Temporal fluctuation of phytoplanktonic chlorophyll a and primary production in a turbid floodplain lake of the river Parana (Argentina)

13 Pages·1999·3.5 MB·English

by  Irina Izaguirre

CayanaBot.36(I):39-31. 1999 ISSN 0016-5301
TEMPORAL FLUCTUATION OF PHYTOPLANKTONIC CHLOROPHYLL
A AND PRIMARY PRODUCTION IN ATURBIO FLOODPLAIN LAKE OF
THE RIVER PARANÁ (ARGENTINA)
FLUCTUACIONES TEMPORALESDELA CLOROFILA A YDELA
PRODUCCIÓNPRIMARIA FITOPLANCTONICA EN UNA LAGUNA TURBIA
DELA LLANURA DEINUNDACIÓNDELRIOPARANÁ (ARGENTINA)
&
IrinaIzaguirre* Inés O'FarreH*
ABSTRACT RESUMEN
The seasonal pattern of vertical distribution of Enelpresentetrabajoseanalizalavariaciónestacionalde
chlorophyllííandprimaryproduction vvasstudied in ladistribución verticaldeclorofilaí;ydelaproducción
a floodplain lake ofthe Lower Paraná River from primariafitoplanctónicadeunalagunade lallanurade
May 1995toMay 1996.Nostablestratification was inundacióndelParanáInferior. Losmuéstreosabarcaron
observedduringthestudyperiodforlakeMontiel.a un cicloanual,entre mayode 1995 y mayode 1996.
typical turbulent and shallow lake. Chlorophyll ív, Debidoalafrecuentemixisdelasaguas,noseevidenció
mainly regulatedby the hydrological regime and by ningunaestratificaciónverticalestable.Laconcentración
seasonal changes in temperature and light. attained de clorofila a estuvo regulada principalmente porel
concentrations whichexceeded 10 pg 1' during late régimen hidrológicoyporlasvariacionesestacionalesde
spring and early summer. Severe dilution occurred luzytemperatura. Lasmáximasconcentracionesfueron
duringhighwaterlevelperiodswhilelightlimitationin registradashaciafmesdelaprimaveraycomienzosdel
the watercolumn was observedforthe driest periods verano,convaloressuperioresa 10pg1'.Enlosperiodos
due to sediment resuspension from the bottom. deaguasaltasseobservóunamarcadadilución,mientras
Gross primary production perunitárea ranged from queenlasfasedeaguasbajasseevidencióciertalimitación
0.114g m-h' to 1.235 g in-h'. In general, produc- porluzdebidoalaresuspensióndelossedimentos.Lapro-
tion sharply declined with depth because oflight ducciónprimariabrutaporáreafluctuóentre0.114gm-h'
attenuation by suspended solids. Net production y1.235gm-h"'.Engeneralsedetectóunabruscadisminu-
appeared to be Hniited by light penetration and by cióndelaproducciónprimariaenfiíncióndelaprofundidad
hydrological mechanisms which exerted a signifi- debidoalagrancantidaddesólidosensuspensión.Lapro-
cant influenceon the limnological parametersofthe ducciónnetadeestalagunaestaríalimitadaporladisponi-
lake. bilidaddeluzyporladinámicahidrológica.
Keywords: Floodplain lake. primary production, Palabrasclan'es: Laguna,llanuradeinundación,pro-
chlorophylla,phytoplankton.ParanáRiver,Argentina. ducción primaria,clorofilaa,fitoplancton,ríoParaná,
Argentina.
