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1.
The soil microbiota of a grassy ecosystem in the subalpine belt of the Rile Mountain National Park showed greater amounts
of fungal biomass. This remained relatively constant throughout the months of sampling while bacterial biomass was a dynamic
value fluctuating within a wide range. The two groups of microorganisms also differed in their in-depth distribution in the
soil profile: the bacterial biomass was relatively homogeneously distributed while the fungal biomass gradually decreased
with depth. Good correlation between the amount of biomass and the values of some abiotic factors of the environment was shown
by correlation analysis in a “warm” period of investigation; no distinct correlation between microbial biomass and environmental
factors was observed in a “cold” period. 相似文献
2.
Zooplankton composition and distribution were investigated on the Laptev Sea shelf, over the continental slope and in the
adjacent deep Nansen Basin during the joint German-Russian expedition “Arctic 93” with RV Polarstern and Ivan Kireyev in August/September 1993. In the shelf area biomass decreased from west to east with the lowest values in the area influenced
by the Lena river runoff. A gradual increase of biomass from the shallow to the deep area correlated with water depth. Total
biomass ranged between 0.1 and 1.5 g m−2 on the shelf and 4.7 and 7.9 g m−2 in the adjacent Nansen Basin. On the shelf Calanus glacialis/finmarchicus dominated overall. The contribution of brackish-water taxa was low in the west, where high salinity and southward currents
from the Arctic Basin supported a marine neritic community, but on the southern and eastern Laptev shelf, in the areas of
freshwater influence, brackish-water taxa contributed up to 27% of the total biomass. On the slope and in deep areas a few
large Arctic copepod species, Calanus glacialis, C. hyperboreus and Metridia longa, composed the bulk of biomass and determined the pattern of its vertical distribution. The export of Calanus species from the Nansen Basin onto the Laptev shelf appears to be of great importance for the shelf communities. In turn,
the eastern outer shelf and slope area of the Laptev Sea are thought to have a pronounced effect on the deep basin, modifying
the populations entering the central Arctic.
Received: 25 March 1997 / Accepted: 18 July 1997 相似文献
3.
Breaking the ice: large-scale distribution of mesozooplankton after a decade of Arctic and transpolar cruises 总被引:4,自引:4,他引:0
Mesozooplankton collected during five summer expeditions to the Arctic Ocean between 1987 and 1991 was analysed for regional
patterns in biomass and species distribution, distinguishing between an epipelagic (0–100 m) and a deeper (0–500 m) layer.
A total of 58 stations was sampled mainly in the Nansen, Amundsen and Makarov Basins of the central Arctic Ocean and in areas
of the Greenland Sea, West Spitsbergen Current and Barents Sea. Results from the different expeditions were combined to create
a transect extending from the Fram Strait across the Eurasian Basin into the Makarov Basin. Mesozooplankton dry mass in the
upper 500 m decreased from 8.4 g m−2 in the West Spitsbergen Current to less than 2 g m−2 in the high-Arctic deep-sea basins. In the central Arctic Ocean, biomass was concentrated in the upper 100 m and was dominated
by the large copepods Calanus hyperboreus and C. glacialis. In contrast, the mesozooplankton in the West Spitsbergen Current was more evenly distributed throughout the upper 500 m,
with C. finmarchicus as the prevailing species. The distribution of abundant mesopelagic species reflected the hydrographic regime: the calanoid
copepod Gaetanus tenuispinus and the hyperiid amphipod Themisto abyssorum were most abundant in the Atlantic inflow, while Scaphocalanus magnus was a typical component of the high-Arctic fauna. The relatively high mesozooplankton biomass and the occurrence of boreal-Atlantic
species in the central Arctic Ocean are indicators for the import of organic material from allochthonous sources, especially
from the northern North Atlantic. Hence, in spite of its enclosure by land masses, the Arctic Ocean is characterized by an
exchange of water masses and organisms with the North Atlantic, and advection processes strongly influence the distribution
of plankton species in this high-latitude ecosystem.
Received: 18 December 1997 / Accepted: 11 April 1998 相似文献
4.
Temporal changes in soil microbial biomass carbon in an arable soil. Consequences for soil sampling 总被引:2,自引:0,他引:2
Sugar beet, winter wheat and winter barley were planted within a crop rotation on an arable soil with conventional soil management.
