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1.
The use of high-spectral-resolution radiometer data for detection of low chlorophyll concentrations in Lake Kinneret 总被引:2,自引:0,他引:2
Gitelson A.; Mayo M.; Yacobi Y.Z.; Parparov A.; Berman T. 《Journal of plankton research》1994,16(8):993-1002
Chlorophyll distribution in Lake Kinneret was estimated in aperiod of low chlorophyll-a concentrations (37 mg m3)using remotely sensed data. The data set included high-spectral-resolutionradiometric measurements in the range 400750 nm, chlorophylland suspended matter concentrations, Secchi disk transparencyand vertical attenuation coefficients at 20 stations. The spectroradiometricdata were used to create the algorithms suitable for quantitativedetermination of chlorophyll content. The present paper presentsexperimental field evidence showing that fluorescence can besuccessfully used for remote monitoring of chlorophyll-a content(with an estimation error <0.5 mg m3) in productiveinland waters with a background of variable and relatively highsuspended matter concentration. 相似文献
2.
Cobelas M.Alvarez; Haering F.J.; Velasco J.L.; Rubio A. 《Journal of plankton research》1992,14(7):979-996
The seasonal time course of phytoplankton primary productivitywas studied weekly in a hypertrophic, gravel-pit lake closeto Madrid, Spain. Chlorophyll a ranged 22445 mg m2.Gross primary productivity attained 0.28±0.14 g C m2h1 (range: 0.060.60), its yearly value being 900g C m2, but the shallow euphotic depths and the highplankton respiration ensured that net productivity was generallylow. Respiration losses amounted to 0.31±0.24 g O2 m2h1, with phytoplankton respiration roughly attainingone-half of overall plankton respiration. Areal phytoplanktonproductivity and plankton respiration followed a seasonal trendbut this was not the case for photosynthetic capacity. Surfacephotoinhibition was evenly distributed throughout the study.Quantum yields showed an increasing depth trend, but no seasonaltrend. Both Pmax and Ik were both temperature- and irradiance-dependent.As compared with lakes of lesser trophic degree, phytoplanktonprimary production in hypertrophic lakes might be increasednot only by higher nutrient contents but also by low chlorophyll-specificattenuation coefficients and low background, non-algal attenuation,thereby allowing for higher areal chlorophyll contents and hencehigher areal productivity. Our study suggests that physical(irradiance and water column stability) as well as chemicalfeatures (dissolved inorganic carbon and soluble reactive phosphorus)may control seasonality of phytoplankton primary productionin this lake despite recent claims that only physical factorsare of significance in hypertrophic lakes. However, this doesnot explain all the variability observed and so a food web controlis also likely to be operating. 相似文献
3.
During the spring of 1994, we determined the factors responsiblefor the decline of the seasonal diatom bloom in the Gullmarfjord, on the west coast of Sweden. Four species constituted>75% of the biomassDetonula confervacea, Chaetocerosdiadema, Skeletonema costatum and Thalassiosira nordenskioeldiireachingconcentrations of 4900, 350, 8200 and 270 cells ml1,respectively. Growth of phytoplankton was exponential (growthrate = 0.12 day1) from 3 to 21 March, after which a galewith winds >15 m s1 caused massive aggregation. Amaximum of 130 p.p.m. (v/v) of marine snow aggregates was observedby in situ video at the peak of the bloom. Critical concentrations(Jackson, Deep-Sea Res., 37, 11971211, 1990) were similarto observed showing that coagulation theory could explain thesudden decline of the bloom. The heterotrophic dinoflagellateGyrodinium cf. spirale increased exponentially after the peakof the bloom with maximum (temperature-adjusted) growth rates.After the rapid aggregation and sedimentation of the bloom,they were able to control any further growth of diatoms. Nitrateand silicate were never depleted, but phosphate may have beenlimiting by the end of the study period. We conclude that massaggregation during a gale marked the end of the bloom, and thatintense grazing by heterotrophic dinoflagellates prevented anysubsequent increase of diatoms. 相似文献
4.