INTRODUCTION Chemicalcharacteristics. Thus, the bioproductive
mechanisms ofthe water bodies ofthe alluvial
TheParanáRiverhydrological regimeregú- valley are also influenced by the hydrological
lales most ofthe floodplain lakes physical and tluctuations (Bonetto & Wais, 1987). As it was
discussedbyJunketal. (1989),thefloodpulseis
considered to be the principal driving forcé for
theexistence.productivityandinteractionsofthe
biota in Ihese ecosystems. Several studies on
'Depto. Ciencias Biológicas. Facultad Ciencias phytoplankton have been conducted in South
E1x4a2c8tBausenyosNaAtiurreas,leAsr,geUntniinvae.rsidad Buenos Aires. American floodplain lakes (Bonettoetal.. 1994;
39
CayanaBot.56(1), 1999
GarcíadeEmiliani, 1993;ZalocardeDomitrovic, combinationoferosiónandsedimentdeposition.
1990, 1992). Detailedstudiesonprimary produc- These lakes are annually filled during the rising
tion ofthe different type ofAmazonian waters waterphase as aconsequence ofthe riverwater
werecarriedoutbySchmidt(1976, 1982),Fisher inflow. Atfalling stages, the surpluspondwater
(1978), Fisheretal. (1988),Fittkauetal (1975) flowsbackintotheriver.Thestronginfluenceof
and Rai & Hill (1984). The Orinoco River, its theseasonalflucmationsoftheParanálevelonthe
tributaries and related lakes have been surveyed hydrologicalcharacteristicsofthefloodplainlakes
byLewis(1988)andLewis&Weibezahn(1976) has also been well documented by García de
originating comprehensive works on the energy Emiliani(1993).FoUowingJunk'scriterion(1983),
flow of these systems. In contrast with the thiskindofwaterbodycanbeconsideredasinter-
Amazon,theParanálakeswerescarcelystudied. medíate between aclosed lake as accumulating
Most investigations referto the ParanáRiveron systemandariverasadischargingone.
its UpperandMiddle reaches and specially toits Lake Montiel has an área about 5.4 km-,
main channel (Bonetto etai, 1979, 1982, 1983). which is subject to a great variation due to the
Inrelationtotheprimaryproductionoftheflood- nature ofthis waterbody. Although the morpho-
plainshallowlakes,PerottideJorda(1977)carried metricfeaturesofthelakehavenotbeen studied,
outastudyonphytoplanktonbiomassandproduc- observations carried out by Prefectura Naval
tion in Los Matadores pond (Middle Paraná). Argentina from Villa Constitución (Santa Fe
Later on, Carignan & Planas (1994) compared Province), establish that the máximum depth
three approaches for the recognition ofnutrient would be higherthan 10 meters. The máximum
and light limitation ofproductivity in different depth at the incubation site forthe study period
lakesoftheParanáfloodplain. variedbetween3and6meters.
The LowerParaná has a large floodplain,
whichextendsovertheleftsideoftherivervalley.
Themaincourseisdividedintoseveralchannels METHODS
enclosing a complex formation oflow islands.
The present study was conducted on a shallow The study comprised one yearofmonthly
andturbidlakelocatedonthefringingfloodplain samplings,between24May1995and14May1996.
oppositethecityofVillaConstitución,Argentina AsamplingsitewasestabUshedinthepelagiczone
(LakeMontiel). ofthe lake where depth was approximately 4-6
The main objectives ofthis study were to meters. Sample collections and incubations were
determine the seasonal pattem ofvertical distri- performed at five depths, encompassing com-
butionofchlorophylla,grossprimaryproduction pletely the euphotic zone ofthe lake at regular
andcommunityrespirationinafloodplainlakeof intervals from the surface up to a depth below
theLowerParaná River and to evalúate factors Z u X 3 level. Water samples at the different
controllingbothprocesses. depths were obtained by means ofa peristaltic
pump. Water temperature, pH and conductivity
weremeasuredwithHannaHI8314andHI8033
STUDYSITE portable sensors, andtransparency with aSecchi
disk. Dissolvedoxygen was estimated according
The study was carried out in a floodplain to Winkler method (APHA, 1975); the titration
shallow lake ofthe Lower Paraná River (Lake endpointwasdetectedvisually with starch indi-
Montiel), which is located in the left margin of cator (precisión ± 0.2 mgl'). Water samples for
themaincourse(33°15'S;60°30'W)(Fig. 1). Chemical analyses were also collected at each
Accordingtotheclassificationproposedby depth,andfilteredthroughWhatmanGF/Ffilters.
