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BALWOIS 2010 - Ohrid, Republic of Macedonia - 25, 29 May 2010
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Biological Water Quality of Lake Shkodra Based on the
Diatoms and cyanobacteria Bioindicator Species
Marash Rakaj
Department of Biology-Chemistry, University of Shkodra “Luigj Gurakuqi”
Sheshi 2 Prilli, Shkoder, Albania
ABSTRACT
Diatom species have a narrow optima and tolerances for many environmental variances, which make them
exceptionally useful in quantifying environmental characteristics to a high degree of certainty. Regarding to
the trophy valences of the bioindicator species of the Lake Shkodra diatoms, the highest number of them
belong to oligo-mesotrophic and tolerant groups, which show a good situation of lake for life.
Cyanobacteria are distributed in rich organic waters, wetlands and soils. In some shallower localities of the
southern part of the Lake Shkodra, some large forms and water blooms filamentous of the cynobacteria
species (Merismopedia, Microcystis, Oscillatoria) during summer were observed, but unpleasant odor or
the harmful substances of Cyanobacteria during our investigation were not evidenced.
During last six years a list of Microalgae of Lake Shkodra was compiled, which included 214 genera with
1069 taxa, 98 of which belong to Cyanophyta/Cyanobacteria and 421 to Bacillariophyta.
In this paper phytoplankton diversity and biological water quality based on the bioindicator species of the
Cyanobacteria and Diatoms for the Lake Shkodra is given.
Keywords: Phytoplankton, diatoms, cyanobacteria, Lake Shkodra, bioindicator, trophy valences, water
blooms.
Introduction
Lake Shkodra is situated transboundary between Montenegro and Albania. The Lake is large, shallow
(mean depth: 5.1m), with high oscillations of lake water level (4.4-9.8m), slightly alkaline, with the average
temperature 14.9˚ C.
Diatoms are single-celled microscopic algae (Bacillariophyta) commonly distributed in different water
ecosystems: oceans, lakes, rivers, wetlands and even soils. Diatoms species, both phytoplankton and
periphyton communities have a narrow optima and tolerances for many environmental variances, which
make them exceptionally useful in quantifying environmental characteristics to a high degree of certainty.
Diatoms respond quickly to environmental change because they immigrate and replicate rapidly. Also,
changes in diatom assemblages correspond closely to shifts in other biotic communities, such as other
algae, zooplankton, aquatic macrophytes and fishes. This away, diatoms can be used as indicators of
biological conditions and to accurately inter a variety of water chemistry and other limnological
characteristics, including lake acidification, lake eutrophication and climatic change.
Cyanobacteria are colonial and filamentous photosynthetic organisms, distributed in rich organic waters,
wetlands and soils. In the special conditions, such increased temperatures, summer stagnation and in rich
organic waters, some large forms of cyanobacteria (Merismopedia, Microcystis) development quickly and
may appear water – blooms or red – tides, sometimes with an unpleasant odour. Also, cyanobacteria could
produce the harmful substances for zooplankton, molluscs, fishes and other aquatic organisms, as
neurotoxic alkaloids (Anabaena, Aphanizomenon etc.) or hepatotoxic peptides (Microcystis, Nodularia etc.).
During last decades were published several data on the phytoplankton species composition, horizontal and
vertical distribution and seasonal changes togather with some evaluation of the Lake Shkodra water quality
(RAKAJ, HINDAK & HINDAKOVA 2000; RAKOCEVIC & RAKAJ 2001; RAKAJ, MIHO & KASHTA 2002;
RAKOCEIC-NEDOVIC & HOLLERT 2005; RAKAJ 2002, 2008). Also a checklist of phytoplanbkton taxa of
Lake Shkodra was compiled (RAKAJ, ALUSHI & DHORA 2007), included 214 genus with 1069 species
and intraspecific taxa. The most of the taxa belong to two groups: 1. Archeoplastida with 478 taxa,
composed by green algae (Chlorophyta 237, Charophyta 241) and 2. Chromalveolata with 476, mainly
composed by diatoms (Bacillariophyta 421), while Cyanophyta/Cyanobacteria 98 taxa.
