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1.
Stratification of microorganisms and nutrients in the surface microlayer of small freshwater ponds 总被引:2,自引:2,他引:0
Using two different surface microlayer sampling devices (the Harvey and Burzell glass plate and the Garrett screen), two microlayer fractions could be distinguished. The first was from 0 to 50 µm and the second was from 51 to 320 µm. Significantly different (p < 0.05) concentrations of dissolved nutrients between the two microlayer fractions strongly suggests stratification within the surface microlayer. This apparent stratification is also examined for phototrophs, bacteria and other material found within the surface microlayer.Based in part on an M.S. thesis, submitted to the Graduate School of University of Wisconsin - Milwaukee. 相似文献
2.
The relationship of individual algal species to the surface microlayer of a small freshwater pond 总被引:1,自引:0,他引:1
Surface microlayer and subsurface algal communities were comparedon 14 sample dates over a 5 month period in a small Wisconsinpond. Similarities in species composition indicate that themicrolayer community had many species in common with the subsurfacecommunity. Relative species abundances, however, were differentfrom surface to subsurface. Analysis of the depth distributionof individual species indicates that the response to the uniquephysical/chemical conditions in the microlayer is species specific,with flagellates often in low numbers in the surface microlayeras a result of negative phototaxis; and diatoms often in highnumbers in the surface microlayer, as a result of a specificphysical/chemical affinity. These species specific differencesmay help to explain phytoneuston enrichment found in other studies.
1Present address: University of Rhode Island, Department ofOceanography, Kingston, R1 02881, USA.
2Author to whom reprint requests should be directed. 相似文献
3.
Role of aquatic surface microlayer in the dynamics of nutrients and organic compounds in lakes,with implications for their ecotones 总被引:1,自引:1,他引:0
Anders Södergren 《Hydrobiologia》1993,251(1-3):217-225
The origin and mechanisms of formation of aquatic surface microlayers are reviewed, and processes within the layer responsible for enrichment of inorganic and organic substances, particles, and microorganisms are discussed. In a study of the chemical and biological composition of microlayers in three lakes of different levels of productivity, surface slicks were sampled with a revolving cylinder coated with hydrophilic Teflon. DOC, POC, DON and various forms of phosphorus were enriched in the microlayer compared to those in the subsurface water. In eutrophic and oligotrophic lakes the DOC:DON ratio shows that the slicks were more influenced by allochtonous sources than was the subsurface water, which indicates that processes in the ecotone influence the microlayer composition. 相似文献
4.
5.
Agogué H Casamayor EO Bourrain M Obernosterer I Joux F Herndl GJ Lebaron P 《FEMS microbiology ecology》2005,54(2):269-280
Bacterial populations inhabiting the sea surface microlayer from two contrasted Mediterranean coastal stations (polluted vs. oligotrophic) were examined by culturing and genetic fingerprinting methods and were compared with those of underlying waters (50 cm depth), for a period of two years. More than 30 samples were examined and 487 strains were isolated and screened. Proteobacteria were consistently more abundant in the collection from the pristine environment whereas Gram-positive bacteria (i.e., Actinobacteria and Firmicutes) were more abundant in the polluted site. Cythophaga-Flavobacter-Bacteroides (CFB) ranged from 8% to 16% of total strains. Overall, 22.5% of the strains showed a 16S rRNA gene sequence similarity only at the genus level with previously reported bacterial species and around 10.5% of the strains showed similarities in 16S rRNA sequence below 93% with reported species. The CFB group contained the highest proportion of unknown species, but these also included Alpha- and Gammaproteobacteria. Such low similarity values showed that we were able to culture new marine genera and possibly new families, indicating that the sea-surface layer is a poorly understood microbial environment and may represent a natural source of new microorganisms. Genetic fingerprinting showed, however, no consistent differences between the predominant bacterial assemblages from surface microlayer and underlying waters, suggesting that the presence of a stable and abundant neustonic bacterial community is not a common trait of coastal marine environments. 相似文献
6.
