cyanobacterial blooms in argentinean inland waters

5
INTRODUCTION The main inland waters of Argentina that are dominated by cyanobacteria are documented and those which represent a real or potential risk from algal toxins, especially for human health, are noted. Toxic blooms have been recorded in Argentina since the 1950s; the first comprehensive report was by Kühnemann (1965), and updated 10 years later by Emiliani and Rodriguez (1974). However, at present the issue has new dimensions not fully recognized; indeed, only four articles have been published in 10 years (Accorinti 1993; Pizzolon 1996; García de Emiliani & Emiliani 1997; Pizzolon et al. 1997). The data base is heterogeneous; data differ in sampling schedules (subsurface or stratified), counting methods (cells or colonies, inverted microscope or Burker chamber), and also in the purposes they were obtained for. Thus, only a qualitative and general comparison is possible. Even so, it is useful to document the available data. FIRST REPORTS Ringuelet et al. (1955) noted the first case of massive fish deaths in a eutrophic Pampa pond, following a large bloom of Anabaena inaequaliz (Kutz) Born, Anabaena circinalis Rab. and ‘Policystis flos aquae (Witr.)’ (Policystis Kg 5 Microcystis Kutzing 1833) and others. They showed the presence of a lethal factor in the algae by carrying out in vitro experiments. Kühnemann (1965) reported the death of more than one thousand ducks due to Anabaena flos- aquae, and many other cases of wildlife poisoning in Argentina, and made a distinction between toxic and non- toxic species of cyanobacteria. During summer 1973–74, the Belgrano Park pond (Santa Fe City) developed a bloom composed mainly of Microcystis aeruginosa and containing up to 60 000 colonies per mL (García de Emiliani 1978). Massive fish deaths, gastro- intestinal disorders, dermatitis, otitis and conjunctivitis in bathers and swimmers were associated with the bloom (Apesteguia et al. 1974). Appropriate policies and control measures (Emiliani & Rodriguez 1974) allowed this envir- onment to recover several years later. Odriozola et al. (1984) reported the death of 72 cows in 24 h after their introduction to a pasture having a pond with dense scums of M. aeruginosa. Mouse bioassays were 100% positive, including those carried out on the contents of the digestive tract of the animals. PRESENT ENVIRONMENTS AT RISK Potentially toxic blooms occur in many kinds of Argentinean inland waters, most of them are reser voirs used as supplies of drinking water or for recreation. These environments are located from 25° to 44°S (Fig. 1) in a great climatic diver- sity, and they have varied limnological features (Table 1). Species of Anabaena and Microcystis were the most con- spicuous (Table 1) blue-green algae in them. However, Aphanizomenon sp., Gomphosphaeria lacustris and Oscillatoria sp., were rare as dominant species. Scum for- mation occurred in all cases examined, except in localities 2, 6 and 7, where cyanobacteria were present but not dense. Lakes & Reservoirs: Research and Management 1999 4: 101–105 Cyanobacterial blooms in Argentinean inland waters L. Pizzolon, 1 * B. Tracanna, 2 C. Prósperi 3 and J. M. Guerrero 4 1 Laboratorio de Ecología Acuática, Facultad Ciencias Naturales, Universidad Nacional de la Patagonia, Sarmiento 849 (9200), Esquel, Chubut*, 2 Instituto de Limnología Noroeste Argentino CONICET, Universidad Nacional Tucumán, (4000) Tucumán, 3 Facultad Ciencias Exactas, Físicas y Naturales, Universidad Nacional de Córdoba (5000), Córdoba and 4 AGOSBA Departamento Laboratorio, Sección Control Biológico (1900), La Plata, Argentina Abstract The occurrence of cyanobacterial blooms in Argentina is documented and note is made of particular water-bodies at risk from blooms. Key words Argentina, blue-green algae, cyanobacterial blooms, toxins. *Email: [email protected] Accepted for publication 12 May 1999.

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Page 1: Cyanobacterial blooms in Argentinean inland waters

INTRODUCTIONThe main inland waters of Argentina that are dominated bycyanobacteria are documented and those which representa real or potential risk from algal toxins, especially for humanhealth, are noted. Toxic blooms have been recorded inArgentina since the 1950s; the first comprehensive reportwas by Kühnemann (1965), and updated 10 years later byEmiliani and Rodriguez (1974). However, at present the issuehas new dimensions not fully recognized; indeed, only fourarticles have been published in 10 years (Accorinti 1993;Pizzolon 1996; García de Emiliani & Emiliani 1997; Pizzolonet al. 1997).

