Palaearctic gastropod gains a foothold in the dominion of endemics: range expansion and morphological change of Lymnaea (Radix) auricularia in Lake Baikal

In and around the endemic-dominated Lake Baikal, palaearctic species are generally restricted to shallow, sheltered bays and in- and out-flowing river floodplains. However, we observed populations of the palaearctic snail Lymnaea (Radix) auricularia on the steep, rocky littoral of Lake Baikal proper. We compared the morphology of 542 shells sampled from this new habitat with potential source populations from conventional habitats. A size-free Discriminant Analysis indicated a strong morphological differentiation of the newly established populations from their likely sources. The new populations had a more compact shell shape with a wide aperture, which may be advantageous in wave-exposed habitats where a firm attachment to the substrate is needed. Shells from the conventional habitats were more elongated, with a narrow aperture, which may be advantageous in habitats that have a dry period where retreating into the mud is required and water loss should be limited. These results may suggest that selection is acting on shell shape in Lake Baikal. The apparent recent arrival of this pandemic gastropod in a habitat previously dominated by endemics constitutes a potential ecological threat and an alert to possible ecological change.     

Finding a new form of the grayling Thymallus arcticus (thymallidae) in the basin of lake baikal

A dwarf form of the Arctic grayling Thymallus arcticus, inhabiting a group of small lakes at the origin of the Yakchii stream, which flows into the Verkhnyaya Angara River (basin of Lake Baikal), has been found in the northeastern watershed of the Baikal and Lena basins. The form is similar to upper Lena populations in body coloration and the pattern of dorsal fin. Our comparison by meristic characters indicated that the grayling of the Yakchii Lakes is more similar to the fish from Kutima River (basin of the upper courses of the Lena River) than to the black Baikal grayling T. arcticus baicalensis. The presence in Lake Baikal of a population similar to upper Lena graylings may have three causes: (1) possible drainage from Baikal to the pra-Lena via ancient valleys of the Barguzin and the Upper Angara; (2) appearance of transit zones as a result of glacial or tectonic events during the periods of watershed development between the Baikal and Lena basins; (3) the upper Lena grayling could be an endemic of the Baikal basin which was replaced by graylings penetrating from the Yenisei basin and remained in the form of relic populations in the upper courses of certain tributaries of the northern and northeastern parts of Lake Baikal.     

Diversity of 16S rRNA genes in metagenomic community of the freshwater sponge Lubomirskia baicalensis

Phylogenetic analysis of the nucleotide sequences of 16S rRNA genes in the metagenomic community of Lubomirskia baicalensis has revealed taxonomic diversity of bacteria associated with the endemic freshwater sponge. Fifty-four operational taxonomic units (OTUs) belonging to six bacterial phyla (Actinobacteria, Proteobacteria (class ??-Proteobacteria and ??-Proteobacteria) Verrucomicrobia, Bacteroidetes, Cyanobacteria, and Nitrospira) have been identified. Actinobacteria, whose representatives are known as antibiotic producers, is the dominant phylum of the community (37%, 20 OTUs). All sequences detected shared the maximal homology with unculturable microorganisms from freshwater habitats. The wide diversity of bacteria closely coexisting with the Baikal sponge indicate the complex ecological relationships in the community formed under the unique conditions of Lake Baikal.     

Centric diatoms from Lake Frolikha (Transbaikal area) and peculiarities of distribution of some taxa in Asia

The species composition of centric diatoms from Lake Frolikha (Transbaikal area) has been studied. The lake is located on the eastern shore of Lake Baikal and connected with it by a river. Twenty-three species of Centrophyceae from 7 genera (Aulacoseira, Cyclostephanos, Cyclotella, Discostella, Handmania, Pliocaenicus, and Stephanodiscus) have been found. The most represented genus is Aulacoseira (11 species). Fifteen species and 4 genera are new for the lake record. All revealed species are known in other lakes of the Baikal region; however Baikal endemics are absent in Lake Frolikha. The flora of centric diatoms in Lake Frolikha can be divided into two groups. The first group includes taxa common in Lake Baikal, and the second group includes taxa not typical for Lake Baikal. The level of differences between flora in Lake Baikal and Lake Frolikha is high (43%) despite the close location and connection to the river. An analysis of distribution of interesting species in Asia is presented.     

