THE QUALITATIVE COMPOSITION OF PLANKTONIC DIATOMS IN BICAZ LAKE

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1 Analele Ştiinţifice ale Universităţii AL. I. CUZA Iaşi, s. Biologie animală, Tom LII, 2006 THE QUALITATIVE COMPOSITION OF PLANKTONIC DIATOMS IN BICAZ LAKE OANA MARIA DARABĂ and IONEL MIRON Al.I.Cuza University, Iasi, Carol I Bvd., 20A, oana_daraba@yahoo.com, mironi@uaic.ro Abstract. The following study presents the qualitative composition of planktonic diatoms in Izvorul Muntelui Accumulation Lake Bicaz, between May September The samples under our attention have been gathered and analysed from seven representative sites, and, thus, they offer a general image of the spacial and temporal diversity of planktonic diatoms. Keywords: phytoplankton, planktonic diatoms, relative abundance, centric diatoms Rezumat. Compoziţia calitativă a diatomeelor planctonice din lacul Bicaz. Lucrarea prezintă compoziţia calitativă a diatomeelor planctonice din lacul de acumulare Izvoru Muntelui Bicaz, din perioada mai septembrie, Au fost prelevate şi analizate probe din şapte staţii reprezentative, având astfel o imagine de ansamblu asupra divesităţii spaţiale şi temporale a diatomeelor planctonice. Au fost identificate 44 de specii de diatomee planctonice (Tab. 1). S-a calculat abundenţa relativă pentru întreaga perioadă de prelevare a fiecărei specii, din fiecare secţiune şi global, la nivelul întregului ecosistem. La nivelul întregului ecosistem, diatomeele centrice (30,40%) şi (14,40%) au avut procentele cele mai ridicate, urmate de astraea (9,23%). Cuvinte cheie: fitoplancton, diatomee planctonice, abundenţă relativă, diatomee centrice Introduction Most accumulation lakes are built for hydroenergetic purposes. The great level variations in accumulation lakes lead, as a consequence, to the limitation, and nearly total absence, of macrophyte development on the sea coast area. Due to the absence of macrophytes, within the ecosystem of accumulation lakes, the role of essential primary producer is assumed by the phytoplankton (Burian, 2002). In its turn, the phytoplankton of these lakes grows only on the surface layer, which is penetrated by light, with a photosynthetic value, corresponding to the photic zone. Starting with the first years of its construction (Popescu & Oltean, 1963; Cărăuşu, 1969), the research performed in the Bicaz Accumulation Lake has proved the existence of the following phytoplanktonic components: Cyanobacteria, Euglenophyta, Pyrrophyta, Cryptophyta, Chrysophyta, Bacillariophyta, Chlorophyta, Conjugatophyta and Xanthophyta. Diatoms represent more than half of them, followed by chlorophyceae, conjugates, chrysoficeae, cyanophyceae, euglenophyceae, dinophyceae, cryptophyceae and xanthophyceae. Material and Methods Between May September 2005, a number of 35 qualitative samples have been gathered every month, from seven representative sections in Izvorul Muntelui Accumulation Lake Bicaz: Potoci (1); Rugineşti (2); Buhalniţa (3); Hangu (4); Coada Lacului (5); Izvorul Alb (6); Secu (7). The species were gathered with a planktonic net, Winsconsin type, n o 20, through horizontal movements at the surface layer. The concentrated samples were introduced in plastic containers, preserved immediately with a M3 fixing solution (a proportion of 1 ml of fixing solution for 50 ml of sample), and then labeled. The algological material was analysed on a Fuchs