Soil samples were taken monthly from different depths of the whole plough layer (0–10, 10–20 and 20–30 cm) during a 56 month
period. The samples were analysed for microbial biomass carbon using the substrate-induced respiration technique.
Temporal changes in the amount of microbial biomass carbon were observed. Within a year, microbial biomass-C varied from low
values (−15% of total mean) in winter to high values (+15% of total mean) in summer. Relative deviations from the annual means
were calculated for each month in the year to demonstrate these fluctuations.
Temporal changes in microbial biomass-C depended on the sources of sample variation (5 years, 3 crops, 3 sampling depths).
The highest relative deviation from the annual mean microbial biomass-C was attributable to the factor “year”. Less variations
were caused by “crops” and “sampling depth”.
Soil microbial biomass-C remained constant during frost periods. From the observed temporal changes, recommendations for a
suitable date for soil sampling are given, which allows a representative estimation of the mean annual microbial biomass-C
content in arable soils. 相似文献
5.
Phytoplankton distribution patterns are still largely unknown for the Pacific region of the Southern Ocean. Pigment distributions
were determined by HPLC on 40-m samples collected from the mixed layer during the ANTXII/4 cruise in March–May 1995 aboard
RV “Polarstern”. A transect was covered (90°W, from 51°S to 70°S), crossing the Subantarctic Front in the north, the Polar
Front, and the Southern Polar Front in the south. Coinciding with high concentrations of silicate, diatoms dominated in the
Antarctic waters south of the Polar Front. North of the Polar Front, silicate concentrations dropped to values less than 10 μM.
In this area flagellates (Prymnesiophyceae and green algae) were the dominant phytoplankton group. Nutrient depletion of the
surface waters near the Southern Polar Front indicated formerly enhanced productivity. These findings confirmed previous observations
by the British Sterna expedition, which described locally elevated chlorophyll a biomass near the southern boundary of the Southern Polar Front. We propose a role for supply of bioavailable iron via the
front, and emphasise the importance of frontal systems for phytoplankton productivity in the Southern Ocean.
Received: 11 June 1997 / Accepted: 16 November 1997 相似文献
6.
This paper is the second in a pair investigating potential mechanisms for ecological regime change in salinising wetlands.
The first paper in this series focused on the responses of the salt-tolerant submerged macrophyte community to salinity. In
this second paper, we investigated some of the environmental conditions required for initiation and dominance of benthic microbial
communities using a combination of experimental and observational data. Two experiments were carried out. One investigated
the importance of prior establishment of benthic microbial communities on their ability to maintain prevalence over macrophyte
colonisation (‘persistence’ experiment), while the other investigated hydrology and its effect on sediment perturbation, potential
nutrient release and subsequent benthic microbial community establishment (‘flooding’ experiment). The ‘persistence’ experiment
measured the biomass of benthic microbial communities and emergence of macrophytes from sediments kept either wet or dry for
4 weeks then flooded at a range of salinities. Benthic microbial biomass was similar across all of the salinities tested (15,
45 and 70 ppt), with a slight increase at higher salinities, suggesting that none of these limited benthic microbial community
development. Pre-wetting of sediments usually increased benthic microbial community biomass and reduced macrophyte germination,
but the latter was attributed to the presence of anoxic sediments rather than the increased benthic microbial community biomass.
Germinating macrophytes emerged through benthic microbial communities or dense heterotrophic bacterial blooms, demonstrating
that they could become dominant even when another community was already established. Field data supported these results, suggesting
that the development of benthic microbial communities is not limited by salinity alone, but includes other factors, such as
the water regime. In the ‘flooding’ experiment, the largest differences in nutrient concentrations ultimately lay between
the pre-wet and pre-dry treatments (due to the greater release of nutrients and development of anoxia in the latter) rather
than those subjected to fast versus slow flooding. In response to this, highest benthic microbial community biomass was in
treatments with pre-wet sediment, corresponding with lower phytoplankton biomass. 相似文献
7.
