Proceedings Changes in Algal Species Composition of Alpine Lake Nesamovyte (Eastern Carpathians, Ukraine) from 100 Years Ago to Present † Petro M. Tsarenko 1, Olena P. Bilous 2,*, Olha M. Kryvosheia-Zakharova 1, Halyna H. Lilitska 1, Yuriy Malakhov 3 and Janne Soininen 4 1 M.G. Kholodny Institute of Botany, National Academy of Sciences of Ukraine, Tereschenkivska Str. 2, 01004 Kyiv, Ukraine; [email protected] (P.M.T.); [email protected] (O.M.K-Z.); [email protected] (H.H.L.) 2 Institute of Hydrobiology, NAS of Ukraine, Geroiv Stalingrada 12, 04210 Kyiv, Ukraine 3 Ecocare Ukraine, Kyiv, Ukraine; [email protected] 4 Department of Geosciences and Geography, University of Helsinki, 00100 Helsinki, Finland; [email protected] * Correspondence: [email protected] † Presented at the 1st International Electronic Conference on Biological Diversity, Ecology and Evolution, 15– 31 March 2021; Available online: https://bdee2021.sciforum.net/. Abstract: The species diversity of algae in different ecotopes of the alpine lake Nesamovyte was studied. In total, 233 species were identified comprising globally and regionally rare species. We also documented a temporal change in species composition from the first investigations conducted 100 years ago to present. An increase in the species diversity of Bacillariophyta and Chlorophyta, the constancy of the number of Euglenophyta and Cyanoprocaryota species, a decrease in the composition Citation: Tsarenko, P.M.; Bilous, of Charophyta and the disappearance of Dinophyta species were revealed. We further documented O.P.; Kryvosheia-Zakharova, O.M.; Lilitska, H.H.; Malakhov, Y.; Soin- some changes in the most abundant species and indicator species for certain limnological condi- inen, J. Changes in Algal Species tions, the disappearance of montane species and the colonization of species with a wide ecological- Composition of Alpine Lake geographical amplitude. Benthic and plankton-benthic conditions became dominant and indicators Nesamovyte (Eastern Carpathians, of low-alkaline mesotrophic waters as well as mass development (“blooming”) of some species in- Ukraine) from 100 Years Ago to Pre- creased. The studied features of the species diversity of the “algoflora” indicate high species rich- sent. 2021, 68, x. ness and high number of indicator species, as well as lake ecosystem degradation and an increase https://doi.org/10.3390/xxxxx in organic pollution. Overall, there was a shift of the lake from oligotrophic to mesotrophic state, as indicated by certain algal groups. The noted changes in the species diversity of algae in Lake Published: date Nesamovyte could be attributed to the increased anthropogenic influence leading to change of the trophic status of the lake. Publisher’s Note: MDPI stays neu- tral with regard to jurisdictional Keywords: algae; diversity; Eastern Carpathians; mountains lakes; ecosystems; Nesamovyte claims in published maps and institu- tional affiliations. 1. Introduction Copyright: © 2021 by the authors. Lakes of the Carpathian mountain system have a rich and distinctive biodiversity of Submitted for possible open access algae and algal communities. They constitute an integral part of the highland landscape, publication under the terms and con- serve as a core algae habitat in the region, and as a shelter for rare and characteristic algal ditions of the Creative Commons At- taxa [1–5]. At the end of 20th century, the alpine lake algal biodiversity was actively stud- tribution (CC BY) license (http://crea- ied in the western part of the Carpathians (Carpathian-Tatra region). However, much less tivecommons.org/licenses/by/4.0/). is known about the species composition and taxonomic structure of the algal flora in the analogous Eastern Carpathian lakes [6]. In this study, we summarise the data from the three stages of algal biodiversity research in one the high-elevation lakes in the Eastern Carpathi- ans—Lake Nesamovyte. First, we conduct a comparative analysis of the changes in algal biodiversity that span a period of more than one hundred years [7–10]. We then characterise Proceedings 2021, 68, x. https://doi.org/10.3390/xxxxx www.mdpi.com/journal/proceedings Proceedings 2021, 68, x FOR PEER REVIEW 2 of 7 these changes by analysing bioindicator species and establish the main ecological features of Lake Nesamovyte algal flora. 