2 Oana Maria Darabă & Ionel Miron Rosenthal counting chamber (Ivancea, 1995) using a microscope with a light source, as well as the one with a phase contrast. We had calculated the relative abundance and Sorensen index. Figure 1. Bicaz Lake : Potoci (1); Rugineşti (2); Buhalniţa (3); Hangu (4); Coada Lacului (5); Izvorul Alb (6); Secu (7). Results and Discussion A number of 44 planktonic diatoms have been identified (Table 1). Calculations have been made in order to establish the relative abundance for the entire period of analyzing of each species, both from each section, and as a whole, at the level of the ecosystem. Thus, in Potoci (Fig. 1A), (Ehr) Grunow registered a 27.46% relative abundance, followed by Kitton with 17.70%, and ocellata Pantocsek with 17.22%; the rest of the species registered a relative abundance below 10%. In Rugineşti (Fig. 1B), ocellata Pantocsek registered a 23.10% relative abundance, followed by (Lyngb) Agardh with 12.34%, (Ehr) Kutz. with 10.50%; the rest of the species registered a relative abundance below 10%. In Buhalniţa (Fig. 1C), (Ehr) Kutz registered a 25.99% relative abundance, followed by Kitton with 19.80%, ocellata Pantocsek with 11.88% and Hass with 10.54%; the rest of the species registered a relative abundance below 10%. In Hangu (Fig. 1D), (Ehr) Kutz. registered a 25.92% relative abundance, followed by (Lyngb) Agardh with 19.44%; the rest of the species registered a relative abundance below 10%. In Lake entrance (Fig. 1E), ocellata Pantocsek registered a 55.06% relative abundance, followed by (Lyngb) Agardh with 13.29%; the rest of the species registered a relative abundance below 10%. In Izvorul Alb (Figure 1F), (Ehr) Kutz. registered a 30.40% relative abundance, followed by ocellata Pantocsek with 14.40%; the rest of the species registered a relative abundance below 10%. In Secu (Fig. 1G), (Ehr) Kutz. registered a 64.40% relative abundance, followed by Coscinodiscus Grunow with 20.99%; the rest of the species registered a relative abundance below 10%. At the level of the entire lake (Fig

3 Analele Ştiinţifice ale Universităţii AL. I. CUZA Iaşi, s. Biologie animală, Tom LII, H), a number of 6 species had a relative abundance over 5%, throughout the whole lacustrian ecosystem - (Ehr) Kutz. (30.40%); ocellata Pantocsek (14.40%); (Ehr) Grunow (9.23%); Coscinodiscus Grunow (8.53%) and Kitton (7.99%). One may notice the clear domination of centric diatoms, at the level of each section and at the level of the entire lake. This domination could be the result of the increasing flow of the affluents (the high floods in the summer of 2005 led to the lake reaching its maximum capacity), as the high turbidity determined the decrese of transparency and a domination, within the lake, of species belonging to the affluents phytoplankton; such a phenomenon is the species called (Ehr) Kutz., in certain areas strongly influenced by the affluents (Coada Lac, Izvorul Alb, Secu, Hangu, Buhalniţa ), and not so much in deep areas (Potoci and Ruginesti ). The Sorensen index has also been calculated, as a representation of the degree of similarity of the habitats (sections of sample gathering). Figure 2. Sorensen index. Conclusions The research performed between May September 2005 has facilitated the accumulation of certain information regarding the qualitative composition of planktonic diatoms in Izvorul Muntelui Accumulation Lake Bicaz. A number of 44 species have been identified. At the level of the entire ecosystem, the highest percentage belongs to centric diatoms, such as (Ehr) Kutz. (30.40%) and ocellata Pantocsek (14.40%), followed by astraea (Ehr) Grunow (9.23%). In order to study the phytoplankton in general, as well as the diatoms in particular, Izvorul Muntelui Accumulation Lake Bicaz should be submitted to the investigation of the qualitative and quantitative composition, but also the spacial and temporal dynamics, the study of the algae periphyton and of the microphytobenthos, the trophic stage and the population interrelations, at the level of the entire lacustrian ecosystem

