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1.
The principal environmental factors influencing the seasonal dynamics of phytoplankton were examined from September 1997 to
July 1998 in three stations along a 26-km stretch of the lowland course of River Adige (northeast Italy). Nutrient concentrations
did not appear to be limiting for the phytoplankton growth. Annual minimum concentrations of reactive and total phosphorus,
and dissolved inorganic nitrogen were 22 μg P l−1, 63 μg P l−1 and 0.9 mg N l−1, respectively. The most critical forcing factors were physical variables, mainly water discharge and other variables related
to hydrology, i.e. suspended solids and turbidity, which acted negatively and synchronously by diluting phytoplankton cells
and decreasing light availability. Higher algal biomass was recorded in early spring, in conditions of lower flow velocity
and increasing water temperature. In late spring and summer, higher water discharge caused a decrease in phytoplankton biomass.
Conversely, low algal biomass in late autumn and winter, during low discharge, was mainly related to low water temperatures
and shorter photoperiod. Physical constraints had a significant and measurable effect not only on the development of total
biomass, but also on the temporal dynamics of the phytoplankton community. Abiotic and biotic variables showed a comparable
temporal development in the three sampling stations. The small number of instances of spatial differences in phytoplankton
abundance during the period of lower flow velocity were related to the increasing importance of biological processes and accumulation
of phytoplankton biomass. 相似文献
2.
Convergent succession of phytoplankton in microcosms with different inoculum species composition 总被引:3,自引:0,他引:3
Ulrich Sommer 《Oecologia》1991,87(2):171-179
Summary Different initial mixtures of phyto-and zooplankton from different lakes were grown under identical chemical and physical conditions in medium size (8-and 12–1) laboratory microcosm cultures until convergence of phytoplankton species composition was attained. Five such experiments with four (four experiments) or three (one experiment) microcosm cultures were run. Three experiments were performed with weak stirring which permitted sedimentary elimination of the diatoms. Two experiments were conducted with stronger stirring to prevent sedimentation. In the three sedimentation intensive experiments, the final phytoplankton community was composed of the filamentous chlorophyte Mougeotia thylespora together with a smaller biomass of nanoplanktic algae. In the two sedimentation free experiments the final phytoplankton community consisted of pennate diatoms. Both dissolved nutrient concentrations and the chemical composition of biomass suggested strong nutrient limitation of algal growth rates in the final phase of the experiments. The zooplankton communities at the end of the experiments were composed of species that were apparently unable to ingest the large, dominant algae and that presumably fed on the nanoplanktic undergrowth and the bacteria. There was a distinct sequence of events in all experiments: first, the large zooplankton species (Daphnia and Copepoda) were replaced by smaller ones (Chydorus, Bosmina, rotifers); second, all cultures within one experiment developed the same nutritional status (limitation by the same nutrient); and third, the taxonomic composition of phytoplankton of the different cultures within one experiment converged. The last took 7–9 weeks, with is about 2–3 times as long as the time needed in a phytoplankton competition experiment to reach the final outcome. 相似文献
3.
J. W. Moore 《Hydrobiologia》1977,53(3):213-219
The standing crop of phytoplankton in a canal in southern England remained low during 1973 and 1974, seldom exceeding 5 × 104 cells/1. Since phosphorus, nitrogen and silicon occurred abundantly in the water, competition with higher plants for some other substance must have limited development. Although the standing crop of epiphytic algae associated withNasturtium officinale andGroenlandia densa seemed to be limited by the number of attachment sites, this factor was of little importance in the case of algae attached toCladophora glomerata. Achnanthes minutissima v.cryptocephala was always predominant in the epiphytic assemblages, representing 50–8o% by numbers of the flora. The limited pool of predominant epiphytic taxa may have restricted the communities' ability to adapt to fluctuations in environmental conditions. The grazing of isopods, amphipods and molluscs probably never limited algal densities. 相似文献
4.
Phytoplankton composition and production are highly unpredictable within an estuary, due to the high variability of forcing
factors, such as freshwater flow, salinity, nutrients and light. The Guadiana estuary has shown sharp inter-annual differences
in freshwater flow, related to variable precipitation, which is expected to affect nutrient loadings, light availability and
phytoplankton succession. Water retention due to dam construction will further enhance changes in river flow and ecosystem
dynamics. The main goal of the present study was to describe and relate phytoplankton succession and environmental conditions,
namely nutrients and light, in the Guadiana upper estuary (south-western Iberian Peninsula), a dam regulated temperate estuary.