Diatom succession trends in recent sediments from Lake Baikal and their relation to atmospheric pollution and to climate change

Recent environmental change in Lake Baikal has been attributed to anthropogenic influences on the ecosystem, especially through pollution and cultural eutrophication. These hypotheses are tested in this paper principally by diatom analyses in 20 short sediment cores. Most of the cores were collected with a new type of box corer specifically designed for use on Lake Baikal. Most cores contain a good sediment record but turbidites occur in some sediment profiles which may be best recognized using a combination of techniques, such as radiometric dating and percentage dry weight analyses. The most recent sediments, especially those in the southern basin and in the very north of Baikal, contain a record of anthropogenic contamination in the form of lead and spheroidal carbonaceous particles, which confirms that the southern basin of Baikal is most affected by atmospheric sources of pollution. However, there is no sedimentary diatom evidence indicating offshore water quality deterioration in Baikal owing to air pollution or eutrophication. Small increases in diatoms which indicate nutrient enrichment (e.g. Stephanodiscus minutulus, Synedra acus v. radians and Synedra acus v. acus) may reflect local eutrophication of the shallow waters close to the Selenga Delta and certain coastal sites in the southern basin near to the Baikalsk paper and pulp mill. By using numerical techniques, Lake Baikal can be split into at least four regions on the basis of its surface sediment flora: the south, middle and north basins, and the shallow waters surrounding the Selenga Delta region. Diatom analyses reveal that the endemic flora of Lake Baikal has been constantly changing over at least the last 2000 years and that these fluctuations are probably responses to natural climatic variability. Recent sediments of Baikal may be affected by taphanomic processes (e.g. dissolution) and turbidite deposition, and these must be taken into account when interpreting the sedimentary diatom record. The diatom flora of the lake is currently dominated by several species, such as Aulacoseira baicalensis, A. islandica, Cyclotella minuta and Stephanodiscus binderanus v. baicalensis. All these species, except for C. minuta, have become more common in the lake in approximately the last 130 years, and we hypothesize that these changes may be attributed to a number of different processes linked to an ameliorating climate after the end of the Little Ice Age. The results presented here have important implications for this recently designated World Heritage Site, with regard to future pollution controls and catchment management policies.     

Lipid composition in muscle and liver of sympatric coregonid fishes from Lake Baikal (<Emphasis Type="Italic">Coregonus</Emphasis> spp.) under common garden experiment

The content of total lipids, total phospholipids, and fatty acids of total lipids in muscles and liver of juvenile Lake Baikal sympatric coregonid fishes have been analyzed for the first time under a common garden experiment. Baikal omul, Coregonus migratorius Georgi, is an active migrant of the pelagic zones of the lake. Baikal (lacustrine) whitefish, C. baicalensis Dybowski, is a colonizer of the bottom habitats, which are relevant to the pelagic zones of the littoral and underwater slope. Structural lipids (phospholipids and cholesterol) dominated in total lipids of the tissues of all fish under study. Spare lipids significantly prevailed in omul muscles when compared to whitefish. The highest variability of fatty acid composition was reported in muscles of coregonid fishes. Statistically significant differences were revealed in the content of the ω3 polyunsaturated fatty acids in muscles of lacustrine whitefish and omul. Associations of lipid compositions revealed in tissues of the whitefishes under the study with their respective ecotypes have been discussed.     

New data on the distribution of the Upper Lena form of grayling (Thymallidae) in the basin of Lake Baikal and its taxonomic status

The habitation of the Upper Lena form of grayling in the upper reaches of the Tiya (the northwestern tributary of Lake Baikal) and Barguzin rivers, where Baikal grayling Thymallus baicalensis Dyb. also occurs, was established. The listed forms can be diagnosed from the body coloration, dorsal fin pattern, combination of meristic characters, as well as by molecular-genetic methods. The sympatric habitation of the Upper Lena and Baikal graylings in the northern tributaries of Baikal, considerable phenotypic and genetic differences, as well as the absence of individuals with intermediate characters, make it possible to consider them as independent species. The results indicate the need to revise the intraspecies structure of the Arctic grayling T. arcticus (Pall.) and the entire genus Thymallus. The localization of populations of the Upper Lena grayling in the upper reaches of Baikal tributaries testifies to its possible penetration of the Baikal basin by means of temporary river catchments that formed in the past and which are probable at present at watersheds with the Lena River. A wider distribution of this form is apparently hindered by the pressure of aboriginal species.     