We tested the hypothesis that the growth rate of Anabaena circinalis,under diurnally stratified conditions, would increase as flotationvelocity increased owing to higher light availability. An insitu experiment compared the growth of diurnally stratifiedpopulations of A. circinalis with flotation velocities of 0.5and 1.0 m h1, with neutrally buoyant populations thatwere exposed to either mixed or persistently stratified conditions.The experiment was conducted in the turbid lower Murray Riverin South Australia (vertical attenuation coefficient = 4.52± 0.36 m1). To represent the mixing patterns,A. circinalis was contained in diffusion chambers that weremoved to different positions in the water column throughoutthe day. Diurnal populations with flotation velocities of 1.0and 0.5 m h1 grew at 0.23 ± 0.01 and 0.15 ±0.01 day1, respectively. Mixed populations grew at 0.19± 0.01 day1, whereas persistently stratified populationsgrew at 0.43 ± 0.01 day1. Results were used toextend a model that predicts growth of A. circinalis when exposedto the different mixing patterns. The model showed that bloomsare unlikely to be formed when the period of diurnal stratificationis <1 week, regardless of flotation velocity. When the diurnallystratified period is >1 week, flotation velocity is importantand a bloom may form depending on values assigned to the growthperiod and maximum mixed depth (Zm). 相似文献
5.
In a coastal area of southern Chile (41° S), the major ammoniumassimilating enzyme glutamine synthetase (GS) was detected ina green dinoflagellate bloom during April 2003. High chlorophylla concentrations (1000 µg L1) attributable to Gymnodiniumcf. chlorophorum in surface waters were associated with highand very low nitrate reductase activities. Coincident with thebloom, dissolved inorganic nitrogen concentrations were nearthe detection limit (NO3 + NH4+ <0.5 µM). SinceGS correlates with the use of ammonium as an external nitrogensource, we suggest that GS activity seems to be a good indicatorof ammonium utilization in a period dominated by a single dinoflagellatespecies. 相似文献
6.
The relationships between photosynthesis and photosyntheticphoton flux densities (PPFD, P-l) were studied during a red-tideof Dinophysis norvegica (July-August 1990) in Bedford Basin.Dinophysis norvegica, together with other dinoflagellates suchas Gonyaulax digitate, Ceratium tripos, contributed {small tilde}50%of the phytoplankton biomass that attained a maximum of 16.7µg Chla 1 and 11.93 106 total cells I1.The atomic ratios of carbon to nitrogen for D.norvegica rangedfrom 8.7 to 10.0. The photosynthetic characteristics of fractionatedphytoplankton (>30 µm) dominated by D.norvegica weresimilar to natural bloom assemblages: o (the initial slope ofthe P-l curves) ranged between 0.013 and 0.047 µg C [µgChla]1 h1 [µmol m s1]1the maximum photosynthetic rate, pBm, between 0.66 and 1.85µg C [µghla]1 h1; lk (the photoadaptationindex) from 14 to 69 µ,mol m2 s1. Carbonuptake rates of the isolated cells of D.norvegica (at 780 µmolm2 s1) ranged from 16 to 25 pg C cell1h and were lower than those for C.tripos, G.digitaleand some other dinoflagellates. The variation in carbon uptakerates of isolated cells of D.norvegica corresponded with PBmof the red-tide phytoplankton assemblages in the P-l experiments.Our study showed that D.norvegica, a toxigenic dinoflagellate,was the main contributor to the primary production in the bloom. 相似文献
7.
Response of Leaf Spectral Reflectance in Loblolly Pine to Increased Atmospheric Ozone and Precipitation Acidity 总被引:1,自引:0,他引:1
CARTER GREGORY A; MITCHELL ROBERT J.; CHAPPELKA ARTHUR H.; BREWER CHARLES H 《Journal of experimental botany》1992,43(4):577-584
Leaf reflectance responses to increased ozone and precipitationacidity were determined at visible (400720 nm) and infra-red(7202500 nm) wavelengths for field-grown seedlings ofloblolly pine (Pinus taeda L.). Treatments were maintained continuouslyfrom 3 April to 3 November. In a relatively ozone-sensitivevariety of pine, increased ozone decreased visible and infra-redreflectance by late May. By late August, continued exposureto ozone increased visible and infra-red reflectance. As oflate November, ozone at 17ambient or greater concentrationshad increased visible reflectance substantially in an ozone-insensitiveas well as the ozone-sensitive variety. Acidic precipitationdecreased visible and infra-red reflectances in both varietiesin May and decreased infra-red reflectances in the ozone-sensitivevariety in August, but did not produce significant reflectanceresponses in November. Visible reflectance responses to ozoneand acidic precipitation, particularly those near 700 nm, werespectrally similar to reflectance responses reported previouslyfor other deleterious environmental influences. Key words: Pinus taeda, reflectance, ozone, acidic precipitation 相似文献
8.