From March 2004 to October 2005, water samples were collected in three stations along a longitudinal transect covering the
upper estuary. Several water variables were determined and phytoplankton composition was studied through inverted and epifluorescence
microscopy. A typical freshwater phytoplankton succession was observed, from a diatom spring bloom to cyanobacteria dominance
in the summer, and a second diatom bloom in the autumn. Neither nutrients nor light availability seemed to be related to the
observed succession, especially the seasonal variation of diatom abundance. During summer, nutrient concentrations (especially
Si) were high and non-limiting, whilst light was available in the mixing layer. However, diatoms were present in low numbers.
Grazing pressure was probably responsible for the regulation of diatom seasonal succession in the Guadiana upper estuary,
which should be addressed in future studies.
Handling editor: K. Martens 相似文献
5.
Seasonal and spatial patterns in phytoplankton photosynthetic parameters in a tidal freshwater river
The photosynthetic response to irradiance wasquantified for phytoplankton from the tidalfreshwater Potomac River biweekly to monthly over aperiod of six years. Samples were collected from twoshallow embayments and portions of the deeper rivermainstem. Photosynthetic rate was measured in thelaboratory at in situ temperature over a range ofirradiance levels and photosynthetic parameters werecalculated using nonlinear regression.PB
max,the maximum photosynthetic ratestandardized to chlorophyll a, increased withtemperature up to 25 °C with a Q10 of 2.02. Above 25 °C, PB
max was essentiallyconstant with temperature. Lesser correlationbetween PB
max and ambient irradiance couldbe explained by the correlation of irradiance withtemperature. , the slope of the P–I curve atlow light, was correlated with both ambientirradiance and temperature. Highest valueswere found in late summer when high temperature andintermediate ambient irradiance were observed. Spring and early summer were characterized by low. Despite low light penetration, Ik and values were indicative of sun limitationpossibly due to intermittent high light levelsexperienced during mixing. Ik showed a clearseasonal trend directly related to days from summersolstice. Spatial patterns were minimal except thatIk was consistently lower in one shallowembayment than in the other two areas. Seasonalpatterns in photosynthetic parameters correspondedroughly to changes from a spring diatom populationto summer cyanobacterial assemblage. 相似文献
6.
Tariq Al-Najjar Mohammad I. Badran Claudio Richter Michael Meyerhoefer Ulrich Sommer 《Hydrobiologia》2007,579(1):69-83
Seawater samples were collected biweekly from the northern Gulf of Aqaba, Red Sea, for Phytoplankton analysis during the period
May 1998 to October 1999. Microscopic counts and HPLC methods were employed. Procaryotic and eucaryotic ultraplankton dominated
throughout most of the year, with larger nano- and microplankton making up only 5% of the photosynthetic biomass. Moderate
seasonal variations in the 0–125 m integrated Chl a contrasted with a pronounced seasonal succession of the major taxonomic groups, reflecting the changes in the density stratification
of the water column: Prochlorococcus dominated during the stratified summer period and were almost absent in winter. Chlorophyceae and Cryptophyceae were dominant
during winter mixing but scarce or absent during summer. Diatoms and Synechococcus showed sharp and moderate biomass peaks in late winter and spring respectively, but remained at only low Chl a levels for the rest of the year. Chrysophyceae, Prymnesiophyceae and the scarce Dinophyceae showed no clear seasonal distribution
pattern. The implications of alternating procaryotic and eucaryote dominated algal communities for the Red Sea pelagic food
web are discussed.
Electronic Supplementary Material Electronic supplementary material is available for this article at
and accessible for authorised users. 相似文献
7.
