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.     

Finding of the subarctic leeches, Acanthobdella peledina and Cystobranchus mammillatus, in the Lake Baikal basin and the reasons for their absence in Lake Baikal itself]

Acanthobdella peledina was first found in the basin of Lake Baikal on the fluvial form of the Balkal grayling Thymallus arcticus baicalensis and Coregonus lavaretus pidschian from the Upper Angara. Cystobranchus mammillatus, a parasite of burbot, is widely distributed in the tributaries of Baikal. The absence of these subarctic leeches from Baikal itself is explained by their rheophily.     

The history of the formation of fish parasite fauna in lake Baikal

The fauna of fish parasites in Lake Baikal is represented by 5 faunistic complexes, namely the boreal plain, boreal submountain, arctic freshwater, Baikal, and Sino-Indian ones. The parasites of the boreal plain complex are dominant by the number of species (43 %). Hypotheses on the origin of the recent fish and parasite faunas of Lake Baikal were advanced on the base of the data on the parasite species composition and their distribution among hosts, as well as on the base of paleontological data. It is shown that invasion of new fish species and their parasites to Baikal led to the change of the composition of natural faunistic fish complexes and parasite systems. Invading fishes play the roles of intermediate and definitive hosts in parasite systems of Baikal, that led to the change of the initial structure of these systems.     

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.     

Zooplankton seasonal dynamics in 2005–2007 at the eastern coast of southern Baikal,near the Pulp-and-Paper plant

The study investigated zooplankton seasonal dynamics in the pelagic and shelf zones at the eastern coast of Lake Baikal, near the Baikal Pulp-and-Paper Plant, in August and September of 2005, 2006, and 2007. It was shown that zooplankton development in the 0–50 mdepth over the study period followed a characteristic Baikal pattern despite increased industrial pressure on the study site.     

Diet of the Symbiotic Amphipod,Brandtia parasitica parasitica (Crustacea,Amphipoda), Living on Diseased Baikal Sponges of the Family Lubomirskiidae in Southern Lake Baikal

Biology Bulletin - The diet of a symbiont, Brandtia parasitica parasitica (Dybowsky 1874), of Baikal sponges collected during an ecological crisis in the littoral zone of Lake Baikal is analyzed....     

The determination of the species classification of Baikal planarian cocoons found in the stomach of the black grayling (Thymallus arcticus baicalensis) by a comparative analysis of the nucleotide sequences of the ribosomal RNA gene]

Comparative analysis of nucleotide sequences of gene 18S of ribosome RNA was carried out. The results show that the genetic sequences of the given locus could be used as a molecular marker to identify the species of planaria irrespective of ontogenetic stage. The articles deals with problem of specific determination of cocoons of Baikal planaria from the stomach of Baikal black grayling using comparative analysis of nucleotide sequences of ribosome RNA fragments with known sequences determined earlier for Baikal planaria. The cocoons belong to two species of Rimacephalus. The authors discuss also the importance of feeding relationships of planaria and benthophage fish to investigate the biotic factors that influence the evolution of Baikal planaria.     

Dynamics of parasite communities in an age series of Baikal omul Coregonus migratorius (Georgi, 1775)

Parasite communities of Baikal omul from Chivyrkuiskii Bay of Lake Baikal have been analyzed at levels of a host individual (infracommunity), a separate age group of a host (set of infracommunities), and a host population (component community). Significant positive correlations of parameters of species richness (number of parasite species, Margalef and Menhinick indices) with the age of Baikal omul were recorded only at the level of parasite infracommunities. The absence of linear positive correlations between the parameters of species richness and the age of Baikal omul at the level of sets of parasite infracommunities were revealed for the first time for fishes of Lake Baikal. The peculiarity of the dynamics of parasite communities of Baikal omul is determined by specific features of the host physiology and ecology, primarily by the age dynamics of the feeding spectrum.     

Diversity of laboratory-reared prokaryotes in the bottom sediments of the Akademichesky Ridge,Lake Baikal

Microbial communities in the bottom sediments of the Akademichesky Ridge, Lake Baikal, were studied. The samples were taken by deep drilling BDP-96 (a 100-m core). Vertical distribution of the prokaryotes with different physiological characteristics was studied for the core. The phylogenetic analysis of the organotrophic laboratory-reared microorganisms revealed the clusterization of Baikal strains and species which have not been identified yet.     

Phytomonitoring of air pollution in the Baikal region

Phytomonitoring of air pollution has been performed using the Scots pine as a highly sensitive bioindicator. Needles have been sampled from key plots along the macrotransect Sayansk-Irkutsk-Listvyanka (with a total length of 320 km) covering the main industrial centers of the Baikal region and stretching up to the shoreline of Lake Baikal. The content of inorganic pollutants (sulfur, fluorides, heavy metals, etc.) has been determined. The highest level of air pollution has been registered in the following industrial centers: Angarsk, Irkutsk, Usol’e-Sibirskoe, and Shelekhov. The degree of pollution is lower in industrial centers such as Sayansk and Cheremkhovo. The data provide evidence that most pollutants reach the shoreline of Lake Baikal.     

