Assessment of the water quality and trends at the Drini cascade system based on plankton data

Spase Shumka1, Aleko Miho2 1Agriculture University of Tirana, 2 FNS Tirana University Tirana-

Abstract

Its well known that eutrophication processes caused by an enrichment in nutrients results in an increase of photosynthetic biomass. In the water ecology however, the factors which drive the shift in species composition of the assemblage along trophic gradients are yet poorly understood (Reynolds, 1996). Being rather tolerant to different environmental conditions, many zooplankton species are good indicators of water quality and can be used for the ecological monitoring of water bodies. The aim of this study done in the course of /Drim POL (A Norwegian Research Council support) was to explore fauna of Rotifera-Cladocera and Copepoda (Cyclopoda & Calanoida) from Lake Ohri, Micro Prespa, Macro Prespa, and Shkodra and to determine the water quality on the basis of the noted bioindicative zooplankton species. During the investigated period 118 species were identified. Their qualitative composition varied dependent on season and locations. The most diverse composition was recorded in summer. The rotifer composition in the quiet bays with macrophyte vegetation is rich and more exuberant then in sand localities. The most of the noted species were oligo- β-mesosaprobic and _- mesosaprobic indicators, except Rotaria rotatoria that belongs to α-mesosaprobic water. Saprobiological testing based on rotifera showed that the water was oligo- β.mesosaprobic.

Key words: ; Rotifera; bioindicator; qualitative and quantitative composition; saprobiological testing; oligo- β- mesosaprobic

Introduction

Drini River watershed comprises a considerable area of 14173 km2 (within Albania) (Kabo, 1990-91), continuing also beyond Albanian borders, covering very important aquatic ecosystems, not only from the economic point of view but also naturally. Beside the river course, its related tributaries and closely related artificial lakes of Drini cascade (Fierza, Komani and Vau-deja) in Drini watershed are situated the big trans-boundary lakes of Ohrid, Prespa and Shkodra, three groups of mountainous glacial lakes of Lura, Ballgjaj and Dhoksi. Close to Drini delta an important lagoon system is situated, with three main lagoons: Merxhani, Ceka and Kenalla. Increase in human population and development of tourism cause harmful changes in ecosystems. The consequences of that are changes in qualitative and quantitative compositions of biocenoses. Because of that is possible to explore conditions in some ecosystems by using composition of organisms that live in it - bioindicators. Being rather tolerant to different environmental conditions, many rotifer species are good indicators of water quality and can be used for the ecological monitoring of water bodies (Ramadan et al., 1963;c Sladacek & Tucek, 1975; Sladacek, 1983; Pujin, 1982, 1987; Reh, 1997; Kostoski et al., 2001). The aim of this study was to explore fauna of Rotifera from eastern littoral zone of Lake Ohrid and to determine the water quality on the basis of the noted bioindicative rotifers. In the present paper is also given a view of microscopic algae (diatoms – Bacillariophyta). The reporting is considering all the diatom taxa found and already published by different authors, from Albania and from the neighbouring or other European countries, together with the personal data taken during different expeditions (some of them not published). A checklist of species is given and discussed, both in floristic and ecological aspects. Some problems that endanger the biodiversity and water quality will be emphasized, with some recommendations to maintain or restore the water quality.

