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-Albania 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 Drin/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, Fierza 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: Lake Ohrid; 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