Ecosystem properties and microbial community changes in primary succession on a glacier forefront 总被引:13,自引:0,他引:13
We studied microbial community composition in a primary successional chronosequence on the forefront of Lyman Glacier, Washington,
United States. We sampled microbial communities in soil from nonvegetated areas and under the canopies of mycorrhizal and
nonmycorrhizal plants from 20- to 80-year-old zones along the successional gradient. Three independent measures of microbial
biomass were used: substrate-induced respiration (SIR), phospholipid fatty acid (PLFA) analysis, and direct microscopic counts.
All methods indicated that biomass increased over successional time in the nonvegetated soil. PLFA analysis indicated that
the microbial biomass was greater under the plant canopies than in the nonvegetated soils; the microbial community composition
was clearly different between these two types of soils. Over the successional gradient, the microbial community shifted from
bacterial-dominated to fungal-dominated. Microbial respiration increased while specific activity (respiration per unit biomass)
decreased in nonvegetated soils over the successional gradient. We proposed and evaluated new parameters for estimating the
C use efficiency of the soil microbial community: “Max” indicates the maximal respiration rate and “Acc” the total C released
from the sample after a standard amount of substrate is added. These, as well as the corresponding specific activities (calculated
as Max and Acc per unit biomass), decreased sharply over the successional gradient. Our study suggests that during the early
stages of succession the microbial community cannot incorporate all the added substrate into its biomass, but rapidly increases
its respiration. The later-stage microbial community cannot reach as high a rate of respiration per unit biomass but remains
in an “energy-saving state,” accumulating C to its biomass.
Received: 4 June 1998 / Accepted: 11 January 1999 相似文献
8.
Verena Fettinger Frans J. M. Smulders Peter Lazar Irem Omurtag Peter Paulsen 《European Journal of Wildlife Research》2010,56(6):943-947
In two surveys, thighs of a total of 137 hunted hares were tested for the presence of intramuscular shots and femur fractures,
which were detected in 42.7% and 29.2% of 274 thighs, respectively. Femur fractures were significantly associated with the
presence of intramuscular shots. In the second survey (46 hares), 92 thighs were grouped into three categories, “A” (no fractures,
no intramuscular shot), “B” (one intramuscular shot), and “C” (multiple shots and hematoma), with 49.0%, 33.6%, and 17.4%,
respectively. Category “C” was found unfit for human consumption. During 7-day storage of vacuum-packed “A” and “B” thighs,
total aerobic counts increased from initially 3.3 ± 0.3 (mean ± SD) and 4.1 ± 0.6 log cfu/g by ca. 2 log units when stored
at 3–4°C, whereas the increase was clearly <1 log unit at 0°C. In comparison to temperature, differences between “A” and “B”
category were less pronounced. Similar dynamics were observed for Enterobacteriaceae. In all categories, muscle pH values
(mean = 5.83) were similar. It is concluded that storage at temperatures of ca. 4°C, although in compliance with EU legislation,
does not afford keeping microbial contaminants in check, and thus will not preserve microbiological quality of vacuum-packed
hare meat. 相似文献
9.
The rhodophytes Hypnea cervicornis and Cryptonemia crenulata are abundant along the Brazilian coastline and are rich in nutrients. They may therefore be used as a source of protein in
shrimp diets. The aim of the present study was to test this hypothesis. The experiment was conducted in a laboratory, where
10-day-old post-larvae aged underwent 7 days of acclimation in a 1,000 L tank. They were then kept in plastic aquariums, each
containing 10 L, and 20 larvae were fed daily (10% of biomass) in four equal portions with one of four diets (five repetitions
of each) for a period of 45 days. All diets contained 30% crude protein (isoprotein) and 300 kcal 100 g−1 (isocaloric), with different percentages of seaweed powder: Diet “A” 39%; Diet “B” 26%, Diet “C” 13%, and Diet “D” without
seaweed (control diet). Algae were collected, rinsed, dried and ground up for the feed formulations. Weight of the animals
was measured at the beginning of the experiment and at 15-day intervals to assess their growth. The physico-chemical variables
of the water were measured every 2 days. Final biomass, biomass gain and specific growth rate (SGR) exhibited no significant
differences between treatments (P > 0.05). Survival rate was equal under the four experimental conditions, being consistent within four decimal places 95.2%
to 97.00% (P > 0.05). Diets “A” and “B”, with a greater content of algae, exhibited better feed conversion (1.79:1 and 1.82:1) than Diets
“C” and “D” (2.04:1 and 2.08:1) (P < 0.05). The physical-chemical variables of the water showed no significant variation and remained within the standards necessary
for the wellbeing of the animals. If sufficient biomass of beached algae can be practically and economically collected, it
may be used as a component in the making of shrimp feed. 相似文献
10.