The data base is heterogeneous; data differ in samplingschedules (subsurface or stratified), counting methods(cells or colonies, inverted microscope or Burker chamber),and also in the purposes they were obtained for. Thus, onlya qualitative and general comparison is possible. Even so, itis useful to document the available data.

FIRST REPORTSRinguelet et al. (1955) noted the first case of massive fish deaths in a eutrophic Pampa pond, following a largebloom of Anabaena inaequaliz (Kutz) Born, Anabaenacircinalis Rab. and ‘Policystis flos aquae (Witr.)’ (PolicystisKg 5 Microcystis Kutzing 1833) and others. They showed thepresence of a lethal factor in the algae by carrying out invitro experiments. Kühnemann (1965) reported the death

of more than one thousand ducks due to Anabaena flos-aquae, and many other cases of wildlife poisoning inArgentina, and made a distinction between toxic and non-toxic species of cyanobacteria.

During summer 1973–74, the Belgrano Park pond (SantaFe City) developed a bloom composed mainly of Microcystisaeruginosa and containing up to 60 000 colonies per mL(García de Emiliani 1978). Massive fish deaths, gastro-intestinal disorders, dermatitis, otitis and conjunctivitis inbathers and swimmers were associated with the bloom(Apesteguia et al. 1974). Appropriate policies and controlmeasures (Emiliani & Rodriguez 1974) allowed this envir-onment to recover several years later.

Odriozola et al. (1984) reported the death of 72 cows in24 h after their introduction to a pasture having a pond withdense scums of M. aeruginosa. Mouse bioassays were 100%positive, including those carried out on the contents of thedigestive tract of the animals.

PRESENT ENVIRONMENTS AT RISKPotentially toxic blooms occur in many kinds of Argentineaninland waters, most of them are reservoirs used as suppliesof drinking water or for recreation. These environments arelocated from 25° to 44°S (Fig. 1) in a great climatic diver-sity, and they have varied limnological features (Table 1).Species of Anabaena and Microcystis were the most con-spicuous (Table 1) blue-green algae in them. However,Aphanizomenon sp., Gomphosphaeria lacustris andOscillatoria sp., were rare as dominant species. Scum for-mation occurred in all cases examined, except in localities2, 6 and 7, where cyanobacteria were present but not dense.

Lakes & Reservoirs: Research and Management 1999 4: 101–105

Cyanobacterial blooms in Argentinean inland watersL. Pizzolon,1* B. Tracanna,2 C. Prósperi3 and J. M. Guerrero4

1Laboratorio de Ecología Acuática, Facultad Ciencias Naturales, Universidad Nacional de la Patagonia, Sarmiento 849 (9200),Esquel, Chubut*, 2Instituto de Limnología Noroeste Argentino CONICET, Universidad Nacional Tucumán, (4000) Tucumán,

3Facultad Ciencias Exactas, Físicas y Naturales, Universidad Nacional de Córdoba (5000), Córdoba and 4AGOSBA Departamento Laboratorio, Sección Control Biológico (1900), La Plata, Argentina

AbstractThe occurrence of cyanobacterial blooms in Argentina is documented and note is made of particular water-bodies at risk from blooms.

Key wordsArgentina, blue-green algae, cyanobacterial blooms, toxins.

*Email: [email protected]

Accepted for publication 12 May 1999.

Page 2: Cyanobacterial blooms in Argentinean inland waters

In locality 14, they were dominant in the phytoplankton com-munity, but did not form scums. Blooms occurred in sum-mer–autumn in the centre-north of the country (except inlocality 4), and mainly in spring in Patagonia (localities 13,14, 15). Scums have been recurrently observed for twodecades at localities 5, 6, 8, 10, 11, 12 and 13 (Table 1), buthave appeared only recently in localities 3 and 4 as a resultof a sharp increase in their trophic state. Blooms also occurin an oligotrophic environment (locality 13), and the recentAnabaena sp. bloom in locality 15 does not seem to be relatedto trophic change.

