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1.
Abstract
Seasonal variation in bacterioplankton abundance, biomass, and bacterioplankton production was studied over eight years in
hypertrophic Lake S?byg?rd. Biologically, the lake is highly variable; this is due mainly to large interannual variation in
fish recruitment. Bacterioplankton production was low during winter, typically 1–3 × 107 cells l−1 h−1, and high during summer, albeit greatly fluctuating with maximum rates typically ranging from 60 to 90 × 107 cells l−1 h−1 (or 0.4 to 0.6 mg C l−1 day−1). Less pronounced variations were found in bacterioplankton abundance, which typically ranged from 3–8 × 109 cells l−1 in winter to 15–30 × 109 cells l−1 during summer. The specific growth rate of bacterioplankton varied from 0.02–0.2 d−1 in winter to 0.5–2.3 day−1 during summer. Interpolated mean bacterioplankton production, in terms of carbon, ranged from 0.08 to 0.16 mg C l−1 day−1, corresponding to 1.6–5.5% of the phytoplankton production, while biomass ranged from 0.28 to 0.36 mg C l−1, corresponding to 1.9–4.6% of the phytoplankton biomass. We conducted regression analysis, relating the bacterioplankton
variables to a number of environmental variables, and evaluated the interannual parameter variability. Chlorophyll a and phytoplankton production contributed less to the variation in the bacterioplankton variables than in most previous analyses
using data from less eutrophic systems. We suggest that the proportion of phytoplankton production that is channelized through
bacterioplankton in lakes decreases with increasing trophic state and decreasing mean depth. This probably reflects a concurrent
increase in fish predation on macrozooplankton and loss by sedimentation. An important part of the residual variation in the
equations hitherto proposed in the literature could be explained by variation in macrozooplankton biomass and pH > 10.2. A
negative effect of high pH on bacterioplankton production was confirmed by laboratory experiments. The impact of different
zooplankton varies considerably, with Daphnia seeming to have a negative impact on bacterioplankton abundance and, thereby, indirectly on bacterioplankton production,
while Bosmina, rotifers, and cyclopoid copepods seem to stimulate both abundance and production. Bosmina apparently also stimulate the bacterioplankton specific growth rate.
Received: 8 February 1996; Accepted: 16 July 1996 相似文献
2.
Abstract
The investigation of the bacterial community in the Kühw?rter Wasser, a macrophyte-dominated arm of the River Danube backwater
system near Vienna, revealed that variation in microbial densities and biomass could be related to a characteristic sequence
in morphotype composition over the seasons. Maximal bacterial cell numbers and biomass occured in early summer, with values
of up to 9 × 109 cells l−1 and 122 μg C l−1, respectively, caused by a massive increase of vibrio-shaped cells. On the other hand, in early spring, filamentous bacteria
were responsible for a marked increase in bacterial biomass, making up 40% of the total bacterial biomass. Over the year,
rod-shaped cells were the dominating morphotype, while the biomass of cocci was rather negligible. In winter, cell numbers
and biomass showed minimal values with 2.0 × 109 cells l−1 and 28 μg C l−1, respectively, and bacteria were considered to be substrate and temperature limited during this period. Saturation values
of the incorporation of 3H-thymidine into DNA, for the estimation of bacterial secondary production, varied seasonally, ranging from 5 nm to 40 nm. Thus, saturation experiments needed to be conducted on a regular basis. Also, the amount of labeled thymidine in the DNA,
as a percentage of labeled thymidine in the TCA precipitate, varied over the year. Minimum values of 45% were recorded during
the cold season, while maximum values of 75–80% at the beginning of June coincided with high chlorophyll a values and minimal K
m-values derived from saturation experiments. The potential role of the nitrogen-rich nucleoside thymidine as a readily utilizable
substrate for bacteria during labeling experiments, under varying conditions of substrate availability, is discussed. Bacterial
secondary production rates ranged from 0.3 μg C l−1 h−1 in winter to values of 10 μg C l−1 h−1 in August, where phytoplanktonic biomass reached the summer maximum, and bacterial biomass was calculated to be renewed 3
times per day. An estimation of the bacterial carbon demand showed that for the major part of the year, with the exception
of early spring, the bacterioplankton community in the Kühw?rter Wasser was dependent on carbon sources other than phytoplanktonic
primary production.
