Seasonal Variation of the Mountain Phytoplankton in the Arid Mendoza Basin, Westcentral Argentina Patricia Peralta Instituto Argentino de NillOlogia Glaciologfa y Cienciss Ambientales (IAN/GLA)- CRICYT Av. Ruiz Leal shI, C.C. 330 5500 Mendoza, Argentina (pperal/a@/ab.cricyt.edu.er) and Cristina Claps instituto de Limnologla "Dr. R. Ringuelef' All. Calchaqui km 23,5 1888 FIorencio Varela, Argentina ([email protected])
ABSTRACT We anaJyzed the seasonal composition of phytoplankton from the Mendoza River and its rnoutaries from the High Cordillera to the plain in centralwest Acgenlina. A total of 72 algae species were identified; among them, 36 species were diatoms, 17 chlorophytes. 15 cyanophytes, three cuglenophytes and one pyrrophyte . A marked seasooaliry was observed. Diatoms were dominant in all seasons at most of the sampling sites. with abundance peaks in autumn and winter. Cyanophytes were found throughout the year but with highest numbers in summer and spring. Chlorophytes were well represented throughout the year except in winter. The pyrropbytes were represented by Poidinium gatunensis. which was recorded exclusively in the spring along with the chlorophyte Sraurast1Um s~ba/dii at most of the sampling sites. Eugienophytes were found only in the lower basin and with maximum richness and density in autumn. Most of the diatoms were benthic. Nitzschia paka. Eugl~ruJ proxima and E. oxyUtuS were limited to ce rtain sectors of the river that receive sewage discharge. The remainder of the river is generally free from significant anthropogenic impact.
INrRODucnON The Me ndoza Rjver in cenlralwest Argentina is fonned by tributaries that arc fed largely from snowmelt and from the glaciers of the Cordillera de Los Andes. Annual spring and summer precipitation is insignificant (approximately 250 mm). In spite of tbe arid climate, the Mendoza River basin comprises rich and diVerse environments. but its freshwater ecosystems have been poorly studied. Limnologieal studies are limited to the ichthyological record of PefIafort (1993) in the b~ i n of the Mendoza River, to a characterization of the summer phytoplankton of the Grande, Atuel. Salado Rivers and of the Uancanelo pond by Peralta and Claps (2001): and to a srudy of the daily phytoplankton variation in the Mendoza River at the High Cordillera by Fuentes et al. (2000). The topography of the region and the wide annual, seasonal and daily temperature fluctuations produce significant variations in the velocities and discharges of tbe area rivers. These conditions undoubtedly detennine changes in the annu31 structures and dynamics ofihe aquatic communities (Al lan 1993). We would expect marked seasonal differences in the succession of communities as well as .... ariations 310ng the longitudinal gradient from the high elevations to the plain (Vannote et 31. 1980). 445
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River f d Riv STUDY f o the of y Uspallata., sampl r Mend km some r until is nami the 10) as dam 446 m 8) diff th at re e . the (6 loca season low r upstream 2 e 1 su belonging asl s • upstream Mend Penitente and .962 at I) M High e ignificant Th influenc AND cs it oza ing phyt lts urgency. on rent ted e (Fig. Mend middle Penit . reache AREA e of nd and , 12 the s m river . River 6) o oza Co in tati , _aJl_ , oza n th topographic 9 ) METIIODS plankt on asl) •• e e 1) M 1999 oza of Mend the Mend rdill e ons nte s. of s to th ~Cjtt Ri .10 phytoplankton . basin: c Ri e h of he . Thus, the U 3) hang in nd at of ver Cac s, later ve era River a s certain in o (February, Tupungat dwate th - oza pallata. Ev oza 3) e oza . n Mend r Guanacache 11 Mend at e heut es downstream community high to and arsa. Tupungat th characterization n River P River R.jver at characteristics i o e the n o rs . rth a. oza h " goals tr II basin Ci th oza y 8) 6) are eri dr pla ' to) . e o p a and , at down is Mendoz Mend pr o May system, fr ologi nd llo Riv River i in ileti, ; o o currently o M n, Lavalle. ovi 5, wetlands s f Tupungato m i 12 the e River . n e o to . o 6 s 9) n c nd r. 