The origin and genetic relationships of the Baikal seal, Phoca sibirica, by restriction analysis of mitochondrial DNA

The origin and genetic relationships of the Baikal seal, Phoca sibirica, were studied by restriction fragment length polymorphism analysis of mitochondrial DNA (mtDNA). Using 17 different six-base recognition restriction endonucleases, we examined 98 Baikal seals, and two other related species, the ringed seal, P. hispida, (n=87), and the Caspian seal, P. caspica, (n=94). Analysis revealed the existence of 87 mtDNA haplotypes in the total of 279 specimens. The haplotypes of each species were divided into different clusters on a dendrogram obtained by UPGMA based on haplotype frequency and mtDNA base substitution. No common haplotypes were found among the species examined. The Baikal seal is much more closely related to the ringed seal than the Caspian seal. The amount of divergence suggested that an ancestor of the Baikal seal came down to the lake approximately 0.4 million years ago as was previously indicated by paleontological studies. The seals examined here showed lower variabilities.     

Experimental study of some Siberian and Baikal endemic species of hydrobionts: Comparative analysis of oxyphility and frigophility

Adaptive features of some hydrobionts of the Baikal and Siberian faunas have been studied. It is revealed that the studied groups of invertebrates living in near-Baikal water bodies and streams are less stable to the action of some abiotic factors than representatives of the Baikal endemic fauna. Some of the hypotheses proposed to explain the “immiscibility” of Baikal endemics and Siberian ubiquists are questioned.     

Phosphorus Budget of Lake Baikal and the Angara Cascade Water Reservoirs: Modeling,Reconstruction, and Prognosis

A mass balance model of phosphorus flow in a system of connected water reservoirs has been developed and used for quantitative assessment of phosphorus budget elements in Lake Baikal and water reservoirs on the Angara River, the only river that drains Lake Baikal.     

Comparative aspects of adaptive radiation and speciation in Lake Baikal and the great rift lakes of Africa

Lakes Baikal, Tanganyika and Malawi have similar origins, are physiographically similar, and of similar size. The hydrological regime of Baikal is, however, very different from that which prevails in its African sisters. Apart from being much cooler, it differs fundamentally in being oxygenated to all depths while the two great African rift lakes possess only a relatively thin oxygenated surface layer and have vast oxygenless, and therefore azoic, abyssal regions. Nevertheless, like Baikal, they have rich endemic faunas.That these faunas originated largely by intralacustrine speciation and not by multiple invasion is now well established. They provide some of the world's most spectacular examples of species flocks, and some groups display what has been aptly described as explosive speciation. Certain features, and especially the adaptive radiation, of some of the groups involved, are noted. Comparisons between lakes are illuminating. Some species flocks, such as those of amphipods, sponges and turbellarians of Baikal and the atyid prawns and potamid crabs of Tanganyika, have no counterparts in the other lakes. Other groups, such as the prosobranch gastropods, ostracods and harpacticoid copepods of Baikal and Tanganyika, and the fishes of all three, involve representatives of the same major group, though often of different families or even higher taxonomic categories.That allopatric speciation has been involved is universally acknowledged but the problems posed by species multiplication in deep water in L. Baikal have led to suggestions that sympatric speciation could have played a part. Notwithstanding the difficulties, it is suggested that the process can be explained without invoking the assistance of the sympatric model.The faunas of these lakes provide immense fields for investigation and enormous intellectual challenges. While each is an entity in itself, comparative studies may be particularly enlightening.The substance of this paper was presented as a lecture at the First International Baikal Vereshchagin Conference held in Listvyanka, Irkutsk Region, U.S.S.R. in October 1989.     

Heavy metal content and response of the blood system of Siberian dace <Emphasis Type="Italic">Leuciscus leuciscus baicalensis</Emphasis> (Cypriniformes,Cyprinidae) under anthropogenic impact

Chemical, hematological, and immunological characteristics of the Siberian dace Leuciscus baicalensis from different areas of Lake Baikal basin were first determined. It was established that the most considerable changes in hemopoesis, cellular, and humoral links of immunity were in individuals with a high content of heavy metals in the liver from populations inhabiting the Selenga River downstream the Ulan Ude Industrial Center and the Selenga Pulp-and-Cardboard Plant. Changes in immunohematological responses of L. leusiscus baicalensis from Cherkalov Bay of Lake Baikal proceeded within the adaptive possibilities of the species and indicated the development of compensatory reactions in response to the accumulation of heavy metals in the body. The results obtained make it possible to assert that Chivurkuiskii Bay of Baikal may serve as a control polygon during monitoring of immunobiological states of fish populations from Baikal basin.     

