EFFECTS OF ENVIRONMENTAL FEATURES ON THE CHRYSOPHYCEAE OCCURRENCE IN A STRATIFIED CHARA-LAKE Aleksandra Pełechata 1 , Mariusz Pełechaty 2 , Andrzej Pukacz 3 1 Adam Mickiewicz University - Europa-Universität Viadrina, Collegium Polonicum, Kościuszki 1, 69-100 Słubice, Poland, e-mail: ola.p@amu.edu.pl 2 Adam Mickiewicz University, Faculty of Biology, Department of Hydrobiology, Umultowska 89, 61-614 Poznań, Poland 3 Polish-German Research Institute, Collegium Polonicum, Kościuszki 1, 69-100 Słubice, Poland STUDY AIM STUDY AREA AND METHODS RESULTS Chrysophyceae occur in clear fresh waters of low nutrient concentrations, preferring spring and autumn months. Along with other representatives of flagellates, Chrysophyceae are the main component of phytoplankton in macrophyte lakes, especially those dominated by charophyte vegetation. The aims of this study was to describe the species composition of Chrysophyceae in a small, stratified Chara-lake and recognize the factors responsible for the variation within this phytoplankton group. The study was conducted in Lake Złoty Potok (Pojezierze Lubuskie Lake District, Fig. 1). In this lake, the occurrence of 8 stonewort species was noted. It is an ecosystem of small surface and catchment area, mid-forest location and a limited degree of anthropogenic pressure (Tab. 1). Samples for algological and hydrochemical analyses were collected monthly during the growing season 2008 from the pelagic surface layer (P1-P3) and from above the charophyte meadows of Chara tomentosa (Cht1-Cht2) and Nitellopsis obtusa (No1-No3, Fig. 1). Generally 16 taxa of chrysophytes were identified: Erkenia subaequiciliata, Dinobryon sociale, D. sociale v. stipitatum, D. borgei, D. acuminatum, D. divergens, D. sertularia, D. elegantissimum, D. suecicum, Kephyrion petasatum, K. sitta, K. rubri-claustri, Pseudokephyrion circumvallatum, P. cylindricum, P. gallicum, Epipyxis minuta (Tab. 2). The highest abundance of Chrysophyceae was noted in the peak of growing season (July-August) and in autumn (October), whereas biomass in June and October (Fig. 2 A, C).The share of Chrysophyceae in the total abundance and biomass of phytoplankton respectively ranged from 23 to 87% and from 2 to 91% (Fig. 2 B, D). Abundance and biomass of Chrysophyceae were significantly negatively correlated with water conductivity and temperature (Tab. 2). While D. sociale, D. sociale v. stipitatum, D.sertularia and D.suecicum were negatively correlated with water temperature, conductivity, N-NO 2 and N-NO 3 concentration, D. divergens was positively related to these factors (except temperature) and to water hardness. Erkenia subaequiciliata was the most abundant chrysophyte. Both abundance and biomass of this species was related negatively to the total abundance and biomass of Dinobryon and alkalinity, and positively to water temperature and total nitrogen concentration. Temporal variation in the Chrysophyceae abundance and biomass was evidenced (Fig. 2, 3) while no spatial differences were detected. E. subaequiciliata, D. divergens, D. elegantissimum, E. minuta occurred abundantly in the summer and D. sertularia, D. sociale, D. sociale v. stipitatum, D. suecicum distinguished autumn period. Figure 1. Location of Lake Złoty Potok and sampling sites: pelagic (P1-P3), above Chara tomentosa (Cht1-Cht2), above Nitellopsis obstusa (No1-No3). Dinobryon elegantissimum Dinobryon divergens Dinobryon sertularia Dinobryon sociale Dinobryon sociale var. stipitatum Dinobryon suecicum Dinobryon acuminatum Epipyxis minuta Figure 3. PCA for species abundance showing differences in species composition of Chrysophyceae in Lake Złoty Potok during growing season 2008 (species abbreviations are explained in table 2). Figure 2. The structure of phytoplankton in Lake Złoty Potok: A, B - abundance, C, D – biomass A B C D Unit Lake Złoty Potok Surface area ha 32.8 Mean depth m 5.9 Maximum depth m 13.7 Stratification - complete Trophic state TSI 45.2 Lake type - natural, closed Catchment area km 2 3.8 Main land use - forests, recreational use limited Table 1. Morphometry and land use of the studied lake *p<0.05, **p<0.01, ***p<0.001 Table 2. The Pearson’s correlations between the main water parameters and quantities of Chrysophyceae species in Lake Złoty Potok. To save space, the species abundance is presented in the table only; very similar correlations were found for species biomass. Taxa Abbreviations Water temp. Conductivity Alkalinity N-NO 3 N-NO 2 SO 4 2- Ca 2+ Mg 2+ Total hardness Na + K + Chrysophyceae - abundance - -0.43** -0.70*** 0.04 -0.18 -0.30 -0.23 0.04 -0.26 0.21 -0.07 0.06 Chrysophyceae - biomass - -0.72*** -0.75*** 0.41* -0.31 -0.35* -0.47** 0.31 -0.38 0.33* 0.04 0.09 Dinobryon acuminatum Ruttner D. acu -0.06 0.22 0.12 0.12 -0.07 -0.10 0.06 0.11 -0.24 -0.09 -0.05 Dinobryon borgei Lemm. D. borg -0.25 -0.17 0.08 -0.13 -0.18 -0.16 0.10 0.09 0.11 -0.02 0.01 Dinobryon divergens Imhof D. div 0.31 0.46** 0.44** 0.44** 0.50** 0.39 0.65*** -0.26 0.61*** 0.57*** 0.61*** Dinobryon elegantissimum (Koršikov) Bourrelly D. eleg 0.16 0.04 -0.11 -0.08 -0.13 0.09 -0.11 0.04 -0.04 -0.11 -0.03 Dinobryon sertularia Ehrenberg D. sert -0.60*** -0.67*** 0.26 -0.34 -0.32 -0.42** 0.18 -0.51*** 0.19 0.05 0.02 Dinobryon sociale Ehrenberg D. soc -0.78*** -0.80*** 0.37* -0.39* -0.42** -0.55*** 0.23 -0.36* 0.23 -0.03 0.01 Dinobryon sociale Ehrenberg var. stipitatum (Stein) Lemm. D. soc v -0.81*** -0.81*** 0.38* -0.41** -0.44** -0.58*** 0.24 -0.31 0.24 -0.04 -0.03 Dinobryon suecicum Lemm. D. suc -0.48** -0.14 0.25 -0.34* -0.36* -0.61*** -0.03 0.14 -0.21 -0.33* -0.53*** Epipyxis minuta (Mack) Hillard et Asmund E. min 0.18 -0.05 -0.23 -0.13 0.15 0.01 -0.27 -0.02 -0.17 -0.22 -0.19 Erkenia subaequiciliata Skuja E. sub 0.62*** 0.21 -0.61*** 0.32* 0.18 0.52*** -0.40* 0.20 -0.18 -0.12 0.03 Kephyrion petasatum Conrad K. pet -0.08 0.07 -0.06 0.09 -0.05 -0.06 -0.08 0.13 -0.01 -0.13 -0.08 Kephyrion rubri-claustri Conrad K. r-c -0.13 0.06 0.08 0.20 -0.04 -0.12 -0.02 0.09 0.02 -0.16 -0.12 Kephyrion sitta Pascher K. sit -0.08 0.09 -0.06 -0.02 0.00 -0.04 -0.08 0.17 -0.03 -0.16 -0.38* Pseudokephyrion circumvallatum Bourrelly P circ -0.34* -0.46** 0.21 -0.10 -0.21 -0.24 0.11 -0.38 0.12 0.03 0.02 Pseudokephyrion cylindricum Bourrelly P. cyli -0.13 0.05 -0.03 -0.15 -0.07 -0.14 -0.03 -0.08 -0.02 -0.15 -0.07 Pseudokephyrion gallicum Bourrelly P. gall 0.13 0.04 -0.15 0.23 0.03 0.19 -0.05 0.29 0.02 0.10 0.15 Abundance of Dinobryon species - -0.78*** -0.77*** 0.42** -0.37* -0.40* -0.55*** 0.29 -0.36* 0.28 0.01 0.03 View publication stats View publication stats