Drago(1990),LakeMontielcanbeconsideredas Solublereactivephosphorus(SRP) wasanalysed
atypical pond with "indirect connection" to the according to the stannous chloride method
river, since it is communicated with the River (APHA, 1975) and NO3-N was determined
Paranáby a stream. Nevertheless during periods following the spongy cadmium technique
ofhigh riverdischarge, its connection is direct. (Mackereth etai, 1978). Total phosphorus (TP)
As other floodplain waterbodies ofthe Paraná, was determined in non filtered samples after an
LakeMontielhasanalluvialorigin,formadbya aciddigestiónbythestannous chloride method.
40
Temporalfluctuationofphyloplanktcinicchlorophvllu:Izagliirrk,I.&I.O'Farrell
Suspended solids concentrations weie obtained Temperature ranged from 9.9 to 25.4"C.
filtering the water samples through predried Differences among the five depths were usually
glassfibrefilters(WhatmanGF/F);dry masswas less than 1°C, thus revealing the absence of a
determinedaccordingtoAPHA(1975). thermocline. Mean conductivity was of 100 pS
Water samples for chlorophyll a analyses cm' with the lowest figure in August 1995 (59.1
werealsofilteredthrough WhatmanGF/F. Filters pS cm') and máximum in November 1996 (173
were stored at -20°C, and then pigments were pScm').Secchitransparencywaslowthroughout
extractedwithhotethanol(60-70°C).Theextracts the year varying between 15 and 48 cm.
were centrifuged andchlorophyll a (corrected for Transparency was least during drought periods
phaeopigments) was measured by spectropho- and relatively high during the flooding season.
tometry before and after acidification with HCl Water level of the main course influenced the
(0.1 N). Chlorophyll a concentrations were cal- contentofsuspendedsolidsinthelake,whichon
culated using the equations given by Marker et timedeterminedthetransparencyvalúes(Fig. 3).
al. (1980). Lightpenetrationprotllesshowedasignificantlight
Phytoplanktonprimaryproduction wasesti- attenuationwithdepthasaconsequenceofthehigh
mated by means ofthe oxygen light-dark bottle content ofsuspended solids. In general terms, the
technique, following recommendations given by mixing depth (Zm) exceeded 4-5 times the
Dokulil(1984).Bottlesweresuspendedbymeans euphotic zone. Light penetration was influenced
ofthe dispositives proposed by Boltovskoy & by river discharge. registering the highest Z,,j|^
Velez (1983/4), and incubated for 5-6 hours duringperiodsofhighwaterlevelinthelake.
between 10:00/11:00 - 16:00/17:00 h. Incident Soluble reactive phosphorus (SRP) concen-
irradiancewasmeasuredeachhalfanhourduring trationswere máximumin summer(>50pg 1"'),
incubation with a quantum sensor (Photovolt and exhibited the lowest valúes during high
Corp.). Average irradiance at each incubation water periods. Total phosphorus (TP) ranged
depthwasestimatedassumingthatatSecchi disk between9and245pg1' withameanof95.4pg
depththeirradianceisabout20% thatofthe sur- 1'. In the same way as SRP, TP was strongly
face (Golterman. 1975). Since the water level of influenced by water level (Fig. 4). Nitrate (N-
lakeMontielisdirectlyregulatedbythedischarge NO,) mean concentrations for each sampling
oftheRiverParaná,thedailyrecordsofthewater daterangedfrom6.1 to309.2pgI' andaveraged
levelintheriveratthispoint(VillaConstitución) about 181.35 pg r'(Fig. 5). No seasonal pattern
recorded by Prefectura Naval Argentina were wasobserved.
used.
