Microalgae as Bioindicators of Changes in Permafrost Catchments: A Reference Area of the Olyokma Nature Reserve, Yakutia

Abstract

Olyokma Nature Reserve, where we conducted our research, is in Eastern Siberia in the middle taiga zone in an area characterized by continuous permafrost. This is the only protected area in the region with a complete reserve regime, where there is no human activity. Here, we studied 14 different types of water bodies located along the Olyokma River valley, 13 of which were studied for the first time. For some of the studied water bodies, a high content of biogenic elements was noted, which may be associated with the characteristics of permafrost water bodies, which are under nutrient release from permafrost thaw. The concentration of several biogenic elements, including ammonium, nitrates and phosphates, increases in the water of the lakes toward the bottom of the river valley. In the composition of various communities of these water bodies, including both planktonic and non-planktonic, we identified 246 species and varieties of microalgae. The abundance and biomass of phytoplankton, as well as the number of species, decreased down the river valley. At the same time, at the upper stations there were more diatoms; while at the stations down the valley, green algae came to the fore; and even lower down, cyanobacteria prevailed. At the lower stations, the indicators of microalgae development were minimal. In accordance with the bioindicative properties of microalgae, a decrease in the trophic status of water bodies was noted down the river valley, which, in our opinion, is a characteristic feature of the waters of an undisturbed catchment basin in the permafrost area. This indicates that the studied aquatic ecosystem changes within a set of environmental and biological indicators, that is, it exists in natural conditions for this catchment basin. Research on the territory of Olyokma Nature Reserve allowed us to obtain information on natural transformation and removal of nutrients in permafrost catchments, while excluding the likelihood of anthropogenic impact on these processes.

1. Introduction

Permafrost catchments are impacted by the influx of nutrients into water bodies from the active soil layer. Climate warming and permafrost thawing can change the abiotic conditions and trophic properties of cryolithozone water bodies [1] and also contribute to the growth of nutrients in them, since permafrost is capable of releasing more nutrients into surface runoff than the already depleted active layer [2]. The impact of nutrient influx on the development of primary producers in permafrost catchments is noted in various regions of the world [3,4,5,6,7,8].

Water characteristics such as physical and chemical properties taken alone may not reflect the actual state of water quality or the impact of dissolved substances on aquatic organisms. Therefore, biological methods have been developed and applied to assess water quality and the impact of pollutants on various aspects of the life of organisms exposed to them [9]. The presence, quantity and distribution of certain species, called bioindicators, can help determine water quality. One of the most used water quality indicators is microalgae. These single-celled organisms can be found in freshwater or saline water environments and play a key role as primary producers in the food chain. Microalgae are widely used as water quality bioindicators in various studies [10,11], and since these organisms quickly respond to physical and chemical changes in water, we selected them as indicators of nutrient content in permafrost water bodies.

Olyokma Nature Reserve was organized in 1984 with the purpose of preserving the mountain taiga complexes of the south of Yakutia in their natural state with all their components, studying the natural course of natural processes and phenomena in them and developing scientific foundations for nature management, to compensate for anthropogenic impact in the Baikal–Amur Mainline zone and the South Yakut industrial complex. The territory of the reserve, with an area of 8.5 thousand square kilometers, is in the northeast of the Asian subcontinent, on the right bank of the Olyokma River, at the junction of the Lena Plateau and Aldan Highlands. Within the reserve, there is a complete reserve regime, which implies a ban on all types of human activity. The nearest settlement is the Kudu-Kyuyol rural area, located 100 km from the northern border of the reserve, on the Olyokma River. Natural complexes on the territory of Olyokma Nature Reserve are preserved in their original, undisturbed state, and being a reference, are highly representative of the middle taiga zone. Olyokma Nature Reserve is the only protected area in the region, with a complete absence of any economic and recreational or tourist activities. The natural state of the aquatic ecosystem on the territory of Olyokma Nature Reserve, excluding any anthropogenic impact, significantly increases its value as an object for our research.

To date, the study of the algal flora of Olyokma Nature Reserve has been limited to the investigation of algal communities of river plankton. Collection of algological material within the reserve was carried out on the Olyokma, Amga and Tuolba Rivers during the open water period from 1992 to 1995. A total of 240 species and varieties of algae from eight divisions were identified in the flora of the reserve [12,13,14,15,16]. In 2011, we obtained data on the plankton algae of the Olyokma River, which includes data not only on the section of the river within the Olyokma Nature Reserve, but also upstream and downstream [17]. However, the large diversity of non-planktonic biotopes in the Olyokma Nature Reserve, as well as many lakes and other standing water bodies along the river valley, remain unstudied in terms of algology. At the same time, the relationship between the diversity of algae and the influx of nutrients from the Olyokma River catchment basin has also not been studied, although it is known that nutrients availability is a key determinant of the capacity for phytoplankton biovolume in lentic systems [18]. It should be clarified that this is precisely where natural and laboratory systems differ. While in experimental controlled systems the term “dilution” is appropriate, when diluting the concentration of a solution, in natural systems the term “ecosystem” is appropriate, implying the interrelated changes in the environment and the organisms that inhabit it, which is what we discuss in this paper.

The aim of our work was to evaluate the changes in the community of algae and cyanobacteria in response to changes in nutrients in the permafrost landscape and water system using data on the chemical composition of waters and microalgae-bioindicators under the conditions of a typical natural system of natural protected area.

2. Materials and Methods

2.1. Site Description

The territory of the reserve is in the zone of continuous permafrost, within the subzone of the middle taiga, in the region of the sharply continental climate of Central Siberia, at the junction of two physical–geographical countries—Central Siberian and mountainous Southern Siberia. According to the geological and geomorphological structure, the territory is divided into clearly distinguishable parts corresponding to the two types of structures mentioned above: hilly-plain with a thick cover of carbonate sedimentary rocks, and mid-mountain, with average heights in the territory of the reserve of 500–700 m (up to 1119 m in the spurs of the Amginsky Range), composed of crystalline rocks, including Archean granites and gneisses [19].

This region is characterized by significant annual air temperature fluctuations. The minimum temperature in January is −60 °C and the maximum temperature in July is +34 °C [20]. Stable snow cover lasts for about 200 days. The vegetation period lasts 101 days. In the year of our observations (2024) for the Jikimdya weather station located on the terri-tory of the Olyokma Nature Reserve, the lowest average monthly air temperature was rec-orded in January (−29.8 °C) and the highest average monthly air temperature was in July (20.1 °C); the average annual air temperature was −3.9 °C [21].

The hydrographic network of the protected area belongs to the Lena River basin and is represented by the tributaries of the Olyokma River and the upper part of the Amga River basin. There are no large lakes, but there are quite a few small ones, mainly of oxbow origin and mainly confined to river valleys. There are common areas of raised bogs with permafrost underlay.

We studied various types of water bodies located in the floodplain of the Olyokma River, including several small lakes of oxbow origin, a swamp, a pool on a salt lick, streams and the Olyokma River itself (

Table 1. Information on the type of samples and sampling locations in the Olyokma Nature Reserve in 2024.

Station No	Name of Water body	Altitude, m a.s.l.	Sample Type and Its Number								Geographical Position
			1	2	3	4	5	6	7	8	Latitude	Longitude
1	Lake 7	189	9a, 9b						20	Ch13	58°30′7″	121°37′12″
2	Podskalnoye Lake	184	8a, 8b			14	16	18	21	Ch12	58°35′31″	121°30′22″
3	Lake 1	171	1a, 1b	23						Ch1	59°2′2″	121°46′48″
4	Lake 4	171	4a, 4b							Ch4	59°1′48″	121°45′40″
5	Lake 3	170	3a, 3b	24						Ch3	59°1′55″	121°45′25″
6	Lake 2	170	2a, 2b							Ch2	59°2′6″	121°47′6″
7	Olyokma River	162					17			Ch14	59°2′13″	121°46′19″
8	Bolshoy Sordonokh Lake	173	7a, 7b			13			19	Ch11	59°4′26″	121°49′5″
9	Pool 1	170		22						Ch10	59°4′41″	121°48′29″
10	Swamp 1	167			10					Ch6	59°11′6″	121°45′43″
11	Lake 5	162	5a, 5b							Ch5	59°11′6″	121°45′32″
12	Stream 1	180			11	12				Ch7	59°11′53″	121°46′59″
13	Stream 2	161					15			Ch8	59°13′8″	121°41′46″
14	Mundunda Lake	163	6a, 6b							Ch9	59°13′8″	121°42′7″

Note: Sample type—1, plankton (“a”—qualitative sample, “b”—quantitative sample); 2, biofilm on lake sediment; 3, moss extract; 4, colony of filamentous algae; 5, scraping from stone; 6, colony of Nostoc commune; 7, turf; 8, hydrochemistry.

). Lake 5, Swamp 1, Stream 2, Pool 1, Mundunda and Bolshoy Sordonokh Lakes are in the protected area of the reserve and the remaining water bodies are located within its boundaries (Figure 1 and Figure 2). In Table 1, the first column shows the numbers of the sampling stations, the second column shows the corresponding names of water bodies, and the location of these sampling stations is shown on the map (Figure 1). The numbers of algological samples (24 in total) are given in seven subcolumns in accordance with the seven types of samples; the eighth subcolumn shows the numbers of hydrochemical samples.

2.2. Sampling

The sampling was carried out from 12 to 18 August 2024. A total of 24 algological samples were collected, including plankton, biofilms, moss squeezes, filamentous algae colonies, stone scrapings, Nostoc commune colonies, and turf (Table 1). In parallel with the qualitative samples, quantitative samples of 30 L were also collected of the plankton. An Apstein net (SEFAR NITEX fabric, mesh size 15 µm, Sefar Holding AG, Thal, Switzerland) was used to collect plankton and moss squeezes. Biofilm was removed from the surface of the lake silt using a spatula, and stone scrapings were washed off with a brush. All algological samples were fixed by adding formalin. Samples for hydrochemical analysis were collected by scooping up 2 L of water.

2.3. Water Chemistry Analysis

Chemical analysis of water samples was performed using generally accepted methods [22,23]. Measurements were made using a PE-5300VI spectrophotometer (GK “EKROS”, Saint Petersburg, Russia), a Fluorat-02-2M device (LLC “Lumex-Marketing”, Saint Petersburg, Russia) and an AAnalyst 400 atomic-absorption spectrometer (PerkinElmer Inc., Waltham, MA, USA). Water temperature was measured with a Checktemp electronic thermometer (Hanna Instruments Deutschland GmbH, Vöhringen, Germany)) and the hydrogen index was measured with a Multitest IPL-101 pH-meter/ion meter (LLC NPP “SEMIKO”, Novosibirsk, Russia).

2.4. Algological Analysis

An Olympus BH-2 light microscope (Olympus, Tokyo, Japan) was used to study the algological samples. Species identification was performed using identification guides [24,25,26,27,28,29,30,31,32]. The taxonomic affiliation of species was clarified using data from the Algabase.org portal [33]. The number of phytoplankton cells was counted using a 0.01 mL Nageotte chamber in triplicate. Phytoplankton biomass was calculated using the volumetric counting method [34]. The abundance of algae in non-planktonic samples was assessed using a six-point frequency scale [35].

The Shannon–Wiener index diversity [36] of the phytoplankton community was calculated via the Biodiversity Pro 2.0 program [37]. Calculation of similarity and the network graphs was completed as part of the network analyses in JASP via the bootnet package in R 0.16.4.0 [38]. Pearson correlation coefficients were calculated with the Wessa.net version 1.2.1 program [39], accessed on 30 May 2025. Using these statistical programs, an analysis of the similarity of species richness, abundance, biomass, composition of indicator groups and environmental indicators was made step by step, combining biological and chemical indicators in different combinations, which allowed us to identify the most significant among them.

The saprobity index of the algae community was calculated on the base of the species-specific index saprobity S and the cellular abundance of each indicator species [35,40].

Bioindicator analysis was performed according to [41] with species-specific ecological preferences of revealed indicator taxa [35]. The BioDiversity Pro 2.0 program was used for similarity calculations [37].

The WESI index [35,40,41] was calculated to assess the toxic pollution influence on the aquatic ecosystems by the following equation:

WESI = Rank Index S/Rank N-NO₃

where WESI is an aquatic ecosystem state index, Rank Index S is the rank number from 1 to 9 calculated for each community index S in the water quality class of [41], and Rank N-NO₃ is the rank number from 1 to 9 of the defined N-NO₃ concentration for each sampling point in the water quality class of [41]. The index values vary from 0 to 5. If the index value is below one, then the ecosystem is exposed to toxic pollution, which inhibits photosynthesis.

3. Results

3.1. Physico-Chemical Parameters of Waters

The temperature in the water bodies corresponds to the sampling period. Streams (1 and 2) are the coldest at 3.1 °C and 15.9 °C, respectively; the other water bodies are warmer—18.1–27.0 °C (Appendix A 

Table A1. Averaged data of environmental variables in 14 studied water bodies of the Olyokma Nature Reserve, August 2024. Station numbering as in Table 1.