Received: 22 March 1996; Revised: 1 August 1996 相似文献
3.
Heike Link Philippe Archambault Tobias Tamelander Paul E. Renaud Dieter Piepenburg 《Polar Biology》2011,34(12):2025-2038
Seasonal dynamics in the activity of Arctic shelf benthos have been the subject of few local studies, and the pronounced among-site
variability characterizing their results makes it difficult to upscale and generalize their conclusions. In a regional study
encompassing five sites at 100–595 m water depth in the southeastern Beaufort Sea, we found that total pigment concentrations
in surficial sediments, used as proxies of general food supply to the benthos, rose significantly after the transition from
ice-covered conditions in spring (March–June 2008) to open-water conditions in summer (June–August 2008), whereas sediment
Chl a concentrations, typical markers of fresh food input, did not. Macrobenthic biomass (including agglutinated foraminifera >500 μm)
varied significantly among sites (1.2–6.4 g C m−2 in spring, 1.1–12.6 g C m−2 in summer), whereas a general spring-to-summer increase was not detected. Benthic carbon remineralisation also ranged significantly
among sites (11.9–33.2 mg C m−2 day−1 in spring, 11.6–44.4 mg C m−2 day−1 in summer) and did in addition exhibit a general significant increase from spring-to-summer. Multiple regression analysis
suggests that in both spring and summer, sediment Chl a concentration is the prime determinant of benthic carbon remineralisation, but other factors have a significant secondary
influence, such as foraminiferan biomass (negative in both seasons), water depth (in spring) and infaunal biomass (in summer).
Our findings indicate the importance of the combined and dynamic effects of food supply and benthic community patterns on
the carbon remineralisation of the polar shelf benthos in seasonally ice-covered seas. 相似文献
4.
Hidenobu Kunii 《Ecological Research》1988,3(3):305-318
In order to determine the seasonal growth and biomass ofTrapa japonica Flerov, field observations were carried out at Ojaga-ike Pond, Chiba, Japan, during 1979 and 1980. In spring, the plant showed
exponential growth (c. 0.080 g g−1 day−1) and shoot elongation was as rapid as 10 cm day−1. The plant attained its maximum biomass (380.5±35.1 g m−2) in late August, and about 50% of this was concentrated in the topmost 30-cm stratum (645.7±33.1 g m−3); maximum total stem length exceeded 6m. The plant produced large (500–800 mg per fruit), but small numbers of nut-like fruit
(maximum, 5 fruits per rosette). Defoliation occurred almost linearly with time at a rate of 30.6 leaves m−2 day−1; annual net leaf production was estimated to be about twice as large as the seasonal maximum leaf biomass. While the number
of leaves per rosette showed moderate seasonal change, rosette density, rosette area and leaf dry weight changed considerably
during the year. From the negative log-log correlation between mean total leaf dry weight per rosette and rosette density,
density-dependent rosette growth was assumed. The cause of the wide spread of this species in aquatic habitats is briefly
discussed in terms of its seed size and morphology. 相似文献
5.
Specific growth rates of heterotrophic bacterioplankton have been frequently estimated from in situ bacterial production (BP)
to biomass (BB) ratios, using a series of assumptions that may result in serious discrepancies with values obtained from predator-free
cultures. Here, we used both types of approaches together with a comprehensive assessment of single-cell physiological characteristics
(membrane integrity, nucleic acid content, and active respiration) of coastal bacterioplankton during a complete annual cycle
(February 2007–January 2008) in the southern Bay of Biscay off Xixón, Spain. Both leucine and thymidine incorporation rates
were used in conjunction with empirical tracer to carbon or cells conversion factors (eCFs) to accurately derive BP. Leu and
TdR incorporation rates covaried year-round, as did the corresponding eCFs at 0 and 50 m depth. eCFs peaked in autumn, with
mean annual values close to the theoretical ones (3.4 kg C mol Leu−1 and 2.0 × 1018 cells mol TdR−1). Bacterial abundance (0.2–1.5 × 106 cells L−1) showed a bimodal distribution with maxima in May and October and minima in March. Live (membrane-intact) cells dominated
year-round (79–97%), with high nucleic acid cells (42–88%) and actively respiring bacteria (CTC+, 1–16%) showing distinct
surface maxima in April and July, respectively. BB (557–1,558 mg C m−2) and BP (7–139 mg C m−2 day−1) presented two distinct peaks in spring and autumn, both of similar size due to a strong upwelling event observed in September.