Twowayanalysesofvariancewithphysical b)Chlorophyllaandprimaryproductionmeasure-
and Chemical variables were used to test the ments
hypothesis ofvertical homogeneity. Correlation Chlorophyll a concentrations were very low
analyses between biotic and abiotic variables fromMaytoAugust 1995(lessthan5pg1"');from
were performed using Spearman's rank correla- September on a clear increasing pattern was
tionprocedure. observed, reaching a máximum of22.5 pg 1"' in
November.Lateron,concentrationsdecreasedupto
valúessimilartothoseregisteredatthebeginningof
RESULTS thestudy (Fig. 6). Mean chlorophyll aandchloro-
phyll a perunit área were inversely correlated to
a)Physicalandchemicalfeatures riverwaterlevel(r=-0.66,p<0.01 andr=-0.49.p<
ThewaterleveloftheParanáRiveratVilla 0.06) due to the dilution effect. On the other
Constitución varied between 1.45 and 3.86 hand. a direct correlation was found between
meters. The flood peaks were registered in May mean chlorophyll a and temperature (r = 0.56,
1995 and 1996, a minor increase was observed p<0.05) and with nutrients, being more signifi-
duringNovember(Fig.2). cant the relation with TP (r = 0.73, p<0.01).
The analyses ofvariance revealed that the Chlorophyll a shows an increasing trend with
mixingofthewatercolumnwascomplete, while enhanced mean incident light (Fig. 7), revealed
significant differences were observedamong the by a significant correlation (r = 0.59, p< 0.05).
samplingdates(p<0.001). Mean gross primary production (GPP) foreach
41
CayanaBot.56(1), H
sampling date varied between 1085 and 133 |ag rabletootherturbidsystems(Padisák&Dokulil,
O,l''h"' ,con-espondingthesevalúestoMay 1995 1994;Yinetal., 1996).Duetoitsdirectconnec-
andMay 1996respectively. Withtheexceptionof tion with the Paraná River, waterretention time
thefigures recordedforMay 1995 andJune 1995, is strongly influenced by riverdischarge. In this
mean GPP showed atemporal pattern similarto sense, LakeMontielexhibitsasimilarbehaviour
chlorophylla,withaclearmáximuminspring(Fig. asotherfloodplainlakes(Drago, 1990).
8). Meancommunityrespiration (CR) was máxi- According to the nutrient concentrations
mumin May 1995 duringhigh waterlevel (1910 and following Lee etal. (1981), the lake can be
|igO, l'h' ). whereasthelowestvaluéwasregis- considered as eutrophic. In general terms, in
teredatthebeginningofAugust(8.6pgO,l'h'). lowland rivers with large catchment áreas, the
GPPperunitárearangedfrom0.114gO-,m"-h"' to nutrient input from the watershed is likely to
1.235gO,m-h',CRperunitaieabetween0.09g exceed the requirements ofprimary production
O,m-h'and2.29gO,m-h'(TableI). (Descy etai, 1987). The high TP figures regis-
In general, máximum production was found teredduringlowwaterlevelperiodsareprobably
at the surface or at the first 40 cm, declining relatedtotheresuspensionofsedimentsfromthe
shaiplywithdepthbecauseoflightattenuationby bottom due to the shallowness of the lake.
suspendedsolids.Thus,GPPperunitáreashowed Soluble reactive phosphorus (SRP) and nitrate
a significant correlation with Z^^jj^ (r=-0.52, concentrations are within the range reported for
p<0.05). Regarding the vertical profiles ofGPP anothermarginallakeoftheLowerParanáRiver
andCRforeachsamplingdate(Fig.9),ingeneral (Bonetto etai, 1994). In this study, the authors
NPPisconfinedtothefirst40-60cmdepth. speculate that nitrogen limitation may occur in
The P:R ratio (GPP:CR) varied between thissystem.Inthesameway,Carignan&Planas
0.54 (May 1995) and 2.61 (July 1995), with an (1994) indicated that in some floodplain lakes
average of 1.47. The lowest figures coincided surveyedintheMiddleParaná,planktonicprima-
withperiodsofhighriverdischargeandflooding. ry production can be limited by nitrogen and/or
Theratioofproductionperunitbiomass of light.