Methodology Applied
The phytoplankton was sampled during spring – autumn 2009, monthly from 4 different stations: 1 – Zogaj,
2 – Kamica, round 400m far from lakeside, 3 – Open water dhe 4 – Shegan (Figure 1). During sampling
water temperature, pH, transparency and disolved oxygen were measeured (Table 1). Phytoplankton bottles
and scrached samples were preserved with 4% formaldehyde or with 1% Lugol solution. Determination of
species were performed with an optic microscope Leitz-Diaplan with immersion objective 63/1.4 Plan-APO
BALWOIS 2010 - Ohrid, Republic of Macedonia - 25, 29 May 2010
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and inverse universal microscope. Taxa determination was made according to KOMAREK &
ANAGNOSTIDIS (1999), KRAMMER & LANGE-BERTALOT (1986-1991a). The density was counted
seasonally according to UTERMOHL (1958), while biological evaluation quality of water quality was done
according to PANTLE & BUCK (1955), SLADECEK (1973), ROTT (1999).
Density was evaluated with 3 scales: 1 – rare, 3 – medium, 5 – high.
The lake water classification was done according to values of the parameters: diversity indices
(MENHINICK 1964), pollution indices (BECK 1954), saprobic indices (PANTLE & BUCK 1955; SLADECEK.
1973) and index of relative purity (KNÖP 1954).
Figure 1. Sampling points of Lake Shkodra
Results Obtained
1.Cyanobacteria as bioindicator
Development of Cyanobacteria began with warming water, stable limnological conditions and increased
quantity of the organic material at the time. The abundance peak of cyanobacteria occurred in summer.
The water – blooms or red – tides were not observed, but water-blooms species and genera with potential
toxin-producing species of cyanobacteria such as: Microcystis aeruginosa, M. wesenbergii,
Plantolyngbbya limnetica, P. circumcreta, Nostoc coeruleum, Anabaena flos-aquae (rarely), Oscillatoria
limosa and Aphanizomenon flos-aquae near the inhabited villages (Zogaj, Kamice) were commonly found.
The development of these cyanobacteria prevents all forms of aquaculture, apart from direct exploitation of
the phytoplankton and zooplankton.
2. Diversity indices
About 72 genera with 340 species and infraspecific taxa of phytoplankton composed mostly by diatoms
(Bacillariophyceae 296) and less cyanobacterial species (Cyanophyceae 44) were recorded.
High diversity, quantitatively dominated by diatoms composed by 24 taxa (8.1 %) centric diatoms
(Coscinodiscales) and 272 (91.8 %) taxa pennates diatoms (Naviculales) was observed.
Among the diatoms, the Naviculales have the largest number of genera and species: Navicula with 67,
Nitzschia 26, Cymbella with 21, Fragillaria 17, Gomphonema 19, Acnanthes 12 species etc.
The most occurring species were Cyclotella ocellata and Aulacoseira ambigua, Asterionella formosa,
Cyclotella distinguenda, Fragillaria ulna, F. capucina, F. elliptica, Diatoma ehrenbergii, Cymbella
caespitosa, C. microcephala, Gomphonema angustatum, G. truncatum, Navicula scutelloides, N. radiosa
and Nitzschia recta, Merismopedia glauca, Microcystis aeruginosa, Planktolyngbya limnetica, Radicystis
aphanothecoides and Oscillatoria limosa.
Diatoms assemblages of Lake were not uniform in horizontal distribution. Species composition differs in
different sampling stations. More species were found in Zogaj and less in Shegan. Average cell number for
liter water during Maj - Shtator at different stations rate from 1020 in Shegan (st. 4) to 92000 in Kamica (st.
2), while diversity indices rate from 0.42 to 1.20 (Table 2).
In the wintertime the hydrological and meteorological regimes are unstable and the diatoms and
cyanobacteria were rather poorly developed. Species density was low (850 – 3700 ind/l).
BALWOIS 2010 - Ohrid, Republic of Macedonia - 25, 29 May 2010
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Table 1. The average values of the physico-chemical parameters
Stations Temperture (ºC) pH DO (mg/l)
1 20.7-26.8 8.1 8.0
2 20.3-26.3 7.6 7.5
3 19-26.2 7.8 8.3
4 10.1- 11.6 7.2 10.6
Table 2. Diversity indices of analized diatoms
Stations Number of species Density (Cell/l ) Diversity
indices
1 246 54000 1.16
2 220 92000 0.82
3 236 46000 1.20
4 18 1020 0.42
In spring, with the approach of more stable water conditions, decreasing of the lake level and increasing of
water temperature, the number of species and density of diatoms increased. The peaks of diatoms in
abundance usually occurred in the early spring and fall.
The geochemichal preferences for majority of diatoms (96 species) found are cosmopolitan and
alkalophilic, which corresponds well with the physical and chemical conditions for lake (pH 7.4 – 8.5,
alkalinity:1.5 – 4.2 mval/l etc.)