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In were ce a the number Th o c l n by anl"1onic highest . e diversity \10'35 average highe v r 2) 3.7 m proximo we n 1,059 } lt and e bed r a in in alue lIs and winter 1e and ecorded ance high e · high pbytoplankton T utumn Tupungato give fol 1,000 1 a otaJ waten highest minimum recorded st eit hi spring tbe °C h S mr' upun in s recorded done 30 ,3 ea ghest s cou s conductivity, s diversity l E (UIcthrix h o the pecifi t 1 j..i$ abundance the n of and concentrations . of e .... of dwat 983) 72 middle co J.Ull temper . e ) proxima r H as ing ~ . ld values d gato th u and (Fig em cyanophytes ce 40 1 species of ndu wi During algae e glenop (F ' o ' lowe at diversity ,432 species e be a num m n cm c e ntr th was th · or in physica s f i phytoplankton s maximum w es ] div g. r . E. c ity at it River. River 127 see values 3). e in · a ti sampling len an a a al r th 1 e h n h 2). ~ 100 were ber t spec vity nd oxy tur ersily the Mendoza in bas e at applied at 3, the hyles, e s samples occurred emma) n inverte At winter, r of it et. c ri p (F , l e Vacas s the high si u transparency while during o o I e in. m with c l H ite i Lavall values i ris (accord of w n A the higher f t es al LavaJle, (0 and i orlhe hne Th e 5 e - g. , cells (Fig. I er of (Osci/tatoria su s so ow The l transparency . of75 ower the vur 15 in we 54) 2). bas s e 12 diatom d m d to ss mm the s basi (1 tati the Lyngbya che.mical observed River, ( were the uspende sa e cya ve sum . River l Fig w (12,640 e i , calculate ml-l was c i c in likewi 2). high charcawiensis but 068 n basin, showed sites m mple in ntire e ere ons exce l ic basin temperature n s oc s Gc. th n d iddle . r higher g r umm o In m sector 3d). en oscope Sites (Table obtained e i in the 4 . est ce t Fra RESULTS ties ph in recorded h er had was o 47 Th ( s pti maximum tifi r 3,483 ad river {imnetic autumn se ll . d to egards ytes. spite the were , ce para formosa, in values bas s gilla In highe e e o while l so varied e (Secch 9, ow autumn 737 d r. b the n m r n ll Shannon d ( the eco e spri as ive sed , s lid La and in I). . The of r to utra] m with ce ria and of fixed of ml ') num in, lowest with st s, r j.1S valle) (2.12 eters sa rd a Lavalle t and The th sity im a during n of ll a rose with o w its co virtsce known while . s density i g nd s nd 1,098 e ed m was 1), e o cm h e it th L disc), bers 11 cond to ff mrl) and yie . n n e ich lower nt with a high yngl7ya es th sa ected e 9 1 side F e a e in were s a si - maxima "C alkaline co in a 2 ] i t . due l ld e phytoplanktonic a n (2,470 of e mpl ightly, n te s 36 during aurumn virtscens s n we ~ m of d in n u spri d 6 d mper nt e diatom with umm :; vo umm pyrrophyle a in species 1 rabl s, ctivity (2,853 d the ou Weaver 0% the nd ainer basin s was specie the r c i t recorded th lum e the togeth winter pec o ma11esiana) n m re ng nt g s e y flow th mi a cells the hi e er with - mi spec in Lugol's pH l : ] a rure hi wi th r e owe i transported ose gh high t e in the utumn Nic:.schia , an of dd were (12) a ce and dd gh s ca both s and e richness, co th ab ti e velociry wit i were the with freque a d l ll tively a on d mr s known nd m r l with r e ndu e es lowest nd s e in undance : etermi (Ta with winter minimum with basin s e l had water basin ( Cy~/ta h ex ml evati bas in pring l t at b iodine the r middle ), 25 as and the as an ctivity density diatoms ) b and greate t (Lege . and Lavalle . in h 1) . n . le minimum s in high po/ea 9 . The e capac middle cy The average it o had (Table pH n , h with by with winter °C and 5 2) n e Cuevas a and ighest . 