BOTANY WITH BASICS OF HYDROBOTANY (AQUATIC PLANTS OF UKRAINE) - B.Ye. Yakubenko - 2011

VI. THE PLANT WORLD SYSTEM

LOWER SPORE PLANTS

GENERAL CHARACTERISTICS AND FEATURES

Diversity of algae and their distribution in Ukraine

As noted previously, The Diversity of described algal species on Earth exceeds 40,000. However, taking into account the wealth of forms in understudied regions, their estimated number may increase 4-8 fold or even 250-fold, potentially reaching around 10 million species. Currently, probably only about 15% of the total number of algal species is known.

The Study of algal diversity in Ukraine has been underway for over a century and a half, and its algoflora is considered one of the richest in Europe. The first records of individual Black Sea algal species appear in the works of C. Agardh and D. Leveille from the 1830s and 1840s; however, targeted research into the species composition of Algae in both marine areas and freshwater bodies of our country began only in the 1860s and 1870s. Subsequent studies focused on investigating the algal wealth across various types of Water bodies and soils in Ukraine.

In the late 20th century, Ukrainian phycologists completed the publication of the 12-volume (16 books) "Flora of Freshwater Algae of the Ukrainian SSR" (1938–1993), dedicated to the main algal phyla and their diversity in freshwater habitats. In addition, the species richness of Ukraine's algae is reflected in a series of independent identification guides and individual publications on general algology (e.g., "Algae: A Reference Book" - Kyiv: Naukova Dumka, 1989), as well as in the publications "Flora of Algae of Continental Water Bodies of the Ukrainian SSR", "Flora of Algae of Continental Water Bodies of Ukraine", "Flora of Continental Water Bodies of Ukraine" (1996–2007), the recently initiated series "Flora of Algae of Ukraine" (2009), and the summarizing nomenclatural-taxonomic and floristic-geographic compendium "Algae of Ukraine" (2006, 2009). Nevertheless, the degree of exploration of certain algal groups and specific territories of Ukraine is far from complete, making such work relevant to this day.

The algoflora of Ukraine (including freshwater, marine, soil, and aerophytic algal forms) currently numbers over 5,000 species, represented by approximately 6,000 infraspecific taxa (infraspec. taxa), belonging to 967 genera and 14 phyla of algae. These data indicate that Ukraine's algoflora encompasses over 42% of the global continental algal species composition and about 10% of Earth's total algoflora. The limited marine areas, the absence of oceanic basins, and the incomplete study of Ukraine's marine algoflora (especially the diversity of its microscopic representatives) significantly underestimate the region's contribution to planetary-scale algal diversity.

The core of species richness in Ukraine's algoflora is formed by green, streptophyte, diatom, blue-green, and euglenoid algae. These groups combine about 83% of the species (86% of infraspec. taxa) of continental habitats, or approximately 89% (79.6% of infraspec. taxa) of the total algal species composition in Ukraine's flora.

Green algae (Chlorophyta, excluding Streptophyta) number over 1,300 species (about 1,460 infraspec. taxa), accounting for 22.4% of the total species diversity in the country's continental water bodies, or 24.3% when marine forms are included. Green algae are the leading group in terms of species diversity, which is shaped primarily by true green (Chlorophyceae), trebouxiophyte (Trebouxiophyceae), and oedogoniophyte (Oedogoniophyceae) algae. These taxonomic groups (at the Class level) comprise about 80% of the species diversity of Ukraine's green algae, 23% of the algoflora of continental water bodies, or 23.2% of the total number of algal species in our country.

Other algal phyla in the flora of Ukraine are also quite diverse. In particular, streptophyte algae (Streptophyta) represent a species-rich group comprising over 1,100 taxa of species and infraspecific rank (775 species). This diversity is driven by zygnematalean algae (conjugates — Zygnematophyceae (Conjugatophyceae)), which are the richest in species diversity and are represented in our flora by over 700 species (about 950 infraspec. taxa). The basis of this class is formed by desmids (order Desmidiales) with over 600 species (820 infraspec. taxa). Charophytes, belonging to the same phylum, are sparse, numbering only about 60 species; however, this accounts for over 19% of the species Diversity of the global flora.