Mitochondrial and nuclear DNA phylogeography of Thymallus spp (grayling) provides evidence of ice-age mediated environmental perturbations in the world's oldest body of fresh water,Lake Baikal

Theories on the hydrological history of Lake Baikal, the world's oldest and deepest body of freshwater, and its surrounding great rivers, are currently based solely on geological evidence and are conflicting. Baikal is inhabited by numerous zoogeographical enigmas but their high level of endemism has hindered phylogeographic inferences. We provide a biological perspective of the region's palaeo-hydrological development based on the demographic and genealogical history of the widespread Thymallus spp. (grayling). Phylogenetic reconstruction reveals that old lineages of grayling (pre-Pleistocene) currently inhabit the Enisey, Lena and Amur River basins. For Lake Baikal however, we conclude that a mid-Pleistocene colonization (110000-450000 years ago) of an unoccupied niche has occurred. Population genetic inferences support an Enisey-Angara river route of colonization into Baikal, corresponding to the cataclysmic palaeo-hydrological event that led to the formation of the lake's only contemporary outlet, and a subsequent range expansion several thousand kilometres into the uppermost reaches of the Selenga River basin. The evolutionary history of Lake Baikal grayling is congruent with the controversial hypothesis of repeated glaciation. However, considering the extraordinary levels of endemism and proposed Miocene or Oligocene coalescence of other faunal lineages, a less profound but equally consequential cycle of environmental perturbations may have taken place. Bi-parentally inherited microsatellite DNA loci supported the phylogenetic relationships of Thymallus spp. and the geographical expansion of Baikal grayling strikingly well. A Markov Chain Monte Carlo modelling approach suggested severe contemporary population decline during the last century, possibly reflecting the influence of an uncontrolled fishery on this treasured ecosystem. These complementary pictures of the demographic history of grayling underscore the breadth of historical inquiry that can be entertained through the modelling of sufficient molecular data, and may significantly alter the zoogeographical and limnological perspectives of Baikal's history.     

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.     

Influence of long-distance climate teleconnection on seasonality of water temperature in the world's largest lake--Lake Baikal, Siberia

Large-scale climate change is superimposed on interacting patterns of climate variability that fluctuate on numerous temporal and spatial scales--elements of which, such as seasonal timing, may have important impacts on local and regional ecosystem forcing. Lake Baikal in Siberia is not only the world's largest and most biologically diverse lake, but it has exceptionally strong seasonal structure in ecosystem dynamics that may be dramatically affected by fluctuations in seasonal timing. We applied time-frequency analysis to a near-continuous, 58-year record of water temperature from Lake Baikal to examine how seasonality in the lake has fluctuated over the past half century and to infer underlying mechanisms. On decadal scales, the timing of seasonal onset strongly corresponds with deviation in the zonal wind intensity as described by length of day (LOD); on shorter scales, these temperature patterns shift in concert with the El Nino-Southern Oscillation (ENSO). Importantly, the connection between ENSO and Lake Baikal is gated by the cool and warm periods of the Pacific Decadal Oscillation (PDO). Large-scale climatic phenomena affecting Siberia are apparent in Lake Baikal surface water temperature data, dynamics resulting from jet stream and storm track variability in central Asia and across the Northern Hemisphere.     

New species of Myxosporidia (Myxosporea: Cnidosporidia) from cottids (Abyssocottidae) and the oilfishes (Comephorus spp.) of Baikal Lake

Two new species of Myxosporidia, Myxidium baicalensis sp. n., Myxidium donecae sp. n. are described from the gall bladder of fishes from Baikal. Myxidium baicalensis sp. n. parasitising gobies Cyphocottus megalops, Asprocottus platycephalus, and other host species, while Myxidium donecae sp. n. parasitising Baikal oil fishes Comephorus baicalensis and C. dybowski.     

Polymorphism of the harlequin ladybird Harmonia axyridis (Coleoptera, Coccinellidae) Baikal population

The phenotypic composition of the Baikal population of the harlequin ladybird Harmonia axyridis (Pallas, 1773) was analyzed based on the material collected in Irkutsk Province in 2009–2010. Significant microgeographic phenotypic variation was revealed on the Baikal coast and in the city of Irkutsk. The morph axyridis, widespread in Siberia, was dominant (80–90%) but the light-colored morph succinea was also present with high frequencies (43–59%) in some samples. Some individuals possessed an elytral ridge, their frequency in the Baikal population being low (4–6%). An increase in the number of the morph succinea in Irkutsk Province is not related to hybridization between the populations from the Far East and Siberia.