4 Table 1. Qualitative composition of planktonic diatoms from Bicaz lake (mai septembrie 2005). Taxon Potoci Ruginesti Buhalnita Hangu Lake entrance Secu Izv Alb Global lake Achnanthes minutissima 0.00% 0.00% 0.00% 0.00% 3.16% 0.00% 0.25% 0.25% Achnantes lanceolata 0.29% 0.79% 0.00% 0.56% 0.00% 0.00% 0.25% 0.25% Achnanthes sp. 0.00% 0.00% 0.00% 1.69% 0.00% 0.00% 0.15% 0.15% Formosa 5.36% 3.64% 10.64% 0.00% 2.85% 3.87% 4.48% 4.48% Caloneis amphisbaena 0.10% 0.32% 0.00% 0.00% 0.00% 0.00% 0.07% 0.07% Coconeis placentula 0.00% 0.00% 0.99% 0.00% 0.00% 0.00% 0.10% 0.10% Coconeis pediculus 0.00% 0.00% 2.23% 0.00% 0.00% 0.00% 0.22% 0.22% Coscinodiscus 0.77% 4.43% 5.20% 4.79% 0.00% 20.99% 8.53% 8.53% 6.60% 10.60% 25.99% 25.92% 0.00% 69.40% 30.40% 30.40% meneghiniana 0.48% 6.65% 0.00% 7.61% 0.63% 1.01% 2.20% 2.20% 17.22% 23.10% 11.88% 9.58% 55.06% 0.00% 14.40% 14.40% Cymatopleura eliptica 0.10% 0.00% 0.00% 0.28% 0.95% 0.00% 0.12% 0.12% Cymbella affinis 0.00% 0.00% 0.74% 1.97% 0.00% 0.00% 0.25% 0.25% Cymbella ventricosa 0.00% 1.11% 0.74% 0.00% 0.00% 0.00% 0.25% 0.25% 2.78% 12.34% 2.48% 19.44% 13.29% 0.00% 5.64% 5.64% hiemale 0.96% 0.95% 0.00% 0.00% 5.38% 0.00% 0.82% 0.82% vulgare 0.19% 2.53% 0.00% 0.00% 0.00% 0.00% 0.45% 0.45% Didymosphenia geminata 0.00% 0.00% 0.99% 0.00% 0.00% 0.00% 0.10% 0.10% construens 2.11% 0.00% 0.00% 6.76% 0.00% 0.00% 1.14% 1.14% 17.70% 7.91% 19.80% 2.25% 0.00% 0.00% 7.99% 7.99% intermedia 5.26% 1.90% 2.48% 0.00% 0.00% 0.00% 1.90% 1.90% Gomphonema constrictum 0.00% 0.00% 0.00% 0.56% 0.00% 0.00% 0.05% 0.05% Gomphonema olivaceum 0.00% 0.00% 0.00% 0.00% 1.27% 0.00% 0.10% 0.10% Gyrosigma acuminatum 0.00% 0.00% 0.00% 2.54% 0.00% 0.00% 0.22% 0.22%

