Spread of Elodea canadensis in Lake Baikal

In Lake Baikal Elodea canadensis Michx. was first observed at the end of the 1970's.Suggestions have been made as to the bringing of E. canadensis to Baikal by aquarists or by transport vehicles and transport together with fishes taken from lakes of the Urals where mass development of the plant was observed at the beginning of the present century. The spread of E. canadensis along Lake Baikal must be due to navigation, but natural factors also affect its spread.The quantitative biomass development of E. canadensis in various areas of the lake is reviewed, and discussed in relation to historical aspects of spread and regulation by environmental factors.The fast spread of E. canadensis, its high competitive quality and metabolic capacities for purifying sewage waters deserve attention.Expansion of E. canadensis may be referred to as a catastrophic phenomenon. Its effect has now covered practically the whole perimeter of Lake Baikal.     

Spread of Elodea canadensis in Lake Baikal

Elodea canadensis Michx. was first observed in Lake Baikal at the end of the 70's. E. canadensis was probably introduced to Baikal by aquarists or by transport vehicles and transport together with fishes taken from lakes of the Urals, where mass development of the plant was observed at the beginning of the present century. The spread of E. canadensis along lake Baikal may be due to navigation, but natural factors also affect its spread.The fast spread of E. canadensis, its high competitive quality and metabolic properties for purifying sewage waters are of interest.The expansion of E. canadensis may be considered a catastrophic phenomenon; its effect now covers practically the whole perimeter of Lake Baikal.     

Microbial biodiversity in the Lake Baikal water

The investigation of the microbial community of Lake Baikal by the methods of general and molecular microbiology showed that culturable bacterial strains were represented by various known genera. The lake water contains a great number of bacterial morphotypes, as revealed by electron microscopy, and a great diversity of nonculturable microorganisms belonging to different phylogenetic groups, as revealed by 16S rRNA gene fragment sequencing. The inference is made that the microbial community of Lake Baikal contains not only the known species but also new, possibly endemic to the lake, bacterial species.     

Oligochaete fauna of Lake Baikal

Oligochaetes are one of the most abundant groups of invertebrates in Lake Baikal. They compose up to 70–90% of the biomass and numbers of zoobenthos and are distributed from the water edge to the maximum depth. There are 207 identified species and subspecies belonging to 44 genera and seven families, of which 160 species and 13 genera are endemic. Many are relict species. The main peculiarities of oligochaete fauna of Lake Baikal are: immiscibility of its ecologically different complexes (Palaearctic and Baikalian), its antiquity and heterogeneity, and intense radiation of the species.     

Carotenoids, photoprotection and food web links in Lake Baikal

1. Carotenoids were extracted from macrophytes, sponges, amphipods, fish stomachs, fish livers, fish ovaries and zooplankton in samples collected from various depths in Lake Baikal. 2. Acetone extracts from macrophytes showed a ratio of absorption at wavelengths of 430 and 665 nm consistently in the range 2.1–2.5. Sponges from very shallow water (1.5m) showed a similar ratio, but a sponge from 25m gave a ratio of 6.6, indicating a reduction in the concentration of chlorophyll relative to carotenoids. 3. Extracts from amphipods gave some support for the photoprotection hypothesis, with lower concentrations of carotenoids in amphipods from the deepest water. 4. Some fish took high concentrations of carotenoids into their stomachs, but the concentrations found in their Livers and ovaries were very much lower. Fish appear to be one of the carotenoid sinks in Lake Baikal. 5. Plankton samples showed an apparent inversion, with the highest concentration of carotenoid in the deepest sample, but this was a result of the sinking into deep water of the filamentous diatom Melosira.     

Microbial Biodiversity in the Water of Lake Baikal

An investigation of the microbial community of Lake Baikal by the methods of general and molecular microbiology showed that culturable bacterial strains are represented by various known genera. The lake water contains a great number of bacterial morphotypes, as revealed by electron microscopy, and a great diversity of nonculturable microorganisms belonging to different phylogenetic groups, as revealed by 16S rRNA gene fragment sequencing. The inference is made that the microbial community of Lake Baikal contains not only known species but also new bacterial species that are possibly endemic to the lake.     

