Distribution of fish in the river system of the Lower Irtysh

We report the results of investigation of fish distribution in water bodies of different types (open floodplain complex, closed lake, floodplain channels, and a riverbed depression) of the river system of the Lower Irtysh obtained by application of differently aimed hydroacoustic complexes and by traditional ichthyological methods. Distribution, composition, and abundance of fish aggregations and their diurnal movements are determined in different water areas. Periodicity, range, and direction of fish migrations, rhythm of downstream migrations of juveniles under various conditions are recorded. Distribution of fish is considered as a continual process controlling the biological integrity of the river system. Significant presence of nomadity (various migrations and local movements) is demonstrated in fish, reflecting multilevel lability of the environment in the floodplain-channel system of the Lower Irtysh. A set of notions is suggested defining application limits of principal terms characterizing fish movements of various scales: migrations, wanderings, and short-term movements.     

Distribution of fishes in the floodplain-channel complex of the lower reaches of the Irtysh River

The composition of fish, their location and movements in the channel, channel depressions, and flood waters of the lower reaches of the Irtysh River are investigated. This study is conducted with computer sonar systems used for different purposes. Diurnal and seasonal dynamics of movements of the fish and the abundance and composition of fish aggregations are revealed in the studied sites. The biological unity of the fish community of the floodplain-channel complex is demonstrated.     

Comparative analysis of fish aggregation in channel depressions of the Irtysh

We present the results of ichthyological studies in principal channel depressions of the Irtysh developing the notions on polyfunctional biological role of these formations. The study is made by means of a computerized hydroacoustic complex “Askor”. Quantitative estimation of the size composition, abundance, density, and spatial distribution of fish on water area of channel depressions in different seasons confirms the hypothesis of multifaceted biological significance of these formations. Universal traits in the organization of fish aggregations, specificity of distribution, composition, and seasonal dynamics of the fish population on the largest channel depressions of the Irtysh are revealed.     

Irregularities of the bottom and fish aggregations on a stretch of the Irtysh

An original method for estimation of the effect of bottom irregularities on density of fish aggregations is elaborated. Calculation of the investigated relationship is based on material of surveys collected by an AsCor hydroacoustic complex and is made by means of special software. With reference to a deep-water stretch of the Irtysh channel, the quantitative parameters of the relationship between densities of fish aggregations and the index of bottom irregularity are revealed. The diagram of the relationship between bottom irregularities and density of fish aggregations, the three-dimensional model of bottom relief of the investigated water area, and echograms of fish aggregations on various stretches of the river are presented.     

Distribution of the fish rotan (Perccottus glenii Dybowski, 1877) in the Irtysh River basin and analysis of possible consequences for environment and people

Since 1916, rotan (Perccottus glenii Dybowski, 1877) has widely distributed in northwestern Eurasia. In 1973–1976, rotan populations were first detected in the basin of the Irtysh River: in Lake Peschanoe (Mertvoe) of Chelyabinsk oblast in the basin of the Tobol, a tributary of the Irtysh. In 1975, this fish was introduced to one of the ponds of the city of Chelyabinsk. Analysis of the spatiotemporal dynamics of findings shows that earlier records of the fish correlate with the network of roads, and later findings, with the river network. The results of a special inspection of isolated and floodplain water bodies (n = 77) performed within Chelyabinsk, Kurgan, Omsk, and Tyumen oblasts in 2006 indicate that at present this unwanted invader occurs in the major part of the Tobol basin. The northernmost finding of this species is from the floodplain of the Tobol in the vicinity of Tobolsk, from the Karachino oxbow (58°02′N, 68°10′E). Rotan has also been found at the Irtysh headwaters as well as in the basins of its other tributaries: Ishim and Om. The expansion of rotan threatens the floodplain water bodies of the middle Irtysh. This species carries diseases, competes with other fish species for food, and actively eats young fish of these species. Therefore, the data on rotan distribution in the tributaries of the Irtysh should be taken into account when analyzing the dynamics of the fish community of this river. Biology of rotan assumes its influence on the functioning of the natural foci of opisthorchiasis.     