Ecological and geographic variability of Hedysarum theinum and features of its propagation in vitro

The relationship between the morphological variability of the productivity characteristics and the genetic variability of the electrophoretic spectra of seed polypeptides in the valuable medicinal species Hedysarum theinum Krasnob was established based on analyzing six cenopopulations. The protocols for the microclonal propagation of advanced samples were developed. The most efficient multiplication was achieved in an MS medium supplemented with 5 μM BAP, 200 mg/L^?1 glutathione, and 200 mg/L^?1 casein hydrolyzate. The shoots were successfully rooted on the half-strength MS basal medium supplemented with 7 μM NAA.     

New host species and new distribution areas of <Emphasis Type="Italic">Salmincola lavaretus</Emphasis> (Copepoda: Lernaeopodidae): A parasite of coregonid fishes of Siberia

Data on the infestation of certain fish species by the parasitic copepod Salmincola lavaretus are presented for the first time. The infested fish species included Bauntovsky whitefish (Coregonus baunti), an endemic species from the Maloye and Bolshoye Kapylyushi lakes; Siberian whitefish (C. pidschian) and Siberian cisco (C. sardinella) from Bolshoye Kapylyushi Lake and Baunt Lake, which belong to the Tsypo-Tsypikan lake system (the Lena River basin, Transbaikalia); and Teletsky whitefish (C. lavaretus natio smitti) from Teletskoe Lake (the Ob River basin). Previously, S. lavaretus had been described as a parasite of Baikal omul (C. migratorius) and Baikal whitefish (C. baicalensis) from Baikal. The taxons of S. longimanus complex (S. longimanus, S. l. sibirica, S. svetlanovi, and S. lavaretus)—parasites of nasal fossae of grayling and coregonid fishes—were registered in the lakes of the Lake Baikal basin (Lake Baikal and Khovsgol Lake), the Lena River, the Yenisei and the Ob rivers (the largest rivers of the Arctic zoogeographic province), and the Kobdo River (the Western Mongolian province). It was assumed that S. longimanus complex is more widely distributed in the water bodies of the Arctic zoogeographic province of the Palearctic.     

Graylings of Baikal Lake basin (Thymallus, Thymallidae): Diversity of forms and their taxonomic status

The morphological characters, molecular-genetic features, and patterns of the dorsal fin in different subspecies and forms of Arctic grayling Thymallus arcticus populating Lake Baikal and its tributaries, Irkutsk Reservoir, and Lake Khubsugul have been studied. Three groups are discernable. The first includes the white and black Baikal graylings T. a. baicalensis, as well as the western Siberian T. a. arcticus; the second group is represented by the Kosogol grayling T. a. nigrescens, and the third is composed of T. arcticus ssp. from the Yakchii lakes (the Verkhnyaya Angara basin) with a phenotype close to graylings populating the upper reaches of the Lena River. All of them are distinguished by some morphological characters, elements of the dorsal fin pattern, and by body coloration. The populations of black Baikal graylings are genetically uniform, and their distinctions from white Baikal graylings are insignificant, which agrees with the absence of a considerable divergence of these forms by a complex of meristic characters. It is assumed that in the black and white Baikal graylings the exchange by genetic information has either ceased quite recently, or persists, although, insignificantly. Some genetic remoteness of the west Siberian grayling from Irkutsk Reservoir and Nizhnyaya Tunguska, closely related to the Baikal grayling, is recorded. The formation of the Khubsugul subspecies is possibly a result of the contact of grayling populations during the rearrangements of the river system in the last glaciation period in the upper reaches of Yenisei and Selenga in Mongolia. The habitation in the Baikal system of the Upper Lena graylings indicates a connection between the Lena and Baikal basins in the past. The results of a multivariate analysis of meristic characters and the sequences of mitochondrial DNA confirm the conclusion made by Svetovidov (1931, 1936), concerning the absence of grounds to assign a species status to the Baikal forms.     