Variable	St 1	St 2	St 3	St 4	St 5	St 6	St 7	St 8	St 9	St 10	St 11	St 12	St 13	St 14
T °C	18.3	20.9	27.0	23.0	23.3	24.0	18.1	21.5	25.0	19.2	22.3	3.1	15.9	23.0
pH	6.89	6.85	7.20	6.68	7.15	6.72	8.26	7.52	4.65	6.46	7.62	8.10	8.20	8.02
Color, Pt/Co°	19	47	185	72	113	377	13	97	27	92	101	8	42	39
COD, mgO2 L−1	7.46	20.00	81.75	55.50	50.45	80.20	5.85	58.15	30.95	81.35	50.15	5.25	11.15	6.70
TDS, mg L−1	54	49	74	44	57	104	359	148	3405	95	151	745	495	643
Hardness, mg L−1	0.7	0.6	0.9	0.5	0.7	1.3	4.5	2.0	38.0	1.2	1.9	9.8	6.6	8.2
Ca, mg L−1	4.41	4.81	10.42	4.81	8.02	12.42	45.29	15.23	585.17	6.41	20.44	141.88	76.15	86.57
Mg, mg L−1	5.35	4.37	4.62	3.64	3.64	8.26	27.22	15.07	106.92	10.69	11.18	33.54	33.54	47.63
Na, mg L−1	1.70	1.27	1.23	0.73	0.92	1.34	5.17	0.78	186.40	1.47	0.82	2.84	1.42	2.93
K, mg L−1	0.54	0.64	0.73	0.34	0.34	0.63	0.89	0.21	10.00	0.46	0.13	1.27	0.65	1.10
HCO3, mg L−1	30.0	28.0	51.0	31.5	41.0	76.0	257.5	90.0	1846.0	70.0	110.0	410.0	308.0	485.0
Cl, mg L−1	1.30	2.30	2.50	1.20	1.50	2.23	7.00	1.20	291.08	1.40	1.10	4.46	2.80	3.66
SO4, mg L−1	10.50	7.10	3.20	1.41	1.60	3.20	15.90	25.50	379.46	4.20	7.00	151.40	72.70	16.55
N-NH4, mg L−1	0.22	0.48	1.48	0.93	1.06	2.25	0.20	1.02	2.42	1.43	0.96	0.46	0.50	0.80
N-NO2, mg L−1	0.005	0.006	0.012	0.010	0.010	0.022	0.004	0.007	0.005	0.008	0.007	0.004	0.004	0.006
N-NO3, mg L−1	0.03	0.06	0.26	0.13	0.15	0.51	0.02	0.14	0.35	0.24	0.15	0.19	0.10	0.07
Ptot, mg L−1	<0.04	<0.04	0.05	<0.04	<0.04	0.10	<0.04	<0.04	<0.04	<0.04	<0.04	<0.04	<0.04	<0.04
P-PO4, mg L−1	<0.016	<0.016	<0.016	<0.016	<0.016	0.017	<0.016	<0.016	<0.016	0.017	<0.016	<0.016	0.017	<0.016
Si, mg L−1	2.76	1.18	4.57	1.92	2.99	8.84	2.41	2.54	5.92	5.28	2.32	3.88	7.68	4.12
Fetot, mg L−1	0.10	0.34	0.66	0.27	0.64	2.35	0.05	0.67	0.25	0.60	0.70	0.05	0.20	0.11

). Differences in the pH values were noted. The waters of Swamp 1 are slightly acidic (pH 6.46), Pool 1 are acidic (pH 4.65), and the other water bodies have a neutral or slightly alkaline pH (pH 6.68–8.26).

The waters of Mundunda Lake and Stream 1 are very hard (8 mg L⁻¹), fresh, and have increased mineralization (643 mg L⁻¹). The waters of Olyokma River and Stream 2 are fresh, medium mineralized (359 and 495 mg L⁻¹, respectively), and have medium hardness (4.5 and 6.6 mg L⁻¹, respectively). The waters of Pool 1 are brackish, highly mineralized (3405 mg L⁻¹), and very hard (38 mg L⁻¹). The other surveyed objects are fresh, low mineralized (44–151 mg L⁻¹), and have a hardness index of “very soft–soft” (0.5–2 mg L⁻¹). The waters of all the surveyed water bodies are of the hydrocarbonate class, calcium-magnesium group, and type II.

Lake 2, Lake 1, and Lake 3 are distinguished by an increased color index (113–377). The waters of the other objects are colored less brightly (8–101). Eight water bodies are characterized by an increased COD value: Lake 1, Swamp 1, Lake 2, Bolshoy Sordonokh Lake, Lake 4, Lake 3, Lake 5, and Pool 1 (31–82).

The concentration of ammonium nitrogen is high in all objects (0.8–2.4 mg L⁻¹) except Olyokma River, Lake 7, Stream 1, Podskalnoye Lake, and Stream 2 (0.2–0.5 mg L⁻¹). The content of nitrite nitrogen is characterized by relatively low values; the maximum concentration was found in Lake 2 (0.02 mg L⁻¹). In Olyokma River, Lake 7, Podskalnoye Lake, Mundunda Lake, and Stream 2, the concentration of nitrate nitrogen is the lowest (0.02–0.1 mg L⁻¹). In the remaining objects, its content is higher, and the maximum concentration was found in Lake 2 (0.5 mg L⁻¹). The silicon content in most of the surveyed objects is low (1.2–4.6 mg L⁻¹) and only in four water bodies was its concentration found to be greater than 5 mg L⁻¹ (Swamp 1, Pool 1, Stream 2, and Lake 2). In all the surveyed water bodies the content of total phosphorus does not exceed 0.10 mg L⁻¹, with mineral phosphorus at 0.017 mg L⁻¹. The concentration of total iron is high in all water bodies (0.05–2.35 mg L⁻¹). The maximum value was found in Lake 2 and the minimum concentration (≤0.35 mg L⁻¹) was detected in eight water bodies (Olyokma River, Stream 1, Lake 7, Mundunda Lake, Stream 2, Pool 1, Lake 4 and Podskalnoye Lake).

Figure 3a shows the JASP plot for the entire chemical database for 14 stations. It is evident that the similarity of environmental parameters is observed for stations grouped into three clusters. The first includes all flowing habitats, as well as Pool 1 and Mundunda Lake. Cluster 2 unites two lakes at the very top of the Olyokma River valley. The third cluster includes the remaining lakes, the environment of which is most similar at sites 3 and 4, located at the same altitude. Figure 3b reflects the dynamics of water production indicators—nitrogen and phosphorus, only at sites where it was possible to collect phytoplankton and located down the Olyokma River valley. The trend lines show that the concentrations of ammonium, nitrates and phosphates increase in the water of the lakes toward the bottom of the river valley, despite the fact that stations 3 and 6 have synchronous bursts of values.

3.2. Taxonomical and Floristic Analysis of Microscopic Algae

For 14 studied different types of water bodies in the territory of Olyokma Nature Reserve and its protected zone, 246 species and varieties of algae and cyanobacteria were identified, and three determinations were made only to the genus (Appendix A 

Table A2. Algae and cyanobacteria species richness in 14 studied water bodies of the Olyokma Nature Reserve, August 2024. Station numbering as in Table 1.