3 o of nt a and Th 10 . went f n (7.4) the one in r , nd Th . dr . F for i w th a t ry e . o 17 as e e e Downloaded By: [informa internal users] At: 11:48 13 January 2011 Osciluuoria princeps Schi::olhrix s tumida abundance observed va found as mo Table ite lue well st s. s abundant and o Several I were as being n So highly all in O at me s . was formosa, p~ three recorded sites samplings formosa tbe ph,,,,,,~ phytoplankton Srigrocionium frequent. up recorded 6 most of strea and the c. and and at abundant occasions. m 7 tumida sites High Sites of at chemical with Zygnema si the te sp., components to Cordillera high , 10 Diatoma middle 12 and (Fig. (935 Microspara characu:r1stlcS Cri1Uliium (1,759 sp frequcncies 12 . 3). cells at basin. (1.69 448 rivers vw~. the A ce s '-- t= mrl how == '--- - lls marked endophyticum. first ahreviatta, and Nevertheless, mr ) - of e of Horcon d and F sam statio 2.19 l C. ) a . virescens with ri mark tumida 7 pling se respectively) (635 n UlothriJ: es, . in E e statio . d the Spirufinll proxima C cells the seasona and and uev species n highe s ten as mr F Fragilaria of . . t and viresans Mendoza Th l and rrina.. l spttni, ) st pr were number e diversity Tupungato, efe Oscillatoria greatest CycioteiJo. r ultta the ence. River at was bOlh n were en _a , " o"spp H' , I.2 _.i 2 ,• " 10 / 8 1\'/·····11 8 ~/ , " '/"0 , . ·..... 1\11 .... J 0.8 , ~ n"spp -- diversiry , 2 Iv ~ o OL..--'2L--JJ"---",L--","---·,L--"7<---",---c,L--J'~0---""L---',~ , 2 J , , , 7 8 9 locality , " ,------~ , 2 2.2 , " 20 2.0 ,, , 1.8 I. " 0 , c:J , " I. ", , V " , / • L2 , 2 "'" '
80 •
Di;)iOmS
o UillWilJ.llllJ. 1 , 6 2 5 i 10 12 Summer Figure 3. Seasonal density of phytoplankton recorded in the Mendoza River basin during 1999.
DISCUSSrDN Significant seasonal flow variation due to snowmelt and the fusion of cordilleran glaciers eauses essential differences of certain physical and chemical parameters, such as conductivity, temperature, transparency and flow speed. The values recorded during autumn and winter were of higher conductivity, lowcr temperatures, greater transparency and lower velocity than those found in summer and spring. The phytoplankton community showed seasonal differences as many species were found in only one climatic season, which is in agreement with thermal variations and with differences in the water transparency and the flow volume (Whitton 1975).
451 A marked spacial and temporal variation was observed. In spring and autumn, the community was different within different basin sectors. Summer and winter did not show marked spatial vanation throughout the basin. The phytoplankton community showed similarities in composition and abundance in the middle basin sector in spring and autumn, respectively. The phytoplankton showed structural and abundance changes in the longitudinal gradient, being more complex and numerous in the lower middle basin and during spring and aurumn. This characteristic would be linked to a decrease of the flow speed and to the increase of the order number of the main watercourse (Molloy 1992). This enrichment is not exaggerated as this basin does not have lentic environments that could function as inocula (Reynolds 1995) The phytoplankton of Mendoza River and its tributaries was fanned by rypical species, as well as by algae belonging to other communities. A large number of the algae recorded are characteristic of benthic communities and typical of poor environments (Biggs 1996). The low number of species coincides with the results obtained by Kawecka ( 1980) in non-polluted glacial creeks. The diatom supremacy, either in tbe number of species or as density, is linked to their ability to survive in unstable environments (Rojo et at. 1994) and in those with low temperarures (Kawecka 1980). Most of the diatoms are ticoplanktonic and prefer alkaline pH (Lowe 1974). These algae are incorporated fa the free water by the washing action exercised by current in the epilithic community (Hynes 1970, Cox 1990). The cbJorophytes and cyanophytes were best represented during summer and spring. Among the first ones were the predominant the filamentous forms (Microspora abreviallD. M. quadratla, M. wirhrokii. Oedogonium sp.. Spirogyra sp., UlOlhrix renemma, U variabilis, Zygnema sp.), which are common in pristine environments (Deniseger et al. 1986). Phytoplankton found at Lavalle was totally different from that found in the