3. Pollution indices
Data about the valences of 148 indicator species were performed according to ROTT (1999). The values of
pollution indices rated from 6 to 8 for the three first stations, which indicate that water of lake are slightly
polluted by organic matters especially the littoral waters (st. 1 and 2), while value of pollution indices 4 at
Shegan (st. 4) indicates that water is not polluted (Table 3).
Table 3. Trophic valences of the indicator species
Trophic
valences
Ot Ot-βmt Ot-αmt Amt-eu Tol Eu Sap Pollution
indices
Station: 1 4 7 6 23 20 25 2 7
2 6 9 8 28 32 36 3 8
3 3 6 5 21 25 20 2 6
4 2 2 1 1 5 0 1 4
The most of analized diatoms belonged to oligo-mesotrophic and tolerant groups (round 110 species):
Cyclotella ocellata, Asterionella formosa, Fragillaria capucina etc., but also a high number of benthic
species of the eutrophic group (36 species) were found in the littoral zone (st. 2 Kamica): Fragillaria ulna, F.
construens, Gymphonema acuminata, Navicula capitatoradiata, N. reichardtiana, N. trivialis, N.
cryptotenella, N. menisculus, Nitzschia recta, Cocconeis placentula etc.
We have found more euplanktonic taxa from the open water then in stations with development aquatic
macrophytes (Kamica) or in station of karstic spring (Shegan). The east and north-east sides of Lake are
characterized by much developed aquatic macrophytes, namely species of the genera Nymphea, Nuphar,
Najas, Potamogeton, Valisneria, Trapa, Myriophyllum, Scirpus and Phragmites, which are preferred
substrates for epiphytes. The most of the pennate diatoms which belong to epiphytic species:
Gomphonema, Acnanthes, Cymbella, Navicula and Fragillaria (round 180 species) were found on aquatic
macrophytes and in detritial base.
4. Saprobic indices
Data about saprobity classes, saprobic valences and saprobic indices of the 148 indicator diatom species
for different stations (Table 4) are calculated according to STREBLE & KRAUTER (2002).
BALWOIS 2010 - Ohrid, Republic of Macedonia - 25, 29 May 2010
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Table 4. Saprobity Classes of the lake waters
Sabrobity Classes I I-II II II-III III III-IV IV
Saprobic Valences Os Os/β-ms β-ms β-ms/α-ms α-ms α-ms/psb psb
DO (mg/l) >6 >5 >4 >3 >2 >1 >0.1
Saprobic indices 1-1.5 1.5-1.8 1.8-2.3 2.3-2.7 2.7-3.2 3.2-3.5 3.5-4.0
Average values of saprobic indices of three first stations rated from 2.02 to 2.38 (Kamica), which
corresponded to β-mezosaprobic to β-mezo/α-mezosaprobic level or to Second Class (IInd– IIId) of the water
quality, while value 1.4 in Shegan (st.4) corresponds to oligosaprobic level or to First Class of water quality.
5. Index of the relative purity
The relative purity was performed according of KNÖP (1954) taking in consideration indicator species that
influence only in a class of saprobity (Table 5). The values of relative purity rated from 0.75 to 0.85 which
mean that lake waters are moderately polluted by organic matters.
Table 5. Values of the Indexes of relative purity
Stations Index of relative purity (I)
1 0.76
2 0.75
3 0.78
4 0.85
High diversity of diatoms and low abundance dominated namely by oligo-mesotrophic group taxa, in
general showing a good situation of Shkodra Lake water and conditions for life, and it may be perfect for
fish breeding. But, the presence of some large forms of the eutrophic diatoms and water bloom filamentous
species with potential toxin-producing of cyanobacteria during the summer, especially in littoral part of lake
showed a high level of the organic matters, due to discharged directly to lake of a part of the urban and
wastewaters from Shkodra city and some villages round it. The treatment of urban and wastewaters, strong
measures to restore and protect the whole watershed, supporting reforestation activities and permanent
monitoring would be applied.
Concusions
1. The values of diversity indices and Trophic valences indicate that of the Lake Shkodra waters
belong to Second Classes of the water quality or mesotrophic level.
2. Average values of the saprobity indices (1.45-2.36) and relative purity (0.75 – 0.85) calculated for
dissolved and indicator species indicate that waters of Lake Shkodra belong to β-mezosaprobic
level, which mean that waters are moderately polluted by organic matters
3. Differences of the values for some parameters at different stations indicate heterogeneity of Lake
Ecosystem.
4. High values for some parameters and presence of some species with high trophic and saprobic
valences indicate human influence on this ecosystem.