Sedimentation of phytoplankton populations dominated by Microcystis in a shallow lake 总被引:1,自引:0,他引:1
The sedimentary flux of phytoplankton was measured using sedimenttraps in a shallow hypertrophic lake (Lake Kasumigaura), whereMicrocystis bloomed, from June to November 1983 The sedimenttraps were set at 0.5, 1.5 and 3.0 m depth in Takahamairi Bay(3.5 m depth). Microcystis spp. (including M.aerugmosa and M.viridis)in the traps were rare until early August, but increased thereafter.Sinking rates of Microcystis were 0.0045, 0.020 and 0.24 m day1in JuneAugust, September and October respectively, whichwere far lower than those of Melosira (0.21.7 m day1)and Syncdra (0.21.0 m day1). The total sedimentaryfluxes of POC and that of algal carbon during the study periodwere 283.2 and 96.7 gC m2 which were 59.5% and 20.3%of the gross primary production (475.8 gC m2) respectively.The sedimentary flux of living algae measured by algal countswas large in June but small in August and September. On theother hand, the flux of detritus obtained by subtracting totalalgal carbon from POC was small in June and July but large inAugust and September. Therefore diatoms, which appeared mostlyin June, tended to sink as live algae, while Microcystis sankas detritus after being decomposed or consumed in the waterIt was concluded from the results of carbon budget calculationsand the respiration rate of the 1- to 20-µm fraction thatthe activity of decomposers or consumers increased greatly inthe short period at the end of the bloom of Microcystis. 相似文献
9.
A recurrent, prolonged and singular bloom of Alexandrium tayloriBalech in an open beach (La Fosca, Spain, NW Mediterranean)is described. Alexandrium taylori appears at several placesalong a wide area of the NW Mediterranean (Costa Brava) duringthe summer, reaching concentrations up to 105 cells l1,but it only proliferates persistently, massively (densities>106 cells l1) and recurrently during August in LaFosca beach. The A.taylori bloom can be considered a manifestationof large-scale proliferation in a restricted area, where couplingbetween resting cysts in the sediment and bloom outbreak isnot a major factor compared to the interaction of local environmentalconditions with the planktonic organism's life history. Fromobservations of environmental conditions (the environmentalwindow) and the multiscale spatio-temporal distributions andlife history of A.taylori, we describe the bloom dynamics andanswer some critical questions about the different phases ofthe bloom. Some of these answers are: (i) the source of theA.taylori population is widespread offshore and is not locateddirectly at the beach; (ii) high cell densities are reachedand maintained with a moderate in situ growth and low loss rates;(iii) temporary cysts act as a reserve of the population. 相似文献
10.
The population carbon budget and seasonality of Boeckella minutain a newly formed subtropical reservoir were examined 3 yearsafter the reservoir filled. Average daily biomass was 26.4 mgC m3 and the annual population carbon budget was: consumption2470, egestion 1482, assimilation 988, production 493 and respiration495, mg C m3 year1, and the average P/B and P/Aratios were 0.08 and 0.5 respectively. Clutch size and reproductiveeffort (egg production/assimilation) were low, and the proportionof males decreased throughout the population cycle. The seasonalabundance pattern changed from perennial (pre-filling years)to a 7 month cycle. It is suggested that eutrophication andthe spring bloom of cyanobacteria may have accentuated a seasonaldecrease in reproductive effort and survival, leading to anabsence of planktonic stages during summer, and that restingeggs facilitated population survival during the summer periodof stratification. 相似文献
11.