OAutumn cells ml-1 fSlSummer 12.640 mr ' .Winter lSI Spring 5 ,000 _. 4 .500 - . 4 .000 - . 3 ,500 - 3000 J .. · 2 .'500 1, ... 2.000 J i 1.500 1 J 000 - . 500 o 1 2 3 4 5 6 7 8 9 10 11 12 Locality Figure 4. Seasonal distributiun of phytoplankton groups present in Mendoza River basin during 1999
452 rest of The basin due to the more leolic character of this sector (Ward 1992). Biologically, the basin does not show signs of eutrophication as there have not been species detected that would indicate this condition - species such as CoccOlleis placenmla (Cox 1990). The presence of N. palea. E. proxima and E. oxyurns is limIted 10 certain ri .... er sectors that are impacted by sewage discharge; this shows a degree of incipient organic pol!ution (Rakowska 1990). Acknowledgements We thank to A.M. Zavattieri, M. Morales, A. Peralta. Gendanneria Nacional (Rescue Group). Direcci6n de Recursos Naturales de la Provincia (Forester staff). for help in the field work. We also thank to M. E. Soler for English assistance. LITERATURE CITED Allan, O. J. 1995. Stream Ecology. Structure and function of running water. Chapman & Hal. London. 386 pp. Biggs. B.F. 1996. Pattern in benthic algae of streams: 31-56. In: R. Stevenson, M. Botbwell and R. Lowe (Eds.). Algal Ecology. Freshwater Benthic Ecosystems. Academk Press. 753 pp. Cox, E.. 1990. Studies on the algae of a small software stream I. Occurrence and distnbution with particular reference to the diatoms. Arch. Hydrobiol. (Suppl.) 83525-552. Oeniseger, J., A. Austin and P. Lucey. 1986. Periphyton communities in a pristine mountain stream above and below heavy metal mining operations. Freshwater Biology 16:209-218. Fuentes. Y., P. Peralta and C. Claps. 2000. Variaci6n diaria del plancton en un rio de Alta Cordillera (Mendoza, Uspallata): analisis cuali-cuantitativo. Tesis Fac. Cs. Ex. Fis.y Nat., Univ. Nac. COrdoba. 90 pp. Hynes. RB.N. 1970. 'The Ecology of Runrung Waters. University of Toronto Press. 555 pp. Kawecka, B. 1980. Sessile algae in European mountain streams 1. The ecological characteristics of communities. Acta Hydrobiol. 22:361-420. Legendre, L. and P. Legendre. 1983. Numerical Ecology. Elsevier Scient. Publ Company. 419 pp. Lowe, R. L. 1974. Environmental requirements and pollution tolerance of freshwater diatoms. National Environmental Research Center. Office of Research and Development. U.S. Environmental Protection Agency. Cincinnati, Ohio. 333 pp. Molloy, J. 1992. Diatom communities along stream longitudinal gradients. Freshwater Biology 28:59-69. Pefiafort, M. B. 1981. Relevamiento de la ictiofauna y detenninaci6n de areas naturales en dos nos mendocinos. Bol. Museo 0. Nat. "J. C. Moyano" 2:27-60. Peralta. P. and C. Claps. 200t. Caracterizaci6n del fitoplancton estival de ambicntes 16ticos y lenticos del sur de [a Provincia de Mendoza (Argentina). Aetas V Congreso Latinoamerieano y del Caribe de Ficologfa (in press). Rakowska. B. 1990. Diatom communities in the microbenthos of the river Rawka (central Poland). Acta Hydrobiol. 32:363-375. Rojo. c., M. AJvarez Cobelas and M. Arauzo. 1994. An elementary, structural analysis of river phytoplankton. In: J. Dcscy, C. Reynolds and J. Padisak (Eds.) Phytoplankton in turbid envi ronments: rivers and shallow lakes. Hydrobiologia 289:43-55.
453 Reynolds, C.S. 1995. The long, the short and the stalled: on the attributes of phytoplankton selcClcd by physical mixing in lakes and rivers. Hydrobiologia 289,9-21. Vannote, R.L., G.W. Minshall, KW. Cummings, J.R. SedelJ and C.E. Cushing. 1980. The n\'er continuum concept. Can. J. Fish. Aquae Scies. 37: 120-l37. Ward, l.v. 1992. A mountain river: 493-510. In: Calow, P. and G. Pctts (Eels.). The River Handbook. Blackwell Sc. Pub!. 526 pp. Whitton, BA. (Ed.). 1975. River Ecology. Blackwell Scient. Publ., Oxford. 725 pp.
454
Accepted 13 April 2001