Material and methods

A qualitative study was carried out with seasonal dynamic during 2001 - 2004. The samples were taken from localities in eastern littoral zone of the lakes as a part od Drini Watershed. Saprobiological analysis was done by using standard Pantle-Buck method (Pantle-Buck, 1955) based on qualitative and relative quantitative composition of Rotifera, Cladocera and Copepoda species. Bibliographic list dealing with floristic data from Drini watershed areas were taken into consideration. The number of the taxa reported for each group of algae is also presented. The list of diatoms obtained in Albanian samples (some of them not published before) has been added. Our study have consisted on collecting plankton or periphyton samples during sporadic expeditions (during 1993-2003), mainly into littoral habitats of Ohrid, Prespa, Shkodra, Merxhani, Ceka, Lura, Ballgjaj and Dhoksi, Komani and Vaudeja, etc. Investigations were based on microscopic examinations, using the microscope LEICA DML (objective 63x PL APO). Cleaning of diatom frustules, preparation of permanent slides and determinations follow Krammer & Lange-Bertalot (1986-2001). The species structure, examination of the most interesting species, the new or endemic ones is evaluated. Very often even the quantity is evaluated, and ecological comments have been given. From the structure of the epiphytic microscopic algae the trophy state is calculated using the formula of Zelinka et al. (1961), the respective values for each species and the trophy classes were taken from Rott et al. (1999). Considerations on each habitat are given previously in different publications (Miho, 1998; Miho & Mitrushi, 1999; Miho & Lange-Bertalot, 2001; 2003; Rakaj et al., 2001). Former samples, permanent slides and photos were deposited in Section of Botany, Tirana University.

Results and discussion

During the investigated period 118 species were identified. Their qualitative and quantitative composition varied depending on season and locations.

Table. 1 Water categories of Macro and Micro Prespa according to Sladecek (s-. saprobe cl. and S-index saprobe)

Family Genus Species Macro Micro Macro Micro Prespa Presp Prespa Prespa (s) a (S) (S) (s) ROTATORI A Brachionida Brachionus B. angularis (Gosse) ß-α ß-α 2,5 2,5 e B. calyciflorus (Pallas) ß-α 2,5 2,5

Keratella K. cochlearis (Gosse) o o 1,55 1,55 Epiphane Epiphane sp. o- ß o- ß Gastropodid Gastropus G. stylifer (Imhof) o 1 ae Ascomorpha A. ecaudis Perty o 1,3 Asplanchida Asplanchna A. priodonta (Gosse) o o 1,55 1,55 e Testudinellid Filinia F. longiseta (Ehren.) ß ß 2,35 2,35 ae Pompholyx P. sulcata (Hudson) ß ß 2,4 2,4 Pedalion. sp α CLADOCER A Sididae Sida Sida cristalina o 1,3 (O.F.Müller) Daphnidae Daphnia D. longispina (O.F.Müller) ß ß 2,05 2,05 D. cucullata (Schodler) ß-o ß-o 1,75 1,75 Simochephal S. vetulus (O.F.Müller) o- ß o- ß 1,5 1,5 us S. serrulatus (Koch) o 1,5 Ceriodaphnia C. quadrangula G.O.Sars o 1,115 C. megalops G.O.Sars o 1,3 Scapholeberi S. mucronata ß ß 2,0 2,0 s (O.F.Müller) Chidoridae Camptocercu C. rectirostris (Schodler) o 1,2 s Acroperus A. arpae angustatus o- ß 1,4 G.O.Sars Graptoleberis G. testudinaria (Fischer) o- ß 1,5 Leidygia L. acanthocercoidae α 2,0 (Fischer) Chidorus Ch. sphaericus leonardi o 1,75 (King.) Rinchotalona R. rostrata (Koch) o o 1,3 1,3 Pleuroxus P. laevis (G.O.Sars) ß ß P.aduncus (Jurine) o 1,2 Alona A. gutata (Sars) o- ß o- ß 1,5 1,5 A. rectangula (G.O.Sars) o 1,3 A.quadrangularis o- ß o- ß 1,4 1,4 (O.F.Müller) Leptodorida Leptodora L. kindti o- ß o- ß 1,65 1,65 e Alonella A. exigua (Lillejborg) o 1,2 Bosminidae Bosmina B. longirostris o- ß o- ß 1,55 1,55 (O.F.Müller) Diaphanoso D. brachiurum o o 1,4 1,4 ma (O.F.Müller) COPEPODA Eucyclopina Macrocyclops M. albidus (Jurine) ß 2,0 e M. fuscus (Jurine) ß-o 1,6 Eucyclops E. serrulatus (Fischer) ß 1,85 E. macruroides ß 1 (Lillejborg) Paracyclops P. finitimus (Kiefer) ß 1,25 Megalocyclop M. viridis (Jurine) ß-o 1,65 s Cyclops C. vicinus vicinus ß ß (Uljanin) Ectocyclops E. phaleratus (Koch.) α 1,5