Specific growth rates (0.35–3.8 day−1) were one order of magnitude higher in predator-free incubations than bacterial turnover rates derived from integrated BP:BB
ratios (0.01–0.16 and 0.01–0.09 day−1, for Leu and TdR, respectively) and were not correlated, probably due to a significant contribution of low activity cells
to total standing stocks. The Leu:TdR molar ratio averaged for the water column (6.6–25.5) decreased significantly with higher
integrated BB, indicating that low standing stocks tend to present unbalanced growth. Discrepancies about the true magnitude
of specific growth rates must be solved before fully appreciating the role of bacteria in the ocean carbon cycle. 相似文献
6.
The summer Phaeocystis antarctica bloom increases under-ice phytoplankton biomass in McMurdo Sound, Antarctica. The magnitude of mesozooplankton grazing on
this bloom is unknown, and determines whether this production is available to the pelagic food web. We measured mesozooplankton
abundance and body content of dimethylsulfoniopropionate (DMSP) during the McMurdo Sound austral summer (2006 and 2006–2007).
Abundance varied from 20 to 4,500 ind. m−3 (biomass 0.02–274.0 mg C m−3), with peaks in mid-December and late-January/February. Abundance was higher but total zooplankton biomass lower in our study
compared to previous reports. Copepods and the pteropod Limacina helicina dominated the zooplankton in both abundance and biomass. DMSP was detected in all zooplankton groups, with highest concentrations
in copepod nauplii and L. helicina (95 and 54 nmol mg−1 body C, respectively). Experiments suggested that L. helicina obtains DMSP by directly grazing on P. antarctica, which often accumulates to high biomass under the summer sea ice in McMurdo Sound. 相似文献
7.
We examined the importance of picoplankton and virioplankton to reef trophodynamics at Ningaloo Reef, (north-western Australia),
in May and November 2008. Picophytoplankton (Prochlorococcus, Synechococcus and picoeukaryotes), bacterioplankton (inclusive of bacteria and Archaea), virioplankton and chlorophyll a (Chl a) were measured at five stations following the consistent wave-driven unidirectional mean flow path of seawater across the
reef and into the lagoon. Prochlorococcus, Synechococcus, picoeukaryotes and bacterioplankton were depleted to similar levels (~40% on average) over the fore reef, reef crest and
reef flat (=‘active reef’), with negligible uptake occurring over the sandy bottom lagoon. Depletion of virioplankton also
occurred but to more variable levels. Highest uptake rates, m, of picoplankton occurred over the reef crest, while uptake coefficients, S (independent of cell concentration), were similarly scaled over the reef zones, indicating no preferential uptake of any
one group. Collectively, picophytoplankton, bacterioplankton and virioplankton accounted for the uptake of 29 mmol C m−2 day−1, with Synechococcus contributing the highest proportion of the removed C. Picoplankton and virioplankton accounted for 1–5 mmol N m−2 day−1 of the removed N, with bacterioplankton estimated to be a highly rich source of N. Results indicate the importance of ocean–reef
interactions and the dependence of certain reef organisms on picoplanktonic supply for reef-level biogeochemistry processes. 相似文献
8.