A. B. Viner 《Hydrobiologia》1977,52(2-3):185-196
Summary The relationships of nitrogen and phosphorus in the plankton of tropical Lake George (Uganda) have been investigated. The data used are from analyses of samples collected from mid-lake areas during one year, and along transects of increasing plankton concentration, at various times when conditions allowed, and also from results of nutrient uptake experiments. These data are discussed in relation to previously reported information about general limnological conditions in Lake George, and in relation to physiological effects of nutrient enrichments. The features are compared with other waters.The peculiarities of the lake make difficult the precise calculations of long term primary production using oxygen exchange techniques, so that the determination of nutrient turnover rates based upon metabolic activity measured in this way could be misleading. Nevertheless, reasonable overall assessment of nitrogen and phosphorus turnover might be obtained from the proportions of these elements in the plankton. This could be done mainly due to the low variability of the limnological conditions, the apparent limitation of both nitrogen and phosphorus nutrients and the extreme predominance of algal metabolism over the remaining biota.It was also considered that the multiplicity of growth limiting factors which the nitrogen and phosphorus conditions impart contribute to an inherantly stable biomass.
Zusammenfassung Die Beziehungen zwischen Stickstoff und Phosphor im Plankton des tropischen Sees Lake George (Uganda) wurden untersucht. Die benutzten Daten stammen aus Analysen vom Proben, die über ein Jahr hinweg aus einem Gebiet in Seemitte entnommen wurden. Des weiteren wurden Proben entlang von Profilen mit steigender Planktonkonzentration untersucht. Ferner wurden Ergebnisse von Nährstoffaufnahme-experimenten benutzt. Die Daten wurden mit denen verglichen, die bereits über die algemeinen limnologischen Bedingungen des Sees veröffentlicht wurden. Auch wurden sie in Bezug auf die physiologischen Einflüsse einer erhöhten Nährstoffzufuhr diskutiert. Die Merkmale des Sees wurden mit denen anderer Gewässern verglichen.Die charakteristischen Besonderheiten des Sees machen eine genaue Berechnung von lang anhaltender Primärproduktion unter Anwendung der Sauerstoffaustausch-Methode schwierig, so dass die Bestimmung der Raten des Nährstoffwechsels, basiert auf gemessener metabolischer Aktivität, ein falsches Bild geben könnte. Immerhin konnten annehmbare allgemeine Werte von Stickstoff und Phosphorstoffwechsel aus der Verteilung dieser Elemente im Plankton gewonnen werden. Diese Werte konnten vor allem durch die geringen Schwankungen in den limnologischen Bedingungen, durch die auffallende Beschränkung im Auftreten von Stickstoff und Phosphor und durch das extreme Überwicht vom Algenmetabolismus über die übrige Biota, gewonnen werden.Es wird angenommen, dass die Vielfalt der wachstumbegrenzenden Faktoren, die mit dem Stickstoff- und Phosphorhaushalt zusammenhängen, zu einer von Natur aus stabilen Biomasse führen.相似文献
8.
Photosynthetic energy storage efficiency controls the development and decline of phytoplankton biomass. All abiotic environmental
factors such as light intensity; temperature, nutrient availability and pollutants will exert detectable changes in the photosynthetic
energy storage efficiency of phytoplankton, and subsequently affect total biomass and composition of phytoplankton assemblages.
Since this efficiency is a sensitive amplifier of ambient conditions, it thereby is an excellent reporter of water quality
parameter. We demonstrate the applicability of the novel photoacoustic method in easily and directly estimating the energy
storage efficiency of phytoplankton in a drinking water reservoir of different nutrient status.
Electronic Supplementary Material Supplementary material is available in the online version of this article at and accessible for authorised users
Handling editor: J. Padisak 相似文献
9.
Seasonal succession of phytoplankton in Lake Yogo over 2 years: effect of artificial manipulation 总被引:1,自引:0,他引:1
We studied the seasonal variation in concentrations of nutrients and phytoplankton in Lake Yogo for 2 years, from May 2000
to May 2002, in order to clarify the seasonal succession of phytoplankton and the effect of various manipulations on it. It
was revealed that in spite of the installation of aeration systems and the pumping of mesotrophic water from Lake Biwa during
the summer season, the trophic state of Lake Yogo overall has not improved during the past few decades. However, the pumping
of water from Lake Biwa did affect the concentrations of nutrients and the periods of cyanobacterial bloom during the summer.