the producer (GPP: milligram ofchlorophyll a) Algalgrowth,measuredbymeansofchloro-
perunittimeestimatedforLakeMontiel showed phyll a. is mainly regulated by the hydrological
reladvely high valúes, probably due to the lew regime and seasonal changes in temperature and
pigment concentration found for some sampling light. Thus, máximum chlorophyll a concentra-
dates. Since the oxygen technique is not so pre- tions were registered for late spring and early
cise as the C|^ method, in the estimation ofthe summerwithadequatelightintensitiesandmédi-
photosynthetic capacity we only consider data um waterlevéis. Moreover, the high nitratecon-
correspondingtodates when meanchlorophylla centrations which are related to the inputs from
was higher than 5 |ig 1"'. Thus. figures ranged theriverduringthefillingphaseofthelake,may
from20to50mgO,(mgchla)h'.Ontheother also explain the November chlorophyll a peak.
hand,ifthequotientsarebasedontheNPP,their The influence ofthe river discharge on phyto-
valúesvariedfrom 11 to42mgO,(mgchla)h"'. plankton developmentin the lake isevidentdur-
Considering only these sampling dates, daily ing the high waterphase when algal populations
GPPperunitáreavariedbetween 1.14and3.65g are severely diluted. During these periods the
O,m-day' . hydraulic retention time strongly decreases. In
this sense. Van den Brink (1994) discussed the
influence ofthe connectedness ofthe floodplain
lakestothemainchannelonthedevelopmentof
DISCUSSIONSANDCONCLUSIONS its plankton communities. The direct connection
of Lake Montiel to the river during floods
Lake Montiel is a typical turbulent, turbid explains the fact that changes in phytoplankton
shallow lake lacking stable stratification. This abundanceareimmediatetotheincreaseinwater
was evidenced from the homogeneous distribu- discharge. On the other hand, during the driest
tion ofphysical and chemical parameters in the period(latesummer),eventhoughin'adiancewas
incubation profile. Suspended solid concentra- high,pigmentconcentrationwaslowduetolight
tion, as well as Secchidiskvalúes, werecompa- limitationbyturbidityinthewatercolumn.
42
TemporallluL'tuaUoiiofpliyloplaiikloniccliloiupliylla:IZACLUKKiC.1.&I.O'Farrkí.I.
According to chloiophyll a concentiations. light penetration and by hydrological mecha-
Lake Montiel could be characteiised as a typical nisms which exert a significant inlluence on the
mesoto eutrophic system. reaching valúes higher limnological paramelers ofthe lake. According
than 10 (jg 1"' in spring time. In general, our to Talling (1971), net photosynthesis may be
chlorophyllavaliiesarehigherthanthosereponed negative when the mixing depth exceeds 4-5
fortheParanáRiveratitsUpperreach(Tiiomaze! times the euphotic zone. This condition was
al., 1992),andsimilartothoseregisteredbyPerotti repeatedly registered in Montiel Lake where tur-
deJorda(1977)forafloodplainlakeoftheMiddie bulence together with the morphometric charac-
Paraná. AsThomaz (1991) inThomaz(1992)and teristics (shallowness, relatively short residence
Bonettoe!al.(1969)retenedto,phytoplankton in time)severelylimittheeuphoticzone. Ingeneral
water bodies ofthe alluvial valley reaches sub- terms, and considering an annual cycle, net pro-
stantial densities, with concomitant high chloro- duction ofthe whole watercolumn is restricted
phyllaconcentrations. toshortperiods.Thesuppressionofproductionby
The vertical distribution ofchlorophyll a in lowtransparencyhasbeenobservedthroughoutthe
the euphotic zone is fairly homogeneous due to LowerOrinocoSystem(Lewis, 1988).