Aurélie Bessière Christian Nozais Sonia Brugel Serge Demers Gaston Desrosiers 《Polar Biology》2007,30(9):1123-1135
Pelagic–benthic coupling is relatively well studied in the marginal seas of the Arctic Ocean. Responses of meiofauna with
regard to seasonal pulses of particulate organic matter are, however, rarely investigated. We examined the dynamics of metazoan
meiofauna and assessed the strength of pelagic–benthic coupling in the Southeastern Beaufort Sea, during autumn 2003 and spring–summer
2004. Meiofauna abundance varied largely (range: 2.3 × 105 to 5 × 106 ind m−2), both spatially and temporally, and decreased with increasing depth (range: 24–549 m). Total meiofauna biomass exhibited
similar temporal as well as spatial patterns as abundance and varied from 25 to 914 mg C m−2. Significant relationships between sediment photopigments and various representatives of meiofauna in summer and autumn likely
indicate the use of sediment phytodetritus as food source for meiofauna. A carbon-based grazing model provided estimates of
potential daily ingestion rates ranging from 32 to 723 mg C m−2. Estimated potential ingestion rates showed that meiofauna consumed from 11 to 477% of the sediment phytodetritus and that
meiofauna were likely not food-restricted during spring and autumn. These results show that factors governing the distribution
and abundance of metazoan meiofauna need to be better elucidated if we are to estimate the benthic carbon fluxes in marginal
seas of the Arctic Ocean.
This paper is dedicated to the memory of our dear friend and colleague Gaston Desrosiers who contributed so much to benthic
ecology. We will continue in his spirit. 相似文献
11.
Distribution of abundance, biomass, production and productivity of macrozoobenthos in the sub-Antarctic Magellan Province (South America) 总被引:3,自引:3,他引:0
Distribution of abundance, biomass, productivity and production of macrozoobenthos was investigated in four study areas in
the Magellan region (South Patagonian Ice-Field, Strait of Magellan, Beagle Channel, Continental Shelf). Using a Reineck box
corer and a multibox corer, a total of 277 quantitative benthos samples were taken at 78 stations in water depths between
8 and 1139 m during the Joint Chilean-German-Italian Magellan “Victor-Hensen Campaign” in 1994, the “Polarstern” expedition
ANT XIII/4 in 1996 and the Chilean expeditions “Cimar Fiordo II + III” in 1996 and 1997, respectively, on board RV “Vidal
Gormaz”. Mean abundance in the South Patagonian Ice-Field was significantly lower than in the Strait of Magellan and the Beagle
Channel. Biomass and abundance decreased clearly with depth (20–300 m to 700–1500 m: 3.9 gC m−2 to 0.6 gC m−2; 2832 ind. m−2 to 569 ind. m−2). Average abundance, biomass and production of the whole Magellan region are lower (2318 ind. m−2, 3.2 gC m−2, 0.62 gC m−2 year−1) than in the high Antarctic Weddell Sea. In the Magellan region, macrozoobenthos composition of abundance is mainly dominated
by polychaetes (56%), followed by arthropods (16%), echinoderms (10%) and molluscs (11%). Comparisons of our present results
with those of high Antarctic areas make it clear that the Magellan region has a transitional character.
Accepted: 21 December 1998 相似文献
12.
Integrated abundance and biomass of sympagic meiofauna in Arctic and Antarctic pack ice 总被引:3,自引:0,他引:3
R. Gradinger 《Polar Biology》1999,22(3):169-177
The abundance and biomass of sympagic meiofauna were studied during three cruises to the Antarctic and one summer expedition
to the central Arctic Ocean. Ice samples were collected by ice coring and algal pigment concentrations and meiofauna abundances
were determined for entire cores. Median meiofauna abundances for the expeditions ranged from 4.4 to 139.5 × 103 organisms m−2 in Antarctic sea ice and accounted for 40.6 × 103 organisms m−2 in Arctic multi-year sea ice. While most taxa (ciliates, foraminifers, turbellarians, crustaceans) were common in both Arctic
and Antarctic sea ice, nematodes and rotifers occurred only in the Arctic. Based on the calculated biomass, the potential
meiofauna ingestion rates were determined by applying an allometric model. For both hemispheres, daily and yearly potential
ingestion rates were below the production values of the ice algal communities, pointing towards non-limited feeding conditions
for ice meiofauna year-round.