Taxa	St 1	St 2	St 3	St 4	St 5	St 6	St 7	St 8	St 9	St 10	St 11	St 12	St 13	St 14
Cercozoa Cavalier-Smith
Spongomonas splendida (F.Stein) M.Hartmann & Chagas	0	0	0	0	0	0	1	0	0	0	0	0	0	0
Charophyta Migula
Actinotaenium capax var. minus (Schmidle) Teiling ex Ruzicka & Pouzar	0	0	1	0	1	0	0	0	0	0	0	0	0	0
Actinotaenium cucurbita (Brébisson ex Ralfs) Teiling	1	1	0	0	0	1	0	0	0	1	0	0	0	0
Bambusina borreri (Ralfs) Cleve	1	1	0	0	0	1	0	0	0	0	1	0	0	0
Closterium abruptum West	0	0	0	0	0	0	0	0	0	1	0	0	0	0
Closterium closterioides var. intermedium (J.Roy & Bisset) Ruzicka	0	0	1	0	0	0	0	0	0	0	0	0	0	0
Closterium dianae var. arcuatum (Brebisson ex Ralfs) Rabenhorst	0	1	0	0	0	0	0	0	0	0	1	0	1	0
Closterium gracile Brébisson ex Ralfs	0	0	0	0	0	1	0	0	0	0	0	0	0	0
Closterium intermedium Ralfs	0	0	0	0	1	1	0	0	0	0	0	0	0	0
Closterium jenneri Ralfs	0	0	1	0	0	1	0	0	0	0	0	0	0	0
Closterium juncidum Ralfs	0	0	0	0	0	1	0	0	0	0	0	0	0	0
Closterium kuetzingii Brébisson	0	0	0	0	0	0	0	0	0	0	1	0	0	1
Closterium leibleinii Kützing ex Ralfs	0	0	0	0	1	0	1	0	1	0	0	0	0	1
Closterium lineatum Ehrenberg ex Ralfs	0	0	0	0	0	0	0	0	0	0	0	0	0	1
Closterium littorale F.Gay	0	0	1	0	0	0	0	0	0	0	0	0	0	0
Closterium moniliferum Ehrenberg ex Ralfs	0	0	1	0	0	0	0	0	0	0	0	0	0	1
Closterium navicula (Brébisson) Lütkemüller	0	1	0	0	0	0	0	0	0	0	0	0	0	0
Closterium setaceum Ehrenberg ex Ralfs	0	0	0	0	0	0	0	0	0	1	0	0	0	0
Closterium venus Kützing ex Ralfs	0	1	1	0	0	0	0	0	0	1	0	0	0	0
Cosmarium baileyi Wolle	0	1	0	0	0	0	0	0	0	0	0	0	0	0
Cosmarium bioculatum Brébisson ex Ralfs	1	1	1	1	1	0	1	1	0	0	1	0	0	0
Cosmarium blyttii var. novaesylvae West & G.S.West	1	0	1	0	1	0	0	0	0	0	0	0	0	0
Cosmarium botrytis Meneghini ex Ralfs	0	0	0	0	1	0	1	0	1	0	0	0	0	0
Cosmarium brebissonii Meneghini ex Ralfs	0	1	0	0	0	0	0	0	0	0	1	0	0	0
Cosmarium circulare Reinsch	1	1	0	0	1	0	0	0	0	0	0	0	0	0
Cosmarium contractum O.Kirchner	0	1	0	0	0	0	0	0	0	0	1	0	0	0
Cosmarium crenulatum Nägeli	0	0	0	0	0	1	0	0	0	0	0	0	0	0
Cosmarium formosulum Hoff	1	1	1	0	1	0	1	1	1	0	0	0	0	1
Cosmarium granatum Brébisson ex Ralfs	0	0	0	0	0	0	0	0	1	0	0	0	0	0
Cosmarium hammeri Reinsch	0	0	0	0	0	0	0	0	0	1	0	0	0	0
Cosmarium humile Nordstedt ex De Toni	1	1	0	0	0	1	0	0	0	0	0	0	0	1
Cosmarium impressulum Elfving	0	0	0	0	0	0	1	1	0	0	0	0	0	0
Cosmarium meneghinii Brébisson ex Ralfs	0	0	0	0	0	0	0	0	1	0	0	0	0	0
Cosmarium obsoletum (Hantzsch) Reinsch	1	1	1	0	1	0	0	0	0	0	0	0	0	0
Cosmarium ochthodes Nordstedt	0	0	0	0	0	0	0	0	0	0	0	1	0	0
Cosmarium pachydermum P.Lundell	0	0	0	0	1	0	0	0	0	0	0	0	0	0
Cosmarium pachydermum var. minus Nordstedt	0	0	1	0	0	0	0	0	0	0	0	0	0	0
Cosmarium porteanum W.Archer	1	0	1	0	0	0	0	0	0	0	0	0	0	0
Cosmarium pseudoexiguum Raciborski	0	1	0	0	0	0	0	0	0	0	0	0	0	0
Cosmarium pseudopyramidatum P.Lundell	0	0	0	0	1	1	0	0	0	0	0	0	0	0
Cosmarium punctulatum Brébisson	1	1	0	0	0	1	1	1	0	0	0	0	1	0
Cosmarium regnellii Wille	0	1	1	0	0	0	0	1	0	0	0	0	0	0
Cosmarium regnesi Reinsch	0	1	0	0	0	0	0	0	0	0	0	0	0	0
Cosmarium reniforme (Ralfs) W.Archer	0	0	0	0	0	0	0	0	0	0	1	0	0	0
Cosmarium sexnotatum var. tristriatum (Lütkemuller) Schmidle	0	0	0	0	0	0	0	1	0	0	0	0	1	0
Cosmarium subprotumidum Nordstedt	0	0	0	0	0	0	0	0	1	0	0	0	0	0
Cosmarium subtumidum Nordstedt	0	1	0	0	0	0	0	1	0	0	0	0	0	0
Cosmarium subundulatum Wille	1	0	0	0	0	0	0	0	0	0	0	0	0	0
Cosmarium trilobulatum var. depressum Printz	0	1	1	0	0	1	0	0	0	0	0	0	0	0
Cosmarium ungerianum var. subtriplicatum West & G.S.West	0	0	1	0	1	0	0	1	0	0	0	0	0	0
Desmidium aptogonum Brébisson ex Kützing	0	1	0	0	0	1	0	0	0	0	1	0	0	0
Desmidium aptogonum var. ehrenbergii Kützing	0	0	0	0	0	0	0	0	0	0	1	0	0	0
Desmidium baileyi (Ralfs) Nordstedt	1	1	0	0	1	0	0	0	0	0	0	0	0	0
Desmidium coarctatum Nordstedt	0	0	0	0	1	0	0	0	0	0	0	0	0	0
Desmidium graciliceps (Nordstedt) Lagerheim	0	1	0	0	0	0	0	0	0	0	0	0	0	0
Desmidium swartzii C.Agardh ex Ralfs	1	1	1	0	1	0	0	1	0	0	1	0	0	0
Elakatothrix parvula (W.Archer) Hindák	0	1	0	0	0	0	0	0	0	0	0	0	0	0
Euastrum ansatum Ehrenberg ex Ralfs	0	1	0	0	0	0	0	0	0	0	0	0	0	0
Euastrum bidentatum Nägeli	0	1	0	0	0	0	0	0	0	0	0	0	0	0
Euastrum binale Ehrenberg ex Ralfs	1	0	0	0	0	0	0	0	0	0	0	0	0	0
Euastrum binale var. minus (West) Willi Krieger	0	1	0	0	0	1	0	0	0	0	0	0	0	0
Euastrum crassicolle P.Lundell	0	1	0	0	0	0	0	0	0	0	0	0	0	0
Euastrum didelta Ralfs	1	0	0	0	0	0	0	0	0	0	0	0	0	0
Euastrum elegans Ralfs	0	0	0	0	0	0	1	0	0	0	0	0	0	0
Euastrum gemmatum Ralfs	0	1	1	0	0	0	0	0	0	0	0	0	0	0
Euastrum neosinuosum O.V.Anissimova & Guiry	0	0	0	0	0	0	0	0	0	1	0	0	0	0
Euastrum pulchellum Brébisson	0	1	0	0	1	0	0	0	0	0	0	0	0	0
Gonatozygon aculeatum W.N.Hastings	1	0	0	0	0	0	0	0	0	0	0	0	0	0
Gonatozygon brebissonii De Bary	1	0	0	0	0	0	0	0	0	0	0	0	0	1
Gonatozygon monotaenium De Bary	1	0	1	0	0	1	0	1	0	0	1	0	0	0
Groenbladia neglecta (Raciborski) Teiling	1	0	0	0	0	0	0	0	0	0	0	0	0	0
Groenbladia undulata (Nordstedt) Kurt Förster	0	1	0	0	0	0	0	0	0	0	0	0	0	0
Haplotaenium rectum (Delponte) Bando	0	1	0	0	0	0	0	0	0	1	0	0	0	0
Hyalotheca dissiliens Brébisson ex Ralfs	0	0	0	1	0	0	0	0	0	0	0	0	0	0
Hyalotheca indica W.B.Turner	0	1	0	0	0	0	0	0	0	0	0	0	0	0
Hyalotheca mucosa Ralfs	1	1	0	1	1	0	0	0	0	0	0	0	0	0
Micrasterias crux-melitensis Ralfs	0	0	0	0	1	0	0	0	0	1	1	0	0	0
Micrasterias pinnatifida Ralfs	1	0	0	0	1	0	0	0	0	0	0	0	0	0
Micrasterias truncata Brébisson ex Ralfs	0	0	0	0	0	0	0	0	0	0	1	0	0	0
Mougeotia laetevirens (A.Braun) Wittrock	0	0	0	0	0	0	0	1	0	0	0	0	0	0
Octacanthium bifidum var. latidivergens (West) Petlovany	0	1	0	0	0	0	0	0	0	0	0	0	0	0
Penium margaritaceum Brébisson ex Ralfs	0	0	1	0	0	0	0	0	0	0	0	0	0	0
Pleurotaenium clavatum (Ralfs) De Bary	0	0	0	0	1	0	0	0	0	0	0	0	0	0
Pleurotaenium coronatum (Brébisson) Rabenhorst	0	0	1	0	1	0	0	0	0	0	0	0	0	0
Pleurotaenium ehrenbergii (Ralfs) De Bary	0	1	0	0	0	0	0	0	0	0	0	0	0	0
Pleurotaenium elongatum (West) Coesel & Meesters	0	0	0	0	0	0	0	1	0	0	0	0	0	0
Pleurotaenium trabecula Nägeli	1	0	1	1	0	0	0	0	0	0	1	0	0	0
Sphaerozosma filiforme Ralfs	0	0	0	0	0	1	0	0	0	0	0	0	0	0
Sphaerozosma laeve (Nordstedt) Thomasson	0	0	0	0	0	1	0	0	0	0	0	0	0	0
Spirogyra sp. ster.	0	0	1	0	1	0	0	0	0	0	0	0	0	0
Spondylosium ellipticum West & G.S.West	0	0	0	0	1	0	0	0	0	0	0	0	0	0
Spondylosium lundellii O.Borge	1	1	0	0	0	0	0	0	0	0	0	0	0	0
Spondylosium planum (Wolle) West & G.S.West	0	1	0	0	1	0	0	0	0	0	0	0	0	0
Staurastrum avicula var. lunatum (Ralfs) Coesel & Meesters	0	0	1	1	1	0	0	1	0	0	1	0	0	0
Staurastrum boreale West & G.S.West	0	1	1	1	1	0	0	1	0	1	0	0	0	1
Staurastrum brevispina Brébisson	0	1	0	0	0	0	0	0	0	1	0	0	0	0
Staurastrum dilatatum Ehrenberg ex Ralfs	0	1	0	0	0	0	0	0	0	0	0	0	0	0
Staurastrum furcatum Brébisson	0	0	0	0	1	0	0	0	0	0	0	0	0	0
Staurastrum furcigerum (Brébisson) W.Archer	0	0	0	0	1	0	0	0	0	0	0	0	0	0
Staurastrum gemelliparum Nordstedt	0	0	0	0	0	0	0	1	0	0	0	0	0	0
Staurastrum gracile Ralfs ex Ralfs	1	1	0	1	0	0	0	1	0	0	1	0	0	0
Staurastrum granulosum Ralfs	0	0	0	0	0	0	0	0	0	1	0	0	0	0
Staurastrum longispinum (Bailey) W.Archer	1	0	0	0	0	0	0	0	0	0	0	0	0	0
Staurastrum manfeldtii Delponte	0	0	0	0	1	1	0	1	0	0	0	0	0	0
Staurastrum muticum Brébisson ex Ralfs	0	0	1	0	1	0	0	1	0	0	0	0	0	0
Staurastrum paradoxum Meyen ex Ralfs	1	1	0	0	1	1	0	0	0	0	0	0	0	0
Staurastrum punctulatum Brébisson	1	1	1	0	0	0	1	0	0	0	0	0	1	0
Staurastrum spiniferum West	0	0	0	0	0	0	0	0	0	1	0	0	0	0
Staurastrum subarmigerum J.Roy & Bisset	0	1	0	0	0	0	0	1	0	0	0	0	0	0
Staurastrum submonticulosum J.Roy & Bisset	1	0	0	0	0	0	0	0	0	0	0	0	0	0
Staurastrum teliferum var. gladiosum (W.B.Turner) Coesel & Meesters	1	0	0	0	1	0	0	0	0	1	0	0	0	0
Staurastrum tetracerum Ralfs ex Ralfs	0	0	0	0	0	0	0	1	0	0	1	0	0	0
Staurastrum vestitum Ralfs	0	0	0	0	1	0	0	0	0	0	0	0	0	0
Staurodesmus convergens (Ehrenberg ex Ralfs) S.Lillieroth	1	0	0	0	1	0	0	0	0	0	0	0	0	0
Staurodesmus cuspidatus (Brébisson) Teiling	1	1	0	1	1	0	0	0	0	0	0	0	0	0
Staurodesmus dejectus (Brébisson) Teiling	0	1	0	1	0	0	0	0	0	0	0	0	0	0
Staurodesmus glaber (Ralfs) Teiling	1	1	0	0	1	0	1	0	0	0	1	0	0	0
Staurodesmus incus (Hassal ex Ralfs) Teiling	1	0	0	0	0	0	0	0	0	0	1	0	0	0
Staurodesmus leptodermus (P.Lundell) Teiling	1	0	0	0	0	0	0	0	0	0	0	0	0	0
Teilingia granulata (J.Roy & Bisset) Bourrelly	1	1	0	1	1	0	1	0	0	0	0	0	0	0
Xanthidium antilopaeum Kützing	1	0	0	0	1	0	0	1	0	0	1	0	0	0
Xanthidium cristatum Brébisson ex Ralfs	0	0	0	1	0	0	0	0	0	0	0	0	0	0
Chlorophyta Reichenbach
Actinastrum hantzschii var. subtile Wołoszyńska	0	0	0	0	1	0	0	0	0	0	0	0	0	0
Acutodesmus acutiformis var. costatus (Huber-Pestalozzi) P.M.Tsarenko & D.M.John	0	0	0	0	0	0	1	0	0	0	0	0	0	0
Ankistrodesmus arcuatus Korshikov	0	0	1	0	0	1	0	0	0	0	0	0	0	0
Ankistrodesmus falcatus (Corda) Ralfs	1	1	1	0	1	0	1	0	0	1	0	0	0	0
Ankistrodesmus fusiformis Corda	1	1	1	0	1	1	0	1	0	0	0	0	0	1
Ankistrodesmus spiralis (W.B.Turner) Lemmermann	0	1	0	0	1	0	1	0	0	0	0	0	0	0
Aphanochaete repens A.Braun	0	1	0	0	0	0	0	0	0	0	0	0	0	0
Botryococcus braunii Kützing	0	1	1	1	1	1	0	1	0	0	1	0	0	0
Coelastrum astroideum De Notaris	0	0	0	0	0	0	0	0	0	0	0	0	0	1
Comasiella arcuata (Lemmermann) E.Hegewald, M.Wolf, Al.Keller, Friedl & Krienitz	0	0	1	0	0	0	0	0	0	0	0	0	0	0
Cosmarium angulosum var. concinnum (Rabenhorst) West & G.S.West	0	1	0	0	0	0	0	0	1	0	0	0	0	0
Crucigenia fenestrata (Schmidle) Schmidle	0	0	1	0	0	0	0	0	0	0	0	0	0	0
Desmodesmus armatus (Chodat) E.H.Hegewald	0	1	0	0	0	0	1	1	0	0	0	0	1	1
Desmodesmus denticulatus var. linearis (Hansgirg) Hegewald	0	1	1	0	0	1	0	1	0	0	0	0	0	1
Desmodesmus microspina (Chodat) P.M.Tsarenko	0	0	0	1	1	0	0	0	1	0	1	0	0	1
Desmodesmus spinosus (Chodat) E.Hegewald	0	0	0	0	0	0	0	0	0	0	1	0	0	0
Dictyosphaerium ehrenbergianum Nägeli	0	0	1	0	0	0	0	0	0	0	0	0	0	0
Dimorphococcus lunatus A.Braun	1	1	0	0	0	0	0	0	0	0	0	0	0	0
Monoraphidium contortum (Thuret) Komárková-Legnerová	1	1	0	0	0	0	1	0	0	0	0	0	0	0
Monoraphidium griffithii (Berkeley) Komárková-Legnerová	0	1	1	0	0	1	1	0	0	0	0	0	0	0
Monoraphidium komarkovae Nygaard	0	1	0	0	0	0	0	0	0	0	0	0	0	0
Mucidosphaerium pulchellum (H.C.Wood) C.Bock, Proschold & Krienitz	0	0	1	0	0	0	1	0	0	0	0	0	0	0
Neglectella solitaria (Wittrock) Stenclová & Kaštovský	0	0	0	0	0	0	1	1	0	0	0	0	0	1
Nephrocytium lunatum West	0	0	0	0	0	0	0	1	0	0	0	0	0	0
Oedogonium undulatum A.Braun ex Hirn	1	1	0	0	0	0	0	0	0	0	0	0	0	0
Oocystis lacustris Chodat	0	0	0	1	1	0	0	0	0	0	0	0	0	0
Oocystis parva West & G.S.West	0	1	0	0	0	0	0	0	0	0	0	0	0	0
Oocystis rhomboidea Fott	0	1	0	0	0	0	0	0	0	0	0	0	0	0
Pandorina morum (O.F.Müller) Bory	1	1	1	0	1	1	0	0	0	0	1	0	0	1
Pseudopediastrum boryanum (Turpin) E.Hegewald	0	1	0	1	1	1	0	0	0	0	1	0	1	1
Quadrigula korsikovii Komárek	0	1	1	1	1	0	0	0	0	0	0	0	0	0
Scenedesmus ellipticus Corda	1	1	1	0	1	1	0	1	0	0	1	0	1	0
Scenedesmus obtusus f. disciformis (Chodat) Compère	0	0	0	0	0	0	1	0	0	0	0	0	0	0
Scenedesmus obtusus Meyen	0	0	0	0	0	1	0	0	0	0	0	0	0	0
Selenastrum bibraianum Reinsch	0	0	1	0	1	0	0	0	0	0	1	0	0	0
Sorastrum spinulosum Nägeli	0	0	0	0	0	0	0	0	0	0	0	0	0	1
Stauridium tetras (Ehrenberg) E.Hegewald	0	1	0	0	0	1	1	0	0	0	0	0	0	1
Tetradesmus obliquus (Turpin) M.J.Wynne	0	0	1	0	0	0	1	0	0	0	0	0	1	1
Tetraëdron minimum (A.Braun) Hansgirg	0	0	0	0	0	0	1	0	0	0	0	0	1	1
Ulothrix zonata (F.Weber & Mohr) Kützing	0	0	0	0	0	0	0	0	0	0	0	1	0	0
Verrucodesmus verrucosus (Y.V.Roll) E.Hegewald	0	0	1	0	0	0	0	0	0	0	0	0	0	0
Volvox aureus Ehrenberg	0	1	1	0	0	1	0	0	0	0	0	0	0	0
Volvox polychlamys Korshikov	0	0	1	0	1	0	0	0	0	0	0	0	0	0
Westella botryoides (West) De Wildeman	0	0	0	0	0	0	1	0	0	0	0	0	0	0
Willea irregularis (Wille) Schmidle	0	1	0	1	1	0	0	0	0	0	0	0	0	0
Cyanobacteria Stanier ex Cavalier-Smith
Anabaena augstumalis Schmidle	0	0	0	0	0	1	0	0	0	0	0	0	0	0
Anabaena oscillarioides Bory ex Bornet & Flahault	0	0	1	0	0	0	0	0	0	0	0	0	0	0
Anagnostidinema amphibium (Gomont) Strunecký, Bohunická, J.R.Johansen & Komárek	0	0	0	0	0	0	0	0	1	0	0	0	0	0
Anathece clathrata (West & G.S.West) Komárek, Kaštovský & Jezberová	0	0	0	1	0	0	0	0	0	1	0	0	0	0
Aphanocapsa conferta (West & G.S.West) Komárková-Legnerová & Cronberg	0	0	0	0	0	0	0	0	0	1	0	0	0	0
Aphanocapsa delicatissima West & G.S.West	0	1	1	1	0	0	0	0	0	0	0	0	0	0
Aphanocapsa holsatica (Lemmermann) G.Cronberg & Komárek	0	0	0	1	0	0	0	0	0	0	0	0	0	0
Aphanocapsa incerta (Lemmermann) G.Cronberg & Komárek	0	0	1	0	0	0	0	0	0	1	0	0	0	0
Chroococcus turgidus (Kützing) Nägeli	0	1	0	0	0	0	0	1	0	1	0	0	0	1
Coelosphaerium kuetzingianum Nägeli	0	0	0	1	1	0	0	0	0	0	0	0	0	0
Lyngbya cincinnata (Itzigsohn) Compère	0	0	0	0	1	0	0	0	0	0	0	0	0	0
Merismopedia glauca (Ehrenberg) Kützing	0	0	1	0	0	1	0	1	0	1	0	0	0	0
Merismopedia tranquilla (Ehrenberg) Trevisan	1	1	1	0	0	0	1	0	0	0	0	0	0	1
Microcystis aeruginosa (Kützing) Kützing	0	0	1	0	0	0	0	0	0	0	0	0	0	0
Nostoc commune Vaucher ex Bornet & Flahault	0	1	0	0	0	0	0	0	0	0	0	0	0	0
Nostoc kihlmanii Lemmermann	0	1	0	0	1	1	0	0	0	1	1	0	0	0
Oscillatoria limosa C.Agardh ex Gomont	1	1	1	0	0	0	0	1	0	1	1	0	0	1
Oscillatoria princeps Vaucher ex Gomont	0	0	1	0	0	0	0	1	0	0	1	0	0	0
Oscillatoria proboscidea Gomont	0	0	0	0	0	0	0	1	0	0	0	0	0	0
Oscillatoria rupicola (Hansgirg) Hansgirg ex Forti	0	0	0	0	1	0	0	0	0	0	0	0	0	0
Oscillatoria tenuis C.Agardh ex Gomont	0	1	0	0	1	0	1	0	0	0	0	0	0	0
Phormidium ambiguum Gomont	0	0	0	0	0	0	0	0	1	0	0	0	0	0
Phormidium breve (Kützing ex Gomont) Anagnostidis & Komárek	0	0	0	0	0	0	0	0	1	0	0	0	1	0
Rivularia biasolettiana Meneghini ex Bornet & Flahault	1	0	0	0	0	0	0	0	0	0	0	0	0	0
Scytonema coactile Montagne ex Bornet & Flahault	0	1	0	0	0	0	0	0	0	0	0	0	0	0
Snowella lacustris (Chodat) Komárek & Hindák	0	1	0	0	1	0	0	0	0	0	0	0	0	0
Spirulina abbreviata Lemmermann	0	0	0	0	0	0	0	0	0	0	0	0	1	1
Woronichinia naegeliana (Unger) Elenkin	0	0	1	0	0	0	0	0	0	0	0	0	0	0
Dinoflagellata Fensome & al.
Ceratium cornutum (Ehrenberg) Claparède & J.Lachmann	0	0	0	0	0	0	0	0	0	0	1	0	0	0
Ceratium hirundinella (O.F.Müller) Dujardin	1	1	1	1	1	0	0	0	0	0	0	0	0	0
Peridinium bipes F.Stein	1	1	0	0	0	1	0	1	0	0	0	0	0	0
Peridinium cinctum (O.F.Müller) Ehrenberg	1	0	1	1	1	1	0	0	0	0	1	0	0	0
Peridinium willei Huitfeldt-Kaas	0	0	0	1	0	0	0	0	0	0	0	0	0	0
Euglenophyta Cavalier-Smith
Colacium vesiculosum Ehrenberg	0	0	0	1	0	0	0	1	0	0	1	0	0	0
Lepocinclis acus (O.F.Müller) B.Marin & Melkonian	0	0	0	0	0	1	0	0	0	0	0	0	0	1
Lepocinclis oxyuris (Schmarda) B.Marin & Melkonian	0	0	0	0	1	0	0	0	0	0	0	0	0	0
Monomorphina pyrum (Ehrenberg) Mereschkowsky	0	0	1	0	1	1	0	0	0	0	0	0	0	1
Phacus limnophilus (Lemmermann) E.W.Linton & Karnkowska	0	0	0	0	0	0	0	0	0	0	0	0	0	1
Phacus longicauda (Ehrenberg) Dujardin	0	0	1	0	0	1	0	0	0	0	1	0	0	0
Phacus orbicularis Hübner	0	0	1	0	1	0	0	1	1	0	0	0	0	1
Phacus pleuronectes (O.F.Müller) Nitzsch ex Dujardin	0	0	0	0	0	1	0	0	0	0	1	0	0	0
Trachelomonas acanthostoma var. minor Dreżepolski	0	0	1	0	0	0	0	0	0	0	0	0	0	0
Trachelomonas armata (Ehrenberg) F.Stein	0	0	0	0	1	0	0	0	0	0	1	0	0	0
Trachelomonas armata var. steinii Lemmermann	0	0	1	0	0	0	0	0	0	0	0	0	0	0
Trachelomonas australica var. granulata (Playfair) Deflandre	0	0	0	0	0	1	0	0	0	0	0	0	0	0
Trachelomonas crenulatocollis Maskell	0	0	0	0	1	0	0	0	0	0	1	0	0	0
Trachelomonas dubia Svirenko	0	0	1	0	0	0	0	0	0	0	0	0	0	0
Trachelomonas dybowskii Dreżepolski	0	1	0	0	1	1	0	0	0	0	0	0	0	0
Trachelomonas granulosa Playfair	1	0	0	0	1	0	0	0	0	0	0	0	0	0
Trachelomonas hispida (Perty) F.Stein	0	1	1	0	0	1	0	0	0	0	0	0	0	0
Trachelomonas lacustris Dreżepolski	0	1	0	0	0	0	0	0	0	0	0	0	0	0
Trachelomonas oblonga Lemmermann	0	0	0	0	1	0	0	0	0	0	0	0	0	0
Trachelomonas superba Svirenko	0	0	1	0	1	0	0	0	0	0	0	0	0	0
Trachelomonas woycickii Koczwara	0	0	0	0	0	0	0	0	1	0	0	0	0	0
Heterokontophyta Moestrup, R.A.Andersen & Guiry
Asterionella tekelili D.M.Williams, T.M.Schuster, E.Cesar & Jüttner	0	0	1	0	1	0	0	0	0	0	0	0	0	0
Aulacoseira sp.	0	0	0	0	0	1	0	0	0	0	0	0	0	0
Didymosphenia geminata (Lyngbye) Mart.Schmidt	0	0	0	0	0	0	0	0	0	0	0	0	1	0
Dinobryon bavaricum Imhof	1	1	1	0	1	1	0	1	0	0	0	0	0	0
Dinobryon cylindricum O.E.Imhof	0	0	0	0	0	0	0	0	0	0	1	0	0	0
Dinobryon divergens O.E.Imhof	0	0	0	0	0	1	0	1	0	0	0	0	0	0
Dinobryon divergens var. schauinslandii (Lemmermann) Brunnthaler	0	0	0	0	0	0	0	1	0	0	0	0	0	0
Dinobryon sertularia Ehrenberg	1	1	1	0	0	0	1	1	0	0	0	0	0	1
Encyonema silesiacum (Bleisch) D.G.Mann	0	0	1	0	0	0	0	0	0	0	0	0	0	0
Entomoneis ornata (Bailey) Reimer	0	0	0	0	0	0	1	1	0	0	0	0	0	0
Epithemia adnata (Kützing) Brébisson	0	0	0	0	0	0	0	0	0	0	0	0	0	1
Epithemia gibba (Ehrenberg) Kützing	0	0	0	0	0	0	1	0	0	0	1	0	1	1
Epithemia turgida (Ehrenberg) Kützing	0	0	0	0	0	0	0	0	0	0	0	0	0	1
Gomphonema sp.	0	0	1	0	0	0	0	0	0	0	1	0	0	0
Gomphonema acuminatum Ehrenberg	1	0	1	0	0	0	0	0	0	0	0	0	0	0
Gomphonema capitatum Ehrenberg	0	0	1	0	0	0	0	0	0	0	0	0	0	0
Meridion circulare (Greville) C.Agardh	0	0	0	0	0	0	0	0	0	0	0	1	1	0
Nitzschia acicularis (Kützing) W.Smith	0	0	0	0	0	0	0	0	0	0	0	0	1	0
Pinnularia nobilis (Ehrenberg) Ehrenberg	0	0	0	1	0	0	0	0	0	0	0	0	0	0
Rhoicosphenia abbreviata (C.Agardh) Lange-Bertalot	0	0	0	0	0	0	0	0	0	0	0	0	1	0
Stauroneis phoenicenteron (Nitzsch) Ehrenberg	0	0	0	0	0	1	0	0	0	0	0	0	0	0
Stenopterobia anceps (F.W.Lewis) Brébisson ex Van Heurck	1	1	1	0	1	1	0	0	0	0	0	0	0	0
Surirella librile (Ehrenberg) Ehrenberg	0	0	0	0	0	0	1	0	0	0	0	0	0	0
Tabellaria fenestrata (Lyngbye) Kützing	1	1	1	1	1	1	0	1	0	0	1	0	0	0
Tabellaria flocculosa (Roth) Kützing	1	1	1	1	1	1	1	0	0	0	1	0	1	0
Tribonema vulgare Pascher	0	1	0	0	0	0	0	0	0	0	0	0	1	0
Ulnaria ulna (Nitzsch) Compère	0	0	1	0	0	0	0	0	0	0	1	0	1	1
Urosolenia eriensis (H.L.Smith) Round & R.M.Crawford	0	0	1	0	1	0	0	0	0	0	0	0	0	0