Primary production of organic matter and phototrophic communities in the soda lakes of the Kulunda steppe (Altai krai) 总被引:1,自引:0,他引:1
E. I. Kompantseva A. V. Komova I. I. Rusanov N. V. Pimenov D. Yu. Sorokin 《Microbiology》2009,78(5):643-649
The rates of photosynthesis and dark CO2 fixation were determined in 12 soda lakes of the Kulunda steppe. Characterization of the phototrophic communities was given,
and the cell numbers of anoxygenic phototrophic bacteria (APB) were determined. The photosynthetic production in different
lakes was substantially different, constituting from 0.01 to 1.32 g C m−2 day−1. The main part of carbon dioxide was assimilated in the process of oxygenic photosynthesis. Anoxygenic photosynthesis was
recorded only in 5 of the 12 lakes studied. Its values varied between 0.06 and 0.42 g C m−2 day−1, constituting from 8 to 34% of the total photosynthetic activity. Anoxygenic photosynthesis was revealed in the lakes where
the number of APB reached 107–109 CFU cm−3. Dark CO2 fixation constituted 0.01–0.15 g C m−2 day−1. Positive correlation was observed between the primary production value and water alkalinity. No relationship between productivity
and water mineralization was revealed in the 30–200 g l−1 range, whereas an increase in salinity above 200 g l−1 suppressed the photosynthetic activity. The mechanisms of influence of the environmental factors on the rate of photosynthesis
are discussed. 相似文献
9.
Production parameters for bacterioplankton were assessed during the spring–summer period in the western parts of the Sea of Okhotsk and the Bering Sea, as well as in northwestern Pacific Ocean. The lowest values of bacterial production were observed in early June during the spring phytoplankton bloom (0.08 mg C day–1 m–3), while the maximum values (up to 55 mg C day–1 m–3) occurred in late July?early August, 1.5 to 2 months after the bloom. The concentration of dissolved organic matter, the substrate for bacterioplankton, was assessed using satellite data. The ratio between bacterial and primary production in the surface samples varied from 0.5% at the peak of phytoplankton bloom to 180% at the peak of bacterioplankton development. 相似文献
10.
Carlos Pedrós-Alió Juan I. Calderón-Paz Núria Guixa Antoni Navarrete Dolors Vaqué 《Polar Biology》1996,16(8):613-622
We determined biomass and activity of microbial plankton across the Polar Front (PF) in Drake Passage during January 1994.
Temperature was around 0°C south and between 3 and 5°C north of the PF. Both biomass and activities of microorganisms were
significantly lower in the Antarctic waters south of the PF than in the sub-Antarctic waters north of it. Thus, values of
chlorophyll a, integrated between 0 and 200 m, reached 150 mgm−2 north, but only 25 mg m−2 south of the PF. Likewise, bacteria varied between 1014 and 4×1013 cells m−2. However, the abundance of heterotrophic nanoflagellates was extremely low throughout Drake Passage (around 3×1010 cells m−2). Bacterial doubling times were long (mean of 25 days). Bacterivory was estimated from the abundance of predators and prey
and from temperature. The grazing impact on bacterioplankton biomass was insignificant (less that 0.05% per day) and low on
bacterial heterotrophic production (15% per day). Neither biomass nor the activities of microorganisms were found to increase
at the PF. The microbial food web was uncoupled and the bacteria did not seem to be controlled by predation. 相似文献
11.
Simultaneous nutrients and carbon removal during pretreated swine slurry degradation in a tubular biofilm photobioreactor 总被引:1,自引:0,他引:1
Ignacio de Godos Cristina González Eloy Becares Pedro A. García-Encina Raúl Muñoz 《Applied microbiology and biotechnology》2009,82(1):187-194
The biodegradation potential of an innovative enclosed tubular biofilm photobioreactor inoculated with a Chlorella sorokiniana strain and an acclimated activated sludge consortium was evaluated under continuous illumination and increasing pretreated
(centrifuged) swine slurry loading rates. This photobioreactor configuration provided simultaneous and efficient carbon, nitrogen,
and phosphorous treatment in a single-stage process at sustained nitrogen and phosphorous removals efficiencies ranging from
94% to 100% and 70–90%, respectively. Maximum total organic carbon (TOC), NH4
+, and PO4
3− removal rates of 80 ± 5 g C mr
−3 day−1, 89 ± 5 g N mr
−3 day−1, and 13 ± 3 g P mr
−3 day−1, respectively, were recorded at the highest swine slurry loadings (TOC of 1,247 ± 62 mg L−1, N–NH4
+ of 656 ± 37 mg L−1, P–PO4
3+ of 117 ± 19 mg L−1, and 7 days of hydraulic retention time). The unusual substrates diffusional pathways established within the phototrophic
biofilm (photosynthetic O2 and TOC/NH4
+ diffusing from opposite sides of the biofilm) allowed both the occurrence of a simultaneous denitrification/nitrification
process at the highest swine slurry loading rate and the protection of microalgae from any potential inhibitory effect mediated
by the combination of high pH and high NH3 concentrations. In addition, this biofilm-based photobioreactor supported efficient biomass retention (>92% of the biomass
generated during the pretreated swine slurry biodegradation). 相似文献
12.