Seasonal succession of phytoplankton and its diversity in two highly eutrophic lakes with different conditions of stratification 总被引:2,自引:2,他引:0
Irina Trifonova 《Hydrobiologia》1993,249(1-3):93-100
Seasonal succession of phytoplankton biomass, its diversity and its photosynthetic activity in two highly eutrophic lakes have been compared. In order to test the intermediate disturbance hypothesis, the lakes have been chosen with almost the same level of trophy but different conditions of stratification, through two ice-free periods of open water with different weather conditions.High phytoplankton diversity throughout the period of investigation was characteristic for the shallower Lake Lobardzu. The number of species here was usually more than 30 and the Shannon diversity changed from 1.2 to 4.2. Owing to the frequent external disturbances, periods characterized by autogenic succession with establishing dominance and declining diversity alternated with periods of biomass reduction and rises of diversity and photosynthetic activity. In the warmer summer of 1983, with more intense warming of bottom layers and predominance of blue-greens, phytoplankton biomass was higher and diversity lower than in the cold summer of 1982.In stratified Lake Rudusku, phytoplankton diversity and number of species were usually much lower. During the long summer stratification up to three-four dominant species of blue-greens and dinoflagellates become established and competitive exclusion leading to low diversity advanced. Some changes in biomass and diversity, were caused by zooplankton activity. 相似文献
7.
Michael Cunliffe Matthew Salter Paul J. Mann rew S. Whiteley Robert C. Upstill-Goddard &J. Colin Murrell 《FEMS microbiology letters》2009,299(2):248-254
The sea surface microlayer is the interfacial boundary layer between the marine environment and the troposphere. Surface microlayer samples were collected during a fjord mesocosm experiment to study microbial assemblage dynamics within the surface microlayer during a phytoplankton bloom. Transparent exopolymer particles were significantly enriched in the microlayer samples, supporting the concept of a gelatinous surface film. Dissolved organic carbon and bacterial cell numbers (determined by flow cytometry) were weakly enriched in the microlayer samples. However, the numbers of Bacteria 16S rRNA genes (determined by quantitative real-time PCR) were more variable, probably due to variable numbers of bacterial cells attached to particles. The enrichment of transparent exopolymer particles in the microlayer and the subsequent production of a gelatinous biofilm have implications on air–sea gas transfer and the partitioning of organic carbon in surface waters. 相似文献
8.
Jan Barica 《Journal of Aquatic Ecosystem Stress and Recovery (Formerly Journal of Aquatic Ecosystem Health)》1993,2(4):243-250
Graphic presentation of weekly rates of change of algal biomass (expressed as chlorophyll a) and nutrient and dissolved oxygen concentrations can be regarded as harmonic oscillation motion. Maximum amplitudes of these oscillations provide a useful tool to assess the degree of stability of aquatic ecosystems in relation to their trophic state. Data sets from seven different lakes ranging from hypereutrophic to oligo-mesotrophic were processed using a computerized method. The high values of oscillation amplitudes of approximately 150 g l–1 wk–1 chlorophyll a, 500 g l–1 wk–1 ammonia nitrogen, 50 g l–1 wk–1 soluble reactive phosphorus and 10 mg l–1 wk–1 dissolved oxygen, indicated strong ecosystem instability, while low values of less than 10 g l–1 wk–1 of chlorophyll a, 20 g l–1 wk–1 ammonia nitrogen, 2 g l–1 wk–1 soluble reactive phosphorus, and 3 mg l–1 wk–1 dissolved oxygen represented a stable system. Oscillation amplitudes of the chlorophyll a values were found to be the most representative indicator of ecosystem stability. 相似文献
9.