The photosynthetic uptake of root-zone CO2 was determined forEriocaulon septangulare, Gratiola aurea, Isoetes macrospora,Littorella uniflora var. americana and Lobelia dortmanna aspart of a study of the photosynthetic carbon economy of submergedaquatic isoetids. The pH and dissolved inorganic carbon (DIC)of the sediment interstitial water in four Wisconsin lakes reflectedthe water column character, where the DIC increased with depthin the sediment to concentrations five to ten times those ofthe water column. Sediment free CO2 concentrations were 550times those in the water column and were similar at all sites(about 051.0mM CO2 in the root-zone). In pH-driftstudies these plants were unable to take up HCO2. Laboratory determinations of the carbon uptake from the rootand shoot-zones were made for all five species. These experimentsshowed that CO2 in the root-zone accounted for 6595 percent of external carbon uptake for the five species. For G.aurea and E. septangulare, root-zone CO2 was > 85 per centof carbon uptake. Carbon, CO2, photosynthesis, sediment, isoetid, Eriocaulon septangulare, Gratiola aurea, Isoetes macrospora, Littorella uniflora, Lobelia dortmanna 相似文献
12.
Colman, B. and Rotatore, C. 1988. Uptake and accumulation ofinorganic carbon by a freshwater diatom.J. exp Bot 39:10251032. The mechanism of uptake of inorganic carbon and its accumulationhas been studied in the freshwater diatom Navicula pelliculosa.No external carbonic anhydrase could be detected, although itwas detected in cell extracts. The rate of photosynthetic O2evolution, in media in the range pH 7.58.5, exceededthe calculated rate of CO2 supply 2- to 5-fold, indicating thatHCO3 was taken up by the cells. At an external pH of7.5, the internal pH, measured by 14C-dimethyloxazolidine-2,4-dione distribution between the cells and the medium, was pH7.6 in the light and pH 7.4 in the dark. Accumulation of inorganiccarbon was determined by the silicone oil centrifugation methodand inorganic carbon pools of 23.5 mol m3 were found,a concentration 21.6-fold that in the external medium. The resultsindicate an active accumulation of inorganic carbon againstpH and concentration gradients in this diatom, probably by activeHCO3 uptake. Key words: Bicarbonate transport, carbon dioxide, carbonic anhydrase, CO2 affinity, CO2 concentrating mechanism, internal pH, Navicula pelliculosa 相似文献
13.
A persistent and unusual bloom of Dinophysic acuta Ehrenbergin the RIas Bajas (Northwest Spain) from early July to mid-November1989, was associated with a diarshetic shellfish poisoning (DSP)outbreak that prevented mussel extraction in some areas fromearly August to mid-December. Integrated samples (05,510 and 1015 m) were taken once or twice a weekat six stations. Maximum numbers of D.acuta (up to 2.3 104intheintegratedsamples)andpercentageofobserveddMdingcells(upto3l%),appearedin August, and formed a maximum in the thermodine. Cellnumbers were minimal when upwelling caused a breakdown of stratification.Fligh numbers of D.acuta (up to 1.8 104 cells 11 appearedagain when persistent south winds in late October caused a reversalof the circulation. Thus, the two cell maxima occurred duringtwo distinct hydrographic regimes, but in both cases at temperaturesof 1517C. Numerous cells with one typical D.acuta valve,but the other valve reduced in size, were seen during the bloom,as well as Dinophysts dens Pavillard cells that might be a lifecycle stage of D.acuta. Other observations include double- walled,unwinged forms that are perhaps some kind of cyst, and a hypotheticalfertilizing tube emerging from the larger cellof a D.acuta/D.dens couplet. It is suggested that the maximaduring stratification and during downwelling episodes couldcorrespond to periods with a predominance of in situ growthand physical accumulation, respectively, and that the exceptionalmeteorological conditions during 1989 provided the optimum scenariofor the unusual occurrence of D.acuta. 相似文献
14.