Note: “0“, not found; “1“, present.

). For 13 water bodies (excluding Olyokma River), information on algae was obtained for the first time.

Table 2. Taxonomical distribution of species richness of algae and cyanobacteria in phyla over 14 sampling stations of the Olyokma Natural Reserve, August 2024.

Phylum	St 1	St 2	St 3	St 4	St 5	St 6	St 7	St 8	St 9	St 10	St 11	St 12	St 13	St 14
Cercozoa	0	0	0	0	0	0	1	0	0	0	0	0	0	0
Charophyta	36	49	26	11	38	18	10	21	6	13	20	1	4	8
Chlorophyta	7	22	18	6	14	11	13	7	2	1	7	1	5	12
Cyanobacteria	3	9	9	4	6	3	2	5	3	7	3	0	2	4
Dinoflagellata	3	2	2	3	2	2	0	1	0	0	2	0	0	0
Euglenophyta	1	3	8	1	9	7	0	2	2	0	5	0	0	4
Heterokontophyta	6	6	12	3	6	7	5	6	0	0	6	1	8	5
Total	56	91	75	28	75	48	31	42	13	21	43	3	19	33

Note: Station numbering as in Table 1.

reflects the distribution of the numbers of species in taxonomic phyla at each of the surveyed stations. The species richness of the identified microalgae varied within 3–91 and was highest in the lakes of the upper part of the river valley. The most diverse were Charophyta, and green algae remained in second place. The remaining phyla were noted to have low diversity.

The abundance of phytoplankton species cells in taxonomic phyla decreased downstream along the river valley stations (

Table 3. Average abundance (thou. cells L⁻¹) of phytoplankton phyla of nine water bodies of the Olyokma Nature Reserve, August 2024.

Phylum	St 1	St 2	St 3	St 4	St 5	St 6	St 8	St 11	St 14
Charophyta	9.2	1.1	1.5	1.2	2.0	3.5	1.1	1.5	1.2
Chlorophyta	0.4	0.5	43.2	0.5	67.9	3.8	0.2	2.3	1.8
Cyanobacteria	0.1	0.2	17.6	0.3	11.5	38.2	0.2	0.2	0.6
Dinoflagellata	0.2	3.6	0.5	0.2	0.6	0.2	0.1	0.2	0
Euglenophyta	0.1	0.2	0.9	9.1	0	0.8	0.1	0.4	0.9
Heterokontophyta	23.6	4.9	11.8	0.2	1.2	17.1	0.4	0.5	2.0
Total	33.5	10.5	75.3	11.5	82.7	63.6	1.9	5.0	6.5

Note: Station numbering as in Table 1.

, Appendix A 

Table A3. Average abundance (thou. cells per L) of algae and cyanobacteria species in nine planktonic samples from water bodies of the Olyokma Nature Reserve, August 2024. Samples numbering as in Table 1.