Gui-Peng Yang Maurice Levasseur Sonia Michaud Anissa Merzouk Martine Lizotte Michael Scarratt 《Biogeochemistry》2009,94(3):243-254
One of the key steps towards predicting dimethylsulfide (DMS) emission to the atmosphere is to understand the distribution
and cycling of biogenic sulfur in the microlayer. In this study, we examined the distribution of DMS and dissolved and particulate
fractions of dimethylsulfoniopropionate (DMSPd and DMSPp) in the surface microlayer and bulk water of the western North Atlantic
during July 2003. DMS concentrations in the bulk water varied from 0.71 to 7.65 nM. In contrast, DMS concentrations in the
surface microlayer were fairly low (0.17–1.33 nM). Average concentrations of DMSPd and DMSPp in the bulk water were 2.09 (1.87–6.25)
and 44.1 (8.06–119.8) nM, respectively, and those in the surface microlayer were 15.4 (4.06–54.3) and 29.9 (7.32–97.0) nM.
In general, DMS was depleted in the microlayer (mean concentration: 0.60 nM) relative to the bulk water (mean concentration:
2.38 nM) with enrichment factors (the ratio of the microlayer concentration to bulk water concentration) ranging from 0.13
to 0.54. There was no consistent enrichment of DMSPp and chlorophyll a in the microlayer. On the contrary, DMSPd appeared to be highly enriched in the microlayer with an average EF of 4.89. The
concentration of phaeopigments was also generally greater in the microlayer than in the bulk water, presumably due to enhanced
photo-oxidation of chlorophyll a under high surface light intensities in the microlayer. In the study area, the concentration of DMSPp was significantly correlated
with the abundance of dinoflagellates in the microlayer. Moreover, a significant correlation between the distributions of
DMS, DMSPp, chlorophyll a and phaeopigment concentrations in the microlayer and the bulk water demonstrated that the biogenic materials in the microlayer
come primarily from the bulk water below. 相似文献
10.
Seasonal studies were undertaken (August 1983–July 1984) toevaluate the algal distribution and ecology of the RiverDelimi, Jos Plateau, Nigeria at three stations: upstream, withlittle allochthonous input; midstream, receiving heavy domesticaffluents; downstream. A wide amplitude of variability wasdiscernible in physicochemical factors, and photosyntheticactivity and abundance of suspended algae in relation to thedegree of pollution along the first 7-km stretch of the river.Conductivity (µS cm-1) showed a 9-fold increase fromupstream (x = 35) to downstream. The standing crop(Chl a) fluctuated markedly, with 6-times higher valuesfor a polluted midstream site (x = 18.2 mg m-3). Production rate measurements (mg C m-3 d-1) showed significant variability with relatively lowvalues (x = 610) recorded for the upstream andhighest (x = 1050) at the midstream site. Apositive correlation was obtained between production rates andChl a for the polluted midstream zone. 相似文献
11.
Field and experimental studies were conducted to evaluate the combined impacts of cyanobacterial blooms and small algae on
seasonal and long-term changes in the abundance and community structure of crustacean zooplankton in a large, eutrophic, Chinese
lake, Lake Chaohu. Seasonal changes of the crustacean zooplankton from 22 sampling stations were investigated during September
2002 and August 2003, and 23 species belonging to 20 genera were recorded. Daphnia spp. dominated in spring but disappeared in mid-summer, while Bosmina coregoni and Ceriodaphnia cornuta dominated in summer and autumn. Both maximum cladoceran density (310 ind. l−1) and biomass (5.2 mg l−1) appeared in autumn. Limnoithona sinensis, Sinocalanus dorrii and Schmackeria inopinus were the main species of copepods. Microcystis spp. were the dominant phytoplankton species and formed dense blooms in the warm seasons. In the laboratory, inhibitory effects
of small colonial Microcystis on growth and reproduction of Daphnia carinata were more remarkable than those of large ones, and population size of D. carinata was negatively correlated with density of fresh large colonial Microcystis within a density range of 0–100 mg l−1 (r = −0.82, P< 0.05). Both field and experimental results suggested that seasonal and long-term changes in the community structure of crustacean
zooplankton in the lake were shaped by cyanobacterial blooms and biomass of the small algae, respectively, i.e., colonial
and filamentous cyanobacteria contributed to the summer replacement of dominant crustacean zooplankton from large Daphnia spp. to small B. coregoni and C. cornuta, while increased small algae might be responsible for the increased abundance of crustacean zooplankton during the past decades. 相似文献
12.