Accepted: 29 March 1999 相似文献
13.
A microphytobenthic species composition of a tidal flat in the northern Wadden Sea was analysed regarding cell numbers and
biomass (in carbon units). The three sampling sites differed in tidal inundation from 15 cm to about 90 cm water depth at
high tide. The sediment was sandy at all three stations. A cluster analysis revealed a separation of the benthic diatoms into
three areas: aNereis-Corophium-belt, a seagrass-bed and theArenicola-flat. Small epipsammic diatoms were most abundant and dominated the microalgal biomass. A microphytobenthic “spring bloom”
even started beneath the ice cover of the flat in January. Lowest values of cell numbers and biomass of benthic microalgae
were found in summer. Highest values were measured in the uppermost area (Nereis-Corophium-belt), and only here was an autumnal increase of benthic microalgae found. Further cluster analysis within each of the three
areas revealed seasonal differences although the majority of species were present all year round. Many species were most abundant
in spring, and some showed a bimodal distribution (spring-autumn) in the year of investigation. 相似文献
14.
Confocal Laser Scanning Microscopy Image Analysis for Cyanobacterial Biomass Determined at Microscale Level in Different Microbial Mats 总被引:1,自引:0,他引:1
We recently published a new method based on determining cyanobacterial biomass by confocal laser scanning microscopy image
analysis (CLSM-IA) (Solé et al., Ultramicrosc 107:669–673, 2007). CLSM-IA allows biomass calculation for microorganisms of
a small size, since the limit of the technique’s resolution is that generated by a voxel, the smallest unit of a three-dimensional
digital image, equivalent to 1.183 × 10−3 mgC/cm3 of sediment. This method is especially suitable for the quantitative analysis of a large number of CLSM images generated
from benthic sediments in which complex populations of cyanobacteria are abundant, such as microbial mats. In order to validate
the new CLSM approach, mats with varying structural characteristics were studied. We have grouped them into three types: Microcoleus mats (laminated), sandy mats (nonlaminated and composed of well-sorted quartz sands), and oil-polluted mats. In this work,
we applied CLSM-IA in natural [the Ebro delta and Sant Jordi colony (Spain), Salins-de-Giraud and Etang de Berre (France),
and Orkney Islands (Scotland)] and artificial [mesocosms (Israel)] microbial mats. A total of 4,103 confocal images were obtained
in order to determine total and individual cyanobacteria biomass profiles, at microscale level. The data presented in this
paper show the efficacy of the method, as it can be applied to highly diverse mat samples. 相似文献
15.
Pore water and solid phase distributions of C, N, P and Si in sediments of the Arctic Ocean (Svalbard area) have been investigated.
Concentrations of organic carbon (Corg) in the solid phase of the sediment varied from 1.3 to 2.8% (mean 1.9%), with highest concentrations found at shallow stations
south/southwest of Svalbard. Relatively low concentrations were obtained at the deeper stations north/northeast of Svalbard.
