Benthic Algal Investigations in the Danube River and Some of Its Main Tributaries from Germany to Hungary*

Biologia, Bratislava, 58/4: 545—554, 2003

Benthic algal investigations in the Danube river and some of its main tributaries from Germany to Hungary*

Éva Ács1, Katalin Szabó2,KeveT.Kiss1 & František Hindák3

1Hungarian Danube Research Station of the Hungarian Academy of Science, H–2131 Göd, Hungary; e–mail: [email protected] 2Department of Microbiology, Eötvös Loránd University, Budapest, Hungary,

3Institute of Botany, Slovak Academy of Sciences, SK–84223 Bratislava, Slovakia

cs Szabó Kiss Hindák, F. Á ,É., ,K., ,K.T.& Benthic algal investigations in the Danube river and some of its main tributaries from Germany to Hungary. Biologia, Bratislava, 58: 545—554, 2003; ISSN 0006-3088. The epilithic algae in the river Danube and some of its main tributaries were studied. Quantitative samples were taken from the upper part of stones of the shoreline of rivers in August 2000 and from the side in current line of stones in August and October 2001. Samples in 2000 were collected from the Danube from Ingolstadt (Germany) to Göd (Hungary), in August 2001 from Nasgenstadt (Germany) to Baja (Hungary), in October 2001 from Bratislava (Slovakia) to Mohács (Hungary), and also from the mouth of some major tributaries of Danube river. The most abundant group of algae was the diatoms, speciﬁcally the Pennales. In some samples the proportion of Chlorophyta was more than 20%. In 2000 the proportion of Cyanobacteria was also high in many samples because samples were taken from the upper part of stones. In some samples the proportion of the Centrales was surprisingly high. On the basis of diatom indices calculated from the relative abundance of diatoms using the OMNIDIA software, the water quality of the German- Austrian-Slovak part of the Danube is generally good, whereas that of the Hungarian part is moderate. Some evidence of organic pollution or more was found at Melk (in August 2000), Gabčíkovo (in October 2001), Komárom (in August 2001) and Göd (in August and October 2001). The water quality of the rivers Isar, Enns, (in August 2000 and 2001), Iller, Lech, Danube-Main Channel, Váh (in August 2001) was good but of other investigated tributaries moderate. Some evidence of organic pollution was found in the Morava river in August 2000, Mosoni Danube in August 2001 and Hron in August and October 2001. The percentage of pollution tolerant taxa indicated a high level of organic pollution also in the Ipeľ river in August and October 2001. Key words: benthic algae, green algae, large rivers, water quality, the Danube, Germany, Austria, Slovakia, Hungary.

* Presented in the International Symposium Biology and Taxonomy of Green Algae IV, Smolenice, June 24–28, 2002, Slovakia.

545 Introduction Benthic diatoms have become one of the most frequently investigated algae in Europe recently. The planktonic algal ﬂora of the Middle Danube On the basis of their abundance and indicator

has been investigated regularly (see e.g. Szemes, values many biological indices were developed for

1964, 1966, 1968, 1969, 1971; Schmidt, 1978,

classifying the water quality based on the Zelinka

ák & Záhumenský, 1983; Kiss, Marvan

1984, 1994; Hind & (1961) formula. For example, in Italian

1985, 1986, 2000; Makovinská, 1994;

1984, waters the diatom based indices correlate signiﬁ-

ák, 1995; Makovinská & Hindák, 1999;

Hind cantly with the water quality shown by chemical

Hindák & Hindáková, 2000 'Uomo, ), but only few stud- analysis ( Dell 1997). The use of OMNI-

ies have been published recently on the benthic DIA software has become widespread not only in

cs & Kiss Ács

ﬂora (e.g. Á , 1991, 1993a, b; et France but also in other countries, e.g. in Poland wecka al., 2000). The benthic algae of German, Aus- where it has been used successfully by Ka trian, Slovak and Hungarian parts of the river et al. (1997) for several rivers. However, in Hun-

Danube were summarised by Szemes (1967a, b) gary in only a few cases were diatom indices used

Kiss Szabó and Kusel-Fetzmann (1998a, b). The latest pa- ( et al.; 2001, et al., in press). pers reveal a growing recognition of the need to The ﬁrst aim of this study was to investigate carry out biological studies of large rivers. the “supply way” of the phytoplankton in a large

Fig. 1. Sampling points.