Diatoms (phylum Bacillariophyta) are represented by about 950 species (over 1,160 infraspec. taxa) inhabiting the continental biotopes and marine areas of Ukraine. Brackish-water forms account for over 36% of the identified diatoms in Ukraine's algoflora. The core of this phylum's species composition is formed by Representatives of the Bacillariophyceae (about 600 species and 800 infraspec. taxa). Central diatoms in the flora of Ukraine exhibit low species diversity (around 100 species).

The species diversity of blue-green and euglenoid algae is lower than that of the aforementioned groups. Specifically, blue-green algae — Cyanoprocaryota (Cyanophyta) are represented by about 580 species (over 680 infraspec. taxa) in continental water bodies, and 650 species (770 infraspec. taxa) including marine forms, while Euglenophyta comprise 370 species (around 520 infraspec. taxa).

The species diversity of red (Rhodophyta) and brown (Phaeophyta) algae stands at about 150 species (over 160 infraspec. taxa) and about 80 species (around 90 infraspec. taxa), respectively, which constitutes 3.1% and 1.6% of the total algoflora composition of Ukraine. The vast majority of species in these two phyla are marine forms, with only 37 red and 7 brown algal species known from freshwater biotopes in Ukraine's flora.

Low species diversity in the algoflora of Ukraine is characteristic of cryptophytes (Cryptophyta — 25 species), rafidophytes (Raphidophyta — 7 species), eustigmatophytes (Eustigmatophyta — 9 species), and glaucocystophytes (Glaucocystophyta — 3 species). However, these groups are generally characterized by low species richness on a global scale and insufficient levels of study.

Over the period of studying Ukraine's algoflora, 53 genera and 552 taxa of species and infraspecific rank have been described and recognized as independent, with the highest number of taxa new to science being described among green, euglenoid, golden, blue-green, and streptophyte algae.

The distribution of Ukraine's algal species composition across natural-climatic zones and geographical regions is uneven. Algae are most richly represented in the biotopes of the Forest-Steppe, where over 2,700 species (3,300 infraspec. taxa) have been identified. Their diversity in other lowland regions of Ukraine — the Ukrainian Polissya and the Steppe — is somewhat lower, numbering 2,400 species (about 3,100 infraspec. taxa) and 2,300 species (over 2,700 infraspec. taxa), respectively. Mountain regions of Ukraine proved to be much poorer, with about 1,200 species (1,700 infraspec. taxa) known for the algoflora of the Ukrainian Carpathians, and only about 700 species (850 infraspec. taxa) for the Crimean Mountains. The physiographic features of each region of Ukraine, the genesis of regional flora, the ecological properties of taxonomic groups, and the degree of their exploration account for the observed differences in floristic and systematic diversity of algae. At the same time, the systematic ratio of leading groups among the compared floras demonstrates a certain constancy and consistency with the general systematic Structure of Ukraine's algoflora—namely, the foundation of species diversity in most regions is formed by representatives of the phyla Chlorophyta, Streptophyta, Bacillariophyta, Cyanophyta, and Euglenophyta (in that order). Green algae (Chlorophyta) are the most diverse across all regions of Ukraine, although specific taxonomic groups within them exhibit certain variations or patterns in the number of forms typical of a particular region. However, this sequence of higher taxa is disrupted in the flora of the Crimean Mountains, which exhibits the highest diversity of diatoms, with this group ranking first in the number of forms. In addition, eco-systematic features of regional algofloras of Ukraine are evident, along with differences in diversity and, consequently, the rank of specific algal groups within the overall systematic sequence of leading taxonomic groups. In particular, desmids (Desmidiales) are most diverse (accounting for over half of the streptophyte species composition) in the forest and forest-steppe zones, as well as the Ukrainian Carpathians; high diversity is characteristic of green (flagellate and coccoid) Algae in the forest-steppe zone, which drops sharply in mountain regions; while the forest zone features the richest species composition of filamentous (oedogoniial) algae, in contrast to the steppe zone and the Crimean Mountains, where blue-greens and diatoms are the leading groups in terms of diversity.

These taxonomic features reflect certain eco-floristic patterns in the distribution of species composition among individual algal groups. At the same time, one must also account for the level of specialized research conducted in specific regions regarding the species composition of particular algal groups within regional algofloras (e.g., diatoms, golden algae, and blue-greens in the water bodies of the Crimean Mountains, or oedogoniial algae in the Ukrainian Polissya). It is precisely these data that contrast sharply against the general Background of other regions or other groups within a specific region.