Taxa	St 1	St 2	St 3	St 4	St 5	St 6	St 7	St 8	St 9
Charophyta Migula
Actinotaenium cucurbita (Brébisson ex Ralfs) Teiling		0.11
Bambusina borreri (Ralfs) Cleve		0.11			0.70				0.70
Closterium dianae var. arcuatum (Brebisson ex Ralfs) Rabenhorst					0.70
Closterium gracile Brébisson ex Ralfs		0.11
Closterium intermedium Ralfs		0.11	0.70
Closterium jenneri Ralfs		0.11
Closterium juncidum Ralfs		0.11
Closterium kuetzingii Brébisson					0.70	0.15
Closterium leibleinii Kützing ex Ralfs						0.15
Closterium lineatum Ehrenberg ex Ralfs						0.15
Closterium moniliferum Ehrenberg ex Ralfs	0.11					0.15
Cosmarium bioculatum Brébisson ex Ralfs	0.11		0.23	0.70	0.70				0.70
Cosmarium blyttii var. novaesylvae West & G.S.West	0.11
Cosmarium botrytis Meneghini ex Ralfs			0.70
Cosmarium brebissonii Meneghini ex Ralfs					0.70
Cosmarium circulare Reinsch			0.70						0.70
Cosmarium contractum O.Kirchner					0.70
Cosmarium crenulatum Nägeli		0.11
Cosmarium formosulum Hoff						0.15	0.70		0.70
Cosmarium humile Nordstedt ex De Toni		0.11				0.15			0.70
Cosmarium obsoletum (Hantzsch) Reinsch	0.11		0.70
Cosmarium pachydermum P.Lundell			0.70
Cosmarium pseudopyramidatum P.Lundell		0.11
Cosmarium punctulatum Brébisson		0.11						0.70	0.23
Cosmarium reniforme (Ralfs) W.Archer					0.70
Cosmarium subtumidum Nordstedt							0.70	0.70
Cosmarium subundulatum Wille									0.70
Cosmarium trilobulatum var. depressum Printz		0.11
Cosmarium ungerianum var. subtriplicatum West & G.S.West							0.70
Desmidium aptogonum Brébisson ex Kützing		0.68			0.70
Desmidium aptogonum var. ehrenbergii Kützing					0.70
Desmidium baileyi (Ralfs) Nordstedt			0.70					0.70	6.80
Desmidium graciliceps (Nordstedt) Lagerheim								0.70
Desmidium swartzii C.Agardh ex Ralfs	0.11				0.70		0.70	0.70	0.70
Euastrum binale Ehrenberg ex Ralfs									0.70
Euastrum binale var. minus (West) Willi Krieger		0.11
Euastrum gemmatum Ralfs	0.34
Gonatozygon aculeatum W.N.Hastings									0.70
Gonatozygon brebissonii De Bary						0.15
Gonatozygon monotaenium De Bary	0.11	1.20			0.70		0.70		0.70
Groenbladia neglecta (Raciborski) Teiling									0.70
Hyalotheca dissiliens Brébisson ex Ralfs				0.70
Hyalotheca indica W.B.Turner								0.70
Hyalotheca mucosa Ralfs			0.70	0.70					0.70
Micrasterias crux-melitensis Ralfs					0.70
Micrasterias pinnatifida Ralfs			0.70						0.70
Micrasterias truncata Brébisson ex Ralfs					0.70
Pleurotaenium coronatum (Brébisson) Rabenhorst	0.11		0.70
Pleurotaenium elongatum (West) Coesel & Meesters							0.70
Pleurotaenium trabecula Nägeli	0.11			0.70	0.70				0.70
Sphaerozosma filiforme Ralfs		0.11
Sphaerozosma laeve (Nordstedt) Thomasson		0.11
Spondylosium ellipticum West & G.S.West			0.70
Spondylosium lundellii O.Borge								0.70	0.70
Spondylosium planum (Wolle) West & G.S.West			0.70					0.70
Staurastrum avicula var. lunatum (Ralfs) Coesel & Meesters	0.11		0.70	0.70	0.70		0.70
Staurastrum boreale West & G.S.West	0.11		0.23	0.70		0.15	0.70	0.70
Staurastrum furcatum Brébisson			0.70
Staurastrum furcigerum (Brébisson) W.Archer			0.70
Staurastrum gracile Ralfs ex Ralfs				0.70	0.70		0.70	0.70	0.70
Staurastrum longispinum (Bailey) W.Archer									0.70
Staurastrum manfeldtii Delponte		0.11	0.70				0.70
Staurastrum muticum Brébisson ex Ralfs			0.70				0.70
Staurastrum paradoxum Meyen ex Ralfs		0.11	0.70
Staurastrum punctulatum Brébisson									0.70
Staurastrum subarmigerum J.Roy & Bisset							0.70	0.70
Staurastrum submonticulosum J.Roy & Bisset									0.70
Staurastrum teliferum var. gladiosum (W.B.Turner) Coesel & Meesters									0.70
Staurastrum tetracerum Ralfs ex Ralfs					0.70		0.70
Staurodesmus convergens (Ehrenberg ex Ralfs) S.Lillieroth									0.70
Staurodesmus cuspidatus (Brébisson) Teiling			0.70	0.70				0.70	0.70
Staurodesmus dejectus (Brébisson) Teiling				0.70
Staurodesmus glaber (Ralfs) Teiling			0.70		0.70			0.70	0.70
Staurodesmus incus (Hassal ex Ralfs) Teiling					0.70				0.70
Staurodesmus leptodermus (P.Lundell) Teiling									0.23
Teilingia granulata (J.Roy & Bisset) Bourrelly			0.70	0.45				0.70	0.70
Xanthidium antilopaeum Kützing					0.70		0.70		0.70
Xanthidium cristatum Brébisson ex Ralfs				0.70
Chlorophyta Reichenbach
Ankistrodesmus arcuatus Korshikov	0.11	0.11
Ankistrodesmus falcatus (Corda) Ralfs			0.70					0.70	0.70
Ankistrodesmus fusiformis Corda	0.68	2.72				0.15			0.70
Ankistrodesmus spiralis (W.B.Turner) Lemmermann			0.70
Botryococcus braunii Kützing	3.40	0.11	3.15	0.70	1.81		0.70	0.70
Coelastrum astroideum De Notaris						0.15
Comasiella arcuata (Lemmermann) E.Hegewald, M.Wolf, Al.Keller, Friedl & Krienitz	0.11
Desmodesmus armatus (Chodat) E.H.Hegewald						0.15
Desmodesmus microspina (Chodat) P.M.Tsarenko			0.70	0.70	0.70	0.15
Desmodesmus spinosus (Chodat) E.Hegewald					0.70
Dimorphococcus lunatus A.Braun								0.70	0.70
Monoraphidium griffithii (Berkeley) Komárková-Legnerová	0.11	0.11
Mucidosphaerium pulchellum (H.C.Wood) C.Bock, Proschold & Krienitz	1.36
Neglectella solitaria (Wittrock) Stenclová & Kaštovský						0.15
Nephrocytium lunatum West							0.70
Oocystis lacustris Chodat			0.70	0.70
Pandorina morum (O.F.Müller) Bory	2.72	0.11	0.70		0.70	0.15		0.70	0.70
Pseudopediastrum boryanum (Turpin) E.Hegewald		0.11	0.70	0.70	0.70	0.15
Quadrigula korsikovii Komárek	0.11		0.70	0.70				0.70
Scenedesmus ellipticus Corda		0.11	0.70		0.70
Selenastrum bibraianum Reinsch	0.11		0.70		0.70
Sorastrum spinulosum Nägeli						0.15
Stauridium tetras (Ehrenberg) E.Hegewald		0.11				0.15
Tetradesmus obliquus (Turpin) M.J.Wynne						0.15
Tetraëdron minimum (A.Braun) Hansgirg						0.15
Volvox polychlamys Korshikov	34.00		0.70
Willea irregularis (Wille) Schmidle			36.95	0.70				0.70
Cyanobacteria Stanier ex Cavalier-Smith
Anabaena augstumalis Schmidle		4.80
Chroococcus turgidus (Kützing) Nägeli						0.15	0.70
Coelosphaerium kuetzingianum Nägeli			11.33	0.70
Merismopedia glauca (Ehrenberg) Kützing		0.11
Nostoc kihlmanii Lemmermann		34.00	0.70		0.70			0.70
Oscillatoria limosa C.Agardh ex Gomont	0.11				0.70	0.15	0.70
Oscillatoria princeps Vaucher ex Gomont	0.11				0.70
Oscillatoria tenuis C.Agardh ex Gomont			0.70
Spirulina abbreviata Lemmermann						0.15
Woronichinia naegeliana (Unger) Elenkin	17.00
Dinoflagellata Fensome & al.
Ceratium cornutum (Ehrenberg) Claparède & J.Lachmann					0.70
Ceratium hirundinella (O.F.Müller) Dujardin	0.34		0.70	0.70				3.17	0.70
Peridinium bipes F.Stein		0.11					0.70	0.45	0.70
Peridinium cinctum (O.F.Müller) Ehrenberg	0.11	0.11	0.70	0.70	0.70				0.70
Peridinium willei Huitfeldt-Kaas				0.70
Euglenophyta Cavalier-Smith
Colacium vesiculosum Ehrenberg				9.70	0.70		0.70
Lepocinclis acus (O.F.Müller) B.Marin & Melkonian		0.11				0.15
Monomorphina pyrum (Ehrenberg) Mereschkowsky	0.11	0.11				0.45
Phacus limnophilus (Lemmermann) E.W.Linton & Karnkowska						0.15
Phacus longicauda (Ehrenberg) Dujardin	0.11	0.11			0.70
Phacus orbicularis Hübner	0.11					0.15
Phacus pleuronectes (O.F.Müller) Nitzsch ex Dujardin		0.11			0.70
Trachelomonas acanthostoma var. minor Dreżepolski	0.11
Trachelomonas armata (Ehrenberg) F.Stein					0.70
Trachelomonas armata var. steinii Lemmermann	0.11
Trachelomonas australica var. granulata (Playfair) Deflandre		0.11
Trachelomonas crenulatocollis Maskell					0.70
Trachelomonas dubia Svirenko	0.11
Trachelomonas dybowskii Dreżepolski		0.11
Trachelomonas granulosa Playfair									0.70
Trachelomonas hispida (Perty) F.Stein	0.11	0.11						0.23
Trachelomonas superba Svirenko	0.11
Heterokontophyta Moestrup, R.A.Andersen & Guiry
Asterionella tekelili D.M.Williams, T.M.Schuster, E.Cesar & Jüttner	2.72		0.91
Aulacoseira sp.		3.23
Dinobryon bavaricum Imhof	0.34	0.34	0.70				0.70	3.63	0.70
Dinobryon cylindricum O.E.Imhof					0.70
Dinobryon divergens O.E.Imhof		8.84					0.70
Dinobryon divergens var. schauinslandii (Lemmermann) Brunnthaler							0.70
Dinobryon sertularia Ehrenberg	1.20					0.15	0.70	1.13	22.67
Encyonema silesiacum (Bleisch) D.G.Mann	0.34
Entomoneis ornata (Bailey) Reimer							0.70
Epithemia adnata (Kützing) Brébisson						0.15
Epithemia gibba (Ehrenberg) Kützing					0.70	1.36
Epithemia turgida (Ehrenberg) Kützing						0.15
Gomphonema sp.	0.23				0.70
Gomphonema acuminatum Ehrenberg	0.11								0.70
Gomphonema capitatum Ehrenberg	0.34
Pinnularia nobilis (Ehrenberg) Ehrenberg				0.70
Stauroneis phoenicenteron (Nitzsch) Ehrenberg		0.11
Stenopterobia anceps (F.W.Lewis) Brébisson ex Van Heurck	0.11	0.11							0.23
Tabellaria fenestrata (Lyngbye) Kützing	0.11	2.38	0.70	0.70	0.70			0.70	0.70
Tabellaria flocculosa (Roth) Kützing	4.76	2.40	0.70	0.70	0.70			0.70	0.45
Ulnaria ulna (Nitzsch) Compère	1.36				0.70	0.15
Urosolenia eriensis (H.L.Smith) Round & R.M.Crawford	0.34		0.70

). However, the proportion of cells of each division of species was unevenly distributed. While diatoms were more abundant at the upper stations, green algae came to the fore at stations downstream, followed by cyanobacteria at station 6. Phytoplankton abundance was minimal at the lower stations.

Phytoplankton biomass also had a similar decreasing trend down the river valley (

Table 4. Average biomass (mg m⁻³) of phytoplankton phyla of nine water bodies of the Olyokma Nature Reserve, August 2024.

Phylum	St 1	St 2	St 3	St 4	St 5	St 6	St 8	St 11	St 14
Charophyta	105.9	9.5	133.4	22.2	62.1	38.2	47.5	58.0	32.1
Chlorophyta	0.1	0.1	5.0	0.1	5.1	0.4	0.02	0.2	0.4
Cyanobacteria	0	0.01	1.0	0	0.1	1.4	1.4	0.3	2.93
Dinoflagellata	16.9	296.5	32.9	13.4	9.8	16.4	7.1	12.5	0
Euglenophyta	0.3	0.3	10.6	11.9	0	5.7	0.1	3.4	4.8
Heterokontophyta	11.6	2.1	46.6	7.3	1.3	36.6	2.8	4.2	49.5
Total	134.7	308.7	229.4	54.8	78.3	98.6	59.0	78.7	89.7

Note: Station numbering as in Table 1.

, Appendix A 

Table A4. Average biomass (mg per m³) of algae and cyanobacteria species in nine planktonic samples from water bodies of the Olyokma Nature Reserve, August 2024. Samples numbering as in Table 1.