DNA barcoding of fishes in Irtysh River China

DNA barcoding was a molecular diagnostic method that provided rapid and accurate species identification. The 650 bp-length cytochrome c oxidase subunit I (COI) gene of 33 species in Irtysh River China was sequenced and analyzed in this study. The average intra-species, -genus, -family, and -order of Kimura two parameter (K2P) distances were 0.003, 0.060, 0.163 and 0.240, respectively. The genetic distance between genus Barbatula and Cobitis was the largest whereas that between genus Hypophthalmichthys and Aristichthys was the smallest. The neighbour-joining tree constructed by all 44 haplotypes was divided into two major clusters: Cypriniformes fishes and other fishes. A cryptic species of Barbatula barbatula was detected according to 2% genetic threshold.     

Highly pathogenic influenza A(H5N1) virus survival in complex artificial aquatic biotopes

Background

Very little is known regarding the persistence of Highly Pathogenic Avian Influenza (HPAI) H5N1 viruses in aquatic environments in tropical countries, although environmental materials have been suggested to play a role as reservoirs and sources of transmission for H5N1 viruses.

Methodology/Principal Findings

The survival of HPAI H5N1 viruses in experimental aquatic biotopes (water, mud, aquatic flora and fauna) relevant to field conditions in Cambodia was investigated. Artificial aquatic biotopes, including simple ones containing only mud and water, and complex biotopes involving the presence of aquatic flora and fauna, were set up. They were experimentally contaminated with H5N1 virus. The persistence of HPAI H5N1 virus (local avian and human isolates) was determined by virus isolation in embryonated chicken eggs and by real-time reverse-polymerase chain reaction. Persistence of infectious virus did not exceed 4 days, and was only identified in rain water. No infectious virus particles were detected in pond and lake water or mud even when high inoculum doses were used. However, viral RNA persisted up to 20 days in rain water and 7 days in pond or lake water. Viral RNA was also detected in mud samples, up to 14 days post-contamination in several cases. Infectious virus and viral RNA was detected in few cases in the aquatic fauna and flora, especially in bivalves and labyrinth fish, although these organisms seemed to be mostly passive carriers of the virus rather than host allowing virus replication.

Conclusions/Significance

Although several factors for the survival and persistence of HPAI viruses in the environment are still to be elucidated, and are particularly hard to control in laboratory conditions, our results, along with previous data, support the idea that environmental surveillance is of major relevance for avian influenza control programs.     

Testate amoebae community structure in the moss biotopes of streams

The specific composition and community structure of testate amoebae in the moss biotopes of streams were studied in the Sura River basin (Middle Volga region). Twenty-nine species and forms were identified. The eurybiont species Trinema enchelys, Euglypha ciliata glabra, Centropyxis aerophila, Tracheleuglypha dentata, Crythion dubium, Centropyxis cassis, Trinema complanatum, and Trinema lineare are dominant. The species richness varies from 2 to 11 species per sample, the abundance is 100 to 4000 ind./g of absolutely dry moss. The degree of forest covering in the basin, hydrochemical peculiarities (the amount of biogenic elements and water hardness) of streams, the size of streams, and environmental contamination are possible factors that determine the specific character of the composition and structure of testate amoebae communities.     

A provisional classification of algal-characterised rocky shore biotopes in the Azores

Recent studies of the rocky shores of the Azores archipelago have provided information on community structure allowing provisional identification of plant-characterised biotopes (habitats and their associated communities). Although the Azores share some littoral and sublittoral biotopes with the Atlantic coast of mainland Europe, shores in the archipelago mostly lack the functionally important leathery macrophyte communities of fucoids and laminarians widespread in the North Atlantic. Intertidal biotopes are mainly turfs typical of warm-temperate and tropical regions, and characterised by articulated Corallinaceae or by non-coralline algae such as Cladophora spp., Gelidium spp., Pterocladiella capillacea, Stypocaulon scoparia, and Valonia utricularis. Subtidal algal biotopes are characterised by Dictyota spp., Halopteris filicina, Sphaerococcus coronopifolius and, most commonly, Zonaria tournefortii.     

Mycoplasma-like sturctures in podzol soils of the southern taiga in the Irtysh region]

Mycoplasm-like organisms were found in taiga podzolic soils of the South Irtish region. They were detected in close contact with soil bacteria more ofter than in a free state. The mycoplasm-like organisms either were absorbed on the bacterial cell walls or grew inside the cytoplasm as filamentous forms; sometimes they filled the whole inner space of the cells, disrupted the cell wall, and were liberated into the surrounding medium.     

