The distribution of Phyllodistomum umblae and Phyllodistomum folium (Trematoda: Gorgoderidae) in the excretory system of fishes

It is shown, that the distribution of Phyllodistomum umblae in the excretory system of all investigated species of salmonids has a principal similarity. The distribution of P. umblae in the excretory system of the Siberian dace and the Siberian roach is distinguished from that of P. folium.     

Characteristics of karyotype structure in Phyllodistomum umblae (Trematoda: Gorgoderidae) from Lake Baikal

Haploid complement of Phyllodistomumn umblae ex baikal whitefish from Lake Baikal consists of 8 chromosomes (6 metacentrics and 2 submetacentrics). The significant difference is observed in the ratio of acrocentrics and metacentrics in the haploid set of chromosomes between isolated populations of P. umblae from Baikal region and from Chukotka. The hypothesis is advanced that these chromosome populations may be chromosome races of P. umblae.     

Abnormalities in adult digeneans, with special reference to Phyllodistomum umblae(Fabricius) (Platyhelminthes, Gorgoderidae)

During examination of a large sample of Phyllodistomum umblae from Arctic char, Salvelinus alpinus , in Lake Tokke (Drangedal, type locality) and Lake Katnosa (Nordmarka, vicinity of Oslo), Norway, several abnormalities were found in the adult specimens. The paper describes the abnormal cases recovered and gives a systematized review of abnormal digeneans reported in the literature. Different terms used in digenean teratology and morphology are also discussed and defined. Abnormal cases occur in P. umblae with regard to the dimensions of specific structures (caeca, ovary, oötype, seminal vesicle, testes, uterus, vitellarium) and in the numbers of ovaries and testes. Polymorphism in testes position was observed and obstructions of the reproductive organs were evident. The size variability of the seminal vesicle and ovary and variable appearance of the vitelline bodies are demonstrated.     

A Redescription of Adult Phyllodistomum umblae (Fabricius) (Digenea, Gorgoderidae) from Salvelinus alpinus (L.) in Norway

Phyllodistomum umblae (Fabricius, 1780), originally described on the basis of specimens recovered from the ureter of Arctic char Salvelinus alpinus in Drangedalen, Norway, is here redescribed with both light (LM) and scanning electron microscope (SEM) from material obtained from the type host and type locality. This species has been overlooked in general text-books of this century, e.g. those of Dawes and Yamaguti, but was discussed by Nybelin in a paper in 1926 in which he suggested its conspecificity with P. conostomum Olsson. The dimensions, shapes, position and arrangement of the internal structures and selected size ratios are described and illustrated with LM-pictures. The SEM-investigation reveals the tegumental microstructure, and special emphasis is given to the arrangement of papillae. The body papillae comprise: (a) constant numbers in a constant bilateral arrangement; (b) a variable number in an orientated bilateral concentration called rows; (c) regional concentrations; (d) randomly distributed ones. This system and its variability are described and figured. Four types of papillae, and their distribution as seen by SEM, are described. These results are compared with the results from other SEM–investigations on gorgoderids.     

Phyllodistomum funduli n. sp. (Trematoda: Gorgoderidae) from Fundulus sciadicus Cope from Cedar Creek in western Nebraska

Phyllodistomum funduli n. sp. is described from the urinary bladder and ureters of the plains topminnow, Fundulus sciadicus, from Cedar Creek in Keith County, Nebraska (41 degrees 11.18'N, 101 degrees 21.77'W). Phyllodistomum funduli differs from most other Phyllodistomum species reported in possessing an oral sucker that is larger than the acetabulum. Currently, 7 other species of Phyllodistomum have been reported to possess this trait. A comparison of P. funduli with these 7 other species indicates that P. funduli is a distinct species, lacking notches, posterior body folds, caudal projections, or cephalic glands found in some congeners. There is no published report on parasites other than monogeneans inhabiting the plains topminnow, and there is no other report of members from the Gorgoderidae inhabiting any members of the Fundulidae.     

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.     

Variability of myxospores in the myxosporidian genus Henneguya depending on host and geography in the transect "Khubsugul Lake (Mongolia)--Baikal Lake--Laptev Sea (Russia)"

Analysis of variability and estimation of significance of the differences in morphometric parameters of spores have been carried out for three species of the genus Henneguya (Myxosporidia). Representatives of these species collected both in the same water body (but from different host species) and in geographically distant localities were compared. Thus, we compared samples of Henneguya zschokkei from different host species in Chivyrkui Bay of Baical Lake and in Laptev Sea, and also we compared samples of this species from Baikal Lake with those from Laptev Sea. Materials on Henneguya cerebralis from Baikal Lake were compared with those from Khubsugul Lake; samples of H. cutanea from one host species (Siberian dace) but from water bodies of different type (lake or river) were compared.     