Microorganisms in the Sediments of Lake Baikal,the Deepest and Oldest Lake in the World

Microbiology - The review summarizes the results of recent studies of microbial communities of the Lake Baikal sediments obtained using diverse techniques. In the sediments of the areas of stable...     

Nutritional diagnosis of phytoplankton in Lake Baikal

To diagnose the nutritional status of phytoplankton in Lake Baikal, surveys for the determination of concentrations of particulate carbon (PC), nitrogen (PN) and phosphorus (PP) and their ratios were conducted at six stations in March, June, August and October 1999. The concentrations of PC and PN were lower than, and those of PP were similar to, those in another mesotrophic lake except at the station near the mouth of the largest input river, Selenga River, of Lake Baikal. The PC : PN : PP ratio was 102 : 13 : 1, considerably close to the Redfield ratio. The ratio was constant against spatiotemporal changes. These indicate that phytoplankton in Lake Baikal were exposed to no deficiency in nitrogen nor phosphorus. From a viewpoint of the nutritional status of phytoplankton, Lake Baikal might be viewed as an ocean rather than as a lake.     

Depleted methane-derived carbon in waters of Lake Baikal,Siberia

Results of hydrochemical and stable isotope measurements during the ice-breaking period on Lake Baikal indicate an apparent lack of relationship between measured δ¹³C of dissolved inorganic carbon (DIC) and phytoplankton below the trophogenic layer. While planktonic values of −31.7 to −33.5‰ are within a typical lacustrine range, the δ¹³C values of DIC turned out to be very negative, from −28.9 to −35.6‰. These isotopic values of DIC appear to be associated with oxidation of methane that accumulated during winter ice cover period. At the time of sampling, however, the observed depletion did not affect the phytoplankton/DIC fractionation relationship, because the difference between phytoplankton and DIC (−20 to −22‰ in surface waters) lies within the expected range of the fractionation coefficient. By analogy with small lakes, we explain this lack of relationship by the time lag between peak productivity and peak methane oxidation. Our interpretation of the Baikal DIC isotopic signature is consistent with methanogenesis in bottom sediments and with the known presence of widespread unstable gas hydrates and active methane seeps on the lake floor. Our findings suggest that methane is an important component of the Baikal carbon cycle, that late winter concentrations of methane in Baikal under ice may be 3–4 orders of magnitude higher than previously reported values for summer, and that the lake may be emitting a significant amount of methane to the atmosphere.     

Antagonistic activity of actinomycetes of Lake Baikal

It was demonstrated that actinomycetes of Lake Baikal are strong antagonists of other microorganisms. Representatives of the genera Streptomyces and Micromonospora inhibit the growth of bacteria isolated from the lake, as well as of antibiotic-resistant microorganisms causing various human diseases. Baikal actinomycetes display a wide range of antagonistic activity and are potential producers of new biologically active substances.     

红嘴鸥在贝加尔湖的分布和繁殖

在对贝加尔湖地区红嘴鸥Larus ridibundus的数量分布及繁殖习性的现场考察中发现,贝加尔湖及其附近广阔的湿地是红嘴鸥繁殖的理想场所,每年至少有50000对红嘴鸥在当地繁殖;红嘴鸥为半早成鸟;红嘴鸥的筑巢、产卵、孵化是在一定的时间范围内先后不一进行的。这次考察为进一步揭示红嘴鸥的繁殖生态和促进对红嘴鸥及其鸟类的保护提供了一些有益的基础资料。     

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....     

Ixodes trianguliceps (Parasitiformes, Ixodidae) in the southern Lake Baikal area

In the southern Lake Baikal area, in the region of the Khamar-Daban ridge, which borders the banks of Lake Baikal, there was found in abundant population the tick I. trianguliceps. Data on the ecology of the tick in this particular part of its distribution area and on its ecological links revealed by factor analysis of the tick's habitat of the first and second order by means of electronic computers are given.     