the continuous mixis ofthe lake. Contrarily, pri- The high valúesyielded when estimating the
maryproduction showsaprofiletypical ofturbid photosyntheticcapacities, probably obey tothe low
and eutrophic systems, where a sharp decline sensibility oftheoxygen technique forlowchloro-
with depth occurs. The high turbidity limits the phyll a concentrations. Nevertheless, when higher
euphoticlayerandcondensestheproductivezone pigmentconcentrations were registered the ratioof
toonemeterorless.Onlyduringperiodsoffairly production perchlorophyll a showedelevated val-
hightransparency,thenetproductionexceedsthe úes.Thehigheftlcienciesobsei-vedlu'etypicaloftur-
first meter. The same pattern was described by bidsystemswherelightlimitationisoneofthemain
PerottideJorda(1977). Nevertheless, itisimpor- factorsregulatingphytoplanktongrowth.
tan!tostressthatinturbulentwaterbodiesprima-
ry production incubation should simúlate the
ACKNOWLEDGMENTS
algal transport by turbulent flow (Uehlinger,
1993).
As illustratedin Fig. 8,community produc- This study was fmancially supported by the
tion and respiration are regulated by the hydro- UniversityofBuenosAires(Ai'gentina).Theauthors
logical changes and by temperature. At the wish to thank Prefectura Naval Argentinaforthe
beginning ofthe study CR is enhanced after an logisticassistancedurinsthefíeldwork.
important flood, probably by an increase of
allochtonous matter and a consequent bacterial
metabolism. Thus the lowest P:R quotient was References
observedatthismoment.Theimportantroleofthe
organic matter from adjacent tloodplains on the Apha.1975. Standardmethodsfortheexaminationof
CR has been reponed by Uehlinger(op. cit.). We Awsastoecriaatnidonw,asWtaeswhaitnegrtso.nA.mericanPublicHealth
hypothesisethatthehighGPPobsei-vedin spiteof BOLTOVSKOY. D. &G. Velez. 1983/4. Asimpleand
the low chlorophyll a valúes, could correspond to inexpensivedeviceforrigginglightanddarkbot-
OatshcetaopbceiroconapslenaeqtnukeptrnoicnmeiacroyffprlraoocdtwuicoCtni.RonFirwnoawsminoJtbuesnre.erveItdno BonetttLtliioeem,scnaosiAlnt.oiAngt.gih:sec.aWlAM.ciitdnaDdvieiHosielndiirPgoaab&triioaolCnn..ás2oP5Rni/i2gvb6nei(aortl1ib)V:cea1rel1il7oe-.m1ym.11u99n.I6ni9t-..
November, withanewwaterpeak,CRincreased Vereinigung Theor. Limnol. Verh. 17:1035-
and once again the P:R quotient was less than 1050.
one. From December to March, GPP decreased Bonetto,A.A.&I.Wais. 1987.Consideracionessobre
following high turbidity. A second period ofnet laincidenciadel Valle Aluvial del ríoParanáen
laproductividad biológicade sus aguas. Revista
production was observed when light conditions Mus. Argcnl. Ci. Nat. Bernardino Rivadavia,
improved (March to May). Finally, with a new 6(8):53-59.
tlooding period (May 1996) CR increased and a Bonetto,A.A.:Y.Zalocar&E.R.Vallejos. 1982.
new heterotophic phase was observed. So, net Contribución al conocimientodel ntoplancU)n
production inthissystem seems tobe limitedby delParanáMedio.1.Ecosur9(18):189-212.
43
CayanaBot.56(1), 1999
BONETTO, C.A.; Y. Zalocar, P.M. Caro & E.R. energyflow,andcommunitystructureinsome
Vallejos. 1979. Producciónprimariadel río Venezuelanfreshwaters.Arch.Hydrobiol.Suppl.
Paranáenel áreade su confluenciacon elrío 50(2/3):145-207.