Yoshikazu Shimizu 《Ecological Research》1986,1(2):185-194
Species-area relationships of flowering plants were analyzed on the habitat-islands (hummocks on a floating bog) of Mizorogaike
Pond, Japan. Three habitat units (Sphagnum cuspidatum unit,Sphagnum palustre unit, and fallen leaves unit) in which habitat conditions were homogeneous and a group of habitat-specific species occurred
were recognized on the hummocks. Six hummock types were determined according to various combinations of the three habitat
units. The most fundamental species-area relationships in which size itself affects the number of species were shown by hummocks
with only one habitat unit. The species-area relationships for hummocks with two or three habitat units included the effects
of habitat diversity in addition to size. The speciesarea curve for all hummocks was an average of these relationships. It
is concluded that area in species-area relationships affects species numbers in two ways: number of habitat units and size
of each habitat unit. 相似文献
13.
Two representative methods for quantitative estimation of soil algae, the culture dilution method and chlorophyll a extraction, were compared using soil samples collected from irrigation land in the flood plain of the River Ili, Kazakhstan,
where the distribution of soil algae had been studied in the previous year. The estimate by the culture dilution method was
almost the same as in the previous year, except for one site, which was enclosed by shrubs of sakusaul, Haloxylon aphyllum (Minkw.) Iljin. The important role of wind in transport of airborne algal cells was pointed out. There was a significant
correlation (p<0.001) between the logarithm of the number of colonies by the culture dilution method andthe logarithm of the concentration
of chlorophyll a, when data from all samples were analyzed. However, no significant correlation was observed with the data of cropland sites
alone. Furthermore, the seasonal variations of both values at each site did not necessarily agree with each other. One reason
for the inconsistency may have been the over estimation of chlorophyll a caused by inclusion of litter from vascular plants. Other reasons may relate to differences between the methodologies. The
density of soil algae estimated by culture dilution reflects the algal biomass in a certain previous period of time. Therefore,
it is suggested that the method is suitable for spatial, but not for seasonal studies.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
14.
The potential interactions of grazing, nutrients and light in influencing autotroph species diversity have not previously
been considered. Earlier studies have shown that grazing and nutrients interact in determining autotroph species diversity,
since grazing decreases species diversity when nutrients (i.e. N or P) limit autotroph growth, but increases it when nutrients
are replete. We hypothesized that increased light intensities would intensify the interactions between grazing and nutrients
on algal species diversity, resulting in even stronger reductions in algal species diversity through grazing under nutrient–poor
conditions, and to even stronger increases of algal species diversity through grazing under nutrient-rich conditions. We studied
the effects of grazing (absent, present), nutrients (ambient, N + P enriched) and light (low light, high light) on benthic
algal diversity and periphyton C:nutrient ratios (which can indicate algal nutrient limitation) in a factorial laboratory
experiment, using the gastropod grazer Viviparus viviparus. Grazing decreased algal biomass and algal diversity, but increased C:P and N:P ratios of periphyton. Grazing also affected
periphyton species composition, by decreasing the proportion of Spirogyra sp. and increasing the proportion of species in the Chaetophorales. Grazing effects on diversity as well as on periphyton N:P ratios were weakened when nutrients were added (interaction between
grazing and nutrients). Chlorophyll a (Chl a) per area increased with nutrient addition and decreased with high light intensities. Light did not increase the strength
of the interaction between grazing and nutrients on periphytic algal diversity. This study shows that nutrient addition substantially
reduced the negative effects of grazing on periphytic algal diversity, whereas light did not interact with grazing or nutrient
enrichment in determining periphytic algal diversity. 相似文献
15.