2. Materials and Methods Lake Nesamovyte is a part of glacial cirque valley and has a glacial erosion origin. It is a part of the Carpathian-Danube algofloristic sub-province within the algofloristic zoning of Ukraine classification scheme [11]. It is located on the southern-western slope of Mt Tur- kul, at the altitude of 1748 m (Figure 1). It has an area of 0.3 ha and a maximum depth of 2 m (Table 1). It is mainly fed by atmospheric water supply and has a β-mesosaprobic water qual- ity status [4]. It is a well-known natural object of the Ukrainian Carpathians and a part of Carpatsky National Park. Figure 1. Map of the Carpathian region and the location of the lake Nesamovyte. Table 1. Morphometry and basic physic-chemical water parameters of Nesamovyte Lake (original measurements). Location Altitude Temperature Conductivity, Surface, ha Depth Max., m pH dO2, mg/L (Coordinates) a.s.l., m H2O μS/cm 48°07′36.6″ N 1748 0.3 ~2.0 18.3 (16.2) 6.2–6.4 5.1–6.0 10.7 24°32′26.4″ E Our study is based on the original samples collected from different ecotopes of Lake Nesamovyte (plankton, benthos, periphython, squeezes from the moss) in 2013–2018. We also analysed historical samples (fixed in 4% formaldehyde) of 1967 that are stored in the collection of M.G. Kholodny Institute of Botany NAS of Ukraine (collection acronym: KW- A). Taxonomic identification was done after consulting the following references [12–19]. The samples were studied by means light and scanning electron (SE) microscopy. Diatom identification was done using the 35% H2O2 treated frustules material [20]. SE microscopy was done on the JEOL-1230 microscope in the Centre of Electron Microscopy, M.G. Kho- lodny Institute of Botany NAS of Ukraine. Some of the species were identified after live samples cultivation on liquid and agarised Bold’s media. Image processing was done in Axiovision 4.3.7. and GIMP 2.8.10 packages. Identified taxa were validated using the Al- gaeBase system [21] and “Algae of Ukraine …” [22] monographic series. Ecological bioindicator species analysis was based both on the historical data (1910– 1920 and 1967–1978 collections) and on the results of original studies (2013–2021). It was based on the following individual algae species characteristics: habitat type, flow velocity, oxygen saturation, pH, salinity, general trophic status and the level of organics pollution [23–28]. Proceedings 2021, 68, x FOR PEER REVIEW 3 of 7 3. Results and Discussion Overall, 233 algae species (including 245 infraspecific taxa, inft) were found in Lake Nesamovyte over a hundred-year period. These species belong to eight taxonomic groups, 15 classes, 33 orders, 55 families, and 99 genera of cyanobacteria and algae (Table 2). Bacillariophyta and Charophyta form the basis of this diversity, accounting for about 57% of the genera richness and 84% of the species and intraspecific richness of algae of all ecotopes. The diversity of Chlorophyta and Euglenozoa is relatively low (ca. 4.9–5.7% of the taxonomic list), and the diversity of Cyanobacteria and Ochrophyta is even lower-near 1.7% of the taxonomic list on average. Finally, the diversity of Cryptophyta and Miozoa accounted for less than 1% of the total taxonomic list (Figure 1). The dominant algal orders were—Des- midiales (15 genera–66 species–75 inft), Naviculales (10 genera–50 species), Cymbellales (5– 25), Achnanthales (5–11), Eunotiales (1–11), Sphaeropleales (6–7), Fragillariales (4–9), Zygne- matales (6–6) and Euglenidida (2–5). Together, these orders account for 56% of the genera and species composition of Lake Nesamovyte algal biodiversity. The dominant genera of the lake’s algal flora were Staurastrum (21–22 inft), Pinnularia (14–16), Euastrum (12–15), Navicula (12), Cosmarium (12), Eunotia (11), Gomphonema (10), Encyonema (5), Planothidium (5) and Closterium (4). These 10 genera account for almost a half (44.5%) of all species composition. At the same time, nearly 60% of algal genera of the lake were monotypic, i.e., represented by a single spe- cies. This taxonomic structure represents a generalization of the 100 years research of Lake Nesamovyte algal biodiversity studies [6–8,10,29–31]. The comparative analysis of the tax- onomic data from the three phycological research stages–early 20th century, middle of the 20th century, and early 21st century–shows a gradual change the lake algal biodiversity. This is evident on the high, taxonomic groups, level, and especially remarkable on the lower, genera diversity, level (Figure 2). 140 120 100 80 60 2013–2021 40 1967–1978 20 1910–1920 Number of species Total 0 Year of investigation Taxonomic group Total 1910–1920 1967–1978 2013–2021 Figure 2. Species composition of algae in Lake Nesamovyte (split by taxonomic groups and three stages of research in 1910–2021). The change of dominating taxonomic groups of algae in terms of species richness– from Charophyta (Desmidiales) and diatom algae (together 87% of the total species compo- sition) is established for the period 1910–1920 [7]. The specific high impact Desmidiales (~58%) is maintained along with the emergence of representatives of Euglenozoa (~15%) and flagellated algae—Cryptophyta and Ochrophyta (~2–5%) in 1967–1978 [6,9], and now– extremely high rates are noted for Bacillariophyta (115 species–117 inft, or ~70%), much lower-Charophyta (~15%), Chlorophyta (~7.3%) and Euglenozoa (~5.0), low for Cryptophyta Proceedings 2021, 68, x FOR PEER REVIEW 4 of 7 (>1%) and Cyanobacteria (>1%) and absence of Dinophyta. A high variety of modern species composition has been established for Bacillariophyta [31] sharply contrasting (sevenfold increase) with the literature data [7].