Inversion polymorphism of the malaria mosquito Anopheles messeae. VIII. Distribution of larvae in biotopes under conditions of co-habitation with Anopheles beklemishevi

The role of chromosomal variability was studied in the process of biotopical distribution of larvae of the sibling species Anopheles messeae and A. beklemishevi. It is shown that frequency of the inversions XL1, XL2, 2R1, 3R1 of A. messeae was changed in the lakes with different larval quantity of the sibling species. Mosquito of A. beklemishevi were developed in the suboptimal biotops having low larwal quantity of A. messeae with the analogous chromosomal arrangement 2R1. The larvae with "northeast" genocomplexes of A. messeae prevailed over A. beklemishevi in the lakes with high larval quantity and this prevalence determined dominant state of A. messeae. It is noted that natural selection on the preimaginal stages of development acts in the direction of karyotypic divergence of the sibling species and promotes more effective utilisation of food resources by each species.     

Distribution and abundance of fish in deep-sea coral habitats

Experimental fishing with long-lines and gillnets was conducted on the continental shelf off southwestern Norway between 150 and 350 m depth. Abundance and distribution of redfish (Sebastes marinus L., 1758), ling (Molva molva L., 1758), and tusk (Brosme brosme Ascanius, 1772) were quantified in Lophelia pertusa (L., 1758) coral reefs and in non-coral habitats. The largest catches of redfish were made with long-line fleets set in coral reef habitats. Ling and tusk were also most numerous in coral habitats, although not statistically significant. Fish caught in coral habitats tended to be larger in size than in non-coral habitats. The diet of redfish, tusk and ling included the same prey groups in all habitats, but they differed at the species level. Lophelia-reefs may provide a profitable feeding place for tusk. For the planktivorous Sebastes, on the other hand, their affinity to the reefs seems primarily to be related to the physical structure offered by the reefs.     

Distribution of major histocompatibility complex antigens in the Bremen area

320 blood donors from Bremen have been typed for HLA-A-, B- and C-antigens. Phenotype and gene frequencies were calculated and compared with data from Kiel, Hamburg, Essen, Frankfurt/M., Mainz, Mannheim, Freiburg/Br., Munich and Vienna. The Bremen data do not differ significantly from these samples. This is also true for the HLA-ABC linkage disequilibrium.     

Distribution and potential role of cytosolic water-soluble phosphodiesters in fish

The distribution of water-soluble phosphodiesters (WSPDEs) visible by nuclear magnetic resonance (NMR) in some intact tissues of rainbow trout (Oncorhynchus mykiss walbaum) and in perchloric extracts after partial purification was examined by (31)P NMR spectroscopy. The compounds of interest were serine ethanolamine phosphate (SEP), threonine ethanolamine phosphate (TEP), glycerophosphorylcholine (GPC), and glycerophosphorylethanolamine (GPE). TEP and SEP were mostly accumulated in the heart and less accumulated in the kidney of intact trout. After the extraction procedure, two additional minor resonances were visible and identified as GPC and GPE. The liver of trout contained large amounts of GPE. Similar investigations were conducted by (31)P NMR on hearts and kidneys of two elasmobranchs (Scyliorhinus canicula, Raja clavata) and four teleosts (Anguilla anguilla, Sparus auratus, Dicentrarchus labrax, Scophtlhalmus maximus); comparison with the trout data showed striking interspecies differences in the identity of WSPDEs. All teleosts, except eel and turbot, accumulated predominantly TEP. However, in elasmobranchs, first GPC and then GPE were the major compounds. Whatever the studied species, the relative abundances in the heart and kidney were similar. In the last two decades, two hypotheses were proposed to explain the occurrence of high levels of cytosoluble phosphodiesters: these compounds may constitute an index of phospholipid catabolism or a protective mechanism through which phospholipid levels are kept high. To test them and elucidate the role of these compounds in membrane phospholipid regulation in fish, we investigated the effects of two physiological stresses, that is, seawater adaptation and induced myocardial ischemia, on trout cytosolic phosphodiester levels. A 32.5-min ischemic stress caused no effect on SEP and TEP levels. On the contrary, significant osmotic stress induced changes in the PDEs levels: 2 d after transfer from freshwater to seawater or from seawater to freshwater, both tissues displayed a transient decrease of TEP; however, a 2-d stay in seawater after transfer from freshwater caused a rise in SEP concentration, whereas a 2-d stay in freshwater after transfer decreased SEP level. In conclusion, our experiments suggest a relationship between the high levels of cytosoluble phosphodiesters observed in some fish tissues and resistance to stress.