Table 2. Presence of various zooplankton species in course of Drini catchment

Nr. Species Ohrid Prespa Prespa Fierza Shkodra Lake Lake Lake Ma A. Lake Lake Micro ROTATORIA 1 Macrohaetus subquadratus + 2 Tricotria pocillum + 3 Platyas patullus + 4 Brachionus quadridentatus + + 5 Brachionus caciciflorus v.brycei + + + + 6 Brachionus c.v. dorcas + 7 Brachionus unceolaris + 8 Brachionus unceolaris v. sericus + 9 Brachionus plicatus + 10 Brachionus forficula + 11 Brachionus diversicornis + + 12 Brachionusangularis + + + + + 13 Lophocaris salpina + 14 Lophocarisoxysternon + 15 Mytilina crassipes + 16 Mytilina mucronata + + 17 Euchlanis mentea + 18 Euchlanis dilatata + 19 Dipleuchlanis propatula + 20 Anuraeopsis fissa + 21 Keratella cochlearis + + + + + 22 Keratella.c.v.macracantha + 23 Keratella cochlearis v. hispida + 24 Keratella ticinensis + 25 Keratella valga + 26 Keratella quadrata + + 27 Kellicotia longispina + + + + + 28 Notholca acuminate + 29 Squatinella rostratum + 30 Squatinella tridentatus v. mutica + 31 Lepadella ovalis + 32 Lepadella patella + + + + + 33 Lepadella rhomboids + 34 Lepadella ehrenbergi + 35 Lecane luna + + + + + 36 Lecane curvirostris + 37 Lecane elsa + 38 Lecane nana + 39 Lecane elasma + 40 Lecane quadridentata + 41 Lecane hamata + 42 Lecane closterocera + 43 Lecane bulla + 44 Lecane lunaris + + + + + 45 Lecane obtuse + 46 Scaridium longicaudum + 47 Monommata aequalis + 48 Cephalodella forficula + 49 Cephalodela misgurnus + + 50 Decphalodela giba + 51 Trichocerca bicristata + 52 Trichocerca capucina + + + + + 53 Trichocerca similes + 54 Trichocerca longispina + + + + 55 Trichocerca myersi + 56 Trichocerca rattus + + + + 57 Trichocerca pusilla + + 58 Trichocerca porcellus + 59 Trichocerca rectangularis + 60 Asplanchna priodonta + + + 61 Polyarthra vulgaris + + + + + 62 Polyarthra trygla + + 63 Synchaeta pectinata + 64 Pleosoma truncatum + + + + 65 Testudinella mucronata + 66 Testudinella patina + 67 Testudinella incise + 68 Testudinella pseudoliptica + 69 Testudinella palladina trilobata + 70 Pompholyx sulcata + 71 Pompholyx complanata + + + 72 Pedalia mira + 73 Pedalion sp. + 74 Dissotroca aculeata + 75 Rotari rotatoria + 76 Phylodina megalotrocha + 77 Epiphane sp. + + 78 Ascomorpha ecuaudis + + + 79 Filinia longiseta + + + + +

CLADOCERA 1 Sida crystalina + + + 2 Diaphanosoma brachiurum + + + + + 3 Daphnia pulex +? 4 Daphnia pulicaria + 5 Daphnia longispina + + + + 6 Daphnia magma + 7 Daphnia cucullata + + 8 Scapholeberis mucronara + + 9 Simocephalus vetulus + + + 10 Simocephalus serrulatus + + + + + 11 Ceriodaphnia laticaudata + 12 Bosmina coregoni + 13 Bosmina longirostris f. typical + + 14 Bosmina longirostris f. brevicornis + 15 Bosmina longirostris f. pellucida + 16 Bosmina longirostris f. similes + 17 Acroperus harpae + + + + 18 Alona rectangulus + + + + + 19 Alona gutatta + 20 Alona quadrangularis + + 21 Alonella excise + + + + + 22 Alonella exigua + 23 Pleuroxus aduneus + + + 24 Pleuroxus laevis + 25 Chydorus sphaericus leonardi + + + + + 26 Leptodora kindti + + + 27 Rinchotalona rostrata +