At the same time, targeted monographic studies of certain algal taxonomic groups across the entire territory of Ukraine and corresponding analyses of the obtained data allow for General Conclusions regarding the patterns and features of their distribution throughout Ukraine, as well as highlighting the General Properties of algoflora in specific territories (or zonal characteristics) using individual algal groups as Examples, and noting their specific traits.

The distribution of specific algal groups exhibits certain regularities and specificities. Overall, the algoflora of Ukraine is a rich and diverse assemblage of species from various taxonomic groups, dominated in terms of species composition by the phyla Chlorophyta and Streptophyta. The core of species diversity in these phyla is formed by desmids (order Desmidiales), chlamydomonads (order Chlamydomonadales), and sphaeroplealeans (order Sphaeropleales). A leading role in the systematic structure of these groups is played by the family Desmidiaceae (86% of the total Desmidiales composition in Ukraine), which is not only a feature of Ukraine's desmid flora but also reflects the systematic ratio within these algal groups. Mountain regions of Ukraine differ sharply from each other in generic flora structure, as well as from the lowland flora. The desmid flora of the Crimean Mountains is characterized by extreme species poverty and a limited number of families and genera—in other words, a "simplicity" of systematic structure—likely caused by the extreme conditions for algal development in this part of Ukraine. The generic STRUCTURE OF THE desmid flora in the Ukrainian Carpathians differs significantly from that of the Crimean Mountains by its relative "complexity" and diversity, bringing it closer to the floras of lowland Ukraine. Overall, There is a trend toward decreasing desmid species diversity from north to south.

The flora of coccoid green algae in Ukraine is characterized by a high level of species diversity and the dominant significance of a limited number of families. This flora comprises over half of the Holarctic coccoid flora (54% of total species and 80% of generic composition). Species diversity of coccoid green algae in Ukraine's water bodies decreases from the Forest-Steppe southward (due to increasing mineralization of natural waters), and from the Forest-Steppe northward and in mountain regions (Ukrainian Carpathians, Crimean Mountains) due to decreasing mineralization and trophic levels of water bodies.

The main Factors Determining the development of coccoid green algae in Ukraine's water bodies are the absence of accelerated runoff, moderate water mineralization, and elevated nutrient content. Coccoid algae exhibit extremely low Abundance and species diversity in oligotrophic water bodies of the boreal and nemoral zones, transitioning from oligotrophic to eutrophic water bodies, and from weakly-to-strongly to moderately mineralized ones (3–6 g/L). Only in eutrophic standing waters or water bodies with slowed runoff do they frequently achieve high abundance and play a leading role as the primary component of phytoplankton.

The primary role in shaping Ukraine's desmid flora is played by three geographical elements: boreal, multizonal, and nemoral; whereas in the flora of coccoid green algae, it is played by the multizonal, nemoral, and evryholarctic elements. The high percentage of boreal and boreal-arctic elements in the desmid flora suggests an allochthonous origin for this flora, which formed As a result of the invasion of more northern migratory elements. At the same time, the elevated content of nemoral and evryholarctic species in the coccoid green algal flora of Ukraine indicates a migratory-autochthonous origin, having formed on the basis of tertiary flora remnants and the migratory expansion of the boreal-nemoral species complex.

The level of endemism (based on conditionally endemic taxa) accounts for only 4.6% of the total composition of coccoid green algae in this territory, and 3.2% among the desmid flora (of the total Desmidiales composition here). The relatively low percentage of endemic desmid taxa in Ukraine's algoflora points to the relative youth of this flora, which likely formed in the post-glacial period through the invasion of elements from adjacent geographical territories, particularly into the lowland areas.

The flora of desmid and coccoid green algae in Ukraine is characterized by a "one-sided" pattern of development, manifested in the dominance of a limited number of families and genera within its taxonomic composition. This clearly indicates significant transformations of this flora in the recent geological past, as well as its relative youth.

A characteristic feature of the taxonomic structure of the euglenophyte algae (Euglenophyta) flora in Ukraine is the dominant position of the typical family Euglenaceae alongside specific genera, such as Trachellomonas Ehrenb., Phacus Duj., and Euglena Ehrenb. This group of algae exhibits the same pattern in the distribution of species composition across Ukraine as do the coccoid green and desmid algae—namely, a gradual depletion of composition and a decrease in abundance in water bodies of the flatland part of Ukraine from north to south. This pattern is primarily driven by the increasing degree of mineralization of natural waters in this direction.