Molecular and morphological evolution of the amphipod radiation of Lake Baikal

Lake Baikal, in Siberia, Russia, contains the highest biodiversity of any extant lake, including an impressive radiation of gammaroidean amphipods that are often cited as a classic case of adaptive radiation. However, relationships among Baikal's amphipods remain poorly understood. The phylogenetic history of 32 Lake Baikal amphipod species, representing most major lineages of the endemic fauna, was examined using three genes (COI, 16S rRNA, and 18S rRNA), and 152 morphological characters. Results support monophyly of the largest and most diverse of the Baikalian families, the Acanthogammaridae. Analyses suggest that a second Baikalian family, the fossorial Micruropodidae, is paraphyletic and composed of two divergent clades, one of which includes Macrohectopus branickii, a morphologically specialized pelagic planktivore traditionally assigned its own family. The extreme morphological and ecological divergence of Macrohectopus from its close genetic relatives, and conversely, the large genetic distances among other morphologically similar micruropodids, suggest that morphological and molecular evolution have often been uncoupled during the radiation of Baikal's amphipods. This study suggests that the amphipod fauna of Lake Baikal is polyphyletic; originating from two independent invasions of the lake.     

Taxonomic composition of Lake Baikal bacterioneuston communities

The taxonomic composition of microbial communities of Lake Baikal surface microlayer was studied by pyrosequencing of the 16S rDNA amplicons. Statistically reliable differences were found between bacterioneuston of the shallow and deep-water stations. The shallow station community was characterized by higher diversity than the deep-water one. While bacterioneuston communities were shown to be less diverse than the water column communities, their diversity was comparable to that of other biofilm associations. Microbial communities of Lake Baikal surface microlayer were shown to be similar to those of the water column in the composition of predominant phyla, while differing considerably at the genus level. Bacterioneuston of Lake Baikal was comparable to microbial communities of the surface microlayer of other freshwater basins, although it was characterized by high abundance of the Alphaproteobacteria and Verrucomicrobia. High abundance of photoheterotrophs compared to the water column communities of other freshwater basins was another distinctive feature of Lake Baikal bacterioneuston. Our results showed the Lake Baikal surface microlayer to be a specific microbial community with low species diversity and relatively high abundance of photoheterotrophic microorganisms.     

Antagonistic activity of actinomycetes of Lake Baikal

It was demonstrated that the actinomycetes of Lake Baikal are strong antagonists of other microorganisms. Representatives of the genera Streptomyces and Micromonospora inhibit the growth of bacteria isolated from the lake, as well as of antibiotic-resistant microorganisms causing various human diseases. Baikal actinomycetes display a wide range of antagonistic activity and are potential producers of new biologically active substances.     

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.     

Analysis of parasitic communities in fishes from Lake Baikal

Analysis of infracommunities and component communities of fish parasites in Lake Baikal has been conducted for the first time. It has been revealed that parasite infracommunities for the majority of Baikal fishes are weakly balanced and impoverished (the Berger-Parker Index is > 0.5; Evension is < 0.5; the Brillouin Index is < 1). The highest diversity and balance of the communities are characteristic for carnivorous fishes (Brachymystax lenok, Hucho taimen, Thymallus arcticus, Esox lucius, and Percafluviatilis). The component parasitic communities of Leuciscus leuciscus baicalensis, Rutilus rutilus, and Leocottus kesslerii are the most diverse in Lake Baikal since the Shennon index for L. leuciscus baicalensis, R. rutilus, and L. kesslerii is 2.4, for Paracotlus knerii--2.2, Limnocoitus godlewskii--2.3, Phoxinus phoxinus--2.1, Lota lota and Limnocuttus pallidus--1.9, P. fluviatilis--1.8, Leuciscus idus--1.8. The component parasitic communities of other fishes in Lake Baikal have low indices of biological diversity (H = 0.5-1.05, Smp is close to 1). A classification of mature and immature components of parasitic communities based on the ratio of specialist species and generalist species has been proposed. It is established that the component parasitic communities in sublitoral, profundal, and pseudoabyssal zones are mature, while in the littoral zone they are immature (impoverished and weakly balanced). The component parasitic communities in benthophagous fishes and predators are mature, in planktivorous fishes they are immature. The component parasitic communities are mature in the family Cyprinidae and immature in the families Coregonidae and Cottidae. The component parasitic communities of the Boreal Plain and Boreal Submountain faunal complexes are mature, but they are immature in Lake Baikal and Arctic freshwater complexes.     

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.     

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.