Taxa	St 1	St 2	St 3	St 4	St 5	St 6	St 7	St 8	St 9
Charophyta Migula
Actinotaenium cucurbita (Brébisson ex Ralfs) Teiling		2.22
Bambusina borreri (Ralfs) Cleve		0.85			0.55				0.57
Closterium dianae var. arcuatum (Brebisson ex Ralfs) Rabenhorst					0.68
Closterium gracile Brébisson ex Ralfs		0.90
Closterium intermedium Ralfs		11.11	1.10
Closterium jenneri Ralfs		0.13
Closterium juncidum Ralfs		0.46
Closterium kuetzingii Brébisson					1.56	6.93
Closterium leibleinii Kützing ex Ralfs						1.00
Closterium lineatum Ehrenberg ex Ralfs						6.86
Closterium moniliferum Ehrenberg ex Ralfs	34.30					1.34
Cosmarium bioculatum Brébisson ex Ralfs	0.20		0.58	0.13	0.13				0.13
Cosmarium blyttii var. novaesylvae West & G.S.West	0.29
Cosmarium botrytis Meneghini ex Ralfs			5.36
Cosmarium brebissonii Meneghini ex Ralfs					2.15
Cosmarium circulare Reinsch			1.82						21.58
Cosmarium contractum O.Kirchner					0.83
Cosmarium crenulatum Nägeli		0.61
Cosmarium formosulum Hoff						4.57	2.28		2.90
Cosmarium humile Nordstedt ex De Toni		0.10				0.32			0.14
Cosmarium obsoletum (Hantzsch) Reinsch	4.96		3.30
Cosmarium pachydermum P.Lundell			5.11
Cosmarium pseudopyramidatum P.Lundell		3.10
Cosmarium punctulatum Brébisson		0.47						1.28	0.95
Cosmarium reniforme (Ralfs) W.Archer					5.87
Cosmarium subtumidum Nordstedt							2.41	3.30
Cosmarium subundulatum Wille									3.34
Cosmarium trilobulatum var. depressum Printz		0.32
Cosmarium ungerianum var. subtriplicatum West & G.S.West							2.60
Desmidium aptogonum Brébisson ex Kützing		3.40			0.18
Desmidium aptogonum var. ehrenbergii Kützing					0.25
Desmidium baileyi (Ralfs) Nordstedt			0.30					0.30	43.80
Desmidium graciliceps (Nordstedt) Lagerheim								0.33
Desmidium swartzii C.Agardh ex Ralfs	1.40				0.78		0.40	0.69	0.69
Euastrum binale Ehrenberg ex Ralfs									0.17
Euastrum binale var. minus (West) Willi Krieger		0.90
Euastrum gemmatum Ralfs	16.94
Gonatozygon aculeatum W.N.Hastings									2.30
Gonatozygon brebissonii De Bary						0.71
Gonatozygon monotaenium De Bary	1.10	9.99			0.73		0.73		0.73
Groenbladia neglecta (Raciborski) Teiling									0.12
Hyalotheca dissiliens Brébisson ex Ralfs				0.19
Hyalotheca indica W.B.Turner								0.14
Hyalotheca mucosa Ralfs			0.60	0.30					0.29
Micrasterias crux-melitensis Ralfs					16.70
Micrasterias pinnatifida Ralfs			2.40						6.87
Micrasterias truncata Brébisson ex Ralfs					9.90
Pleurotaenium coronatum (Brébisson) Rabenhorst	57.33		34.16
Pleurotaenium elongatum (West) Coesel & Meesters							28.72
Pleurotaenium trabecula Nägeli	13.47			16.26	8.81				8.98
Sphaerozosma filiforme Ralfs		0.90
Sphaerozosma laeve (Nordstedt) Thomasson		0.27
Spondylosium ellipticum West & G.S.West			0.90
Spondylosium lundellii O.Borge								0.68	0.68
Spondylosium planum (Wolle) West & G.S.West			0.20					0.10
Staurastrum avicula var. lunatum (Ralfs) Coesel & Meesters	2.96		0.17	1.97	1.97		1.97
Staurastrum boreale West & G.S.West	1.50		2.13	0.70		1.40	0.70	0.70
Staurastrum furcatum Brébisson			0.35
Staurastrum furcigerum (Brébisson) W.Archer			3.00
Staurastrum gracile Ralfs ex Ralfs				0.41	2.80		2.80	2.80	2.80
Staurastrum longispinum (Bailey) W.Archer									0.42
Staurastrum manfeldtii Delponte		4.78	1.55				1.70
Staurastrum muticum Brébisson ex Ralfs			0.32				0.19
Staurastrum paradoxum Meyen ex Ralfs		0.22	0.15
Staurastrum punctulatum Brébisson									1.41
Staurastrum subarmigerum J.Roy & Bisset							0.17	0.90
Staurastrum submonticulosum J.Roy & Bisset									1.32
Staurastrum teliferum var. gladiosum (W.B.Turner) Coesel & Meesters									0.29
Staurastrum tetracerum Ralfs ex Ralfs					0.45		0.20
Staurodesmus convergens (Ehrenberg ex Ralfs) S.Lillieroth									1.28
Staurodesmus cuspidatus (Brébisson) Teiling			0.70	0.70				0.70	0.70
Staurodesmus dejectus (Brébisson) Teiling				0.60
Staurodesmus glaber (Ralfs) Teiling			0.10		0.80			0.10	0.10
Staurodesmus incus (Hassal ex Ralfs) Teiling					0.40				0.13
Staurodesmus leptodermus (P.Lundell) Teiling									1.40
Teilingia granulata (J.Roy & Bisset) Bourrelly			0.20	0.80				0.20	0.20
Xanthidium antilopaeum Kützing					4.90		4.50		4.90
Xanthidium cristatum Brébisson ex Ralfs				1.99
Chlorophyta Reichenbach
Ankistrodesmus arcuatus Korshikov		0.10
Ankistrodesmus falcatus (Corda) Ralfs			0.10					0.10	0.10
Ankistrodesmus fusiformis Corda	0.60	0.25				0.10			0.10
Ankistrodesmus spiralis (W.B.Turner) Lemmermann			0.10
Botryococcus braunii Kützing	0.28	0.10	2.53	0.10	0.15		0.10	0.10
Coelastrum astroideum De Notaris						0.20
Comasiella arcuata (Lemmermann) E.Hegewald, M.Wolf, Al.Keller, Friedl & Krienitz	0.20
Desmodesmus armatus (Chodat) E.H.Hegewald						0.10
Desmodesmus microspina (Chodat) P.M.Tsarenko			0.10	0.10	0.10	0.20
Desmodesmus spinosus (Chodat) E.Hegewald					0.10
Dimorphococcus lunatus A.Braun								0.50	0.50
Monoraphidium griffithii (Berkeley) Komárková-Legnerová	0.10	0.10
Mucidosphaerium pulchellum (H.C.Wood) C.Bock, Proschold & Krienitz	0.90
Neglectella solitaria (Wittrock) Stenclová & Kaštovský						0.16
Nephrocytium lunatum West							0.10
Oocystis lacustris Chodat			0.20	0.40
Pandorina morum (O.F.Müller) Bory	0.72	0.30	0.20		0.20	0.40		0.20	0.20
Pseudopediastrum boryanum (Turpin) E.Hegewald		0.20	0.40	0.20	0.20	0.30
Quadrigula korsikovii Komárek	0.10
Scenedesmus ellipticus Corda		0.10	0.10		0.20
Selenastrum bibraianum Reinsch	0.10				0.10
Sorastrum spinulosum Nägeli						0.40
Stauridium tetras (Ehrenberg) E.Hegewald		0.10				0.20
Tetradesmus obliquus (Turpin) M.J.Wynne						0.20
Tetraëdron minimum (A.Braun) Hansgirg						0.30
Volvox polychlamys Korshikov	3.82		0.10
Willea irregularis (Wille) Schmidle			2.48	0.10				0.10
Cyanobacteria Stanier ex Cavalier-Smith
Anabaena augstumalis Schmidle		0.21
Chroococcus turgidus (Kützing) Nägeli						2.80	1.40
Coelosphaerium kuetzingianum Nägeli			0.50
Merismopedia glauca (Ehrenberg) Kützing		0.10
Nostoc kihlmanii Lemmermann		1.13			0.10			0.10
Oscillatoria limosa C.Agardh ex Gomont	0.30				0.20	0.40	0.20
Oscillatoria princeps Vaucher ex Gomont	0.36				0.24
Oscillatoria tenuis C.Agardh ex Gomont			0.10
Spirulina abbreviata Lemmermann						0.10
Woronichinia naegeliana (Unger) Elenkin	0.57
Dinoflagellata Fensome & al.
Ceratium cornutum (Ehrenberg) Claparède & J.Lachmann					8.68
Ceratium hirundinella (O.F.Müller) Dujardin	27.16		5.97	5.97				253.46	5.97
Peridinium bipes F.Stein		1.66					7.11	43.80	7.11
Peridinium cinctum (O.F.Müller) Ehrenberg	5.72	5.72	3.81	3.81	3.81				3.81
Peridinium willei Huitfeldt-Kaas				3.62
Euglenophyta Cavalier-Smith
Colacium vesiculosum Ehrenberg				11.87	0.10		0.10
Lepocinclis acus (O.F.Müller) B.Marin & Melkonian		0.17				0.23
Monomorphina pyrum (Ehrenberg) Mereschkowsky	0.49	0.49				2.00
Phacus limnophilus (Lemmermann) E.W.Linton & Karnkowska						0.39
Phacus longicauda (Ehrenberg) Dujardin	1.69	1.69			1.13
Phacus orbicularis Hübner	1.55					2.13
Phacus pleuronectes (O.F.Müller) Nitzsch ex Dujardin		0.61			0.21
Trachelomonas acanthostoma var. minor Dreżepolski	0.37
Trachelomonas armata (Ehrenberg) F.Stein					0.83
Trachelomonas armata var. steinii Lemmermann	2.47
Trachelomonas australica var. granulata (Playfair) Deflandre		0.62
Trachelomonas crenulatocollis Maskell					1.16
Trachelomonas dubia Svirenko	1.35
Trachelomonas dybowskii Dreżepolski		0.84
Trachelomonas granulosa Playfair									0.25
Trachelomonas hispida (Perty) F.Stein	0.74	1.29						0.34
Trachelomonas superba Svirenko	1.90
Heterokontophyta Moestrup, R.A.Andersen & Guiry
Asterionella tekelili D.M.Williams, T.M.Schuster, E.Cesar & Jüttner	1.80		0.36
Aulacoseira sp.		2.40
Dinobryon bavaricum Imhof	0.90	0.90	0.20				0.20	0.94	0.20
Dinobryon cylindricum O.E.Imhof					0.40
Dinobryon divergens O.E.Imhof		4.50					0.30
Dinobryon divergens var. schauinslandii (Lemmermann) Brunnthaler							0.50
Dinobryon sertularia Ehrenberg	0.31					0.60	0.20	0.35	6.93
Encyonema silesiacum (Bleisch) D.G.Mann	1.47
Entomoneis ornata (Bailey) Reimer							2.70
Epithemia adnata (Kützing) Brébisson						0.30
Epithemia gibba (Ehrenberg) Kützing					2.58	47.00
Epithemia turgida (Ehrenberg) Kützing						1.64
Gomphonema sp.	1.15				0.27
Gomphonema acuminatum Ehrenberg	0.17								0.13
Gomphonema capitatum Ehrenberg	2.24
Pinnularia nobilis (Ehrenberg) Ehrenberg				6.42
Stauroneis phoenicenteron (Nitzsch) Ehrenberg		5.39
Stenopterobia anceps (F.W.Lewis) Brébisson ex Van Heurck	0.45	0.45							0.90
Tabellaria fenestrata (Lyngbye) Kützing	0.45	9.52	0.30	0.30	0.30			0.30	0.30
Tabellaria flocculosa (Roth) Kützing	34.27	14.69	0.54	0.54	0.54			0.54	3.26
Ulnaria ulna (Nitzsch) Compère	4.57				0.50	0.50
Urosolenia eriensis (H.L.Smith) Round & R.M.Crawford	0.31		0.70

). In general, the stations in the upper part of the valley were dominated by Charophyta, while in the lake’s plankton in the lower part of the river valley, diatoms were actively connected to them. A special position was occupied by the lake community at station 2, where Dinoflagellata dominated.

The statistical comparison of biological parameters (number of species, abundance and biomass) showed that three clusters can be distinguished (Figure 4). The first one unites Lakes 3, 5 and 6 with high species richness, abundance and biomass, where charophytes and green algae, as well as cyanobacteria, predominate. The second cluster includes lakes with medium diversity at stations 8 and 11, where charophytes come to the fore. The third cluster is represented by lakes in the upper part of the valley at stations 1 and 2 with the highest diversity. Thus, the biological parameters divide the basin into approximately three parts with characteristic features of the communities of the studied lakes: upper (stations 1 and 2), middle (stations 3, 5 and 6) and lower (stations 8 and 11).

Table 5. Biological variables of 14 sampling stations of Olyokma Nature Reserve, 2024.

Variable	St 1	St 2	St 3	St 4	St 5	St 6	St 7	St 8	St 9	St 10	St 11	St 12	St 13	St 14
No of Species	56	91	75	28	75	48	31	42	13	21	43	3	19	33
Abundance, thou. cells L−1	34	11	75	12	83	64	n/a	2	n/a	7	5	n/a	n/a	n/a
Biomass, mg L−1	135	309	230	55	78	99	n/a	59	n/a	90	79	n/a	n/a	n/a
Shannon H′ plankton	0.238	0.671	0.838	0.329	0.379	0.924	n/a	1.114	n/a	1.256	1.033	n/a	n/a	n/a
Index S plankton	1.25	1.32	1.91	2.35	1.52	1.66	n/a	1.42	n/a	1.61	1.57	n/a	n/a	n/a
Index S phytoperiphyton—average	1.59	1.93	1.77	2.35	1.87	1.66	1.87	2.37	2.02	1.45	1.57	1.50	2.06	1.61
Index S average	1.42	1.63	1.84	2.35	1.7	1.66	1.87	1.89	2.02	1.45	1.57	1.50	2.06	1.61

Note: Station numbering as in Table 1; “n/a”, data not available.

presents the average values of microalgae species richness (phytoplankton and phytoperiphyton, Appendix A 

Table A5. Occurrence on a six-point scale of algae and cyanobacteria species in 15 non-planktonic samples from water bodies of the Olyokma Nature Reserve, August 2024. Samples numbering as in Table 1.