Ecogeographic variability and differentiation of Japanese dwarf pine populations in Kamchatka Krai with respect to the characters of generative organs

The assessment of ecogeographic variability and differentiation of 22 cenopopulations of Japanese dwarf pine Pinus pumila (Pall.) Regel (Pinaceae) on the Kamchatka Peninsula and in Koryakia has been carried out in regard to morphological and phenotypic characters of mature seed cones. The viability of seeds in the cones of ten populations has been determined by a radiographic method. A latitudinal nature of phenotypic differentiation of cenopopulations in the region has been revealed. Lower seed viability related to a high percent of seeds without embryos or with underdeveloped embryos has been recorded in the northeastern populations. The average share of viable seeds in the region is 52% and in the northeastern populations it reaches only 6–24%.     

Syntaxonomy of vegetation of the Svyatoi Nos peninsula, Lake Baikal 2. Forests and krummholz in comparison with other regions of northern Buryatia

Using the Braun-Blanquet approach, 7 plant communities of forests and 3 communities of krummholz were distinguished on the Svyatoi Nos Peninsula on the eastern coast of Lake Baikal. Dominant species of these communities areAbies sibirica, Larix sibirica, Pinus sibirica, P. sylvestris, P. pumila andBetula divaricata. The data from Svyatoi Nos were combined with all the available data from the northern part of the Republic of Buryatia (289 relevés) and classified into 23 communities. These have been assigned to the following alliances:Aconito rubicundi-Abietion sibiricae—floodplain forests with tall forbs and the relict occurrence of a few nemoral species,Pino sibiricae-Laricion sibiricae—mesic forests with (sub-Atlantic) boreal species and abundant mosses,Vaccinio-Pinion pumilae—krummholz communities of NE Asian distribution,Cladonio stellaris-Laricion gmelinii—Larix gmelinii dominated open forests on permafrosts with NE Asian distribution, andHieracio umbellati-Pinion sylvestris—xeric forests with southern Siberian species. Phytogeographical affinities of these alliances are discussed and a system of high-ranked syntaxa (orders, classes) is proposed for the northern Buryatian forests and krummholz.     

Sediment formation in Lake Baikal

The following stages in the formation of sediments in Lake Baikal have been distinguished. In the Middle Miocene lacustrine deposits accumulated in the southern depression. In Early and Middle Pliocene, as well as in Early-Middle Pleistocene the bottom of the southern and middle Baikal depressions was occupied by large lakes, but the northern basin was mainly dry with a system of small lakes, streams and rivers. This accounts for the great facies variety and the genetic heterogeneity of sediments in the northern depression. At the end of Middle and in the Late Pleistocene an abrupt warping of the depression took place, and a shore-line similar to the present one was formed. Sands in the upper part of the sediments are considered to be the product of intensive erosion which probably occurred in the pluvial epoch in the Late Pleistocene period.     

Microcystins in Cyanobacterial Biofilms from the Littoral Zone of Lake Baikal

Some species of cyanobacteria synthesize toxins whose concentration during water bloom can reach values dangerous for human and animal health. Planktonic cyanobacteria are the most common and well-studied microcystins producers, hepatotoxic cyclic heptapeptides, whereas microcystin-producing benthic cyanobacteria are less known. In recent years, the mass development of benthic cyanobacteria forming extensive fouling on different substrates has been detected in the littoral zone of Lake Baikal. We found microcystins produced by benthic cyanobacteria in the biofouling on different natural and artificial substrates, including diseased and dead endemic sponges Lubomirskia baicalensis and Baikalospongia spp. collected from the littoral area of Lake Baikal. Microscopic analysis of the biofouling revealed prevalence of representatives of Nostocales and Oscillatoriales with predominance of Tolypothrix distorta that is likely the main microcystin producer in Lake Baikal. According to enzyme-linked immunosorbent assay (ELISA), microcystin concentrations in biofouling were 29.8–3050 μg/kg dry weight. We identified eight microcystin variants using MALDI-TOF/TOF; [Dha7]MC-YR was detected in most samples. The presence of microcystins in biofilms formed on the surface of the artificial substrate by Phormidium autumnale was also recorded. The data obtained demonstrated the necessity to monitor potentially toxic species and concentrations of cyanotoxins in plankton and benthos in the littoral zone of Lake Baikal, especially in the regions with intense tourist and recreational activities.     