Table 1. Sampling points and dates; abbreviations see Fig. 1

Main arms Sampling point/date Nas Öpf Elc Ing Kel B-A Deg Pas Mau Mel B-D

Riv. km 2622 2608 2568 2490 2412 2401 2304 2226 2115 2036 1887 Aug. 2000 x x x x x x Aug. 2001 x x x x x x x x x Oct. 2001 Sampling point/date Bra Hru Gab Med Nag Kom Esz Göd Dun Baj Moh Aug. 2000 x x x Aug. 2001 x x x Oct. 2001 x x x x x x x x

Tributaries Sampling point/date Ill Lec D-M Isa Enn Mor Mos Váh Hro Ipe Aug. 2000 x x x x x x x x Aug. 2001 x x x x x x x x x x Oct. 2001 x x x x

546 Number of species Aug. 2000 Danube Number of species Aug. 2000 tributaries 80 100 70 90 80 60 70 50 60 40 50 30 40 30 20 20 10 10 0 0 Isa Ipe Ing Pas Hro Enn Mel Váh Nag Mor B-A B-D Göd Mos Mau D-M Kom

Aug. 2001 Aug. 2001 70 50 60 45 40 50 35 40 30 25 30 20 20 15 10 10 5 0 0 Ill Elc Pas Kel Esz Nas Öpf Isa Mel Deg Ipe Göd B-D Mau Lec Hro Kom Enn Vah Mor Mos D-M

Oct. 2001 Oct. 2001 80 80 70 70 60 60 50 50 40 40 30 30 20 20 10 10 0 0 Ipe Baj Bra Hru Hro Gab Vah Dun Göd Mor Med

Cyanobacteria Chrysophyceae-Cryptophyta Bacill. Centrales Bacill. Pennales Dinophyta-Euglenophyta benthic green algae planktic green algae

Fig. 2. The species number of the main algal group or forms in the river Danube and some significant tributaries in August 2000 and 2001 and October 2001. Abbreviations: Nas=Nasgenstadt, Öpf=Öpfingen, Elc=Elchingen, Ing=Ingolstadt, Kel=Kelheim, B-A=Bad-Abbach, Deg=Deggendorf, Pas=Passau, Mau=Mauthausen, Mel= Melk, B-D=Bad-Deutch, Bra=Bratislava, Hru=Hrušov, Gab=Gabčíkovo, Med=Medveďov, Nag=Nagybajcs, Kom=Komárom, Esz=Esztergom, Dun=Dunaföldvár, Baj=Baja, Moh=Mohács, Ill=Iller, Lec=Lech, D- M=Danube-Main channel, Isa=Isar, Enn=Enns, Mor=Morava, Mos=Mosoni Danube, Hro=Hron, Ipe=Ipeľ. river, e.g. its recovery after a big flood and its second aim was to study in detail the benthic algal sources (a possible source is the epilithon). The community of the Danube (including the reservoirs

547 relative abundance Aug. 2000 Danube DEXQGDQFH LQG FP Aug. 2000 Danube 100% 3E+06

3E+06 80%

2E+06 60% 2E+06 40% 1E+06

20% 5E+05

0% 0E+00 Ing Pas Mel Ing Nag Göd B-A B-D Pas Mau Mel Kom Nag Göd B-A B-D Mau Kom Aug. 2000 tributaries Aug. 2000 tributaries 100% 3E+06