Brandon K. Swan James M. Watts Kristen M. Reifel Stuart H. Hurlbert 《Hydrobiologia》2007,576(1):111-125
The Salton Sea currently suffers from several well-documented water quality problems associated with high nutrient loading.
However, the importance of phosphorus regeneration from sediments has not been established. Sediment phosphorus regeneration
rates may be affected by benthic macroinvertebrate activity (e.g. bioturbation and excretion). The polychaete Neanthes
succinea (Frey and Leuckart) is the dominant benthic macroinvertebrate in the Salton Sea. It is widely distributed during periods
of mixing (winter and spring), and inhabits only shallow water areas following development of anoxia in summer. The contribution
of N. succinea to sediment phosphorus regeneration was investigated using laboratory incubations of cores under lake temperatures and dissolved
oxygen concentrations typical of the Salton Sea. Regeneration rates of soluble reactive phosphorus (SRP) were lowest (−0.23–1.03
mg P m−2 day−1) under saturated oxygen conditions, and highest (1.23–4.67 mg P m−2 day−1) under reduced oxygen levels. N. succinea most likely stimulated phosphorus regeneration under reduced oxygen levels via increased burrow ventilation rates. Phosphorus
excretion rates by N. succinea were 60–70% more rapid under reduced oxygen levels than under saturated or hypoxic conditions. SRP accounted for 71–80% of
the dissolved phosphorus excreted under all conditions. Whole-lake SRP regeneration rates predicted from N. succinea biomass densities are highest in early spring, when the lake is mixing frequently and mid-lake phytoplankton populations
are maximal. Thus, any additional phosphorus regenerated from the sediments at that time has potential for contributing to
the overall production of the lake.
Guest Editor: John M. Melack
Saline Water and their Biota 相似文献
13.
Using Weddell Sea data collected during a cruise with “FS Polarstern” in austral summer 1992/1993, depletions of nutrients
and TCO2 in the summer surface layer were calculated. The analogous depletion-like properties for temperature (Heat Storage) and salinity
were also computed. The latter properties are useful to describe the physical conditions over the time period pertinent to
the depletions. For different areas a strong correlation exists of Heat Storage and nutrient/TCO2 depletions, which is caused by a common factor – the period of light availability. Offshore of the Larsen shelf, an area
usually inaccessible due to perennial ice cover, high nutrients/TCO2 depletions are achieved over a short period of time, pointing to a rapidly producing biological system. Primary productivity,
calculated from the TCO2 depletion, amounts to about 100 mg C m−2 day−1 for the central Weddell Sea, but 570–1140 mg C m−2 day−1 for the offshore Larsen region. These values agree fairly well with the open-ocean Antarctic and other coastal areas, respectively.
Accepted: 1 August 1999 相似文献
14.
V. I. Kolmakov O. V. Anishchenko E. A. Ivanova M. I. Gladyshev N. N. Sushchik 《Journal of applied phycology》2008,20(3):289-297
Periphyton (epilithon) gross primary production (GPP) was estimated using the DCMU-fluorescence method in the Yenisei River.
In the unshaded littoral zone, chlorophyll a concentration (Chl a) and GPP value varied from 0.83 to 973.74 mg m−2and 2–304,425 O2 m−2 day−1 (0.64–95 133 mg C m−2 day−1), respectively. Positive significant correlation (r = 0.8) between daily GPP and periphyton Chl a was found. Average ratio GPP:Chl a for periphyton was 36.36 mg C mg Chl a m−2 day−1. The obtained GPP values for the Yenisei River have a high significant correlation with values predicted by a conventional
empirical model for stream periphyton. We concluded that the DCMU-fluorescence method can be successfully used for measuring
of gross primary production of stream phytoperiphyton at least as another useful tool for such studies. 相似文献
15.