Paraguay.Ecosur6(12):207-227. Mackereth,F.;J.Hiron&J.Talling. 1978.Water
BoNETTO,C.A.;Y.Zalocar&E.R.Vallejos. 1983. Analysis: some revised methods forlimnolo-
Fitoplanctonyproducciónprimariadel ríoAlto gists.FreshwaterBiol.Assoc.Sci.36,120p.
Paraná (Argentina). Physis (Buenos Aires), Marker, A.F.H.; C.A. Crowther& R.J.M. Gunn.
41(101):81-93. 1980.Methanolandacetoneassolventsforesti-
BoNETTO, C.A.; L. DE Cabo, N. Gabellone, A. mating chlorophyll a and phaeopigments by
VlNOCUR,J. DONADELLI & F. UNREIN. 1994. spectrophotometry.Ergerb.Limnol.14:52-69.
Nutrientdynamicsinthedeltaicfloodplainofthe Padisak, J. & M. Dokulil. 1994. Meroplankton
Lower Paraná River. Arch. Hydrobiol. dynamics in asaline, turbulent, turbid shallow
131(3):277-295. lake (Neusiedlersee, Austria and Hungary).
Descy,J.P.;P.Serváis,J.S.Smitz,G.Billen&E. Hydrobiologia289:23-42.
Everbecq. 1987. Phytoplanktonbiomass and PerottideJorda,N.M. 1977.Pigmentosyproducción
production in the River Meuse (Belgium) primaria en el Paraná Medio: laguna Los
WaterRes.21(12):1557-1566. Matadores(SantaFe,Argentina).Physis(Buenos
Carignan,R.&D.Planas.1994.Recognitionofnutrient Aires),35(92):89-l13.
andlightlimitationinturbidmixedlayers:Three Raí, H. & G. HlLL. 1984. Primaryproduction inthe
approachescomparedattheParanáfloodplain Amazonian aquaticecosystem. In: H. Siolied.,
(Argentina).Limnol.& Oceanogr.39(3):580-596. The Amazon. Limnology and landscape ofa
DOKULIL,M. 1984.Metodologíademedicióndefoto- mighty tropicalriveranditsbasin. TheHague,
síntesisenfitoplancton. En: Programasobreel W.Junk.pp.311-335.
hombreylabiosfera,UNESCO.Embalses,foto- SCHMiDT, G.W. 1976. Primary production ofphyto-
síntesisyproductividadprimaria.Universidadde plankton in the three types ofAmazonian
Chile,p.73-85. waters.IV.Primaryproductionofphytoplankton
Drago,E.C. 1990.Hydrologicalandgeomorphological in a Bay oftheLowerRioNegro (Amazonas,
characteristicsofthehydrosystemoftheMiddle Brazil).Amazoniana5:517-528.
ParanáRiver.Acta.Limnol.Brasil.3:907-930. SCHMiDT, G.W. 1982. Primary production ofphyto-
Fisher,T.R. 1978.Planctoneprodu9áoprimariaem plankton in the three types ofAmazonian
sistemas aquáticos da bacia da Amazonia waters. V. Some investigations on the phyto-
Central.Supl.ActaAmazon.8(4):43-54. plankton and its primary productivity in the
Fisher,T. R.; K.M. Morrisey, P.R. Carlson,L.F. clear water of the Lower Rio Tapajoz
Alves & J.M. Melack. 1988. Nitrate and (Amazonas,Brazil).Amazoniana7:335-348.
ammonium uptake by plankton in an Amazon Talling,J.F. 1971.Theunderwaterlightclimateasa
Riverfloodplainlake.J.Plankt.Res. 10:7-29. controllingfactorintheproductionecologyof
FiTTKAU, E.J.: U. Irmler, W.J. Junk, F. Reiss & freshwaterphytoplankton.Mitt.Int.Vereinigung
G.W. SCHMIDT. 1975. Productivity, biomass Theor.Angew.Limnol. 19:214-243.