3E+06 80%

2E+06 60% 2E+06 40% 1E+06

20% 5E+05

0% 0E+00 Isa Ipe ,VD ,SH Hro Enn Váh +UR Mor (QQ Mos 9iK 0RU 0RV D-M '0

Fig. 3. The relative and &\DQREDFWHULD &KU\VRSK\FHDH&U\SWRSK\WD absolute abundance of the main algal group or forms %DFLOO&HQWUDOHV %DFLOO3HQQDOHV in the river Danube and 'LQRSK\WD(XJOHQRSK\WD EHQWKLFJUHHQDOJDH some significant tributaries SODQNWLFJUHHQDOJDH 3URWRGHUPDYLULGH in August 2000. Abbrevia- tions see Fig. 2. of large dams) and its important tributaries in tap water, homogenised and preserved with formalde- the German, Austrian, Slovak and Hungarian sec- hyde. Abundance was determined according to Uter- tions, in relation to the water qualification based möhl’s method (1958) and analysed statistically as de- on diatom indices. Diatom indices were developed scribed by Lund et al. (1958). An inverted light micro- for the water qualification of creeks, streams and scope was used. Diatoms were treated with H2O2 and washed three times in distilled water, and mounted in small rivers. We also studied the impact of tribu- Naphrax. 400 valves were counted. Small pennate and taries on the biodiversity of benthic algae living in centric species were identified with a transmission or the main arms of the Danube and the impact of scanning electronmicroscope. Diatom indices were cal-

reservoirs on the epilithon. culated using OMNIDIA Version 3 (Lecointe et al., 1993, 1999).

Material and methods Results and discussion Samples of epilithic algae were taken in the river Danube and some of its major tributaries (close to their mouth) from Germany to Hungary in August 2000 and At each sampling sites most diatom taxa belonged

2001 and in October 2001 (from side in current line of to the Pennales (Fig. 2). In the Enns river the yng-

stones). Sampling locations are identiﬁed in Fig. 1 and invasive diatom Didymosphenia geminata (L

W. M. Smith in Tab. 1. The algae were scraped with brush from bye was found in the epilithon. a2cm2 area of stones in three replicates, washed in In some samples the green planktonic algae were

548 Aug. 2001 Danube Aug. 2001 Danube relative abundance DEXQGDQFH FHOOV FP 100% 3E+06

80% 3E+06

2E+06 60%

2E+06 40% 1E+06

20% 5E+05

0% 0E+00 Elc Pas Kel Esz Elc Nas Öpf Pas Kel Mel Esz Deg Göd B-D Nas Öpf Mel Deg Mau Göd B-D Kom Mau Kom

Aug. 2001 tributaries Aug. 2001 tributaries 100% 3E+06

80% 3E+06

2E+06 60% 2E+06 40% 1E+06

20% 5E+05

0% 0E+00 Ill Ill Isa Isa Ipe Ipe Lec Lec Hro Hro Enn Enn Vah Vah Mor Mor Mos Mos D-M D-M

&\DQREDFWHULD &KU\VRSK\FHDH&U\SWRSK\WD %DFLOO&HQWUDOHV %DFLOO3HQQDOHV 'LQRSK\WD(XJOHQRSK\WD EHQWKLFJUHHQDOJDH SODQNWLFJUHHQDOJDH 3URWRGHUPDYLULGH

Fig. 4. The relative and absolute abundance of the main algal group or forms in the river Danube and some

signiﬁcant tributaries in August 2001. Abbreviations see Fig. 2.

ascher Ruttner

also rich in taxa, e.g. Monoraphidium contor- e.g. Mallomonas alpina P et , M.