Genetic differentiation of the three species of genus Astragalus L. of section Cenantrum Bunge (Fabaceae)

Genetic differentiation based on allozyme data was detected between species of the genus Astragalus L., section Cenantrum Bunge (Fabaceae): A. frigidus (L.) A. Gray s. l., A. mongholicus Bunge s. 1., and A. sericeocanus Gontsch, which is endemic to the northeast coast of Lake Baikal. The results of allozyme analysis confirm the natural division of the section into subsections based on morphological features. Differences between A. frigidus (subsection Elliptica Gontsch.) and A. mongholicus and A. sericeocanus (subsection Semilunaria Gontsch.) were observed. These differences were caused by the presence of species-specific alleles and the allele frequencies of the primary alleles, D _N = 1.24. The genetic distance obtained for A. mongholicus and A. sericeocanus (0.10) corresponds to the status of closely related species of one subsection. Between populations of A. frigidus and between populations of A. mongholicus from the central part of areal, D _N = 0.02 and 0.03 respectively. This genetic distance corresponds to the interpopulation level and was determined by the allele frequencies. The peripheral population of A. mongholicus is separated (D _N = 0.36), which is probably due to the long isolation and the “founder effect.”

     

Microsporidian Parasites Found in the Hemolymph of Four Baikalian Endemic Amphipods

At present, approximately 187 genera and over 1300 species of Microsporidia have been described, among which almost half infect aquatic species and approximately 50 genera potentially infect aquatic arthropods. Lake Baikal is the deepest and one of the oldest lakes in the world, and it has a rich endemic fauna with a predominance of arthropods. Among the arthropods living in this lake, amphipods (Crustacea) are the most dominant group and are represented by more than 350 endemic species. Baikalian amphipods inhabit almost all depths and all types of substrates. The age and geographical isolation of this group creates excellent opportunities for studying the diversity, evolution and genetics of host-parasite relationships. However, despite more than 150 years of study, data investigating the microsporidia of Lake Baikal remain incomplete. In this study, we used molecular genetic analyses to detect microsporidia in the hemolymph of several endemic species of amphipods from Lake Baikal. We provide the first evidence that microsporidian species belonging to three genera (Microsporidium, Dictyocoela and Nosema) are present in the hemolymph of Baikalian endemic amphipods. In the hemolymph of Eulimnogammarus verrucosus, we detected SSU rDNA of microsporidia belonging to the genus Nozema. In the hemolymph of Pallasea cancellous, we found the DNA of Microsporidium sp. similar to that in other Baikalian endemic amphipods; Dictyocoela sp. was found in the hemolymph of Eulimnogammarus marituji and Acanthogammarus lappaceus longispinus.     

Colorless sulfur bacteria <Emphasis Type="Italic">Thioploca</Emphasis> from different sites in Lake Baikal

The colorless sulfur bacteria Thioploca spp. found in Lake Baikal are probably a marker for the influx of subterranean mineralized fluids. Bacteria act as a biological filter; by consuming sulfide in their metabolism, they detoxicate it and maintain the purity of Lake Baikal’s water. The bacteria were investigated by various techniques. According to analysis of the 16S rRNA gene fragment, Thioploca sp. from Frolikha Bay, Baikal belongs to the clade of freshwater species found in Lake Biwa and Lake Constance; it is most closely related to Thioploca ingrica.     

Refugium of the Boreal Forests of the Circumpolar Urals

The results of studies of the vegetative cover and ontogenetic composition of the cenopopulations of Picea obovata Ledeb. and Larix sibirica Ledeb. in the Gorno-Khadytinskii Forest Reserve, which is the refugium of the northern taiga forests of Western Siberia, have been summarized. According to the Brown–Blanke system, two associations of forests were identified and described, as well as two tundra associations, for comparison. The unique association of the Aconito septentrionalis–Piceetum obovatae taiga forests Zaugolnova et Morozova 2009 were analyzed in detail, and a comparison of these associations was carried out in the Gorno-Khadytinskii and Pechoro-Ilychskii reserves, where these forests are the reference standards of the zonal-type forests. An estimate of the ontogenetic composition of the cenopopulations of P. obovata Ledeb. and L. sibirica Ledeb. is given, as well as the absolute age of the trees of these species.