COPEPODA 1 Eudiaptomus gracilis + 2 Archtodiaptomus steindachneri + + + 3 Archtodiaptomus kerkyrenchis + + 4 Mesocyclops leukarti + + + + 5 Macrocyclops albidus + + + + 6 Eucyclops serrulatus + + + 7 Eucyclops macruroides + 8 Thermocyclops oithonensis + 9 Cyclops ochridanus + 10 Megacyclops viridis + 11 Acanthocyclops vernalis + 12 Diacyclops bicuspidatus +

The data taken from this compilation work shows the enormous importance of Drini watershed. A checklist of more than 1000 taxa phytoplankton and considerable number of zooplankton (species or other taxonomic forms) were found all together (Table 5), where about 25 belong to centric diatoms and the remaining to pennatae. For each species, the habitat where is found and the relative author is reported. The so far reliably known auto-ecological data, the occurrence in Central Europe, and the relative trophic index is reported for most of the species. The number of taxa is relatively high, if we consider that the total number recordered for all the Europe is about 1600 (Krammer & Lange-Bertalot, 1986-2001). Of the total number recorded, more than 60 taxa were known as endemics in the region, most of them belong to Lake Ohrid. More than 120 taxa belong to the red list of the Central Euope, considered as endangered species, which mean that they grow up in rare habitats. Ohrid is undoubtedly the most important and the most attracting habitat of the whole region. Diatoms (Bacillariophyceae) seem to be an important group of microscopic algae, followed then by Chlorophyceae. As is shown in table 1, the most important are publications of Hustedt (1945) and Jurilj (1954), which have found 355 taxa in Macedonian part. We found more than 380 taxa also in Albania. About 260 taxa were in common, whereas 120 were not recorded before in Ohrid. In addition, we have not found about 180 species or other forms, which have been found already in the Macedonian part. About 80 species belong to the red list of species for the Central Europe (Lange-Bertalot, 1996). Hence, more than 550 taxa of diatoms were reported totally, where about 35 belong to centricae and 520 pennatae. Most of the species in Lake Ohrid are oligotraphentic, mainly present in planktonic samples, growing up only in oligotrophic waters with low nutrient level, like Cyclotella fottii, C. hustedtii, Gomphonema lateripunctatum, Caloneis aerophila, Diploneis ovalis, Gomphonema clavatum, etc. However, in littoral habitats, there have been observed tolerant species as dominant that grow up to a wide range, from oligotrophic to eutrophic waters, like Achnanthes minutissima, A. biasolettiana, Cymbella microcephala, Navicula cryptotenella, N. minima, Neidium dubium, Nitzschia amphibia, Nitzschia angustata, Gomphonema truncatum, G. parvulum, Fragilaria capucina, F. brevistriata, etc. Other species of the highest vitality in stronger mesotrophic to eutrophic waters were observed, like Achnanthes clevei var. clevei, A. lanceolata, Amphora pediculus, Caloneis bacillum, Cocconeis pediculus, Cymbella minuta, Diatoma vulgaris var. vulgaris, Epithemia adnata, E. sorex, Fragilaria capucina var. mesolepta, Gomphonema minutum, Gomphonema pumilum, G. olivaceum, Gyrosigma accuminatum, Meridion circulare, Naviculadicta atomus, N saprophila, Navicula cryptocephala, N. menisculus var. grunowii, N. reinhardtii, Nitzschia dissipata, N. linearis, N. palea, Rhoicosphenia abbreviata, Surirella angusta, etc. Despite some poly-hypertrophentic species of diatoms (Amphora libyca, Cymatopleura solea, Fragilaria ulna, Navicula cuspidata, etc.), high presence of Cyanophytes has been observed in planktonic samples near Pogradeci. Some more considerations about the trophic state of Albanian habitats were reported in a previous publication (Miho & Lange-Bertalot, 2003). Trophic values, reported in table 2, vary from 1.5 to 2.5, changing from oligo-mesotrophic to eutrophic, that shows a worse water quality, compared with pelagic waters. It is worth to point out the stressing state in Driloni River, a very sensitive wetland, where the trophic value, calculated from diatom epiphytes over Helodea cannadensis, was very high (2.5, eutrophic). Of course, as it can be expected, nearby Pogradeci the observed trophic degree was also high. That situation should be a direct consequence of eventual high content of nutrients, mainly total phosphor. From the literature, in such conditions, its total relative values should oscillate from 10-20 µg/l to 30-100 (<250) µg/l (Miho & Lange-Bertalot, 2003). Prespa Lakes From the assessment made in planktonic or/and benthic samples, collected in Albanian part of Macro and Micro Prespa lakes, more than 270 species diatoms have been found, too. 109 species belong to the red list of species for the Central Europe (Lange-Bertalot, 1996). Data about the total number of species in each sample and diversity index have been reported into table 3. Table 3: Data on microscopic algae in Prespa (Albanian part)