Komárk.-Legn Ivanov Krieger Teil-

tum (Thur. ., Pediastrum bo- caudata et , M. tonsurata

Turpin Menegh., Krieger Korshikov

ryanum ( Scenedesmus ecor- ing et , Synura petersenii .It

Chodat nis (Ehrenb. were present in virtu- appears that the periphyton is an important refuge ally every sample. In the samples there were sev- for planktonic species. The tributaries of the rivers

eral planktonic centric species, e.g. Cyclotella cy- sustain and increase the biodiversity of the main

ak. Carter Kütz.,

clopuncta H et , C. comta arm. Hellerman

Stephanodiscus invisitatus Hohn et , In 2000 samples were collected from the up-

ak. Hickel

S. neoastraea H et , Thalassiosira guil- per part of stones. In most of these samples the

Hasle Heim-

lardii Hasle, T. pseudonana et proportion of planktonic centric diatoms was sur-

dal unow G. A. Fryxell , T. weissﬂogii (Gr prisingly high (only living cells were counted)

et Hasle, even in 2001, when samples were col- e.g. in the Danube at Passau, Mauthausen and lected from the side in current line of stones. Some in the Morava and Váh rivers, (Fig. 3), be- planktonic Chrysophyceae were also recognised, cause of their sedimentation. Therefore in 2001

549 Oct. 2001 Danube Oct. 2001 Danube relative abundance abundance (ind cm-2) 100% 3E+06

80% 3E+06 2E+06 60% 2E+06 40% 1E+06

20% 5E+05

0% 0E+00 Baj Baj Bra Bra Hru Hru Gab Gab Dun Dun Göd Göd Med Med Moh Moh

Oct. 2001 tributaries Oct. 2001 tributaries

100% 3E+06 3E+06 80% 2E+06 60% 2E+06 40% 1E+06

20% 5E+05

0% 0E+00 Fig. 5. The relative and Ipe Hro Ipe Vah Mor Hro Vah Mor absolute abundance of the main algal group or forms Cyanobacteria Chrysophyceae-Cryptophyta Bacill. Centrales in the river Danube and Bacill. Pennales Dinophyta-Euglenophyta planktic green algae some signiﬁcant tributaries benthic green algae Protoderma viride in October 2001. Abbrevia- tions see Fig. 2.

the samples were collected from the side in cur- to remove intact when sampling these habitats Lee rent line of stones but in some cases the propor- (John, 2002). (2002) observed this species on tion of centric diatoms was high (e.g. the Mosoni rocks in streams in Minnesota but also found it on Danube and the Danube at Mohács, Figs 4, 5). the surface of underwater roots, branches and logs. The most abundant group of algae was gener- In August 2001 the proportion of Achnanthidium

ally that of the pennates [Achnanthidium minutis- minutissimum was also high (Fig. 6). This diatom Czarnecki

simum (Kütz. , Amphora pediculus is a well-known colonizing species with a fast im-

Grun Ehrenb Hofmann,

(Kütz. ., Cocconeis placentula ., migration rate ( 1999). Its proportion gardh,

Gomphonema angustum C. A Nitzschia was signiﬁcantly lower in August 2000 and Octo-

unow, Grunow

inconspicua Gr N. fonticola in ber 2001 than in August 2001. In 2001 the pro-

Möller C.

Cleve et , Rhoicosphenia abbreviata ( portion of Cyanobacteria was signiﬁcantly smaller

gardh Lange-Bert] A which usually dominated than in 2000. It is known that many ﬁlamentous the samples. However, in many cases the relative Cyanobacteria prefer to live on the upper part of abundance of the green alga Protoderma viride the stones.

Kütz. was extremely high both in August and Oc- Due to the floods, the abundance of epilithic tober 2001 in the main arms and the tributaries. algae was significantly lower in August 2001 than At that time in the Danube and its catchment ar- in August 2000 (Figs 3, 4). The abundance at Bad- eas were experiencing a flood (in August it was Abbach, Bratislava and Gabčíkovo was high, more higher and in October lower), therefore this fila- than 2 million cells per cm2 (Figs3,5),proba- mentous alga may be considered a pioneer species. bly because these samples were taken near reser- It is a common epiphytic and epilithic species, at- voirs (Bad-Abbach and Gabčíkovo) where the re- tached firmly to the substrate since it is difficult tention effect can influence the abundance of algae.