Taxa	10	11	12	13	14	15	16	17	18	19	20	21	22	23	24
Cercozoa Cavalier-Smith
Spongomonas splendida (F.Stein) M.Hartmann & Chagas								1
Charophyta Migula
Actinotaenium capax var. minus (Schmidle) Teiling ex Ruzicka & Pouzar														1	1
Actinotaenium cucurbita (Brébisson ex Ralfs) Teiling	1						1				2
Bambusina borreri (Ralfs) Cleve												1
Closterium abruptum West	1
Closterium closterioides var. intermedium (J.Roy & Bisset) Ruzicka														1
Closterium dianae var. arcuatum (Brebisson ex Ralfs) Rabenhorst						1						1
Closterium jenneri Ralfs														5
Closterium leibleinii Kützing ex Ralfs								1					1		2
Closterium littorale F.Gay														1
Closterium navicula (Brébisson) Lütkemüller												1
Closterium setaceum Ehrenberg ex Ralfs	2
Closterium venus Kützing ex Ralfs	1						1							1
Cosmarium baileyi Wolle												1
Cosmarium bioculatum Brébisson ex Ralfs				2				2				1
Cosmarium blyttii var. novaesylvae West & G.S.West											1				1
Cosmarium botrytis Meneghini ex Ralfs								1					1		1
Cosmarium brebissonii Meneghini ex Ralfs												1
Cosmarium circulare Reinsch											1	1
Cosmarium contractum O.Kirchner												1
Cosmarium formosulum Hoff								1			2	1	1	1	1
Cosmarium granatum Brébisson ex Ralfs													3
Cosmarium hammeri Reinsch	1
Cosmarium humile Nordstedt ex De Toni							1
Cosmarium impressulum Elfving				2				1
Cosmarium meneghinii Brébisson ex Ralfs													2
Cosmarium obsoletum (Hantzsch) Reinsch							2				2			1	1
Cosmarium ochthodes Nordstedt		3
Cosmarium pachydermum P.Lundell															1
Cosmarium pachydermum var. minus Nordstedt														1
Cosmarium porteanum W.Archer											2			1
Cosmarium pseudoexiguum Raciborski							1
Cosmarium pseudopyramidatum P.Lundell															1
Cosmarium punctulatum Brébisson				2		1		1				2
Cosmarium regnellii Wille				1			1			1		2		1
Cosmarium regnesi Reinsch							3					1
Cosmarium sexnotatum var. tristriatum (Lütkemuller) Schmidle				1		1
Cosmarium subprotumidum Nordstedt													2
Cosmarium subundulatum Wille											1
Cosmarium trilobulatum var. depressum Printz												1		1
Cosmarium ungerianum var. subtriplicatum West & G.S.West														1	1
Desmidium aptogonum Brébisson ex Kützing							2
Desmidium baileyi (Ralfs) Nordstedt							2				2	3			2
Desmidium coarctatum Nordstedt															1
Desmidium graciliceps (Nordstedt) Lagerheim												1
Desmidium swartzii C.Agardh ex Ralfs				2								1			2
Elakatothrix parvula (W.Archer) Hindák												1
Euastrum ansatum Ehrenberg ex Ralfs							3					1
Euastrum bidentatum Nägeli												1
Euastrum binale var. minus (West) Willi Krieger							2
Euastrum crassicolle P.Lundell							1
Euastrum didelta Ralfs											1
Euastrum elegans Ralfs								1
Euastrum gemmatum Ralfs												1
Euastrum neosinuosum O.V.Anissimova & Guiry	3
Euastrum pulchellum Brébisson												2			1
Gonatozygon aculeatum W.N.Hastings											1
Gonatozygon brebissonii De Bary											1
Gonatozygon monotaenium De Bary				1
Groenbladia undulata (Nordstedt) Kurt Förster							2
Haplotaenium rectum (Delponte) Bando	1											1
Hyalotheca mucosa Ralfs							1
Micrasterias crux-melitensis Ralfs	1														1
Micrasterias pinnatifida Ralfs											1				1
Mougeotia laetevirens (A.Braun) Wittrock				6
Octacanthium bifidum var. latidivergens (West) Petlovany												1
Penium margaritaceum Brébisson ex Ralfs														1
Pleurotaenium clavatum (Ralfs) De Bary															1
Pleurotaenium ehrenbergii (Ralfs) De Bary												1
Spirogyra sp. st.														6	6
Spondylosium lundellii O.Borge							2					3
Staurastrum avicula var. lunatum (Ralfs) Coesel & Meesters															1
Staurastrum boreale West & G.S.West	1			1								1
Staurastrum brevispina Brébisson	2											1
Staurastrum dilatatum Ehrenberg ex Ralfs												1
Staurastrum gemelliparum Nordstedt				1
Staurastrum gracile Ralfs ex Ralfs							1					1
Staurastrum granulosum Ralfs	2
Staurastrum manfeldtii Delponte															1
Staurastrum muticum Brébisson ex Ralfs														1	1
Staurastrum paradoxum Meyen ex Ralfs							1				1
Staurastrum punctulatum Brébisson						2		2				1		2
Staurastrum spiniferum West	1
Staurastrum teliferum var. gladiosum (W.B.Turner) Coesel & Meesters	1														1
Staurastrum vestitum Ralfs															1
Staurodesmus convergens (Ehrenberg ex Ralfs) S.Lillieroth											2				1
Staurodesmus cuspidatus (Brébisson) Teiling												1
Staurodesmus dejectus (Brébisson) Teiling												1
Staurodesmus glaber (Ralfs) Teiling								2
Teilingia granulata (J.Roy & Bisset) Bourrelly							2	3				1
Xanthidium antilopaeum Kützing															1
Chlorophyta Reichenbach
Acutodesmus acutiformis var. costatus (Huber-Pestalozzi) P.M.Tsarenko & D.M.John								2
Ankistrodesmus falcatus (Corda) Ralfs	1							3						1	2
Ankistrodesmus fusiformis Corda				2			1							1	1
Ankistrodesmus spiralis (W.B.Turner) Lemmermann								2				1
Aphanochaete repens A.Braun							1
Botryococcus braunii Kützing												1			1
Cosmarium angulosum var. concinnum (Rabenhorst) West & G.S.West							1						3
Desmodesmus armatus (Chodat) E.H.Hegewald						2		1		1		1
Desmodesmus denticulatus var. linearis (Hansgirg) Hegewald							2
Desmodesmus microspina (Chodat) P.M.Tsarenko													2
Dimorphococcus lunatus A.Braun							1					1
Monoraphidium contortum (Thuret) Komárková-Legnerová							1	3
Monoraphidium griffithii (Berkeley) Komárková-Legnerová							3	3
Monoraphidium komarkovae Nygaard							1
Mucidosphaerium pulchellum (H.C.Wood) C.Bock, Proschold & Krienitz								2
Neglectella solitaria (Wittrock) Stenclová & Kaštovský				1				1
Oedogonium undulatum A.Braun ex Hirn									2		1
Oocystis parva West & G.S.West							1
Oocystis rhomboidea Fott												1
Pandorina morum (O.F.Müller) Bory							1					2			2
Pseudopediastrum boryanum (Turpin) E.Hegewald						1	3								1
Quadrigula korsikovii Komárek							2					1
Scenedesmus ellipticus Corda				1		3	1				2	2		1
Scenedesmus obtusus f. disciformis (Chodat) Compère								1
Stauridium tetras (Ehrenberg) E.Hegewald							1	2				2
Tetradesmus obliquus (Turpin) M.J.Wynne						2		3						2
Tetraëdron minimum (A.Braun) Hansgirg						2		2
Ulothrix zonata (F.Weber & Mohr) Kützing			6
Verrucodesmus verrucosus (Y.V.Roll) E.Hegewald														1
Westella botryoides (West) De Wildeman								1
Willea irregularis (Wille) Schmidle							1					1
Cyanobacteria Stanier ex Cavalier-Smith
Anabaena oscillarioides Bory ex Bornet & Flahault														1
Anagnostidinema amphibium (Gomont) Strunecký, Bohunická, J.R.Johansen & Komárek													2
Anathece clathrata (West & G.S.West) Komárek, Kaštovský & Jezberová	2
Aphanocapsa conferta (West & G.S.West) Komárková-Legnerová & Cronberg	3
Aphanocapsa incerta (Lemmermann) G.Cronberg & Komárek	2													2
Chroococcus turgidus (Kützing) Nägeli	1						1
Lyngbya cincinnata (Itzigsohn) Compère															1
Merismopedia glauca (Ehrenberg) Kützing	1			1										1
Merismopedia tranquilla (Ehrenberg) Trevisan							1	1				2
Nostoc commune Vaucher ex Bornet & Flahault									6
Nostoc kihlmanii Lemmermann	2						1					1
Oscillatoria limosa C.Agardh ex Gomont	1								2	6	1			1
Oscillatoria princeps Vaucher ex Gomont										6				1
Oscillatoria proboscidea Gomont										6
Oscillatoria rupicola (Hansgirg) Hansgirg ex Forti															1
Oscillatoria tenuis C.Agardh ex Gomont								1	2			1
Phormidium ambiguum Gomont													2
Phormidium breve (Kützing ex Gomont) Anagnostidis & Komárek						6							1
Rivularia biasolettiana Meneghini ex Bornet & Flahault											1
Scytonema coactile Montagne ex Bornet & Flahault					6				2			6
Snowella lacustris (Chodat) Komárek & Hindák												1			1
Spirulina abbreviata Lemmermann						1
Dinoflagellata Fensome & al.
Ceratium hirundinella (O.F.Müller) Dujardin							1
Peridinium bipes F.Stein							1
Euglenophyta Cavalier-Smith
Lepocinclis oxyuris (Schmarda) B.Marin & Melkonian															1
Monomorphina pyrum (Ehrenberg) Mereschkowsky															1
Phacus orbicularis Hübner				1									2	2	1
Trachelomonas armata (Ehrenberg) F.Stein															1
Trachelomonas crenulatocollis Maskell															1
Trachelomonas dybowskii Dreżepolski							1								2
Trachelomonas granulosa Playfair															1
Trachelomonas lacustris Dreżepolski							1
Trachelomonas oblonga Lemmermann															1
Trachelomonas superba Svirenko															1
Trachelomonas woycickii Koczwara													1
Heterokontophyta Moestrup, R.A.Andersen & Guiry
Didymosphenia geminata (Lyngbye) Mart.Schmidt						4
Dinobryon sertularia Ehrenberg					1			1				2
Entomoneis ornata (Bailey) Reimer								1
Epithemia gibba (Ehrenberg) Kützing						1		1
Meridion circulare (Greville) C.Agardh		2	2			1
Nitzschia acicularis (Kützing) W.Smith						2
Rhoicosphenia abbreviata (C.Agardh) Lange-Bertalot						3
Stenopterobia anceps (F.W.Lewis) Brébisson ex Van Heurck											1	1			1
Surirella librile (Ehrenberg) Ehrenberg								1
Tabellaria fenestrata (Lyngbye) Kützing				1	2		3		2		3	3		2	3
Tabellaria flocculosa (Roth) Kützing						1	2	2	3		2	1		3	1
Tribonema vulgare Pascher						2	2
Ulnaria ulna (Nitzsch) Compère						2

), phytoplankton abundance and biomass, and index values calculated for the communities of the studied stations along the Olyokma River valley. The summary data show that the total number of species tends to decrease down the river valley, as do the abundance and biomass discussed in detail above (Table 2, Table 3 and Table 4). However, the community complexity, as reflected in the Shannon indices, increases, indicating a healthy ecosystem, even though the saprobity indices increase in the same direction (Figure 5a), indicating an increase in nutrient concentration (Figure 3b). That is, the identified biological indicators change with a downward trend (Figure 5b) under the influence of natural factors, which is typical for a nature reserve.

3.3. Bioindicators

Biodiversity itself can characterize the main features of the dynamics of the identified communities, as shown above and seen in Figure 6a with a downward trend down the river valley. But bioindication based on the preferences of the species that make up the communities under study helps to identify in detail the indicators that affect the communities in this way. Figure 6 and Figure 7 show the distribution of bioindicators for seven main environmental indicators. Only phytoplankton samples were taken for the bioindicator analysis to avoid aberrations in the results. It is evident that the proportion of planktonic inhabitants decreases down the river valley, while the proportion of planktonic-benthic species increases, indicating an expansion of substrate development (Figure 6b). Eurythermal species generally predominate, which are displaced by temperate species in the lakes of the lower part of the river valley (Figure 6c), reflecting a decrease in water warming. The communities are dominated by species that prefer both stagnant waters, typical of small lakes, and stagnant-flowing waters with medium oxygen saturation (Figure 6d).

The dynamics of pH indicators (Figure 7a) is interesting when acidophilic species of the lakes in the upper part of the valley are replaced by indifferent and then alkaliphilic species. Apparently, this is one of the characteristic features of the dynamics of the indicators in the catchment area of undisturbed permafrost areas. The salinity of the waters of the studied lakes has a similar tendency to increase (Figure 7b). The trophic status indicators, on the contrary, show a high proportion of eutrophic species in the lakes of the middle part of the valley, and their replacement by mesotrophic ones in its lower part (Figure 7c). This decrease in trophism can also be a characteristic feature for the waters of the undisturbed catchment area in the permafrost zone. The organic pollution indicators also divided the lake communities into three parts (Figure 7d), separating the lakes of stations 1 and 2 in the upper part of the river valley with the second quality class, then the middle part of the valley with the water quality of class 3 and the lower part again with a predominance of clean water indicators.

The network plot of indicator species abundance similarity in groups based on Appendix A 

Table A6. Average abundance (thou. cells per L) in ecological groups of indicators of phytoplankton in nine planktonic samples from water bodies of the Olyokma Nature Reserve, August 2024. Samples numbering as in Table 1.

Indicator	St 1	St 2	St 3	St 4	St 5	St 6	St 8	St 11	St 14
Habitat
B	598.4	299.2	1579.3	224.4	675.5	1356.6	598.4	598.4	598.4
P-B	2101.2	4676.1	14,708.4	10,866.4	68,890.8	23,772.8	972.4	3832.9	4655.7
P	23,115.5	5134.0	55,528.8	374.0	11,931.7	37,903.2	224.4	448.8	1196.8
Temperature
temp	74.8	0	2152.2	0	0	112.2	0	149.6	1808.8
eterm	528.1	301.5	4984.4	74.8	74.8	2488.8	0	149.6	752.5
warm	0	0	0	0	0	0	0	0	149.6
Oxygen
aer	0	0	0	0	0	224.4	74.8	0	149.6
str	0	0	340.0	0	74.8	0	0	0	0
st-str	1276.1	4152.5	10,859.6	9739.9	37,996.1	19,138.6	523.6	1346.4	4057.3
st	149.6	299.2	23,684.4	224.4	30,445.9	785.4	299.2	2112.5	598.4
Salinity
hb	600.7	149.6	34,224.4	299.2	525.9	1356.6	74.8	374.0	149.6
i	24,391.6	9510.9	18,681.3	1122.0	79,698.3	52,907.4	972.4	3309.3	3903.2
hl	0	0	564.4	149.6	224.4	0	149.6	74.8	299.2
mh	0	0	112.2	0	0	112.2	0	0	453.3
Water pH
acf	8076.1	600.7	5888.8	374.0	673.2	4637.6	374.0	822.8	149.6
ind	1348.7	748.0	6670.8	10,342.8	68,519.1	12,903.0	748.0	2935.3	2547.7
alf	0	0	1812.2	0	0	0	224.4	299.2	2108.0
alb	0	0	0	0	0	0	0	0	149.6
Autotrophy-Heterotrophy
ats	74.8	0	340.0	0	74.8	0	0		149.6
ate	0	0	1360.0	0	0	0	0	149.6	1509.6
hne	0	0	0	0	0	0	74.8	0	0
Trophic state
ot	374.0	149.6	0	528.1	149.6	224.4	0	224.4	149.6
om	224.4	74.8	904.4	224.4	374.0	673.2	224.4	448.8	1659.2
m	7849.5	598.4	3508.8	523.6	12,385.1	785.4	374.0	598.4	897.6
me	149.6	0	336.6	149.6	0	1020.0	149.6	149.6	299.2
e	299.2	3322.9	19,828.8	374.0	37,619.9	3393.2	224.4	374.0	1496.0
Class of Water Quality
Class 1	224.4	0	792.2	74.8	301.5	0	74.8	224.4	0
Class 2	23,641.3	8611.1	5776.6	976.9	30,894.7	10,414.2	598.4	2486.5	2706.4
Class 3	448.8	451.1	22,195.2	9440.7	12,006.5	11,094.2	299.2	822.8	2094.4
Class 4	528.1	149.6	4872.2	74.8	149.6	2264.4	0.0	224.4	149.6

Note: Ecological groups abbreviations: Habitat (P—planktonic, P-B—plankto-benthic, B—benthic); Temperature preferences (temp—temperate, eterm—eurythermic, warm—warm-water); oxygenation and water moving (Oxygen) (aer—aerophiles, str—streaming water, st-str—low streaming water, st—standing); Salinity ecological groups according to [43] (hb—oligohalobes-halophobes, i—oligohalobes-indifferent, hl—halophiles, mh—mesohalobes); pH preferences groups (Water pH) according to [42] (alb—alkalibiontes, alf—alkaliphiles, ind—indifferent, acf—acidophiles); nitrogen uptake metabolism (Autotrophy-Heterotrophy) according to [44]: ats—nitrogen-autotrophic taxa, tolerating very small concentrations of organically bound nitrogen; ate—nitrogen-autotrophic taxa, tolerating elevated concentrations of organically bound nitrogen; hne—facultative nitrogen-heterotrophic taxa, needing periodically elevated concentrations of organically bound nitrogen. Trophic state indicators according to [44]: (ot—oligotraphentic, om—oligomesotraphentic, m—mesotraphentic, me—mesoeutraphentic, e—eutraphentic); Index S, species-specific index saprobity according to [45] (Class of Water Quality).

shows the division of the indicator composition into three clusters (Figure 8). The first unites indicators in lakes in the lower part of the river valley, the second in the upper part of the valley, and the third lakes at stations 4 and 14, which are similar in their proportions of habitat indicators, oxygen and trophic state. Apparently, these three indicators are the factors dividing communities into similarity groups.