5 Melosira italica 0.19% 0.00% 0.00% 0.00% 0.00% 0.08% 0.07% 0.07% Melosira roseana 0.00% 0.00% 0.00% 0.56% 0.00% 0.00% 0.05% 0.05% Melosira granulate 0.00% 3.48% 3.71% 0.00% 1.90% 0.00% 1.06% 1.06% Naviculla cuspidate 0.00% 1.74% 0.00% 1.69% 0.00% 0.00% 0.42% 0.42% Navicula gracilis 0.96% 0.00% 0.50% 0.00% 2.53% 0.00% 0.49% 0.49% Naviculla cryptocephala 0.00% 0.00% 0.00% 0.85% 0.00% 0.00% 0.07% 0.07% Naviculla hungarica 0.00% 1.11% 0.00% 0.00% 0.00% 0.00% 0.17% 0.17% Naviculla 3.54% 0.00% 0.00% 0.56% 0.63% 2.63% 1.86% 1.86% Nitzschia acicularis 3.25% 0.00% 0.00% 0.56% 0.00% 0.00% 0.89% 0.89% Nitzschia gracilis 0.48% 1.27% 0.00% 0.00% 0.00% 0.00% 0.32% 0.32% Nitzschia linearis 0.19% 0.00% 0.00% 0.00% 2.22% 2.01% 0.87% 0.87% Nitzschia sigmoidea 1.53% 2.85% 0.00% 0.00% 3.48% 0.00% 1.11% 1.11% Pinullaria sp. 0.29% 0.00% 1.98% 0.00% 1.58% 0.00% 0.40% 0.40% 27.46% 8.54% 3.96% 2.82% 1.90% 0.00% 9.23% 9.23% dubius 1.24% 0.00% 0.00% 0.00% 0.00% 0.00% 0.32% 0.32% Surirella ovata 0.00% 0.00% 2.97% 0.85% 0.00% 0.00% 0.37% 0.37% Synedra acus 0.19% 1.90% 0.00% 3.94% 1.58% 0.00% 0.82% 0.82% Synedra capitata 0.38% 2.53% 0.00% 0.00% 0.00% 0.00% 0.49% 0.49% Synedra ulna 0.38% 0.00% 2.48% 4.23% 1.58% 0.00% 0.84% 0.84% Synedra sp. 0.00% 0.32% 0.25% 0.00% 0.00% 0.00% 0.07% 0.07% Global lake % % % % % % % %

6 Oana Maria Darabă & Ionel Miron 2,78% Nitzschia acicularis 3,25% Naviculla 3,54% intermedia 5,26% 5,36% 6,60% 10,81% 17,22% 27,46% 17,70% Melosira granullata 3,48% 3,64% Coscinodiscus 4,43% 19,30% meneghiniana 6,65% 7,91% 8,54% 23,10% 10,60% 12,34% A. B. 2,48% Surirella ovata 2,97% Melosira granullata 3,71% 3,96% Coscinodiscus 5,20% 10,64% 13,37% 11,88% 25,99% 19,80% 2,82% Synedra acus 3,94% Synedra ulna 4,23% Coscinodiscus 4,79% construens 6,76% 14.93% meneghiniana 7,61% 9,58% 25,92% 19,44% C. D. Navicula gracilis 2,53% Nitzschia linearis 2,22% 2,85% Achnanthes minutissima 3,16% Nitzschia sigmoidea 3,48% Melosira granullata 1,90% 10,13% 55,06% intermedia 1,90% meneghiniana 2,20% 4,48% 5,64% 15,24% 30,40% hiemale 5,38% 13,29% 7,99% Coscinodiscus 8,53% 9,23% 14,40% E. F

7 Analele Ştiinţifice ale Universităţii AL. I. CUZA Iaşi, s. Biologie animală, Tom LII, ,87% Coscinodiscus 20,99% Naviculla 2,63% Nitzschia linearis 2,01% meneghiniana 1,01% Melosira italica 0,08% 69,40% meneghiniana 2,20% 4,48% 5,64% 7,99% intermedia 1,90% 15,24% Coscinodiscus 9,23% 8,53% 30,40% 14,40% G. H. Figure 3. Percentage structure of planktonic diatoms of Bicaz lake (may septembrie 2005): A. Potoci ; B. Ruginesti ; C. Buhalnita ; D. Hangu ; E. Lake entrance; F. Izvorul Alb ; G. Secu ; H. Global lake. References Burian, P.V., Lacul de acumulare. Supraveghere biologică. Ed. University Press, Tg. Mureş. Cărăuşu, I., Fitoplanctonul lacului de acumulare Bicaz (II). Lucrările Staţiunii de Cercetări biologice, geologice şi geografice Stejarul, II: Ivancea, G., Îndrumări metodologice pentru supravegherea evoluţiei trofice a lacurilor de acumulare şi lacurilor naturale. Ed. I.C.I.M. Bucureşti

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