Atomic carbon to nitrogen ratios in the surface sediment ranged from below 8 to above 10. For some stations, high C/N ratios
together with high concentrations of Corg suggest that sedimentary organic matter is mainly of terrigenous origin and not from overall biological activity in the water
column. Organic matter reactivity (defined as the total sediment oxygen consumption rate normalized to the organic carbon
content of the surface sediment) correlated with water depth at all investigated stations. However, the stations could be
divided into two separate groups with different reactivity characteristics, representing the two most dominant hydrographic
regimes: the region west of Svalbard mainly influenced by the West Spitsbergen Current, and the area east of Svalbard where
Arctic polar water set the environmental conditions. Decreasing sediment reactivity with water depth was confirmed by the
partitioning between organic and inorganic carbon of the surface sediment. The ratio between organic and inorganic carbon
at the sediment-water interface decreased exponentially with water depth: from indefinite values at shallow stations in the
central Barents Sea, to approximately 1 at deep stations north of Svalbard. At stations east of Svalbard there was an inverse
linear correlation between the organic matter reactivity (as defined above) and concentration of dissolved organic carbon
(DOC) in the pore water. The more reactive the sediment, the less DOC existed in the pore water and the more total carbonate
(Ct or ΣCO2) was present. This observation suggests that DOC produced in reactive sediments is easily metabolizable to CO2. Sediment accumulation rates of opaline silica ranged from 0.35 to 5.7 μmol SiO2 m−2d−1 (mean 1.3 μmol SiO2 m−2d−1), i.e. almost 300 times lower than rates previously reported for the Ross Sea, Antarctica. Concentrations of ammonium and
nitrate in the pore water at the sediment-water interface were related to organic matter input and water depth. In shallow
regions with highly reactive organic matter, a pool of ammonium was present in the pore water, while nitrate conoentrations
were low. In areas where less reactive organic matter was deposited at the sediment surface, the deeper zone of nitrification
caused a build-up of nitrate in the pore water while ammonium was almost depleted. Nitrate penetrated from 1.8 to ≥ 5.8 cm
into the investigated sediments. Significantly higher concentrations of “total” dissolved nitrogen (defined as the sum of
NO3, NO2, NH4 and urea) in sediment pore water were found west compared to east of Svalbard. The differences in organic matter reactivity,
as well as in pore water distribution patterns of “total” dissolved nitrogen between the two areas, probably reflect hydrographic
factors (such as ice coverage and production/import of particulate organic material) related to the dominant water mass (Atlantic
or Arctic Polar) in each of the two areas.
The data presented were collected during the European “Polarstern” Study (Arctic EPOS) sponsored by the European Science Foundation 相似文献
16.
Herizo Fabien Rafidinarivo Satoshi Fujimoto Ken Watanabe Kaio Kitazato Nobuyuki Kobayashi 《Hydrobiologia》2007,583(1):205-212
Five published indirect methods to estimate benthic secondary production of intertidal mudflats and a new proposed formulation
based on quarter-power allometric scaling and the “Universal Temperature Dependence” of biological processes (UTD) were compared.
For this purpose, a dataset consisting of an annual series of samples, taken from the Lagoon of Venice from March 1996 to
March 1997, at sites characterised by different seagrass coverage was used. All methods resulted in that biomass and secondary
production decreased progressively when moving from the seagrass meadow toward areas of unvegetated substrate, suggesting
an influence of the available marine phanerogams on the neighbouring sites. The equation proposed in this paper gives results
comparable with those obtained using empirical regression models from literature. The main conclusion from this study is that
general equations proposed by the “metabolic theory of ecology” can be applied for indirect estimations of secondary production
of benthic communities. 相似文献
17.
Mesozooplankton assemblages in the shallow Arctic Laptev Sea in summer 1993 and autumn 1995 总被引:2,自引:0,他引:2
Mesozooplankton distribution and composition in the very shallow part of the Siberian Laptev Sea shelf were studied during
the German-Russian expeditions “Transdrift I” (August/September 1993) and “Transdrift III” (October 1995). Maximum abundances
were found close to the outflow of the Lena River (7,965 ind. m−3) and in the Yana river mouth (38,163 ind. m−3). Lowest abundances occurred in the northeast and west of the Laptev Sea (64–95 ind. m−3). Highest biomass values (104–146 mg DM m−3) were determined in the northern and northeastern part of the shallow Laptev Sea, as well as close to the river outflows,
with a record biomass maximum in the Yana river mouth (270 mg DM m−3). Biomass minima were situated north of the Lena Delta and in the western part of the shallow Laptev Sea (0.3–1.0 mg DM m−3). Copepods dominated in terms of abundance and biomass. Cluster analyses separated four mesozooplankton assemblages: the
assemblage “Lena/Yana” in the southern part, “Eastern-central” in the centre, “Kotelnyy” in the eastern part and “Taimyr”
in the western part of the shallow Laptev Sea. The small-sized neritic and brackish-water copepods Drepanopus bungei, Limnocalanus grimaldii and Pseudocalanus major occurred in enormous numbers and made up the bulk of zooplankton abundance and biomass in the very shallow part of the Laptev
Sea close to the rivers Lena and Yana. In the more northern and northeastern areas, Calanus glacialis, P. minutus and P. major were dominant copepod species, whereas Oithona similis and Acartia sp. became important in the western Laptev Sea. Appendicularians, as well as hydromedusae and the chaetognath Sagitta sp., contributed significantly to abundance and biomass, respectively, but not over the entire area studied. One can identify
taxon-specific distribution patterns (e.g. Sagitta predominated the biomass in a zone between the area heavily influenced by Lena/Yana and the offshore area to the north),
which differ from the patterns revealed by cluster analysis. Hydrographic features, especially the enormous freshwater inflow,
apparently determine the occurrence and formation of zooplankton aggregations. Extremely high numbers of small-sized neritic
and brackish-water copepods occurred locally, which were probably also supported by excellent feeding conditions. 相似文献
18.