In order to establish whether this is so, a calculation of the similarity of the combined data on biological indicators and chemical variables for the same nine stations was carried out (Figure 9). It turned out that three clusters in the analysis of combined environmental and biota data completely coincide with the distribution of similar stations in the comparison of only groups of bioindicators. That is, the number of indicator species can characterize the main sets of diversity and the chemistry of lake waters within the studied river valley. In addition, it can be noted that the similarity in biological indicators and in the chemistry of lake waters is equally allocated to a separate cluster of lakes in the upper part of the valley at stations 1 and 2.

The similarity tree of only biological data at the nine studied stations of the basin identifies two main groups and one lake at station 2 (Figure 10); however, according to this calculation, it is not possible to divide the available set in relation to parts of the catchment basin.

The calculation of the similarity tree for all biological indicators also shows two main groups, one of which can be attributed to the upper part of the river basin and the second is mixed (Figure 11).

The tree of similarity of all biological and chemical data repeats the distribution into groups by biological indicators (Figure 12) at a similarity level of about 50%. This indicates that the ecosystem of the studied lakes changes in the totality of environmental and biological indicators, i.e., it exists in natural conditions for a given catchment area.

3.4. Species–Environmental Relationships

The statistical ratios of the main environmental factors influencing the species richness, the number of species by phyla, and the Shannon and saprobity indices are shown in Figure 13. The site numbers of the studied lakes are also shown here. It is evident that three packages of indicators can be distinguished in general. Nitrates and water temperature stimulate the abundance of phytoplankton and the growth of the diversity of euglenophytes and the saprobity index S at sites 3, 4, and 6. The growth of the total salt saturation (TSS) and carbonates improves the community structure with an increase in the Shannon index at sites 1, 8, 11, and 14. The third package of parameters is associated only with an increase in the concentration of chlorides, which stimulate the total number of species, biomass, and the number of charophyte, green, and cyanobacteria species. Interestingly, this package is positively associated only with the community at station 2 in the upper part of the river valley, while the other stations are in antiphase with it. The results of the RDA analysis detail the previously identified patterns in the distribution of biodiversity data, community structure and environmental parameters. While Figure 5a,b show a general pattern of decreasing species richness, abundance and biomass with a simultaneous increase in the saprobity index and Shannon index with some fluctuations at stations 2, 4 and 8, the RDA relationship analysis details and groups the environmental and phytoplankton data into three groups, thereby identifying the features of community response to changes in the Olyokma River environmental parameters.

4. Discussion

A variety of water bodies were studied in the Olyokma Nature Reserve, differing in water temperature, pH, total mineralization, hardness, and content of nutrients and organic matter. The increased color index and high concentrations of total iron, ammonium nitrogen, nitrate nitrogen, and difficult-to-oxidize organic matter (COD) noted for some of the studied water bodies are due to natural causes and possibly global climatic phenomena. Thus, it is known that due to insufficient drainage of permafrost soil and additional runoff from the catchment area due to intensive thawing processes, water bodies in the cryolithozone are often over-enriched with carbon and organic matter [46]. In addition, the melting of permafrost could result in the release of previously frozen organic matter and nutrients and their entry into surface waters [47,48]. There are studies confirming that atmospheric precipitation can be a significant source of nitrogen and phosphorus compounds in water bodies. However, nutrients entering water bodies from atmospheric precipitation could affect phytoplankton only in areas with developed industry or urban infrastructure [49]. There are no other likely sources of nutrients in the area. However, one should not exclude the possibility of nutrients entering the studied water bodies along with precipitation, since there is data confirming the possibility of nitrogen compounds being transferred with air masses over long distances. Thus, in long-term studies of the concentration of ammonia-nitrogen in the Sargasso Sea off Bermuda, the authors were able to postulate that a large fraction of naturally occurring ammonia is contributed to surface waters by rainfall [49]. The low pH value that we noted in Pool 1 (station 9) is often observed in some water bodies in the taiga part of Yakutia. This phenomenon, according to the famous Soviet geochemist, Professor A.I. Perelman, is caused by the entry of carbonic acid, fulvic acids, and other organic acids into the waters. In the waters of the cryolithozone of taiga Yakutia, dissolved organic matter (DOM) makes up from 10 to 75% of the total amount of dissolved substances, and the main component (DOM) is fulvic acids—substances of a humic nature [50]. A.I. Perelman points out that if there are not enough strong cations in the waters to completely neutralize the acidity, then the environment in such reservoirs is acidic or slightly acidic with a pH of 3–4 to 6.5.

The combined species list of algae of Olyokma Nature Reserve, obtained on the basis of data of O.Yu. Rozhkova [16] and our own collections in 2011 of plankton in the Olyokma River [17], after its revision in accordance with modern taxonomic data, comprised 328 species and varieties, and one determination was made only to the genus. After combining these data with our results obtained from the 2024 collections, the species list of the Olyokma Nature Reserve increased to 519 taxa, and four determinations were made only to the genus. Thus, as a result of processing the materials of the 2024 collections, the species list of algae of Olyokma Nature Reserve was replenished by 191 taxa of the rank below the genus. It is important to note that among the algae identified in 2024, 78% of the taxa were new to the flora of Olyokma Nature Reserve.

To more fully assess the current level of study of the algae of Olyokma Nature Reserve, it is advisable to compare it with the available data on the flora of algae of neighboring protected areas in the region. Vitim Nature Reserve is located 520 km southwest of Olyokma Nature Reserve. Studies of phytoplankton of a few mountain lakes, including the large Oron Lake, as well as floodplain reservoirs, were conducted on its territory. The researchers provided information on 119 species and varieties of algae from 56 genera and seven divisions [51]. The leading position is occupied by diatoms (34 taxa below the rank of genus), making up more than 28% of the total number of species; in second place are green algae (30 taxa below the rank of genus)—more than 25% of the species list of Vitim Nature Reserve algae. In the plankton of the large deep-water reserve Oron Lake, 67 species and varieties from seven divisions have been recorded [51]. Researchers note that more than half of the species composition of the plankton of Oron Lake are common with Lake Baikal, including Baikal endemics: Synechocystis limnetica Popovskaja, Gymnodinium baicalense var. minor N.L.Antipova and Stephanodiscus meyeri Genkal & Popovskaya.

The Bolshoye Toko resource reserve, which will soon be transformed into a federal national park, is located 550 km southeast of the Olyokma Nature Reserve. Algological studies of the large glacial Bolshoye Toko Lake, wetlands on its shores, and the source of the Mulam River flowing out of the lake were carried out on its territory [52,53,54,55,56,57]. The study of the Heterokontophyta flora using scanning electron and transmission microscopy methods allowed us to identify 189 species in the Bolshoye Toko resource reserve, including 162 species and varieties of pennate, 10 centric diatoms, and 17 species and varieties of scaly chrysophyte algae. A new representative of the relict diatom flora, Pliocaenicus bolshetokoensis Genkal, Gabyshev & Kulikovskiy, was found and described for the first time in the plankton of Bolshoye Toko Lake [53]. A rare species, Discostella guslyakovyi Genkal, Bondarenko & Popovskaya, was found in Bolshoye Toko Lake. This is another representative of the diatom flora, which was previously discovered in the mountain Nichatka Lake, located 230 km west of the Olyokma Nature Reserve [58]. Six species of diatoms and two species of scale chrysophytes, first recorded for the flora of Russia, were found in Bolshoye Toko Lake: Cymbopleura cf. lura Miho et Krammer, Fragilaria perminuta (Grunow) Lange-Bertalot, Gomphonema parallelistriatum Lange-Bertalot & E.Reichardt, Pinnularia cf. neomaior var. inflata Krammer, Pinnularia cf. stidolphii Krammer, Planothidium cf. distinctum (Messikommer) Lange-Bertalot, Mallomonas inornata K.H.Nicholls and Synura synuroidea (Prowse) Pusztai, Certnerová, Skaloudová & Skaloud [54,55,56].

Thus, the microalgae flora of Olyokma Nature Reserve is relatively diverse. However, the absence of large mountain lakes of glacial origin here has led to the absence of rare and endemic species.

The significant influence of catchment and bottom sediment variables on the taxonomic diversity and structure of plankton communities has been previously noted by researchers [59,60,61,62]. The high nutrient content that we noted for many of the studied water bodies, due to the influence of permafrost, was the reason for the high abundance and biomass of lake phytoplankton. There are studies demonstrating the effect of increased nutrient availability associated with permafrost degradation on the growth of biomass of primary producers in water bodies [63]. High values of biological indicators of microalgae, including the number of species, abundance, as well as the abundance and biomass of phytoplankton, which we noted at stations in the upper part of the river valley, decreased at stations in the lower part of the relief. At the same time, an increase in the concentration of ammonium, nitrates and phosphates in the water of the lakes was noted toward the bottom of the river valley. The saprobity indices increased in the same direction, indicating an increase in the concentration of nutrients. Apparently, the growth of microalgae, i.e., the inclusion of nutrients for cell reproduction at stations in the upper part of the valley, led to their depletion and a decrease in the concentrations of dissolved nutrients. The taxonomic selectivity of spatial changes in the abundance of phytoplankton in the gradient of altitude and nutrient concentration was manifested in the change of dominants from diatoms at the upper stations to green algae and then to cyanobacteria. Similar patterns were noted by researchers for lakes in the cryolithozone of Western Siberia [64]. Differential needs for nutrients, the difference in the rate of their absorption and in the possibilities of accumulation in different taxonomic groups of microalgae, along with other environmental conditions, control the composition of the phytoplankton community [65,66].

Despite the observed tendency for the total number of species to decrease down the river valley, we have detected a simultaneous increase in the Shannon index values. This indicates that the structure of microalgae communities becomes more complex down the valley. With depletion and decreases in nutrient concentrations, the community levels out, and with the expansion of substrate development down the valley, the proportion of planktonic inhabitants decreases while the proportion of planktonic-benthic species increases. This phenomenon we have noted, as well as the replacement of acidophilic species in the lakes of the upper part of the valley with indifferent and then alkaliphilic species in the lakes of the lower part of the relief, is one of the characteristic features of the dynamics of indicators of undisturbed permafrost catchment basins. This is also indicated by a decrease in trophism from the upper stations of the valley to the lower ones, as evidenced by the replacement of eutrophic species in the composition of trophic status indicators with mesotrophic ones. This suggests that the ecosystem of the lakes under study is transformed in accordance with environmental changes and biological processes, that is, it functions in accordance with the natural conditions characteristic of a given catchment area.

5. Conclusions

The water bodies in the territory of a natural protected area were studied. Some of them were characterized by increased nutrient content, which was due to the features of permafrost catchment basins. The total number of microalgae taxa identified as result of our work was 246. The species list of microalgae of Olyokma Nature Reserve was replenished by 191 taxa of the rank below the genus, and currently, considering our new data, has 519 taxa. In comparison with other protected areas of the region, the microalgae flora of Olyokma Nature Reserve is distinguished by its diversity. A relationship was established between the nutrient content and an increase in the number of species and abundance of microalgae, as well as the number and biomass of phytoplankton. An increase in the saprobity index was also a response to the high nutrient content. The growth of microalgae leads to the depletion of nutrients and a decrease in their concentration. In the gradient of ammonium, nitrates and phosphates concentrations, a change in dominants was revealed from diatoms at the upper stations to green algae and then to cyanobacteria. With the depletion of nutrients, the alignment of the microalgae community and the complication of its structure were noted, which was confirmed by the growth of the Shannon index. A decrease in trophism, the replacement of eutrophic species with mesotrophic ones, and acidophilic species with indifferent ones and then with alkaliphiles, demonstrates the stability of aquatic ecosystems in the permafrost natural area. Our studies show that the Olyokma Nature Reserve territory is suitable as a reference site for the subsequent assessment of the impact of global climate change in a permafrost area. The prospects for the future development of this study is the need to continue the work on the study of microalgae of the Olyokma Nature Reserve to obtain data on the interannual and seasonal variability of the aquatic ecosystems of the reserve. This will expand knowledge about the species diversity of this group of microorganisms and their relationships with the environment in permafrost conditions.