and ecological population dynamics in Thomaz, S.M.;M.C. Roberto,F.A. LansacToha,
Amazonian waterbodies. In: F.B. Golley &E. A.F.Lima&F.A.ESTEVES. 1992.Características
Medina eds. Tropical Ecological systems. limnológicasdeurnaestagáodeamostragemdo
Springer,Berlinpp.289-311. AltoRioParanáeoutradoBaixoRioIvinheima
GarcíadeEmiliani,M.O.1993.Seasonalsuccessionof (PR,MS-Brasil).ActaLimnol.Brasil.4:32-51.
phytoplanktoninalakeoftheParanáRiverflood- Uehlinger,U. 1993.Primaryproductionandrespiration
plain,Argentina.Hydrobiologia264:101-114. intheoutletofaneutrophic lake (RiverGlatt,
Golterman, H.L. 1975. Physiological limnology. Switzeriand).Arch.Hydrobiol.128(l):39-55.
Amsterdam.Elsevier,489p. Van den Brink, F.W.B.V.; M.M. Katwijk & G.
Junk, W. J. 1983. Aquatic habitats in Amazonia. VenderVedde. 1994.Impactofhydrologyon
Environmentalist,3:24-34. phyto- and zooplankton community composi-
Junk,W. J.;P.B. Bayley& R.E. Sparks. 1989.The tion in floodplainlakes alongtheLowerRhine
floodpulseconceptinriver-floodplainsystems. andMeuse.J.PlankLRes. 16(4):351-373.
In:D.P.Dodge,ed.ProceedingoftheInternational Yin, C; Z. Lan & M. Zhao. 1996. Factors limiting
LargeRiverSymposium.Can. Spec. Publ. Fish. algal growth in eutrophic Chohu Lake, China.
Aquat.Sci.106,p.l10-127. Mitt. Int. VereinigungTheor. Angew. Limnol.
LeeF.G.;R.A.Jones&W. Rast. 1981. Alternative 24:213-218.
approachtotrophicstateclassificationforwater ZalocardeDomitrovic,Y.1990.Efectodelasfluctua-
qualitymanagement..DepartmentofCivilEngi- cionesdelnivelhidrométricosobreelfitoplancton
neering. Colorado State University, Fort entreslagunasisleñaseneláreadeconfluenciade
CoUins,CO.Occationalpaper66.65p. losríosParanáyParaguay.Ecosur16:13-29.
Lewis,W.M. 1988.PrimaryproductionintheOrinoco ZalocardeDomitrovic, Y. 1992. Fitoplanctonde
River.Ecology 69(3):679-692. ambientesinundablesdelRíoParaná(Argentina).
Lewis,W.M. & F.H. Weibezahn. 1976. Chemistry, Rev.Hydrobiol.Trop.25(3): 177-188.
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TemporalfluctuationofPhytoplanktonicchlorophylla:IZACiUIRRK,I.&I.O'Farrell
TableI:Grossprimaryproduction(GPP)andcommiinityrcspiration(CR)perunitárea(gO,m-h').GPP/CR
ratesandmeanchlorophylla(pg1').
GPP CR ¡PP/CR
CayanaBot.56(1), 1999
46
Temporal(luctiuitionofPhytoplaiikUinicL-liloropliyHíí:Iza(;uirri%I.&I.O'FarrELL
1/5/95 1/6 1/7 1/8 1/9 1/10 1/11 1/12 1/1/96 1/2 1/3 1/1 1/5
FlG.2.WaterlevelannualcurvefortheParanáRiveratVillaConstitución.
May
CayanaBot.56(1),1999
TotalPandP-P04(jjg1-1
300
250
200
150
100
May Jun Jul Aug Sep Oct Nov Dec Jan Mar Apr May
-^TotalP +P-P04
FlG.4.Totalandsolublereactivephosphorusconcentrationscorrespondingtomeanvalúesofthewatercolumn
forthestudyperiod.
N-N03(pg1-1)
200
May Jun Jul Aug Sep Oct Nov Dec Jan Mar Apr May
FlG.5.Meannitrateconcentrationsofthewatercolumnduringthestudyperiod.
48