Genetic polymorphism of the erythrocytic enzymes in the Buryat populations

Polymorphism of seven erythrocytic enzymes PGM1, ESD, CLO1, PGD and PGP were studied in five samples of Buryats. The main investment into differentiation between populations has been made by the following systems: CLO1, PGD and PGM1. Analysis of genetic distances between populations demonstrated that there was some parallelism among the genetic and anthropological differentiation in the Buryat populations. The groups of the Agingsky county (the area to the east from the Baikal Lake) have probably the largest proportion of the Caucasian genes as compared to other populations studied. One of the characteristics of the Buryats, especially for the population to the east from the Baikal Lake, is high frequency of the PGD allele. The rate of the genetic variability on the intra-population level is higher than the difference between populations. This means that the divergence between the Buryats populations is not very strong. Consideration of the genetic variability on the intra-population level seems to be more perspective for ecogenetic estimation of the adaptive genetic processes than analysis of the differences between populations studied.     

Seasonal dynamics and distribution of the digenean Phyllodistomum pawlovskii (Trematoda: Gorgoderidae) in the bullhead catfish, Pseudobagrus fulvidraco, in a lake of China

Seasonal population dynamics of the digenean Phyllodistomum pawlovskii in the urinary bladder of the bullhead catfish, Pseudobagrus fulvidraco, were investigated in Liangzi Lake in the flood plain of the Yangtze River in China from February 2001 to July 2002. The overall prevalence of the parasite was high, 41.5% (n = 1,476), while the mean abundance was relatively low, 1.24 +/- 2.11. The parasite exhibited evident seasonality in changes of prevalence and abundance. In brief, prevalence and abundance were very low in midwinter (January), but increased and remained relatively high in other seasons and months. The distribution pattern of this parasite in the fish was overdispersed, with a variance to mean ratio > 1, but its frequency distribution could not be described by the negative binomial model. There were positive correlations between the number of the parasites per fish and the age and length of the fish; a peaked age-parasite abundance curve was not detected in the parasite-host association. It is suggested that the parasite P. pawlovskii has little effect on the population structure of the bullhead catfish.     

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.     

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.     

Prevalence and sequence comparison of Phyllodistomum folium from zebra mussel and from freshwater fish in the Ebro River

We utilised DNA analysis to detect the presence of the digenean Phyllodistomum folium in three cyprinid species, Scardinius erythrophthalmus, Cyprinus carpio and Rutilus rutilus. DNA sequencing of the region containing the genes ITS1-5.8S-ITS2 revealed 100% sequence identity between DNA from the sporocysts found in zebra mussels and DNA from adults located in the urinary system of 29 cyprinid fish. A second genetically different (variation=1.6%) sequence was observed in two samples from R. rutilus. In our opinion, the existence of a complex of species reported as P. folium is supported by recent genetic studies, including our own results. The overall prevalence of P. folium in mussels from the Ebro River was 4.67% in 2006, although during the summer months the rates frequently exceeded 10%.     

Molecular prospecting for cryptic species in Phyllodistomum lacustri (Platyhelminthes,Gorgoderidae)

Rosas‐Valdez, R., Choudhury, A. & Pérez‐Ponce de León, G. (2011). Molecular prospecting for cryptic species in Phyllodistomum lacustri (Platyhelminthes, Gorgoderidae). —Zoologica Scripta, 40, 296–305. Partial sequences of the 28S ribosomal RNA and cytochrome c oxidase I (COI) genes were compared among populations of a widely distributed and morphologically uniform digenean species in North America, Phyllodistomum lacustri, a parasite characteristically associated with ictalurid catfishes. Specimens were collected from the urinary bladder of ictalurid hosts in six localities of North America, spanning most of the latitudinal range of this freshwater fish group. Sequences of other congeneric species, including a potentially close relative, P. staffordi, were also obtained and used for comparison. Analyses of both molecular markers show very low or no intrapopulation variation within each sampling site. However, samples of P. lacustri from different hosts and regions exhibit varying levels of interpopulation genetic differences. Such differences are explained by the wide geographical distribution and host range of the ictalurids they parasitize, particularly in ictalurids distributed in Mexican freshwaters where they experienced a diversification process. Variation in both nuclear and mitochondrial genes and phylogenetic analyses, in conjunction with geographical and host information (drainage isolation and endemicity of the host species), indicate that at least three populations show potential as cryptic species.     