From some casual assessment of the diatom structure in Micro Prespa (Pusteci and Buzeliqenasi), it is mainly observed the domination of tolerant or α- or β-mezo-eutraphent species (Hofmann, 1994), like Achnanthes minutissima, Fragilaria construens, F. capucina, F. crotonensis, F. biceps, Epithemia adnata, Cymbella subminuta, Nitzschia graciliformis, N. dissipata, N. palea, Rhopalodia gibba etc. The diatom composition indicates a moderate mesotrophic until eutrophic state of the lake, corresponding to more than 2° to 3° klass of water quality. The diatom structure in Macro Prespa changes only slightly from that in Micro Prespa. In Kallamasi, Gorica and Liqensi areas, it is observed the increase of eutraphent species like Amphora pediculus, Fragilaria capucina var. perminuta, Epithemia sorex, Cymbella caespitosum, Cocconeis pediculus, Nitzschia dissipata, N. palea and Rh. Gibba. It is also characteristic for α- or β-mesotrophic state, corresponding to 2° until 3° class (or more) of the water quality.

Shkodra Lake The first data on the phytoplankton of Shkodra Lake were given by Forti (1901). Petkovic (1981) publish a limnologic study, realized mainly during years 1972-77 in Montenegrian part, where a checklist of 685 taxa of microscopic is reported. The most dominant are chlorophyta, and only 134 taxa belong to diatoms Rakaj (2002) in his doctorate was the first from Albanian part to study phytoplnakton of Lake Shkodra during years 1995-99. In total he reports about 468 taxa, where diatoms are dominant with about 240 taxa. The most abundant are limnoplanktonic forms, like Cyclotella ocellata, heloplankton forms domined by Aulacoseira granulata, Diatoma vulgaris, Cymbella affinis, Fragillaria ulna, Gomphonema olivaceum, Tabellaria flocculosa, and less the potamoplanktonic forms, like Gyrosigma acuminatum, Surirella elegans, etc. Cymbella scutariana Krammer and Cyclotella skadariensis Jerkovic are rare (or endemic) species found in Lake Shkodra. In plankton diatoms dominate mainly in spring, while during summer as temperature increase, the increasing of chlorophytes and cyanophytes is observed. Considering the trophic values (table 2), the phytoplankton of Shkodra Lake is domined by oligo-mesotraphentic and mesotraphentic species, like Cyclotella ocellata, Asterionella formosa, Fragilaria capucina, etc. Often also eutraphentic species were abundant, like Fragilaria ulna, F. construens, Gyomphonema acuminata, Navicula capitatoradiata, N. reichardtiana var. crassa, N. trivialis, N. cryptotenella, N. menisculus var. grunowii, Nitzschia recta, etc. Density and domination of eutraphentic species increase during summer and autumn, more emphasized it near Buna River outlet and western coast of the lake. Generally, the forms observed correspond to oligo-mesotrophic or even mesotrophic habitats, which shows an eventual increase of nutrients, especially phosphor. It is probably a consequence of human impact from Shkodra town and activities in the watershed area.