5. A detailed insight and an effective permanent monitoring will be necessary.
References
BEKTESHI, A. 2007. Përmbajtja e formave të fosforit në sedimentet e Liqenit të Shkodrës. Buletini
Shkencor i USH “ Luij Gurakuqi”, Nr. 57, Seria e Shkencave të Natyrës. Fq. 43 - 49, Shkodër.
KOMAREK, J. & ANAGNOSTIDIS, K. 1999. Cyanoprokaryota. 1. Teil Chroococales. Süsswasserflora von
Mitteleuropa, 19/1:1-548.
KRAMMER, K. & LANGE-BERTALOT, H. 1986, 1988, 1991. Bacillariophyceae, Süsswasserflora von
Mitteleuropa, Jena, 1-4. Teil. 2/1: 1-876, 2/2:1-596, 2/3:1576, 2/4:1-437.
PANTLE, R. & BUCK, H. 1955: Die biologische Uberwachung der Gewasser und die Darstellung der
Ergenisse. Gas und Wasserfach, 96:604.
BALWOIS 2010 - Ohrid, Republic of Macedonia - 25, 29 May 2010
5
PETKOVIC, S. 1981. Phytoplankton,. In: Karaman G. & Beeton, A. (eds.), The biota and limnology of Lake
Skadar, Titograd.163-189pp.
POPOVSTY, J. & PFIESTER, L. Ann. (PACHER, A). 1988, 1991. Die Süsswasserflora von Mitteleuropas.
Band 2/1:1-365, 2/41-436 Bacillariophyceae. Stuttgart.
RAKAJ M. 2002: Studim mbi fitoplanktonin e Liqenit të Shkodrës (Përbërja floristike, dinamika sezonale
dhe niveli ushqyes), Universiteti i Tiranës, (dissertacion) 146 pp.
RAKAJ, M. 2008. Community of phytoplankton and periphyton as indicators of trofic state of Lake
Shkodra. International Conference on Biological and Environmental Sciences, Tiranë, FNS, 26-28
September, Tirana. Book of Abstracts, p. 57. ISBN 978-99956-686-7-9.
RAKAJ, M., ALUSHI, V. & DHORA, DH. 2006. Lista e protistëve të Liqenit të Shkodrës. C&P, Shkodër, 92
pp.
RAKAJ, M., HINDAK, F. & HINDAKOVA, A. 2000. Phytoplankton diversity of the Albanian part of Lake
Shkodra in 1998-1999. Biologia, 55: 329-342; ISSN 0006-3088, Slovakia.
RAKAJ, M, MIHO, A & KASHTA, L. 2002. Të dhëna mbi Diatomete (Mikroalga) e Liqenit të Shkodrës. Studime
Biologjike, Ins. Kerkimeve Biologjike. Ak.Shk. të Shqipërisë, Tiranë, 5-6/2001: 137-241.
RAKAJ, M. & MIHO, A. 2005. Vështrim i përgjithshëm mbi diatometë (Bacillariophyceae) në Liqenin e
Shkodrës. Buletin Shkencor i USH “ Luigj Gurakuqi”, Nr. 55, Seria e Shkencave të Natyrës. pp. 56-68,
Shkodër.
RAKOCEIC-NEDOVIC & RAKAJ, M. 2001. Biodiversity Database of the Shkodra/Skadar Lake (Checklist of
Species): archive.rec.org/REC/Programs/Biodiversity/Shkoder Biodiversity DB.pdf .
RAKOCEIC-NEDOVIC, J. & HOLLERT, H. 2005. Phytoplankton Community and Chlorophyll a as Trophic
State Indices of Lake Skadar, Intern, Ecol. Journ. 3: 25-34, Aachen.
ROTT, E. 1999: Indikationlisten für Aufwuchsalgen in Österreichischen Fliessgewässern. Teil 2.
Trophieindikation und autekölogische Anmerkungen. Bundesministerium f. Land- und Forstwirtschaft,
Wien, 248 pp.
SLADACEK, V. 1973: -System of water quality from the biological point of view. Arch. Hydrobiol. Beih.
Ergebn. Limnologie 7, 218.
STREBLE, H. & KRAUTER, D. 2002. Atlantia dei microorganismi acquatici. La vita un goccia d’acqua.
Franco Muzzio editore, 17-22, 35-45, 149-151, 213-261, Padova.
UTERMOHL, H. 1958. Zur Verollkommung der quantitaven Phytoplanktonmethodik.-Mitt. Internat. Verein.
Limnol. 9:1-31.