Trace metal or rare earth element (REE) content of marine macroalgae are underexamined and there is a great need for further understanding since macroalgae are used for food and may also be bioindicators of environmental changes. This study, by using high resolution inductive coupled plasma spectrometer in a clean laboratory (class 1000), investigates the trace metal and REE concentrations and composition in the youngest tissue of various species within three algal classes in the Trondheimsfjord, Norway, comprising phaeo‐, chloro‐, and rhodophytes in winter (February) and Spring (May) 2013, with the main focus on phaeophytes. The macroalgae were found in a clear zonation pattern as a function of depth. A significant difference in element concentration and composition was found between the six phaeophyte species along with a significant difference between winter and spring tissue. A zonation depth trend in algal tissue element concentration was also found for the phaeophytes, where the algal species located in both extreme ends (upper vs. lower littoral zone) obtained a lower element concentration than the algae located in the middle part of the littoral zone. This trend seems to result from different algal contact with the metal‐rich sea surface microlayer. The chlorophytes had 5–27 times higher concentration of REE and lead (Pb) than the two other algal classes. Results indicate that the rhodo‐ and chlorophytes are better accumulators than the phaeophytes for several trace metals and REE. 相似文献
16.
Marian L Yallop Alexandre M Anesio Rupert G Perkins Joseph Cook Jon Telling Daniel Fagan James MacFarlane Marek Stibal Gary Barker Chris Bellas Andy Hodson Martyn Tranter Jemma Wadham Nicholas W Roberts 《The ISME journal》2012,6(12):2302-2313
Darkening of parts of the Greenland ice sheet surface during the summer months leads to reduced albedo and increased melting. Here we show that heavily pigmented, actively photosynthesising microalgae and cyanobacteria are present on the bare ice. We demonstrate the widespread abundance of green algae in the Zygnematophyceae on the ice sheet surface in Southwest Greenland. Photophysiological measurements (variable chlorophyll fluorescence) indicate that the ice algae likely use screening mechanisms to downregulate photosynthesis when exposed to high intensities of visible and ultraviolet radiation, rather than non-photochemical quenching or cell movement. Using imaging microspectrophotometry, we demonstrate that intact cells and filaments absorb light with characteristic spectral profiles across ultraviolet and visible wavelengths, whereas inorganic dust particles typical for these areas display little absorption. Our results indicate that the phototrophic community growing directly on the bare ice, through their photophysiology, most likely have an important role in changing albedo, and subsequently may impact melt rates on the ice sheet. 相似文献
17.
Independent and interactive effects of nutrients and grazers on benthic algal community structure 总被引:1,自引:1,他引:0
Algal responses to nutrients, grazing by Helicopsyche borealis, and concurrent grazing by Helicopsyche and Baetis tricaudatus were examined in recirculating stream chambers. Alagl communities, dominated by Achnanthes minutissima, Cocconeis placentula, and Synedra ulna, were primarily phosphorus-limited. Algal populations responded after only 6 days of nutrient enrichment. Initially, both
the adnate diatom Cocconeis and erect diatom Synedra showed positive response to nutrient enrichment. Accumulation of algal biomass between day 3 and 6 in the P enriched treatment
was resulted primarily from the growth of Synedra, an overstory rosette-like diatom colony. Such a shift in dominant growth from adnate to erect diatoms is a general phenomenon
in periphyton succession in the absence of disturbance. Algal species showed differential responses to an increase of Helicopsyche densities. The accrual rate of Achnanthes continuously decreased with increasing grazer densities. The accrual rates of both Cocconeis and Synedra declined but reached plateaus between medium and high grazing densities. Baetis effectively and exclusively depressed Synedra and had no significant impact on Cocconeis. After concurrent grazing, algal communities were mainly dominated by Cocconeis (approximately 80% of total algal biovolume). The grazer' s mouth structures, grazing efficiencies, and mobility may account
for the differential effects of concurrent grazing on algal communities.
Significant interactive effects of P and grazing by Helicopsyche indicated that both nutrient addition and grazing may exert significant impact on algal communities. However, grazing may
have a much stronger effect on algae than nutrients. Our results indicate that enhancement of algal biomass by P was dampened
by grazing activities and that P had no effect on algal biomass in the presence of grazers. 相似文献
18.