Tabela 4. The most abundant taxa (more than 3 %) with their relative trophic and tolerance values (Miho & Lange-Bertalot, 2001) Tolerance velue: ot, oligotrafent; ol-bmt, oligo-β-mezotrafent; ol-amt, oligo-α-mezotrafent; tol, tolerant; am-eut, α-mezo-eutrafent; ind, indiferent. Valenca saprobike: os, oligosaprobe; bms, deri β- mezosaprobe; bams, deri β-a-mezosaprobe; ps, deri polisaprobe; -, e panjohur. (Hofmann. 1994) Name of species Lura Ballgjaj Dhoksi Ecological values Cyclotella sp. (aff. cyclopuncta Häck. var. ?) 0.1-27.2 0.2-5.6 3.4-56.3 - C. radiosa (Grun.) Lemm. 0.1-13.7 0.1 - Achnanthes flexiella (Kütz.)Brun agg. 0.1-3.5 0.1-0.5 1.4 ot/os A. laevis Oestr. var. laevis 0.1-2.2 0.3-3.6 0.2-0.7 tol/os-bms A. minutissima Kütz. gr. (var. gracillima) 4.4-47.2 20.8-47.3 16.7- tol/bams (ot/os) 22.7 Amphora oligotraphenta Lange-B. & Kramm. 0.1-0.2 0.2-3.9 0.1-12.6 ol-bmt/os A. pediculus (Kütz.) Grun. 0.1-3.8 0.3-0.4 0.2 tol/bams Brachysira neoexilis Lange-B. 0.4-6.7 0.3-1.1 0.2 ol-bmt/os Caloneis bacillum (Grun.)Cl. 0.1-0.9 0.1-4.0 0.1 am-eut/bms Cymbella cesatii Raben. 1.1-7.0 2.1-8.8 1.0-2.5 ot/os C. descripta Hust. 0.1-1.1 0.1-3.2 ot/os C. microcephala fo. minores Grun. 1.3-18.4 1.4-10.1 ol-bmt/os-bms C. silesiaca Bleisch 1.2-5.1 0.1-14.7 1.3-5.9 tol/ams C. ventricosa Ag. 0.1-0.3 2.7-22.6 0.1-3.9 - Eunotia arcus Ehr. 0.1-3.6 1.0-6.5 0.2 ol-bmt/os Fragilaria construens (Ehr.)Grun. gr. 0.1-25.1 0.1-6.6 1.1 tol/bms F. nanana Lange-B. 0.3-8.5 0.1-21.9 0.1-11.9 ol-amt/os-bms Navicul minima Grun. gr. 0.1-3.0 0.2 tol/ams-ps Navicula nov. sp. (aff. schoenfeldii Hust.) 0.2 0.1-4.3 0.2 - Nitzschia bryophila Hust. 0.2-3.5 - N. denticula Grun. 0.1-3.5 ol-bmt/os N. graciliformis Lange-B. & Sim. 2.1 0.9-3.2 0.2 tol/bms N. gracilis Hantzsh 0.1-7.7 0.3-1.0 tol/bms N. lacuum Lange-B. 0.1-0.8 0.7-7.0 0.7 tol/os-bms N. palea var. debilis (Kütz.) Grun. 1.5-6.7 0.1-1.5 3.0 tol/- N. tropica Hust. 0.1 3.2 - Pinnularia microstauron (Ehr.)Cl. 0.2-1.0 0.5-3.8 0.5-1. tol/bms P. obscura Krasske 0.1 4.1 ind/bms

Acknowledgements

This paper is a result of a research project supported by the Norwegian Research Council (NRC). The DRIMPOL Project is a project implemented by NIVA-Norwegian Water Research Institute, Tirana Agriculture University and Agriculture Institute Skopje. To that fact we greatly thank the NRC for the given support.

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