550 Aug. 2000 Danube Aug. 2000 tributaries 100% 100% 80% 80% 60% 60% 40% 40% 20% 20% 0% 0% Ing Isa Pas Ipe Mel Nag B-A B-D Göd Hro Enn Mau Váh Mor Mos Kom D-M

Aug. 2001 Aug. 2001 100% 100% 80% 80% 60% 60% 40% 40% 20% 20% 0% 0% Ill Elc Pas Kel Esz Nas Öpf Isa Mel Deg Ipe B-D Göd Mau Lec Kom Hro Enn Váh Mor Mos D-M Oct. 2001 Oct. 2001 100% 100% 80% 80% 60% 60% Fig. 6. The proportion of 40% 40% Achnanthidium minutissi- 20% 20% mum in the river Danube 0% 0% and some signiﬁcant tributaries in August 2000 and Ipe Baj Bra Hru Hro Gab Vah Dun Göd Mor Med Moh 2001 and October 2001. Others means other di- Others Achnanthidium minutissimum atoms. Abbreviations see Fig. 2.

There was no tendency in the changes of abun- Komárom (August 2001) and Göd (August and dance alongside the Danube, because the abun- October 2001). The water quality of the rivers Isar, dance in a large river depends primarily on the Enns (August 2000 and 2001), Iller, Lech, Danube- discharge and the dilution effect of tributaries. The Main Channel, Váh (August 2001) was good and abundance of algae in tributaries also depends on that of other tributaries was moderate. Some evi- the hydrological and hydro-morphological situa- dence of organic pollution was found in the Morava tion (e.g. low or high water period, presence or ab- river in August 2000, the Mosoni Danube in Au- sence of reservoirs on the river or on its tributaries, gust 2001 and the Hron in August and October current conditions, seasonality). In our study the 2001. According to the the percentage of pollution differences in the abundance between the two in- tolerance taxa (PT%) considerable organic pollu- vestigated years could also be caused by different tion was also found in the Ipeľ river in August and collecting methods. October 2001 (PT% = 57.3% in August 2001, at On the basis of diatom indices calculated a time when the abundance of phytoplankton was from the relative abundance of diatoms using 20,000 ind. mL−1, the individual number of green the OMNIDIA software, the water quality of algae was 6,400 individuals mL−1, and the colour the German-Austrian-Slovak part of the Danube of the water was greenish-brown). is generally good, while of the Hungarian part In summary, the periphyton appears to be an (from sampling point Nagybajcs on) it is moder- important refuge for planktonic species, and many ate (Tab. 2). Some evidence of organic pollution planktonic species can survive, and even prolifer- or other pollutants was found at Melk (in Au- ate in the periphyton and “inoculate” the plank- gust 2000, when the percentage of pollution tol- ton. Its abundance in large rivers depends primar- erant taxa was 51), Gabčíkovo (October 2001), ily on the discharge and the dilution effect of trib-

