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The pumpkinseed, Lepomis gibbosus, a centrarchid fish native to eastern North America, was introduced into Europe at the end of the 19th century. Lepomis gibbosus now represents one of the most successful of introduced fish species, having spread widely throughout many European countries. In this study, we collected monogenean parasites of L. gibbosus from four sites in the Danube River Basin. We recorded four monogenean species: Gyrodactylus sp., probably acquired in the area of introduction, and Onchocleidus similis, O. dispar and Actinocleidus recurvatus, species introduced together with their host. Onchocleidus similis dominated the parasite community at all sampling sites. Actinocleidus recurvatus has only been reported from southern Europe to date and, therefore, this is the first report of A. recurvatus from Central Europe and the Danube River Basin. We observed high morphological variability in both anchor pairs of A. recurvatus. Only in O. similis was there a positive correlation observed between haptor metric traits and fish host length. Differences in metric traits between native and introduced O. similis populations may reflect a difference in fish host size, the introduced fish host achieving a smaller size than fish from native populations. A detailed analysis of microhabitat distribution indicated a preference for the second gill arch for both dominant species O. similis and A. recurvatus, with dissimilar site segregation.

In this study, we compared the effects of two diets containing different isoflavone concentrations on the isoflavone transfer from feed into milk and on the rumen microbiota in lactating dairy cows. The on-farm experiment was conducted on twelve lactating Czech Fleckvieh x Holstein cows divided into two groups, each with similar mean milk yield. Twice daily, cows were individually fed a diet based on maize silage, meadow hay and supplemental mixture. Control group (CTRL) received the basal diet while the experimental group (EXP) received the basal diet supplemented with 40% soybean isoflavone extract. The average daily isoflavone intake in the EXP group (16 g/day) was twice as high as that in the CTRL group (8.4 g/day, P

Vztah vývojove nestability hrouzka obecneho, abundance a morfologie jeho ektoparazita Paradiplozoon homoion (Monogenea)

Diplozoids are fish ectoparasites with a direct life cycle. Adults live attached to fish gills, using two haptors with four pairs of clamps for attachment. Three planes of symmetry (the individual, haptor and clamp planes) can be identified in adult diplozoids. In this study, the haptor and clamp planes of symmetry are used to study different asymmetries (fluctuating asymmetry FA, directional asymmetry DA, antisymmetry) in the attachment apparatus of Paradiplozoon homoion(Diplozoidae; Monogenea). DA and antisymmetry may be adaptive asymmetries, whereas FA (measured as the random deviation from perfect symmetry in bilateral characters) is suggested as a useful tool for estimating developmental instability. Fifty individuals of P. homoion were collected from 25 gudgeon Gobio gobio. Asymmetries were estimated for nine morphometric traits in the haptor plane and three morphometric traits in the clamp plane on all four pairs of clamps from each individual. FA did not differ between traits on the individual pairs of clamps. However, significant DA was detected for most traits in the clamp plane.

Summary Metazoan parasites were investigated in three non-native fishes (monkey goby Neogobius fluviatilis, bighead goby Neogobius kessleri and round goby Neogobius melanostomus) collected from the former and current main channel of the River Danube and from the River Hron, Slovakia, in November 2003. Thirteen parasite species were identified: Triaenophorus crassus, Diplostomum sp., Tylodelphys clavata, Metorchis xanthosomus, Nicolla skrjabini, Gyrodactylus proterorhini, Pomphorhynchus laevis, Contracoecum sp., Raphidascaris acus, Anguillicola crassus, Unio tumidus, Anodonta anatina and Pseudoanodonta complanata. The maximum parasite diversity was found in N. fluviatilis. Total parasite abundance was significantly higher in N. kessleri, but no significant differences among sampling sites were observed. Pomphorhynchus laevis and glochidia of Anodonta anatina reached 100% prevalence in N. kessleri in the new channel of the Danube and, in general, these species were also the most prevalent parasites in all three goby species. For endoparasites, gobies served mostly as intermediate (digenean, cestodes and nematodes) or paratenic (acantocephalan and nematodes) hosts. All parasite species found are common parasites in the Middle Danube basin. No parasites specific to Neogobius, known from their native populations, were observed.