Population affinities of Neolithic Siberians: a snapshot from prehistoric Lake Baikal

Archaeological evidence supports the inhabitation of the Lake Baikal region since the Paleolithic. Both metric and nonmetric osteological studies suggest that Neolithic Cis-Baikal populations are the ancestors of contemporary inhabitants of the region. To date, ancient DNA data have not been used to corroborate this biological continuity hypothesis. This study presents a temporal snapshot of the Cis-Baikal Neolithic by examining mtDNA diversity in two cemetery populations situated on the Angara River downstream of Lake Baikal. The 800 years separating the use of the two cemeteries is thought to represent a biocultural hiatus in the Cis-Baikal region, one that ended when a new group migrated into the area. To assess the likelihood that genetic continuity exists between these two Neolithic groups, we examined both mtDNA coding region and hypervariable region I (HVI) polymorphisms from skeletal remains excavated from both cemeteries (Lokomotiv and Ust'-Ida). The mtDNA haplogroup distributions of the two cemetery populations differ significantly, suggesting that they were biologically distinct groups. When the biological distance between these Neolithic groups is compared with modern Siberian and other East Eurasian groups, the posthiatus group (Serovo-Glazkovo) generally aligns with contemporary Siberians, while the prehiatus (Kitoi) individuals are significantly different from all but modern Kets and Shorians living in the Yenisey and Ob River basins to the west of Lake Baikal. These results suggest that the Lake Baikal region experienced a significant depopulation event during the sixth millennium BP, and was reoccupied by a new immigrant population some 800 years later.     

Comparison of rDNA sequences from colchicine treated and untreated sporocysts of Phyllodistomum folium and Bucephalus polymorphus (Digenea)

The most frequently used antimitotic agent in cytogenetic studies is colchicine. We investigated whether the initial treatment of trematodes for karyological analysis with colchicine would have mutagenic or degradational effect on rDNA sequences. Dreissena polymorpha is the intermediate host of Phyllodistomum folium and Bucephalus polymorphus, and the sporocyst stage of these trematode species develop, respectively, in the gills and gonads of this mussel. Sporocysts of P. folium and B. polymorphus were obtained from D. polymorpha collected from waterbodies in Belarus and in Lithuania. 5.8S and 28S rDNA genes, ITS1 and ITS2 of P folium and B. polymorphus were sequenced and compared, and no nucleotide sequence differences between colchicine treated and untreated trematodes were found. Based on these results, we conclude that colchicine treatment for 3-5 h has no mutagenic or degradational effect on rDNA sequences. During the course of this investigation, two genetically different P. folium samples were noted in Belarus.     

The sexual dimorphism of Pallasea cancellus (Pallas, 1772) amphipod from Lake Baikal and the Angara River

The changes in population of Baikal amphipod Pallasea cancellus (Pallas) from four remote local populations is described by comparing 21 morphological features. The population changes of individuals of different sexes, which allows the geographical variability of sexual dimorphism to be found, is shown. The morphological differences between crustaceans inhabiting different parts of Lake Baikal and the Angara River were estimated more precisely by analyzing the principal components. The junction between northwestern and southeastern population groups (which may be considered geographical allopatric races) was found.     

Use of the lateral line for feeding in two Lake Baikal sculpins

Batrachocottus baicalensis , endemic to Lake Baikal, Russia, has wider lateral line canals than Paracottus kneri , which also inhabits Siberian streams. In quiet water B. baicalensis responded to amphipods at a greater distance than did P. kneri. Batrachocottus baicalensis also moves less often from search positions than does P. kneri . Fish responded to faster moving prey at a greater distance than slower prey. They also responded to a greater distance to prey moving more parallel to the fish's body surface. In an artificial stream B. baicalensis responded only to prey that touched them whilst P. kneri responded to both swimming prey and prey that contacted them. It is argued that B. baicalensis is primarily an ambush predator that is a habitat specialist and P. kneri is a cruising predator that visits many habitats.     

Mercury content in muscles of fish of the Selenga River and lakes of its basin (Russia)

Differences between the muscle mercury contents in fish from lakes Gusinoye and Karasinoye and the Selenga River may indicate an inconsiderable income of mercury in aquatic ecosystems with atmospheric precipitation, along with a more intensive migration of mercury with the riverine flux. The minimal concentration of mercury (less than 0.15 mg/kg, dry weight) has been registered in the muscles of Amur sleeper from Lake Karasinoye and of Baikal omul from Lake Baikal, while the maximal concentration (1.0–2.3 mg/kg, dry weight) has been revealed in the fish caught in the Selenga River delta (in predatory pike, Amur catfish, and perch, as well as in omnivorous roach and ide). The muscle metal content in dace decreased along the downstream direction.     

Phyllodistomum folium (Trematoda: Gorgoderidae) infecting zebra mussels (Dreissena polymorpha) in the Ebro River, Spain

Zebra mussels (Dreissena polymorpha) were first found in the Ebro River (Spain) in Ribaroja reservoir, in the summer of 2001. This paper reports a study to detect parasites in this bivalve species. From September 2003 to August 2004, a total of 1380 zebra mussels were collected and dissected or sectioned in paraffin and haematoxylin and eosin staining. We observed the presence of Phyllodistomum folium (Olfers, 1816) in two hosts (prevalence 0.14%). Sporocysts containing metacercariae were located within the gill lamellae. One of the mussels was collected in January and the other one in July. In both cases the shell length was >2 cm. P. folium had not been previously reported in Spain and D. polymorpha is its only known intermediate host. It represents a new invasive species in this river basin, presumably introduced together with the zebra mussels.