribution indicate that the foraminiferal metabarcoding data can be very useful for inferring present and past environmental conditions in the Arctic. 相似文献