The depletion of species composition in the mountain regions of Ukraine is associated with an increase in the altitude of water bodies above sea level. In general, euglenophyte algae in the Ukrainian flora develop most intensively in the water Column and near the bottom of water bodies and watercourses with slow flow (ephemeral water bodies, ponds, and small rivers), featuring moderate water mineralization (up to 700 mg/L) and elevated concentrations of organic matter and nutrients.

The species composition of blue-green algae (Cyanophyta) in Ukraine comprises 650 species (800 infraspecific taxa) belonging to 89 genera. The highest diversity of these algae is observed during the warm summer-autumn period, whereas with the onset of autumn cooling, their diversity declines and the group loses its dominant position within the complex of leading taxa. The foundation of this floristic wealth is formed by representatives of the class Hormogoniophyceae (over 60%), while The Role of the other two classes (Chroococcophyceae and Chamaesiphonophyceae) in the overall composition of this algal group is significantly lower. At the same time, certain geographical patterns are noted regarding the distribution of blue-green algae across Ukraine, as well as the affinity of specific taxa for particular natural Zones of the country. In particular, representatives of the order Stigonematales and the families Stigonemataceae and Scytonemataceae evidently show a preference for the water bodies of the Ukrainian Polissya, whereas the ratio between the orders Oscillatoriales and Nostocales shifts toward an increased proportion of Oscillatoriales in the steppe zone of Ukraine, accompanied by the frequent occurrence of forms inclined toward brackish and saline water bodies.

Thorough floristic studies of blue-green algae in certain regions of Ukraine have shown that they are among the leading algal groups in the flora of Mountain Crimea. They develop most abundantly in watercourses (springs, waterfalls, irrigation canals) on hard inorganic substrates or dominate algal communities On the surface of irrigated rocks. Maximum diversity of Cyanoprokaryota is observed in rivers, springs, and waterfalls, whereas their diversity is minimal in basins and fountains. Periphytic and benthic-periphytic forms constitute the basis of the species composition of this algal group in Mountain Crimea, with their highest diversity recorded in stone foulings.

The primary limiting factors for The Development of blue-green algae in Mountain Crimea are water Temperature, light intensity, current velocity, and the degree of water availability in ephemeral habitats.

The diversity of diatoms (Bacillariophyta) in Mountain Crimea has been studied in considerable detail at the regional level. The diatom flora of Mountain Crimea water bodies is represented mainly by cosmopolitan species, yet it also includes montane elements, which highlights its distinctiveness compared to other floras. The leading position in terms of species number within this flora belongs to the class Bacillariophyceae. Diatoms are most diverse in rivers and springs, whereas they are sparsely represented in waterfalls and basins. The basis of floristic diversity for individual communities and the diatom flora of Mountain Crimea water bodies as a whole is formed by benthic and periphytic species.

The data presented demonstrate the richness of Ukraine's algal flora and the uneven distribution of algal species composition across its territory. The core of algal diversity in Ukraine is formed by representatives of green, streptophyte, diatom, blue-green, and euglenophyte algae. The degree of exploration varies among specific algal groups and their floristic compositions. Only a few taxonomic groups of the Ukrainian algal flora are characterized by a satisfactory level of floristic study. Although the insufficient exploration of certain groups obscures GENERAL PATTERNS OF species diversity distribution, targeted research on euglenophyte, desmid, and coccoid green algae in the flora of Ukraine reveals their substantial diversity, which decreases from northwest to southeast, from north to south, or from the forest-steppe zone toward the south and north. Further in-depth study of Ukraine's algal flora is essential to identify characteristic regional or general patterns and features, or to refine existing floristic concepts regarding the algal diversity of Ukraine.

Algae, like other living organisms and particularly plants, grow in environments subjected to anthropogenic pressure that leads to a loss of species diversity, and thus they require protection and conservation. The second edition of the Red Book of Ukraine (1996) included 18 algal species, whereas in the new 2009 edition, their number increased to 60 species (red algae – 18, brown algae – 11, yellow-green algae – 1, green algae – 13, streptophyte algae – 17). Therefore, it is both appropriate and urgent under current conditions to pursue not only floristic and taxonomic research but also algosozological measures aimed at developing principles and approaches for preserving the existing algal diversity of Ukraine. This issue is the focus of active efforts by phycologists in Ukraine and worldwide, particularly regarding the preparation of regional summaries, checklists, Red Books, and red lists.