Planktonic primary production in the German Wadden Sea 总被引:8,自引:0,他引:8
By combining weekly data of irradiance, attenuation and chlorophylla concentrations with photosynthesis (P) versus light intensity(E) curve characteristics, the annual cycle of planktonic primaryproduction in the estuarine part of the Northfrisian WaddenSea was computed for a 2 year period. Daily water column particulategross production ranged from 5 to 2200 mg C m2 day1and showed a seasonal pattern similar to chlorophyll a. Budgetcalculation yielded annual gross particulate primary productionsof 124 and 176 g C m2 year1 in 1995 and 1996,respectively. Annual amounts of phytoplankton respiration, calculatedaccording to a two-compartment model of Langdon [in Li,W.K.W.and Maestrini,S.Y. (eds), Measurement of Primary Productionfrom the Molecular to the Global Scale. International Councilfor the Exploration of the Sea, Copenhagen, 1993, pp. 2036],and dissolved production in 1996, were both in the range of2439 g C m2 year1. Annual total net productionwas thus very similar to particulate gross production (127 and177 g C m2 year1 in 1995 and 1996, respectively).Phytoplankton growth was low or even negative in winter. Inspring and summer, production/biomass (Pr/B) ratios varied from0.2 up to 1.7. Phytoplankton growth during the growth seasonalways surpassed average flushing time in the area, thus underliningthe potential of local phytoplankton bloom development in thispart of the Wadden Sea. The chlorophyll-specific maximum photosyntheticrate (PBmax) ranged from 0.8 to 9.9 mg C mg1 Chl h1and was strongly correlated with water temperature (r2 = 0.67).By contrast, there was no clear seasonal cycle in B, which rangedfrom 0.007 to 0.039 mg C mg1 Chl h1 (µmolphotons m2 s1)1. Its variability was muchless than PBmax and independent of temperature. The magnitudeand part of the variability of PBmax and B are presumably causedby changes in species composition, as evidenced from the rangeof these parameters found among 10 predominant diatom speciesisolated from the Wadden Sea. The ratio of average light conditionsin the water column (Eav) to the light saturation parameterEk indicates that primary production in the Wadden Sea regionunder study is predominantly controlled by light limitationand that nutrient limitation was likely to occur for a few hoursper day only during 5 (dissolved inorganic nitrogen) to 10 (PO4,Si) weeks in the 2 year period investigated. 相似文献
15.
The Location of the Transporting System for Inorganic Carbon and the Nature of the Form Translocated in Chlamydomonas reinhardtii 总被引:4,自引:0,他引:4
The permeability of the plasmalemma of Chlamydomonas reinhardtiicells was increased by treatment with poly-L-lysine or dimethylsulphoxideas indicated by 3-phosphoglyceric acid dependent O2 evolution.These treatments decreased the ability of the cells to accumulateinorganic carbon internally and hence their photosynthetic affinityfor inorganic carbon in the medium. With saturating light andinorganic carbon, the photosynthetic rate was less affectedby the poly-L-lysine and dimethylsulphoxide treatments. Thusthe poly-L-lysine and dimethylsulphoxide did not alter the activityof the chloroplasts but rather made the intracellular inorganiccarbon pool more freely exchangeable with the medium. It isconcluded that the transporting system for inorganic carbonis located at the plasmalemma. Treatment with Diamox, an inhibitor of carbonic anhydrase, didnot affect photosynthetic rate and accumulation of inorganiccarbon when CO2 was supplied but strongly inhibited both parameterswhen HCO3 was supplied. In a mutant of Chlamydomonasreinhardtii lacking a cell wall, carbonic anhydrase leaks tothe medium and uptake of inorganic carbon is much faster whenCO2 is supplied than when HCO3 is supplied. These resultssuggest that CO2 rather than HCO3 is the inorganic carbonspecies that is actively translocated across the plasmalemma. Key words: Chlamydomonas, Inorganic carbon uptake 相似文献
16.
A monospecific bloom of the coccolithophorid Emiliania huxleyi(Lohmann) Hay & Mohler (Prymnesiophyceae) was detected offRio de La Plata at 36°S and 54°W in November 1989. Thecell densities observed were up to 6x105 cells I1. Thisis the first record of a bloom of E.huxleyi in the area. 相似文献
17.