Some water-bodies had cyanobacteria of potentially toxicspecies, but they were not dominant and scums were notobserved (localities 2, 6 and 7). Blooms in reservoirs are car-ried downstream and transported hundreds of kilometresfrom their origin (localities 3, 4, 5, 10, 11, 13 and 15). Thus,many people are exposed to their potential effects: 600 000(locality 4, Tucumán and Rio Hondo), 1000 000 (locality 5,Córdoba), 325 000 (locality 11, Ba. Blanca and Punta Alta),500 000 (locality 13, cities of Negro River Valley), and 200 000(locality 15, cities of the lower Chubut Valley). Mechanicalproblems at water treatment plants (filter clogging) and

disagreeable odours and taste in drinking water are the mostfrequently perceived effects. Other problems, such as acutediseases, are not reported or widespread. Chronic toxicitywas not studied. The risks of massive poisoning are gener-ally underestimated or sometimes unknown, even by doctorsand veterinarians. Mouse bioassays have rarely been carriedout (Table 1). Considering that in other countries toxicity hasbeen demonstrated in more than 50–60% of environmentswhere cyanobacteria are dominant (Reynolds 1991), theproblem may be more significant than currently recognized,as suggested also by Codd (1995) and Pizzolon (1996). Twoenvironments, localities 8 and 14, used for the drinking watersupply to San Luis and Esquel cities, have been abandonedin the last 5 years due to odours and the presence of poten-tially toxic algae.

Taking into account cell concentrations, the recurrenceof blooms and the number of inhabitants potentially affected,reservoirs 3, 4, 5 and 11 can be regarded as environmentsat highest risk. San Roque reservoir requires particularattention because its blooms are becoming permanent, andbioassays have proved positive (Prósperi 1996). Recent stud-ies using enzyme-linked immunosorbent assay (ELISA) andliquid chromatography/mass spectroscopy methods (Ruibalet al. 1998; Yamashiki et al. 1998) have found high concen-tration of microcystins in lake water, even in winter. The lackof limnological studies of this reservoir during the past 20 years is surprising.

The low number of disease cases is also surprising (local-ities 4, 14). Chronic effects of microcystins should certainlybe studied where Microcystis is dominant (localities 4, 5, 6,11). Effects of microcystins are cumulative, and the tumour-promoting activity of microcystins in small doses has beenwell-documented (Carmichael 1994). Note in this regard thatmouse bioassays lack sensitivity to low toxin concentrations.At least one laboratory is necessary in Argentina in orderto carry out more precise toxin analysis.

Extensive cattle ranching is an important resource inArgentina. Economic damage by stock loss could be higherthan suspected. The Portman pond case (locality 9) is anexample of what may be taking place more frequently thansupposed, especially in the shallow lakes of Pampa plain. Thedeath of 72 cows in 24 h is one of the most outstandingexamples of the risks involved in cyanobacterial blooms,even on a global scale.

The number of environments at risk in Argentina seemsto be increasing as their trophic states alter. This was welldocumented in localities 3, 4, 5, 9 and 11. Scums in locality10 occur recurrently in lateral arms where the residencetime is higher than 0.031. Scums of cyanobacteria occur alsoin oligotrophic or mesotrophic waters where they are notdominant (localities 13, 15), and factors other than nutrients,

102 L. Pizzolon et al.

Fig. 1. Main inland water environments of Argentina at risk of

poisoning by algal toxins. (j), very high; ( ), high; ( ), moderate.

Page 3: Cyanobacterial blooms in Argentinean inland waters

Cyanobacterial bloom

s in Argentina

103

Table 1. Freshwater environments in Argentina at risk of poisoning by cyanobacteria