Fieldwork was carried out at Kerguelen Islands. Two groups of stations in a coastal area, the Morbihan gulf, were surveyed.
At both stations, macroplankton biomass ranged from 2.3 mg dry weight m−3 to 89 mg dry weight m−3 and consisted mostly of Themisto gaudichaudii with values ranging from 1.9 mg dry weight m−3 to 50.6 mg dry weight m−3. Biomass was high for sub-Antarctic waters with marked seasonal and inter-zone differences. Biomass minima were observed
at the end of the winter, from September to November, while maxima were recorded in summer and in early fall at the beginning
of the year between January and April. T. gaudichaudii showed a recruitment of new size classes, mainly from November to January, followed by a rapid growth phase in summer, which
slowed down during the southern winter period. Individuals breed after 1 year. Large individuals, older than 1 year, were
not a significant presence in the gulf of Morbihan. The main pattern of the population dynamics were characterised by an univoltine
life cycle with a very high biomass marked by a strong seasonal signal linked with the hydrological and trophic parameters
of the Gulf. 相似文献
16.
Population of the freshwater amphipod Gammarus fossarum was investigated in a calcareous stream with almost constant temperature (7–8°C) in the Chočské Vrchy Mts (West Carpathians,
Slovakia). Quantitative samples of G. fossarum taken during 2005 showed population densities varying from 100 m−2 in August to 585 m−2 in late November. The population was split into juveniles, mature males, mature females without eggs and females with eggs.
The percentage of juveniles (40–64%) was always the highest of any of the categories. Ovigerous females occurred throughout
the year. The mean sex ratio was 1: 2.4 (male: female), although its values varied considerably with the time of year. Breeding
was continuous, although juvenile recruitment peaked in early spring, summer and early winter. Three discrete cohorts were
distinguished from the size frequency distributions. The life span was 6–7 months and the individuals matured approximately
in the half of life cycle. The mean fecundity was 9.6 embryos per brood. Variation in fecundity was mostly explained by size
of the incubating females. The absolute growth of this species was best described by the Gompertz growth function. Relative
growth rates (% body DM day−1) fluctuated in a nonlinear manner with size and age. The highest values of daily growth (2–4% of dry mass per day) were noted
approximately in the half of life cycle. Annual production, estimated by the size-frequency method, was 1618.9 g dry mass
m−2 and P/B ratio was 5.15. 相似文献
17.
The effects of seasonality and dilution stress on the functioning of Rambla Salada, a hypersaline Mediterranean stream in
SE Spain, were evaluated. The stream is subject to diffuse freshwater inputs from the drainage of intensively irrigated agriculture
in the catchment and periodic losses of water through an irrigation channel. Metabolic rates and the biomass of primary producers
and consumers were estimated over a 2-year period. During the first year several dilution events occurred, while during the
second year the salinity recovery reached predisturbance levels. Functional indicators were compared in the disturbance and
recovery salinity periods. Primary production and respiration rates in the Rambla Salada ranged between 0.07–21.05 and 0.19–17.39 g
O2 m−2 day−1, respectively. The mean values for these variables were 7.35 and 5.48 g O2 m−2 day−1, respectively. Mean net daily metabolism rate was 1.87 ± 0.52 g O2 m−2 day−1 and mean production/respiration ratio was 2.48 ± 1.1, reflecting autotrophic metabolism. The metabolic rates showed the typical
seasonal pattern of Mediterranean open canopy streams. Therefore, gross primary production (GPP) and ecosystem respiration
(ER) registered maximum values in summer, intermediate values in spring and autumn and minimum values in winter. The metabolic
rates and biomass of consumers were greater in the disturbance period than in the recovery period. However, they did not show
significant differences between periods due to their important dependence on seasonal cycle. Seasonality accounted for much
of the temporal variability in GPP and ER (76% and 83% in the multiregression models, respectively). Light availability seems
to be the most important factor for GPP and ER in the Rambla Salada. Autotrophic biomass responded more to variations in discharge
and conductivity than to seasonal variations. In fact, it was severely affected by freshwater inputs after which the epipelic
biomass decreased significantly and Cladophora glomerata proliferated rapidly. Epipelic algal biomass was the most sensitive parameter to dilution disturbance.