Temporal changes in ciliate assemblages during the course ofa bloom of the harmful microalga Heterocapsa circularisquama(Dinophyceae) were investigated and consecutive estimates ofspecies-specific maximum grazing losses were analyzed from Augustto September 1998 at a site in western Hiroshima Bay, the SetoInland Sea of Japan. Temporal increases of the H. circularisquamamean concentration in the water column were observed twice (2529August and 710 September) with the maximum concentration(ca. 4000 cells mL1) being recorded on 25 August. Themain ciliate genera during the bloom were Favella, Tontonia,Eutintinnus, Tintinnopsis and Amphorellopsis. Increases of Favellaand Tontonia were observed when the concentration of H. circularisquamaranged from 260 to 1170 cells mL1. Total maximum grazingloss estimated from the abundance and ingestion rate of eachciliate species on H. circularisquama ranged from 1 to 75% standingstock removed d1 of the H. circularisquama concentration.High grazing losses mainly due to the genera Favella and Tontoniaoccurred during the period when the H. circularisquama concentrationwas decreasing. These results suggest that grazing by ciliateassemblages can influence the population dynamics of H. circularisquamadespite the potentially toxic nature of the phytoplankter. 相似文献
18.
Chlorophyll (Chl) a was measured every 10 m from 0 to 150 min the Transition Domain (TD), located between 37 and 45°N,and from 160°E to 160°W, in May and June (Leg 1) andin June and July (Leg 2), 199396. Total Chl a standingstocks integrated from 0 to 150 m were mostly within the rangeof 20 and 50 mg m2. High standing stocks (>50 mg m2)were generally observed westof 180°, with the exceptionof the sporadic high values at the easternmost station. Thetotal Chl a standing stock tended to be higher in the westernTD (160°E172°30'E) than in the central (175°E175°W)and eastern (170°W160°W) TD on Leg 1, but thesame result was not observed on Leg 2. It was likely that largephytoplankton (210 and >10 µm fractions) contributedto the high total Chl a standing stock. We suggest that thehigh total Chl a standing stock on Leg 1, in late spring andearly summer, reflects the contribution of the spring bloomin the subarctic region of the northwestern Pacific Ocean. Thedistribution of total Chl a standing stock on Leg 2 was scarcelyaffected by the spring phytoplankton bloom, suggesting thattotal Chl a standing stock is basically nearly uniform in theTD in spring and summer. Moreover, year-to-year variation inthe total Chl a standing stock was observed in the western TDon Leg 1, suggesting that phytoplankton productivity and/orthe timing of the main period of the bloom exhibits interannualvariations. 相似文献
19.
Negri Ruben M.; Carreto Jose I.; Benavides Hugo R.; Akselman Rut; Lutz Vivian A. 《Journal of plankton research》1992,14(2):261-269
In October 1988 a bloom of Gyrodinium cf. aureolum was recordedalong a transect across the continental shelf reaching celldensities of 1300 ml1 and chlorophyll a concentrationsup to 16 µg 11. The bloom was restricted to a nutrient-richthin surface layer of 10 m depth at the beginning of seasonalpycnocline. Hydrological conditions showed a particular salinitydistribution. The phytoplankton community was dominated by G.cf. aureolum but the coexisting flora presented a great diversity.UV-absorbing pigments were recorded in the community. 相似文献
20.
The seasonal abundance of the phototrophic ciliate Mesodinium rubrum in Southampton Water, England 总被引:1,自引:0,他引:1
The abundance of the marine phototrophic planktonic ciliateMesodinium rubrum was monitored throughout an annual cycle attwo stations in the Southampton Water estuary. Seasonal changesin the concentration of nitrate, ammonia and phosphate weremonitored both at the inner estuary station (NW Netley) andouter estuary station (Calshot). Nutrient levels in the winterwere similar at both stations, and were diminished during sequentialdiatom blooms dominated initially by Sketetonema costatum andthen by Rhizosolenia dclicatula. Nitrate was reduced to a seasonalminimum in the outer estuary following these spring diatom blooms,but in the inner estuary was sustained >500 µg I1until the onset of the M.rubrum bloom. During the developmentof a visible red tide of M.rubrum in June/July at NW Netley,nutrient concentrations were considerably reduced. Cell numbersof M.rubrum varied between 2 and 3 cells ml during winterto >400 cells ml1 during the bloom at NW Netley, whereasat Calshot cell abundance did not increase above 25 cells ml1at any time of the year. At NW Netley, dense accumulations ofthe ciliate occurred over restricted depth intervals duringthe bloom and possible factors influencing the observed verticaldistribution of cells are considered.
1Present address: Biology Department, Faculty of Science, AddisAbaba University, PO Box 1176, Addis Ababa, Ethiopia 相似文献