The pumping period was different in each year, and the cyanobacterial bloom occurred during the period without pumping in
both years. The aeration destratification was not strong enough to prevent cyanobacterial blooms. Cyanobacteria and Bacillariophyceae
contributed most to the phytoplankton biomass in both years. Aphanizomenon, Anabaena, and Microcystis were the main genera among cyanobacteria. The bloom of Aphanizomenon or Anabaena occurred early in the summer, and was then replaced by Microcystis. Aphanizomenon was almost always present, and often formed bloom even in winter. The seasonal succession of Bacillariophyceae was almost
the same in both years and was well categorized: winter-growing species such as Aulacoseira pusilla (F. Meister) Tuji et Houki and species of Thalassiosiraceae, spring-growing species such as Asterionella formosa Hassall, Fragilaria crotonensis Kitton, and Synedra cf. acus, and fall-growing species such as Aulacoseira ambigua (Grunow) Simonsen, and Aulacoseira granulata (Ehrenb.) Simonsen. 相似文献
10.
Jürgen Voigt Dieter Mergenhagen Irmhild Wachholz Elsbeth Manshard Marianne Mix 《Planta》1991,183(1):65-68
Sporangia were accumulated in autotrophically and mixotrophically growing cultures of the Chlamydomonas reinhardtii mutant strain ls entering the stationary phase. Such an accumulation of sporangia was never observed in stationary-phase cultures of wildtype strains. Sporangia harvested from stationary-phase cultures of the mutant strain ls released their zoospores after being resuspended in fresh culture medium. Liberation of zoospores was also observed during fixation of these sporangia with glutaraldehyde and OsO4. Release of zoospores during fixation was prevented by pretreatment with 3 mol·l–1 LiCl. Ultrastructural analyses of these LiCl-pretreated sporangia revealed that they contained abnormal sporangial walls: sporangia containing sporangia and sporangia surrounded by additional multilayered cell walls have been observed. Similar abnormal cell-wall structures were found in sporangia accumulated at the end of the dark period, when the mutant strain ls was grown photoautotrophically under a 12 h light-12 h dark regime with suboptimal aeration. When grown under optimal conditions, this particular mutant did not show any abnormal wall structures.This work has been supported by a grant from the Deutsche Forschungsgemeinschaft. The authors thank Mrs. C. Adami for the photographic work. 相似文献
11.
Silver and bighead carp were stocked in a large pen to control the nuisance cyanobacterial blooms in Meiliang Bay of Lake Taihu. Plankton abundance and water quality were investigated about once a week from 9 May to 7 July in 2005. Biomass of both total crustacean zooplankton and cladocerans was significantly suppressed by the predation of pen-cultured fishes. There was a significant negative correlation between the N:P weight ratio and phytoplankton biomass. The size-selective predation by the two carps had no effect on the biomass of green alga Ulothrix sp. It may be attributed to the low fish stocking density (less than 40 g m−3) before June. When Microcystis dominated in the water of fish pen, the pen-cultured carps effectively suppressed the biomass of Microcystis, as indicated by the significant decline of chlorophyll a in the >38 μm fractions of the fish pen. Based on the results of our experiment and previous other studies, we conclude that silver and bighead carp are two efficient biomanipulation tools to control cyanobacterial (Microcystis) blooms in the tropical/subtropical eutrophic waters. Moreover, we should maintain an enough stocking density for an effective control of phytoplankton biomass. 相似文献
12.
Early succession of bacterial biofilms in paper machines 总被引:1,自引:0,他引:1
Marja Tiirola Tomi Lahtinen Matti Vuento Christian Oker-Blom 《Journal of industrial microbiology & biotechnology》2009,36(7):929-937
Formation of biofilms causes severe problems in paper machines, and hence financial costs. It would be preferable to prevent
attachment of the primary-colonizing bacteria than to control the growth of secondary communities, which are sheltered by
exopolysaccharide slime layers. We have therefore investigated the early succession of paper-machine biofilms by incubating
stainless-steel test coupons in the process water-flow lines in two paper machines operating in slightly alkaline conditions
in temperatures (45 and 49°C) supporting thermophilic microbes. Microbial succession was profiled using length heterogeneity
analysis of PCR-amplified 16S rRNA genes (LH-PCR) and linking the sequence data of the created 16S rRNA gene libraries to
the dominant LH-PCR peaks. Although the bacterial fingerprints obtained from the attached surface communities varied slightly
in different samples, the biomarker signals of the dominating primary-colonizing bacterial groups remained high over time
in each paper machine. Most of the 16S rRNA gene copies in the early biofilms were assigned to the genera Rhodobacter, Tepidimonas, and Cloacibacterium. The dominance of these sequence types decreased in the developing biofilms. Finally, as phylogenetically identical primary-colonizers
were detected in the two different paper mills, the machines evidently had similar environmental conditions for bacterial
growth and potentially a common source of contamination. 相似文献
13.