Handling editor: Luigi Naselli-Flores 相似文献
18.
North Lake, a small (330 ha. surface area) southwestern U.S.A. cooling water reservoir was found to contain less phytoplankton
production (104.0 mg C m−3 day−1), lower annual mean total organic carbon (3.7 mg l−1) and phytoplankton standing crops (0.9 ml m−3) than other local area reservoirs. Concentrations of inorganic P and N were at or below test detection limits during the
study year 1973–1974.In situ
14C non-filtration primary productivity techniques demonstrated significant (≃13 percent) stimulation of planktonic primary
productivity due to power plant entrainment. Optical counts showed no destruction of entrained phytoplankters. Populations
of Cyanophyta were never dominant, although they frequently bloom in most other local reservoirs. Thermal loading at North
Lake is thought to ultimately depress phytoplankton primary production and standing crop by causing nutrient limitation. 相似文献
19.
Spatial changes of small nanoplankton (2–10 μm) were investigated in relation to sea-ice conditions, hydrography and receding
ice processes in the Ross Sea (Antarctica) during spring 1994. Abundance and biomass of heterotrophic and autotrophic nanoplankton,
as well as bacterioplankton, were determined along a south-north transect from the open waters polynya towards the pack ice.
Autotrophic and heterotrophic nanoplankton biomass ranged from 758 to 4570 mgC m−2 and from 3 to 387 mgC m−2, respectively. Heterotrophic nanoplankton accounted, on average, for about 9% of the total (i.e. autotrophic plus heterotrophic)
nanoplankton biomass. The size structure of both auto- and heterotrophic nanoplankton in the Ross Sea continental shelf receding
ice edge was different from that of nanoplankton associated with the shelf break and open Antarctic ice-edge area. Generally,
the highest heterotrophic biomass was found in the pack-ice zone on the continental shelf, while the highest heterotrophic
contribution to the total nanoplankton biomass (up to 25%) was encountered at the shelf break where phytoplankton was largely
dominated by 2- to 3-μm-size cells.
Accepted: 2 May 1999 相似文献
20.
Margareth da Silva Copertino Thiago Tormena Ulrich Seeliger 《Journal of applied phycology》2009,21(1):31-45
The growth, biofiltering efficiency and uptake rates of Ulva clathrata were studied in a series of outdoor tanks, receiving waste water directly from a shrimp (Litopenaeus vannamei) aquaculture pond, under constant aeration and two different water regimes: (1) continuous flow, with 1 volume exchange a
day (VE day-1) and (2) static regime, with 1 VE after 4 days. Water temperature, salinity, pH, dissolved inorganic nitrogen (DIN), phosphate
(PO4), chlorophyll-a (chl-a), total suspended solids (TSS), macroalgal biomass (fresh weight) and tissue nutrient assimilation were monitored over 12 days.
Ulva clathrata was highly efficient in removing the main inorganic nutrients from effluent water, stripping 70–82% of the total ammonium
nitrogen (TAN) and 50% PO4 within 15 h. Reductions in control tanks were much lower (Tukey HSD, P < 0.05). After 3 days, the mean uptake rates by the seaweed biomass under continuous flow were 3.09 mg DIN g DW day−1 (383 mg DIN m−2 day−1) and 0.13 mg PO4 g DW day−1 (99 mg PO4 m−2 day−1), being significantly higher than in the static regime (Tukey HSD, P < 0.05). The chl-a decreased in seaweed tanks, suggesting that U. clathrata inhibited phytoplankton growth. Correlations between the cumulative values of DIN removed from the water and total nitrogen
assimilated into the seaweed biomass (r = 0.7 and 0.8, P < 0.05), suggest that nutrient removal by U. clathrata dominated over other processes such as phytoplankton and bacterial assimilation, ammonia volatilization and nutrient precipitation. 相似文献