SUMMARYThe aims of the study were (1) to describe the Dactylogyrus communities living on selected South European Barbus species, (2) to analyse morphometric variability of their attachment and reproductive organs, and (3) to perform molecular phylogenetic analyses, in order to investigate the mode of speciation in Dactylogyrus species parasitizing congeneric hosts. In Bulgaria, Dactylogyrus crivellius, D. dyki and D. petenyi were found on B. balcanicus, and D. dyki on B. cyclolepis. In Spain, Dactylogyrus carpathicus and D. dyki were detected on B. meridionalis. Morphometric analyses of D. dyki revealed significant differences in the attachment and reproductive organs when individuals from different Barbus species were compared. Two monophyletic groups were recognized from the molecular phylogenetic analyses: the first included D. carpathicus and D. crivellius which have large body size and anchors, with a weakly supported basal position of D. malleus from B. barbus; the second included D. dyki and D. petenyi which have small body and anchor sizes. The comparison of host and parasite phylogenies did not indicate the intrahost speciation. Intraspecific molecular variability was found between individuals of D. dyki and D. carpathicus from different Barbus species, suggesting the need for a taxonomic revision for these species.

A female specimen of the nematode Philometroides barbi Moravec, Simkova, Hanzelova, Spakulova et Cakic, 2005, a little-known histozoic parasite of the Mediterranean Barbus meridionalis, was recorded from the fin of its fish host in Bulgaria. Scanning electron microscopical examination, used for the first time in this species, made it possible to determine the character of cephalic papillae (14 papillae arranged in 2 circles) and amphids and confirmed the presence of 4 large caudal lobes. These features distinctly distinguish P. barbi from Philometroides cyprini and other congeners parasitizing European fishes.

Diplozoids (Diplozoidae, Monogenea) are fish ectoparasites with a direct life cycle without intermediate hosts. Their free swimming larva, the oncomiracidium, hatches from eggs, invades a fish host and metamorphoses into a post-oncomiracidial larval stage, the diporpa. Later, two diporpae fuse and live as a pair in cross-copulation during their adult life. An experimental study was designed to investigate the life cycle of Paradiplozoon homoion (Monogenea, Diplozoidae) parasitizing their common fish hosts, gudgeon ( Gobio gobio ). A total of 35 gudgeon parasitized by diplozoids were collected from their natural environment of the Vlara River, Czech Republic, and kept together in tanks with 41 non-parasitized gudgeons reared in a laboratory environment. In total, 100 adult specimens of P. homoion were collected from the Vlara River gudgeon and a new parasite generation was expected to be observed on fish reared in the laboratory environment. Eight days after the first diplozoid eggs appeared on fish gills, the presence of diporpae with one or two pairs of clamps was noted. The appearance of the first juveniles was recorded at the same time as diporpae. Development of P. homoion from egg to sexually mature adult stage took 33 days at a constant temperature of 20 °C. The development of eggs in adults of the second generation was observed 2 days after the first observation of these adults. The behavior of oncomiracidia was also studied and this free swimming stage of diplozoids survived for 22 h in the absence of a host. When host fish were experimentally infected by oncomiracidia, diporpae were found attached to the fish gill apparatus within 2 h of infection.

Morphological analyses of the attachment apparatus (clamps and central hooks) of Paradiplozoon homoion (Bychowsky & Nagibina, 1959) (Diplozoinae, Monogenea) parasitising gills of Gobio gobio (L.) showed a high percentage of abnormally developed parasite specimens. Four different localities in the Vlara River basin, Czech Republic, were investigated for the presence of such abnormal individuals. The highest percentage of abnormalities in the attachment apparatus (over 39%) was recorded in the Vlara River, at Bohuslavice. This study provides a comprehensive classification of these abnormalities with 7 types of abnormalities described and illustrated. Abnormalities of parts of the attachment apparatus that form in the later stage of ontogenetic development were the most frequent, the most frequent types of abnormalities being clamps with abnormal sclerites, and combinations of abnormalities. Abnormalities of the central hooks were also found in our material. The abnormalities found in diplozoids are probably connected with environmental pollution; however, this point requires further investigation.