Donald R. Roeder 《Hydrobiologia》1977,56(2):145-151
Relationships between phytoplankton and periphyton communities were investigated in a central Iowa stream. Results generally support the hypothesis that the phytoplankton community arises from the epipelic periphyton community. A high correlation existed between the proportion of benthic diatoms composing the epipelon and phytoplankton. One dominant epipelic species (Nitzschia acicularis) showed a greater tendency to become planktonic than the grouped remainder of Nitzschia spp. There was a significant inverse relationship between the proportion of centric diatoms in the plankton and volume of flow. Centric diatoms were important members of the plankton only when volume of flow was less than 60 ft3 / sec (2.1 m3 / sec). Possible mechanisms explaining these phenomena are discussed.This study represents a portion of a dissertation submitted to the Graduate College, Iowa State University in partial fulfillment of requirements for the degree Doctor of Philosophy. 相似文献
14.
With the proliferation of old fields and the decline of native grasslands in North America, non-indigenous grasses, which tend to colonize and dominate North American old fields, have become progressively more abundant. These new grasses can differ from native grasses in a number of ways, including root and shoot morphology (e.g., density of root mat, height of shoots), growth phenology (e.g., cool season vs. warm season growth), and plant–soil–water relations due to differences in photosynthetic physiology (C3 vs. C4). Woody plants have been slow to colonize some old fields in the prairie-forest border area of North America and it is hypothesized that non-indigenous grasses may be contributing to the poor establishment success of woody plants in this region, possibly through more intense competition for resources. To test this hypothesis, a multi-factorial field experiment was conducted in which water, nitrogen, and grass functional group (non-indigenous C3 and native C4 species) were manipulated in a study of survival of oak seedlings. The grass type variously affected some of the different growth measurements, however, the effects of grass type on seedling growth were small compared to the effects on seedling survival. The results showed that when grown under dry conditions, seedlings growing in non-indigenous grasses experienced up to a 50% reduction in survival compared to those growing in native grasses under the same conditions. Analyses of root and shoot competition showed that the cause for the reduced survival in the non-indigenous grasses was due primarily to underground processes. The findings confirmed our initial hypothesis that non-indigenous grasses are likely contributing to the poor establishment success of woody plants in these old fields. However, the explanation for the reduced oak seedling survival in non-indigenous grasses does not appear to be due to reduced resource availability since soil water levels did not differ between non-indigenous and native grass plots and other resource levels measured (light, NO3, and NH4) were higher in non-indigenous grass plots under dry conditions. An alternative explanation is that the non-indigenous grasses modify the soil environment in ways that, under dry conditions, are deleterious to emerging oak seedlings. Since current climate projections for the upper Midwest are for hotter and drier summers, the results suggest that the resistance of these old fields to oak encroachment will likely increase in the future. 相似文献
15.
Goh Nishitani Satoshi Nagai Chunlan Lian Sanae Sakiyama Akihiko Oohashi Kazuyoshi Miyamura 《Conservation Genetics》2009,10(3):713-715
The marine phytoplankton, Karenia mikimotoi, causes severe red tides which are associated with mass mortality of marine fish, and have expanded their distributions in
the coastal waters of western Japan. To assess the dispersal mechanism, a population genetic study using highly polymorphic
genetic markers is one of the crucial approaches. Here we developed 12 polymorphic microsatellite markers from K. mikimotoi. These loci provide a class of highly variable genetic markers, as the number of alleles ranged from 5 to 23, and the estimate
of gene diversity was from 0.551 to 0.933 across the 12 microsatellites. We consider these loci potentially useful for detailing
the genetic structure and gene flow among K. mikimotoi populations. 相似文献
16.