The effectiveness of a specific fertiliser (INIPOL EAP 22) addition on bioremediation of oil-contaminated Antarctic coastal
seawater was determined in the “Terre Adelie” area. Mesocosm studies were conducted to evaluate the effects of “Arabian light”
crude oil contamination on coastal bacterioplanktonic communities. After oil addition, regular surveys of the bacterial changes
of the oil-contaminated seawater were performed during 5-week periods during the austral summer of 1992/1993 and 1993/1994.
All results (total, saprophytic and hydrocarbon-utilising bacterial abundance) clearly revealed a significant response of
Antarctic bacterial communities to hydrocarbon contamination. A 1 order of magnitude increase of bacterial microflora occurred
in seawater after crude oil contamination. A concomitant enrichment in oil-degrading bacteria was generally observed, from
less than 0.001% of the community in uncontaminated samples to up to 50% after 3 weeks of contamination. Addition of fertiliser
(INIPOL EAP 22) induced clear enhancement of both saprophytic and hydrocarbon-utilising microflora. Chemical analysis of the
residual hydrocarbon fractions confirmed that fertiliser application increased the rate of oil biodegradation.
Received: 27 March 1997 / Accepted: 20 October 1997 相似文献
19.
In ice-covered Arctic seas, the ice algal production can be the main input of organic matter to the ecosystem. Pelagic–benthic
coupling is thought to be particularly tight in those areas. The increase in ice algal production in Franklin Bay from January/February
to April/May 2004 paralleled an increase in benthic oxygen demand. However, sedimentary chlorophyll a, which is usually an indicator of “fresh” organic matter inputs to the sea floor, did not increase. Consequently, it was
asked what was the fate of the ice algal phytodetritus arriving at the sea floor? To answer this question, photosynthetic
pigments from the sea ice, water column particulate organic matter, and sediment, as well as diatom frustules in the sediment,
were studied from January to May 2004. The number of ice diatom cells in the sediment showed an increase in April/May, confirming
higher inputs of fresh ice algae to the sediment. Changes in sedimentary pigment profiles in the first 10 cm suggested an
increase in bioturbation due to enhanced benthic activities. Finally, the decrease in the ratio of chlorophyll a to phaeophorbide a implied an increase in macrobenthic activity. Benthic macrofauna consumed some of the deposited material and mixed some within
the top five cm of sediment. The response of sedimentary pigments to an ice algal input can be studied at different levels
and it is only the combination of these studies that will allow an understanding of the overall fate of phytodetritus in the
benthic compartment. 相似文献
20.
The underwater behaviour of 11 belugas or white whales was examined during summer using time-at-depth records relayed by
satellite-linked data-loggers. Simultaneous tracking information was obtained for each whale. Eight distinct dive profiles
were identified in submergences made to depths of >40 m. Four of these, together comprising 84% of these “deep” dives, were
of a square profile. They were characterised by a continuous descent to a particular depth (usually the sea bed), a “bottom
phase” at or near that depth, and a direct ascent to the surface. These dives are presumed to be made for benthic foraging.
Other, much less common, dive shapes were “V”-shaped, parabolic and trapezoidal. “Shallow” dives (15–40 m depth) were of a
variety of shapes, short duration and high average horizontal speeds. Many probably occurred during periods of directed travel.
This population of belugas treats most of the water column as dead space separating resources of oxygen and nutrition.
Received: 8 January 1998 / Accepted: 27 April 1998 相似文献