1. A 1-year intensive study of nutrient flows in Airthrey Loch, central Scotland, a small eutrophic [mean total phosphorus (TP) = 61.1 μg P l–1 ] well-flushed freshwater body (area, 6.9 ha; mean depth, 1.85 m; volume, 1.274 × 105 m3 ; retention time, 0.44 yr), was undertaken.
2. The nutrient budget was dominated by large allochthonous P inputs, equivalent to an areal load to the loch of 8.56 kg P ha–1 yr–1 , which occurred predominantly during winter. In the summer, when TP inputs were low, water column levels of TP still increased, as a result of aerobic P release from sediments.
3. Sorption experiments indicated potential for sediment P release at water P concentrations of up to 200 μg P l–1 .
4. Aerobic release rate of P from sediments to the water column of Airthrey Loch was estimated to be of the order of 1 mg P m–2 day–1 , and occurred during periods of elevated water column pH.
5. Straw bales placed in the loch to retard algal blooms were found not to have any demonstrable impact on algal concentrations observed during the study. 相似文献
2. The nutrient budget was dominated by large allochthonous P inputs, equivalent to an areal load to the loch of 8.56 kg P ha
3. Sorption experiments indicated potential for sediment P release at water P concentrations of up to 200 μg P l
4. Aerobic release rate of P from sediments to the water column of Airthrey Loch was estimated to be of the order of 1 mg P m
5. Straw bales placed in the loch to retard algal blooms were found not to have any demonstrable impact on algal concentrations observed during the study. 相似文献
19.
Characterization of a small eutrophic Antarctic lake (Otero Lake, Cierva Point) on the basis of algal assemblages and water chemistry 总被引:2,自引:0,他引:2
Otero Lake is the main water body of Cierva Point, Danco Coast (SSSI No. 15). During the 1992/1993 and 1994/1995 seasons,
abiotic parameters and the structure and dynamics of the phytoplankton were studied. Algal assemblages from the phytoplankton,
from algal clumps encased in the lake ice and from the benthic algal felt were compared. Low Jaccard similarity indices between
these three assemblages suggest different survival strategies. The higher species richness of phytoplankton when studied during
the whole summer also suggests that external propagule inputs can heavily influence the structure of this community. High
levels of phosphate, nitrate and ammonium throughout the study periods indicate that they do not limit summer growth of the
phytoplankton community. Blooms of Chlamydomonas subcaudata Wille are apparently characteristic. This group of features define Otero Lake as a highly eutrophic water body, in which
outflow seems to be the main cause of phytoplankton loss during summer.
Received: 23 December 1996 / Accepted: 29 August 1997 相似文献
20.
1. A 1-year intensive study of nutrient flows in Airthrey Loch, central Scotland, a small eutrophic [mean total phosphorus (TP) = 61.1 μg P l–1 ] well-flushed freshwater body (area, 6.9 ha; mean depth, 1.85 m; volume, 1.274 × 105 m3 ; retention time, 0.44 yr), was undertaken.
2. The nutrient budget was dominated by large allochthonous P inputs, equivalent to an areal load to the loch of 8.56 kg P ha–1 yr–1 , which occurred predominantly during winter. In the summer, when TP inputs were low, water column levels of TP still increased, as a result of aerobic P release from sediments.
3. Sorption experiments indicated potential for sediment P release at water P concentrations of up to 200 μg P l–1 .
4. Aerobic release rate of P from sediments to the water column of Airthrey Loch was estimated to be of the order of 1 mg P m–2 day–1 , and occurred during periods of elevated water column pH.
5. Straw bales placed in the loch to retard algal blooms were found not to have any demonstrable impact on algal concentrations observed during the study. 相似文献
2. The nutrient budget was dominated by large allochthonous P inputs, equivalent to an areal load to the loch of 8.56 kg P ha
3. Sorption experiments indicated potential for sediment P release at water P concentrations of up to 200 μg P l
4. Aerobic release rate of P from sediments to the water column of Airthrey Loch was estimated to be of the order of 1 mg P m
5. Straw bales placed in the loch to retard algal blooms were found not to have any demonstrable impact on algal concentrations observed during the study. 相似文献