551 Table 2. The values of some indices on our sampling points; abbreviation see Fig. 1

Sampling point Sampling date Indices

IPS EPI-D IDG CEE IBD TDI %PT

Main arms Nas Aug. 2001 16.7 12.2 9.4 16.2 13.5 69.1 1 Öpf Aug. 2001 13.7 9.2 10.8 13.7 12 83.5 11 Elc Aug. 2001 17.8 12.4 11.8 17.5 15.7 48.2 1.3 Ing Aug. 2000 16.1 11.3 12 15.1 12.4 76.1 5.3 Kel Aug. 2001 15.9 11.6 12.3 14.7 12 64.4 2.4 B-A Aug. 2000 15.1 10.2 9.8 14.5 11.7 92.2 11 Deg Aug. 2001 17.2 10.8 11 14.7 10.7 81.9 3.3 Pas Aug. 2000 15.4 11 11.6 14.9 12.4 87.1 5.8 Pas Aug. 2001 15 10.1 11.7 0 10.9 80.1 1 Mau Aug. 2000 13.8 9 12.2 11.6 11.9 71.8 11 Mau Aug. 2001 19.4 14.1 12.4 16.8 16.5 28.5 3.1 Mel Aug. 2000 9.8 9 10.2 12.2 7.8 74.7 51 Mel Aug. 2001 13.5 11.2 7.9 13 13.1 75.6 9.2 B-D Aug. 2000 15.2 9.9 9.8 14.1 11.5 82.3 7.3 B-D Aug. 2001 17.9 13.5 11.4 16.6 14.3 50.6 5.6 Bra Oct. 2001 13.9 9.3 10.7 13.9 11.7 84.6 14.5 Hru Oct. 2001 15.4 11.4 10.8 14.9 12.1 75.7 6 Gab Oct. 2001 13 7.5 10.7 12.2 11.9 88.2 21.6 Med Oct. 2001 13.8 7.4 12.3 12.6 11.5 81.6 9.4 Nag Aug. 2000 14.8 12.1 11.6 13.5 11.5 61.4 2 Kom Aug. 2000 16.5 14.2 11.5 16 12.7 67.1 3.5 Kom Aug. 2001 10.8 9.3 4.7 13 11.2 71.3 34.7 Esz Aug. 2001 15.8 11.2 10.8 15.1 13.1 70 11 Göd Aug. 2000 12.5 8.4 8.3 12.2 10 89.6 12.5 Göd Aug. 2001 14.9 9.7 9 13.4 11.3 74 24.2 Göd Oct. 2001 12.3 7.8 6 11.8 10.6 89.5 38.9 Dun Aug. 2001 14.9 11.4 10 14.7 11.1 94.5 6.7 Dun Oct. 2001 11 7.8 8.9 10.5 11 86.9 18.2 Baj Aug. 2001 15.1 10.4 9.1 14.7 11.3 95.4 7.7 Baj Oct. 2001 10.6 6.9 8.9 10.3 9.5 86.1 12.6 Moh Oct. 2001 10.3 9.7 7.5 11.1 9.2 83 20.2

Tributaries Ill Aug. 2001 15.6 11.6 10.9 15.8 14 65.2 2.1 Lec Aug. 2001 17.4 12.9 9.5 17.3 13.6 63.2 0 D-M Aug. 2000 15.2 11.2 11.4 14.5 11.6 85.2 7.3 D-M Aug. 2001 15.9 13.2 9.6 16.2 12.2 87.7 2.8 Isa Aug. 2000 13.6 9.4 10.2 12.6 12.2 79.1 10.8 Isa Aug. 2001 15.4 11.9 10.9 15.1 11.8 77.4 7.5 Enn Aug. 2000 19.6 13.8 13.5 17.7 16.6 29.5 0 Enn Aug. 2001 19.5 13.9 12.5 17.7 16.4 29.6 1 Mor Aug. 2000 10 8 8.5 10.1 10.2 82.1 31.8 Mor Oct. 2001 13.1 8.6 10.1 13.4 11.4 88.1 9.5 Mos Aug. 2000 12.6 8.4 7.4 11.8 9.5 89.1 27.5 Mos Aug. 2001 15.1 10.2 9 13.7 12 82.4 20.8 Vah Aug. 2000 13.9 9.7 9.3 13.7 10.6 90.8 11 Vah Aug. 2001 15.5 10.3 10.3 14.7 11.4 92.2 5.7 Vah Oct. 2001 14.8 9.1 10.6 14.3 11.3 83.6 5 Hro Aug. 2000 13.5 8.6 10.4 13.7 11.9 68.3 5 Hro Aug. 2001 12.8 6.9 8.6 12.2 10.5 79.1 21.4 Hro Oct. 2001 11.4 6.9 8.2 10.7 11.8 72.9 23.2 Ipe Ahug. 2000 13.6 9.1 10.7 13.4 10.9 84.7 2.3 Ipe Aug. 2001 11.2 7.7 4.4 10.1 8.8 74.6 57.3 Ipe Oct. 2001 9.3 7.6 6.4 8.8 10.1 84.1 43.1

552

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