Seasonal variation in density of juvenile Atlantic salmon in fluvial shoreline habitats of a large subarctic river 总被引:1,自引:0,他引:1
The densities of Atlantic salmon fry (0+ years) and parr (1+ years and older) in shoreline habitats of the large River Teno watercourse and its tributary, the River Utsjoki generally fluctuated considerably, showing an increase from early summer towards late August and a subsequent decline towards autumn. The seasonal pattern of variation in density was more distinct for parr than for fry. In the period between late July and early September, parr density followed a sinusoidal curve, being highest in late August and lowest in early August and in September. Fry density had a weaker seasonal profile than parr, being highest in late August and in early September. Frequency distributions of the parr age groups (1+, 2+ and 3+ years) were mainly independent of the sampling month. 相似文献
17.
In late summer (13 August–13 September 1998), at water temperatures of 12·0–15·7° C, grayling ( n =14) stayed mainly in the riffle-section where they were captured in a large regulated river in northern Finland, moving little between consecutive days. In autumn (2–30 October 1998), at 1·7–6·7° C, the fish ( n =16) migrated to potential overwintering sites 0–14 km up- or downstream by mid October, moving mainly short distances thereafter. The daily movement rates, and the total ranges covered by the fish in late summer and autumn were 54±32 m (mean± s.d ) and 1053±1636 m, and 190±168 m and 3135±1850 m, respectively. In autumn the fish used deeper habitats (most suitable range 150–400 cm) with lower current velocities (20–80 cm s−1 ) and finer bottom substrata (mainly sand) than in late summer (depth 100–325 cm, velocity 30–110 cm s−1 , and cobble-boulder substrata). 相似文献
18.
Although seasonal floodplains represent one of the most dynamic and productive of aquatic ecosystems, the sources of this
productivity are poorly understood. We examined composition and sources of chironomid drift in the Yolo Bypass, the primary
floodplain of the Sacramento River. We found that invertebrate drift during winter floodplain inundation is dominated by a
single species, the newly identified chironomid Hydrobaenus saetheri (Diptera: Chironomidae). In order to determine sources of chironomids in the Yolo Bypass, invertebrates were sampled from
several potential sources prior to and during initial floodplain inundation. Rehydration of dried floodplain sediments from
several locations showed that H. saetheri dominated insect emergence from this colonization pathway. By contrast, H. saetheri was not a substantial component of inundated floodplain ponds or of tributary inputs to the floodplain. We conclude that
the initial pulse of invertebrate abundance in Yolo Bypass floodwaters is dominated by chironomid emergence from sediments
in multiple regions of the floodplain.
Handling editor: S. Declerck 相似文献
19.
In situ bag experiments were performed during summer and autumn in a small acidic lake, Tibbs Run Lake, West Virginia, USA. The objective was to evaluate phytoplankton responses to pH manipulation and nutrient addition. Increasing the pH from below 4.5 to over 6.3 resulted in great declines in phytoplankton biovolume. There was also a succession from dinoflagellates (Peridinium inconspicuum to small chlorophytes. The trend was more rapid where phosphorus (P) additions were made along with pH enhancement. During summer, P limitation was indicated, while nitrogen (N) appeared to limit production in autumn. In both seasons, nutrient additions greatly altered the phytoplankton composition in high pH treatments, but had no discernable effects at (the natural) low pH. A low pH, P addition treatment in autumn was the single exception. When N was subsequently added, phytoplankton composition changed dramatically, probably because the proceeding P additions caused severe secondary N-limitation. In general, however, the results supported the view that phytoplankton compositional responses to nutrient additions are suppressed in low pH, relative to high pH lake water. 相似文献
20.
L. Arvola 《Hydrobiologia》1983,101(1-2):105-110
Primary production and phytoplankton in polyhumic lakes showed a very distinct seasonal succession. A vigorous spring maximum produced by Chlamydomonas green algae at the beginning of the growing season and two summer maxima composed mainly of Mallomonas caudata Iwanoff were typical. The annual primary production was ca. 6 g org. C · m–2 in both lakes. The mean epilimnetic biomass was 1.1 in the first lake and 2.2 g · m–2 (ww) in the second one. The maximum phytoplankton biomass, 14 g · m–2, was observed during the vernal peak in May. 相似文献