No. Name Province Surface area Depth Tw Catchment Limnological Trophic Taxa Density Blooms Months Mouse

basin/lake max/mean years–1 use features state max. since of bio-

km2/km2 m/m cells mL–1 bloom assay

1 Urugua-í Misiones 2533/88.4 70/13.5 0.85 Subtrop. forest Hypolimnion anoxic e Aph > 40 000* 1990… 3–4 (s)

2 Cabra Corral Salta 32 000/115 67/27 2.6 Forest/agricult. Not monitored o-m Mfa; A n.c. 1991… summer

3 El Cadillal Tucumán 4700/13.5 72/17.8 0.51 Agriculture High sediment. rate m Mae (Afa) n.c. 1996… summer

4 Río Hondo Tcm-Sgo.Est. 18 250/54.3 25/5.3 0.48 Agro-industries High sediment. rate e Mae (Afa) 160 000* 1995… 7–10 (–)

5 San Roque Córdoba 1750/15 25/14 0.64 Urban/tourism High organic load h Mae, Apf n.c. 1963–97 1–12 (1)

6 Río Tercero ” 3300/54 46/13 0.84 Urban/agric. High T°C/nuclear plant m Mae 1990… summer

7 Río Cuarto (r) ” 159 km Urban/industr Multiple pollution

8 Cruz de Piedra San Luis 156/1.4 Tourism/cattle Hypol. anoxic e Asp 1989… 2–5 (–)

9 Portmann (p) Santa Fe /1.5 0.8/ Endorheic Cattle High salinity h Asp 33.000a* 1996–97 12–1 (1)

10 Salto Grande Entre Ríos 224 000/783 33/6.4 0.031 Agriculture High turbidity m Mae, Asp 1982… summer

11 Paso de Piedras Buenos Aires /40 24/8.5 Cattle m–e Asp; Mae 900 000 1982–97 2–6

12 Pellegrini (l) Río Negro /112 18/9.4 Endorheic Tourism/agric. Cond. , 2500 µS cm–1 e Mae, Asp 20 000 1983–97 2–5

13 Ramos Mexía R.N.-Neuquén 20 400/816 60/8.5 1.17 Forest/steppe o–m Aci; Asp; Aph 14 000 1977–97 11–3

Limay-Negro(r) ” 600 km Urban/agricult. Afa 1990… 11–3

14 Willimanco (l) Chubut 24/1 18/7 Steppe/cattle SO4Ca dominant m Gla 8000 1989–97# 9–11 (–)

15 F. Ameghino ” 29 000/65 61/24 1.02 Steppe Erosion/sediment. m–e A 7000 1996–97 12

Chubut inf. (r) ” 130 km Steppe/urban A 1996–97

r, river; l, lake; p, pond; the rest are reservoirs; A, Anabaena sp.; Aci, A. circinalis; Asp, A. spiroides; Afa, A. flos-aquae; Apf, Aphanizomenon flos-aquae; Gla, Gomphosphaeria lacustris;

M, Microcystis sp.; Mae, M. aeruginosa; O, Oscillatoria sp.; *colonies mL–1; a4.9 3 106 on the shore; nc, not counted; #without scums production; o, oligotrophic; m, mesotrophic; e, eutrophic;

h, hypereutrophic.

References: 1, Meitchry de Zaburlin (1994); 2, M. Salusso pers. comm., 1994; 3, 4. Tracanna and Seeligman (1992); Tracanna et al. (1996); Locascio et al. (1997); 5, Gavilán (1981); Prósperi

(1989); Calcagno et al. (1995), Prósperi 1996; 6, 7, Fabricius et al. (1989); Corigliano et al. (1994); Lerda et al. (1995); P. Arenas pers. comm., 1994; 8, Silva et al. (1995); 9, García de Emiliani

& Emiliani (1997); 10, Quirós et al. (1983); Quirós and Luchini (1982); 11, Conzonno et al. (1981); Amalfi and Verniere (1996); 12, Guerrero et al. (1991); Gayoso (1993); 13, Mariazzi et al.

(1991); Alcade et al. (1996); 14, Pizzolon and Hechem (1993); 15, Sastre et al. (1991); Santinelli et al. (1992); Sastre et al. (1996); Santinelli et al. (1997). Other sources: Calcagno et al. (1995),

Pizzolon et al. (1997).

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stratification, and N/P ratios have to be investigated.Eutrophication processess and cyanobacterial proliferationin Argentinean inland waters require more govermentattention.

ACKNOWLEDGEMENTSThanks are due N. Meitchry de Zarbulin, M. Salusso, H. Silva, C. Fernández B., M.O. García de Emiliani, F. Emiliani, A. Otaegui, M. Amalfi S., H. Labollita, V. Sastreand N. Santinelli, for the information facilitated, and to MariaLaura Besio for her assistance.

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